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"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Hierarchical Configuration Inheritance Pattern: A Complete Guide\n",
"\n",
"## The Problem: Configuration Duplication\n",
"\n",
"### Why Traditional Configuration Management Is Painful\n",
"\n",
"Imagine you're building a microservice that needs to run in multiple environments. Without inheritance patterns, your configuration might look like this:"
]
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"# ❌ Traditional approach - lots of duplication\n",
"traditional_config = {\n",
" \"dev\": {\n",
" \"database\": {\n",
" \"host\": \"dev-db.example.com\",\n",
" \"port\": 5432,\n",
" \"pool_size\": 10,\n",
" \"timeout\": 30,\n",
" \"ssl_mode\": \"prefer\",\n",
" \"retry_attempts\": 3\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"dev-redis.example.com\", \n",
" \"port\": 6379,\n",
" \"timeout\": 10,\n",
" \"pool_size\": 20\n",
" },\n",
" \"logging\": {\n",
" \"level\": \"DEBUG\",\n",
" \"format\": \"detailed\"\n",
" }\n",
" },\n",
" \"staging\": {\n",
" \"database\": {\n",
" \"host\": \"staging-db.example.com\",\n",
" \"port\": 5432, # 🔄 DUPLICATE\n",
" \"pool_size\": 10, # 🔄 DUPLICATE\n",
" \"timeout\": 30, # 🔄 DUPLICATE\n",
" \"ssl_mode\": \"prefer\", # 🔄 DUPLICATE\n",
" \"retry_attempts\": 3 # 🔄 DUPLICATE\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"staging-redis.example.com\",\n",
" \"port\": 6379, # 🔄 DUPLICATE\n",
" \"timeout\": 10, # 🔄 DUPLICATE\n",
" \"pool_size\": 20 # 🔄 DUPLICATE\n",
" },\n",
" \"logging\": {\n",
" \"level\": \"INFO\",\n",
" \"format\": \"detailed\" # 🔄 DUPLICATE\n",
" }\n",
" },\n",
" \"prod\": {\n",
" \"database\": {\n",
" \"host\": \"prod-db.example.com\",\n",
" \"port\": 5432, # 🔄 DUPLICATE\n",
" \"pool_size\": 50, # Different value, but pattern repeats\n",
" \"timeout\": 30, # 🔄 DUPLICATE\n",
" \"ssl_mode\": \"require\", # Different value\n",
" \"retry_attempts\": 3 # 🔄 DUPLICATE\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"prod-redis.example.com\",\n",
" \"port\": 6379, # 🔄 DUPLICATE\n",
" \"timeout\": 10, # 🔄 DUPLICATE\n",
" \"pool_size\": 50 # Different value\n",
" },\n",
" \"logging\": {\n",
" \"level\": \"ERROR\",\n",
" \"format\": \"detailed\" # 🔄 DUPLICATE\n",
" }\n",
" }\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### The Pain Points\n",
"\n",
"1. **🔄 Massive Duplication**: 80% of configuration values are repeated across environments\n",
"2. **🐛 Error Prone**: Change a default port? You must remember to update it in 3+ places\n",
"3. **📈 Scales Poorly**: Adding a new environment means copying and modifying everything\n",
"4. **🔍 Hard to Understand**: What values are defaults vs environment-specific overrides?\n",
"5. **🚀 Maintenance Nightmare**: Updating shared settings requires touching multiple sections\n",
"\n",
"---\n",
"\n",
"## The Solution: Hierarchical Inheritance\n",
"\n",
"### The DRY (Do Not Repeat Yourself) Approach with `_defaults`\n",
"\n",
"The hierarchical pattern solves this by introducing a **`_defaults` section** that defines defaults, which automatically inherit to all environments unless specifically overridden:"
]
},
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"execution_count": 2,
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"source": [
"# ✅ Hierarchical approach - DRY and maintainable\n",
"hierarchical_config = {\n",
" \"_defaults\": {\n",
" # 🎯 Define defaults ONCE\n",
" \"*.database.port\": 5432,\n",
" \"*.database.pool_size\": 10,\n",
" \"*.database.timeout\": 30,\n",
" \"*.database.ssl_mode\": \"prefer\",\n",
" \"*.database.retry_attempts\": 3,\n",
" \"*.redis.port\": 6379,\n",
" \"*.redis.timeout\": 10,\n",
" \"*.redis.pool_size\": 20,\n",
" \"*.logging.format\": \"detailed\"\n",
" },\n",
" \"dev\": {\n",
" \"database\": {\n",
" \"host\": \"dev-db.example.com\"\n",
" # 👆 All other database settings inherited from _defaults\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"dev-redis.example.com\"\n",
" # 👆 All other redis settings inherited from _defaults\n",
" },\n",
" \"logging\": {\n",
" \"level\": \"DEBUG\"\n",
" # 👆 format inherited from _defaults\n",
" }\n",
" },\n",
" \"staging\": {\n",
" \"database\": {\"host\": \"staging-db.example.com\"},\n",
" \"redis\": {\"host\": \"staging-redis.example.com\"},\n",
" \"logging\": {\"level\": \"INFO\"}\n",
" },\n",
" \"prod\": {\n",
" \"database\": {\n",
" \"host\": \"prod-db.example.com\",\n",
" \"pool_size\": 50, # 🎯 Override default for production\n",
" \"ssl_mode\": \"require\" # 🎯 Override default for production\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"prod-redis.example.com\",\n",
" \"pool_size\": 50 # 🎯 Override default for production\n",
" },\n",
" \"logging\": {\"level\": \"ERROR\"}\n",
" }\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"---\n",
"\n",
"## Core Concepts\n",
"\n",
"### Setup"
]
},
{
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"execution_count": 3,
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"source": [
"import json\n",
"from rich import print as rprint\n",
"from configcraft.api import DEFAULTS, apply_inheritance, inherit_value\n",
"\n",
"def jprint(data: dict):\n",
" \"\"\"Pretty print JSON data\"\"\"\n",
" rprint(json.dumps(data, indent=2))"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 1. The `_defaults` Section\n",
"\n",
"The `_defaults` section is a **meta-configuration** that defines inheritable defaults:"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {
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"source": [
"config = {\n",
" \"_defaults\": {\n",
" \"*.timeout\": 30, # Apply to all environments\n",
" \"*.retry_attempts\": 3 # Apply to all environments \n",
" },\n",
" \"dev\": {\"host\": \"dev.com\"},\n",
" \"prod\": {\"host\": \"prod.com\"}\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 2. JSON Path Patterns\n",
"\n",
"JSON paths specify **where** default values should be applied:\n",
"\n",
"| Pattern | Meaning | Example |\n",
"|---------|---------|---------|\n",
"| `*.field` | All top-level keys | `*.timeout` → applies to dev.timeout, prod.timeout |\n",
"| `env.field` | Specific environment | `dev.timeout` → applies only to dev.timeout |\n",
"| `*.service.field` | Nested paths | `*.db.port` → applies to dev.db.port, prod.db.port |\n",
"| `*.services.*.field` | Multiple wildcards | `*.apps.*.memory` → all apps in all environments |\n",
"\n",
"### 3. Non-Destructive Inheritance\n",
"\n",
"**Key Principle**: Default values are only applied when the target key **doesn't already exist**."
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {
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"source": [
"config = {\n",
" \"_defaults\": {\"*.memory\": 2},\n",
" \"dev\": {}, # ✅ Will get memory: 2\n",
" \"prod\": {\"memory\": 8} # ✅ Keeps existing memory: 8\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"---\n",
"\n",
"## Basic Usage\n",
"\n",
"### Example 1: Simple Environment Defaults"
]
},
{
"cell_type": "code",
"execution_count": 6,
"metadata": {
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"source": [
"# Define configuration with default values\n",
"config_data = {\n",
" \"_defaults\": {\n",
" \"*.memory\": 2, # Default memory for all environments\n",
" \"*.cpu\": 1 # Default CPU for all environments\n",
" },\n",
" \"dev\": {}, # Empty - will inherit all defaults\n",
" \"staging\": {\n",
" \"memory\": 4 # Override memory, inherit CPU\n",
" },\n",
" \"prod\": {\n",
" \"memory\": 8, # Override memory\n",
" \"cpu\": 4 # Override CPU\n",
" }\n",
"}\n",
"\n",
"# Apply inheritance\n",
"apply_inheritance(config_data)\n",
"jprint(config_data)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Example 2: Nested Configuration Inheritance"
]
},
{
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],
"source": [
"config_data = {\n",
" \"_defaults\": {\n",
" \"*.database.port\": 5432,\n",
" \"*.database.pool_size\": 10,\n",
" \"*.cache.ttl\": 3600\n",
" },\n",
" \"dev\": {\n",
" \"database\": {\n",
" \"host\": \"localhost\"\n",
" # port and pool_size will be inherited\n",
" },\n",
" \"cache\": {\n",
" \"host\": \"localhost\"\n",
" # ttl will be inherited\n",
" }\n",
" },\n",
" \"prod\": {\n",
" \"database\": {\n",
" \"host\": \"prod-db.com\",\n",
" \"pool_size\": 50 # Override default\n",
" # port will be inherited\n",
" },\n",
" \"cache\": {\n",
" \"host\": \"prod-cache.com\",\n",
" \"ttl\": 7200 # Override default\n",
" }\n",
" }\n",
"}\n",
"\n",
"apply_inheritance(config_data)\n",
"jprint(config_data)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Path Execution Order: Exception-Then-Default Pattern\n",
"\n",
"🚨 **Critical Behavior**: Within a single `_defaults` section, paths are processed **from top to bottom**. If multiple paths affect the same node, the **earlier path wins** due to `setdefault` behavior.\n",
"\n",
"This enables powerful **exception-then-default** patterns:"
]
},
{
"cell_type": "code",
"execution_count": 8,
"metadata": {},
"outputs": [
{
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],
"source": [
"# Example: CPU allocation with exceptions\n",
"config_data = {\n",
" \"_defaults\": {\n",
" # ⚠️ ORDER MATTERS! Exception MUST come first\n",
" \"*.servers.high_memory.cpu\": 8, # Exception: high_memory gets 8 CPU\n",
" \"*.servers.*.cpu\": 2 # Default: all other servers get 2 CPU\n",
" },\n",
" \"dev\": {\n",
" \"servers\": {\n",
" \"web\": {}, # Gets cpu=2 (default rule)\n",
" \"high_memory\": {}, # Gets cpu=8 (exception rule)\n",
" \"worker\": {} # Gets cpu=2 (default rule)\n",
" }\n",
" },\n",
" \"prod\": {\n",
" \"servers\": {\n",
" \"web\": {}, # Gets cpu=2 (default rule) \n",
" \"high_memory\": {}, # Gets cpu=8 (exception rule)\n",
" \"database\": {\"cpu\": 16} # Keeps cpu=16 (existing value)\n",
" }\n",
" }\n",
"}\n",
"\n",
"apply_inheritance(config_data)\n",
"jprint(config_data)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"**❌ Wrong Order Example:**"
]
},
{
"cell_type": "code",
"execution_count": 9,
"metadata": {},
"outputs": [],
"source": [
"# This WON'T work as expected - wrong order!\n",
"config_data = {\n",
" \"_defaults\": {\n",
" \"*.servers.*.cpu\": 2, # 🚫 Default comes first\n",
" \"*.servers.high_memory.cpu\": 8 # 🚫 Exception comes second - TOO LATE!\n",
" },\n",
" \"dev\": {\n",
" \"servers\": {\n",
" \"high_memory\": {} # Gets cpu=2 (not 8!) because default ran first\n",
" }\n",
" }\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"**✅ Design Logic:**\n",
"\n",
"The child-override-parent behavior follows the inheritance processing order:\n",
"1. **Recursive Processing**: Children are processed before parents\n",
"2. **Child `_defaults`** runs first → sets `dev.services.web.memory = 2048`\n",
"3. **Parent `_defaults`** runs later → tries to set `dev.services.web.memory = 1024`, but key exists → **ignored**\n",
"4. **Result**: Child settings take precedence, parent fills gaps\n",
"\n",
"**🎯 Real-World Use Cases:**\n",
"\n",
"1. **Exception Handling**: Set specific values before wildcards\n",
"2. **Environment Overrides**: Child environments override global defaults \n",
"3. **Service Specialization**: Specific services override category defaults\n",
"4. **Progressive Refinement**: Broad defaults → environment defaults → service specifics\n",
"\n",
"### Working with Lists of Objects\n",
"\n",
"The inheritance pattern works seamlessly with **lists of dictionaries**:"
]
},
{
"cell_type": "code",
"execution_count": 10,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"{\n",
" \"dev\": {\n",
" \"services\": {\n",
" \"web\": {\n",
" \"memory\": 2048,\n",
" \"log_level\": \"DEBUG\",\n",
" \"timeout\": 30\n",
" },\n",
" \"worker\": {\n",
" \"memory\": 4096,\n",
" \"log_level\": \"DEBUG\",\n",
" \"timeout\": 30\n",
" }\n",
" }\n",
" },\n",
" \"prod\": {\n",
" \"services\": {\n",
" \"web\": {\n",
" \"memory\": 1024,\n",
" \"timeout\": 30\n",
" },\n",
" \"worker\": {\n",
" \"memory\": 1024,\n",
" \"timeout\": 30\n",
" }\n",
" }\n",
" }\n",
"}\n",
"\n"
],
"text/plain": [
"\u001b[1m{\u001b[0m\n",
" \u001b[32m\"dev\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"services\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"web\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m2048\u001b[0m,\n",
" \u001b[32m\"log_level\"\u001b[0m: \u001b[32m\"DEBUG\"\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"worker\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m4096\u001b[0m,\n",
" \u001b[32m\"log_level\"\u001b[0m: \u001b[32m\"DEBUG\"\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"prod\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"services\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"web\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m1024\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"worker\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m1024\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
"\u001b[1m}\u001b[0m\n"
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"# Example: Nested inheritance hierarchy\n",
"config_data = {\n",
" \"_defaults\": {\n",
" \"*.services.*.memory\": 1024, # Parent default: 1GB for all services\n",
" \"*.services.*.timeout\": 30 # Parent default: 30s timeout\n",
" },\n",
" \"dev\": {\n",
" \"services\": {\n",
" \"_defaults\": {\n",
" \"*.memory\": 2048, # Child override: dev services get 2GB \n",
" \"*.log_level\": \"DEBUG\" # Child addition: dev-specific setting\n",
" },\n",
" \"web\": {}, # Gets memory=2048 (child), timeout=30 (parent), log_level=DEBUG (child)\n",
" \"worker\": {\"memory\": 4096} # Gets memory=4096 (explicit), timeout=30 (parent), log_level=DEBUG (child)\n",
" }\n",
" },\n",
" \"prod\": {\n",
" \"services\": {\n",
" \"web\": {}, # Gets memory=1024 (parent), timeout=30 (parent)\n",
" \"worker\": {} # Gets memory=1024 (parent), timeout=30 (parent)\n",
" }\n",
" }\n",
"}\n",
"\n",
"apply_inheritance(config_data)\n",
"jprint(config_data)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"**✅ Design Logic:**\n",
"\n",
"The child-override-parent behavior follows the inheritance processing order:\n",
"1. **Recursive Processing**: Children are processed before parents\n",
"2. **Child `_defaults`** runs first → sets `dev.services.web.memory = 2048`\n",
"3. **Parent `_defaults`** runs later → tries to set `dev.services.web.memory = 1024`, but key exists → **ignored**\n",
"4. **Result**: Child settings take precedence, parent fills gaps\n",
"\n",
"**🎯 Real-World Use Cases:**\n",
"\n",
"1. **Exception Handling**: Set specific values before wildcards\n",
"2. **Environment Overrides**: Child environments override global defaults \n",
"3. **Service Specialization**: Specific services override category defaults\n",
"4. **Progressive Refinement**: Broad defaults → environment defaults → service specifics\n",
"\n",
"### Working with Lists of Objects\n",
"\n",
"The inheritance pattern works seamlessly with **lists of dictionaries**:"
]
},
{
"cell_type": "code",
"execution_count": 11,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"{\n",
" \"dev\": {\n",
" \"databases\": [\n",
" {\n",
" \"host\": \"dev-primary.com\",\n",
" \"type\": \"primary\",\n",
" \"port\": 5432,\n",
" \"timeout\": 30\n",
" },\n",
" {\n",
" \"host\": \"dev-replica.com\",\n",
" \"type\": \"replica\",\n",
" \"port\": 5432,\n",
" \"timeout\": 30\n",
" }\n",
" ]\n",
" },\n",
" \"prod\": {\n",
" \"databases\": [\n",
" {\n",
" \"host\": \"prod-primary.com\",\n",
" \"type\": \"primary\",\n",
" \"port\": 5432,\n",
" \"timeout\": 30\n",
" },\n",
" {\n",
" \"host\": \"prod-replica.com\",\n",
" \"type\": \"replica\",\n",
" \"port\": 5433,\n",
" \"timeout\": 30\n",
" }\n",
" ]\n",
" }\n",
"}\n",
"\n"
],
"text/plain": [
"\u001b[1m{\u001b[0m\n",
" \u001b[32m\"dev\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"databases\"\u001b[0m: \u001b[1m[\u001b[0m\n",
" \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"dev-primary.com\"\u001b[0m,\n",
" \u001b[32m\"type\"\u001b[0m: \u001b[32m\"primary\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m5432\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"dev-replica.com\"\u001b[0m,\n",
" \u001b[32m\"type\"\u001b[0m: \u001b[32m\"replica\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m5432\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m]\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"prod\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"databases\"\u001b[0m: \u001b[1m[\u001b[0m\n",
" \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"prod-primary.com\"\u001b[0m,\n",
" \u001b[32m\"type\"\u001b[0m: \u001b[32m\"primary\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m5432\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"prod-replica.com\"\u001b[0m,\n",
" \u001b[32m\"type\"\u001b[0m: \u001b[32m\"replica\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m5433\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m]\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
"\u001b[1m}\u001b[0m\n"
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"config_data = {\n",
" \"_defaults\": {\n",
" \"*.databases.port\": 5432, # Apply to ALL database objects\n",
" \"*.databases.timeout\": 30 # Apply to ALL database objects\n",
" },\n",
" \"dev\": {\n",
" \"databases\": [\n",
" {\"host\": \"dev-primary.com\", \"type\": \"primary\"},\n",
" {\"host\": \"dev-replica.com\", \"type\": \"replica\"}\n",
" # Both will inherit port and timeout\n",
" ]\n",
" },\n",
" \"prod\": {\n",
" \"databases\": [\n",
" {\"host\": \"prod-primary.com\", \"type\": \"primary\"},\n",
" {\"host\": \"prod-replica.com\", \"type\": \"replica\", \"port\": 5433}\n",
" # First inherits port, second keeps override\n",
" ]\n",
" }\n",
"}\n",
"\n",
"apply_inheritance(config_data)\n",
"jprint(config_data)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Specific Environment Targeting\n",
"\n",
"Sometimes you want to set defaults for **specific environments only**:"
]
},
{
"cell_type": "code",
"execution_count": 12,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"{\n",
" \"dev\": {\n",
" \"web\": {\n",
" \"memory\": 4\n",
" },\n",
" \"worker\": {\n",
" \"memory\": 4\n",
" },\n",
" \"log_level\": \"INFO\"\n",
" },\n",
" \"staging\": {\n",
" \"web\": {},\n",
" \"worker\": {\n",
" \"memory\": 8\n",
" },\n",
" \"log_level\": \"INFO\"\n",
" },\n",
" \"prod\": {\n",
" \"web\": {\n",
" \"memory\": 16\n",
" },\n",
" \"worker\": {\n",
" \"memory\": 32\n",
" },\n",
" \"log_level\": \"INFO\"\n",
" }\n",
"}\n",
"\n"
],
"text/plain": [
"\u001b[1m{\u001b[0m\n",
" \u001b[32m\"dev\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"web\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m4\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"worker\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m4\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"log_level\"\u001b[0m: \u001b[32m\"INFO\"\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"staging\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"web\"\u001b[0m: \u001b[1m{\u001b[0m\u001b[1m}\u001b[0m,\n",
" \u001b[32m\"worker\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m8\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"log_level\"\u001b[0m: \u001b[32m\"INFO\"\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"prod\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"web\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m16\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"worker\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m32\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"log_level\"\u001b[0m: \u001b[32m\"INFO\"\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
"\u001b[1m}\u001b[0m\n"
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"config_data = {\n",
" \"_defaults\": {\n",
" \"dev.*.memory\": 4, # Only dev environments get 4GB\n",
" \"prod.*.memory\": 16, # Only prod environments get 16GB\n",
" \"*.log_level\": \"INFO\" # All environments get INFO logging\n",
" },\n",
" \"dev\": {\n",
" \"web\": {}, # Will get memory: 4, log_level: \"INFO\"\n",
" \"worker\": {} # Will get memory: 4, log_level: \"INFO\"\n",
" },\n",
" \"staging\": {\n",
" \"web\": {}, # Will get log_level: \"INFO\" only\n",
" \"worker\": {\"memory\": 8} # Custom memory, inherits log_level\n",
" },\n",
" \"prod\": {\n",
" \"web\": {}, # Will get memory: 16, log_level: \"INFO\"\n",
" \"worker\": {\"memory\": 32} # Custom memory, inherits log_level\n",
" }\n",
"}\n",
"\n",
"apply_inheritance(config_data)\n",
"jprint(config_data)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Nested `_defaults` Sections (Advanced Override)\n",
"\n",
"You can have **multiple levels** of `_defaults` sections for fine-grained control:"
]
},
{
"cell_type": "code",
"execution_count": 13,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"{\n",
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" \"worker\": {\n",
" \"memory\": 8,\n",
" \"debug\": true,\n",
" \"log_level\": \"INFO\"\n",
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" },\n",
" \"prod\": {\n",
" \"web\": {\n",
" \"log_level\": \"ERROR\",\n",
" \"memory\": 2\n",
" },\n",
" \"worker\": {\n",
" \"log_level\": \"ERROR\",\n",
" \"memory\": 2\n",
" }\n",
" }\n",
"}\n",
"\n"
],
"text/plain": [
"\u001b[1m{\u001b[0m\n",
" \u001b[32m\"dev\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"web\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m4\u001b[0m,\n",
" \u001b[32m\"debug\"\u001b[0m: true,\n",
" \u001b[32m\"log_level\"\u001b[0m: \u001b[32m\"INFO\"\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"worker\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m8\u001b[0m,\n",
" \u001b[32m\"debug\"\u001b[0m: true,\n",
" \u001b[32m\"log_level\"\u001b[0m: \u001b[32m\"INFO\"\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"prod\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"web\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"log_level\"\u001b[0m: \u001b[32m\"ERROR\"\u001b[0m,\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m2\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"worker\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"log_level\"\u001b[0m: \u001b[32m\"ERROR\"\u001b[0m,\n",
" \u001b[32m\"memory\"\u001b[0m: \u001b[1;36m2\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
"\u001b[1m}\u001b[0m\n"
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"config_data = {\n",
" \"_defaults\": {\n",
" \"*.*.memory\": 2, # Global default: 2GB for all services\n",
" \"*.*.log_level\": \"INFO\" # Global default: INFO logging\n",
" },\n",
" \"dev\": {\n",
" \"_defaults\": {\n",
" \"*.memory\": 4, # Dev-specific: Override memory to 4GB\n",
" \"*.debug\": True # Dev-specific: Enable debug mode\n",
" },\n",
" \"web\": {}, # Gets: memory=4, log_level=\"INFO\", debug=True\n",
" \"worker\": {\"memory\": 8} # Gets: memory=8 (override), log_level=\"INFO\", debug=True\n",
" },\n",
" \"prod\": {\n",
" \"_defaults\": {\n",
" \"*.log_level\": \"ERROR\" # Prod-specific: Only log errors\n",
" },\n",
" \"web\": {}, # Gets: memory=2, log_level=\"ERROR\"\n",
" \"worker\": {} # Gets: memory=2, log_level=\"ERROR\"\n",
" }\n",
"}\n",
"\n",
"apply_inheritance(config_data)\n",
"jprint(config_data)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"---\n",
"\n",
"## Understanding the API\n",
"\n",
"The hierarchical configuration pattern provides two main functions with different purposes:\n",
"\n",
"### `inherit_value()` - Low-Level Inheritance\n",
"\n",
"This is the **core building block** that applies a single shared value to its target location(s):"
]
},
{
"cell_type": "code",
"execution_count": 14,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"{\n",
" \"dev\": {\n",
" \"host\": \"dev.com\",\n",
" \"port\": 3000\n",
" },\n",
" \"prod\": {\n",
" \"host\": \"prod.com\",\n",
" \"port\": 8080\n",
" }\n",
"}\n",
"\n"
],
"text/plain": [
"\u001b[1m{\u001b[0m\n",
" \u001b[32m\"dev\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"dev.com\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m3000\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"prod\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"prod.com\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m8080\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
"\u001b[1m}\u001b[0m\n"
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"from configcraft.api import inherit_value\n",
"\n",
"# Example: Set a default value only where it doesn't exist\n",
"data = {\n",
" \"dev\": {\"host\": \"dev.com\"},\n",
" \"prod\": {\"host\": \"prod.com\", \"port\": 8080} # Already has port\n",
"}\n",
"\n",
"# Apply default port to all environments\n",
"inherit_value(path=\"*.port\", value=3000, data=data)\n",
"\n",
"jprint(data)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### `apply_inheritance()` - High-Level Configuration Processing\n",
"\n",
"This is the **main entry point** that processes entire configuration structures with `_defaults` sections:"
]
},
{
"cell_type": "code",
"execution_count": 15,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"{\n",
" \"dev\": {\n",
" \"host\": \"dev.com\",\n",
" \"port\": 3000,\n",
" \"timeout\": 30\n",
" },\n",
" \"prod\": {\n",
" \"host\": \"prod.com\",\n",
" \"port\": 8080,\n",
" \"timeout\": 30\n",
" }\n",
"}\n",
"\n"
],
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" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"dev.com\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m3000\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"prod\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"prod.com\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m8080\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
"\u001b[1m}\u001b[0m\n"
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"# Example: Process a complete configuration\n",
"config = {\n",
" \"_defaults\": {\n",
" \"*.port\": 3000,\n",
" \"*.timeout\": 30\n",
" },\n",
" \"dev\": {\"host\": \"dev.com\"},\n",
" \"prod\": {\"host\": \"prod.com\", \"port\": 8080}\n",
"}\n",
"\n",
"apply_inheritance(config)\n",
"\n",
"jprint(config)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"**When to use `apply_inheritance()`:**\n",
"- ✅ Processing complete configuration files\n",
"- ✅ Standard use case with `_defaults` sections\n",
"- ✅ Production configuration management\n",
"- ✅ Most common use case - start here!\n",
"\n",
"---\n",
"\n",
"## Real-World Examples\n",
"\n",
"### Example 1: Microservice Configuration"
]
},
{
"cell_type": "code",
"execution_count": 16,
"metadata": {},
"outputs": [],
"source": [
"# Real-world microservice configuration\n",
"microservice_config = {\n",
" \"_defaults\": {\n",
" # Database defaults\n",
" \"*.database.pool_size\": 10,\n",
" \"*.database.timeout\": 30,\n",
" \"*.database.retry_attempts\": 3,\n",
" \n",
" # Redis defaults \n",
" \"*.redis.timeout\": 5,\n",
" \"*.redis.pool_size\": 20,\n",
" \n",
" # Logging defaults\n",
" \"*.logging.format\": \"json\",\n",
" \"*.logging.level\": \"INFO\",\n",
" \n",
" # HTTP defaults\n",
" \"*.http.timeout\": 10,\n",
" \"*.http.retry_attempts\": 3\n",
" },\n",
" \"local\": {\n",
" \"database\": {\n",
" \"host\": \"localhost\",\n",
" \"port\": 5432,\n",
" \"name\": \"myapp_dev\"\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"localhost\", \n",
" \"port\": 6379\n",
" },\n",
" \"logging\": {\n",
" \"level\": \"DEBUG\" # Override for local development\n",
" },\n",
" \"http\": {\n",
" \"base_url\": \"http://localhost:8000\"\n",
" }\n",
" },\n",
" \"staging\": {\n",
" \"database\": {\n",
" \"host\": \"staging-db.company.com\",\n",
" \"port\": 5432,\n",
" \"name\": \"myapp_staging\",\n",
" \"pool_size\": 20 # Override for staging load\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"staging-redis.company.com\",\n",
" \"port\": 6379\n",
" },\n",
" \"logging\": {},\n",
" \"http\": {\n",
" \"base_url\": \"https://staging-api.company.com\"\n",
" }\n",
" },\n",
" \"production\": {\n",
" \"database\": {\n",
" \"host\": \"prod-db.company.com\",\n",
" \"port\": 5432,\n",
" \"name\": \"myapp_prod\",\n",
" \"pool_size\": 50, # Production needs more connections\n",
" \"timeout\": 60 # Production can wait longer\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"prod-redis.company.com\",\n",
" \"port\": 6379,\n",
" \"pool_size\": 100 # Production needs larger pool\n",
" },\n",
" \"logging\": {\n",
" \"level\": \"ERROR\" # Production only logs errors\n",
" },\n",
" \"http\": {\n",
" \"base_url\": \"https://api.company.com\",\n",
" \"timeout\": 30 # Production can wait longer\n",
" }\n",
" }\n",
"}\n",
"\n",
"apply_inheritance(microservice_config)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"After processing, each environment gets:\n",
"- ✅ All the appropriate defaults from `_defaults`\n",
"- ✅ Environment-specific host/URL configurations \n",
"- ✅ Performance tuning overrides where needed\n",
"- ✅ No duplication of common settings"
]
},
{
"cell_type": "code",
"execution_count": 17,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"{\n",
" \"local\": {\n",
" \"database\": {\n",
" \"host\": \"localhost\",\n",
" \"port\": 5432,\n",
" \"name\": \"myapp_dev\",\n",
" \"pool_size\": 10,\n",
" \"timeout\": 30,\n",
" \"retry_attempts\": 3\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"localhost\",\n",
" \"port\": 6379,\n",
" \"timeout\": 5,\n",
" \"pool_size\": 20\n",
" },\n",
" \"logging\": {\n",
" \"level\": \"DEBUG\",\n",
" \"format\": \"json\"\n",
" },\n",
" \"http\": {\n",
" \"base_url\": \"http://localhost:8000\",\n",
" \"timeout\": 10,\n",
" \"retry_attempts\": 3\n",
" }\n",
" },\n",
" \"staging\": {\n",
" \"database\": {\n",
" \"host\": \"staging-db.company.com\",\n",
" \"port\": 5432,\n",
" \"name\": \"myapp_staging\",\n",
" \"pool_size\": 20,\n",
" \"timeout\": 30,\n",
" \"retry_attempts\": 3\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"staging-redis.company.com\",\n",
" \"port\": 6379,\n",
" \"timeout\": 5,\n",
" \"pool_size\": 20\n",
" },\n",
" \"logging\": {\n",
" \"format\": \"json\",\n",
" \"level\": \"INFO\"\n",
" },\n",
" \"http\": {\n",
" \"base_url\": \"https://staging-api.company.com\",\n",
" \"timeout\": 10,\n",
" \"retry_attempts\": 3\n",
" }\n",
" },\n",
" \"production\": {\n",
" \"database\": {\n",
" \"host\": \"prod-db.company.com\",\n",
" \"port\": 5432,\n",
" \"name\": \"myapp_prod\",\n",
" \"pool_size\": 50,\n",
" \"timeout\": 60,\n",
" \"retry_attempts\": 3\n",
" },\n",
" \"redis\": {\n",
" \"host\": \"prod-redis.company.com\",\n",
" \"port\": 6379,\n",
" \"pool_size\": 100,\n",
" \"timeout\": 5\n",
" },\n",
" \"logging\": {\n",
" \"level\": \"ERROR\",\n",
" \"format\": \"json\"\n",
" },\n",
" \"http\": {\n",
" \"base_url\": \"https://api.company.com\",\n",
" \"timeout\": 30,\n",
" \"retry_attempts\": 3\n",
" }\n",
" }\n",
"}\n",
"\n"
],
"text/plain": [
"\u001b[1m{\u001b[0m\n",
" \u001b[32m\"local\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"database\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"localhost\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m5432\u001b[0m,\n",
" \u001b[32m\"name\"\u001b[0m: \u001b[32m\"myapp_dev\"\u001b[0m,\n",
" \u001b[32m\"pool_size\"\u001b[0m: \u001b[1;36m10\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m,\n",
" \u001b[32m\"retry_attempts\"\u001b[0m: \u001b[1;36m3\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"redis\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"localhost\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m6379\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m5\u001b[0m,\n",
" \u001b[32m\"pool_size\"\u001b[0m: \u001b[1;36m20\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"logging\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"level\"\u001b[0m: \u001b[32m\"DEBUG\"\u001b[0m,\n",
" \u001b[32m\"format\"\u001b[0m: \u001b[32m\"json\"\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"http\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"base_url\"\u001b[0m: \u001b[32m\"http://localhost:8000\"\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m10\u001b[0m,\n",
" \u001b[32m\"retry_attempts\"\u001b[0m: \u001b[1;36m3\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"staging\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"database\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"staging-db.company.com\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m5432\u001b[0m,\n",
" \u001b[32m\"name\"\u001b[0m: \u001b[32m\"myapp_staging\"\u001b[0m,\n",
" \u001b[32m\"pool_size\"\u001b[0m: \u001b[1;36m20\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m,\n",
" \u001b[32m\"retry_attempts\"\u001b[0m: \u001b[1;36m3\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"redis\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"staging-redis.company.com\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m6379\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m5\u001b[0m,\n",
" \u001b[32m\"pool_size\"\u001b[0m: \u001b[1;36m20\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"logging\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"format\"\u001b[0m: \u001b[32m\"json\"\u001b[0m,\n",
" \u001b[32m\"level\"\u001b[0m: \u001b[32m\"INFO\"\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"http\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"base_url\"\u001b[0m: \u001b[32m\"https://staging-api.company.com\"\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m10\u001b[0m,\n",
" \u001b[32m\"retry_attempts\"\u001b[0m: \u001b[1;36m3\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"production\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"database\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"prod-db.company.com\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m5432\u001b[0m,\n",
" \u001b[32m\"name\"\u001b[0m: \u001b[32m\"myapp_prod\"\u001b[0m,\n",
" \u001b[32m\"pool_size\"\u001b[0m: \u001b[1;36m50\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m60\u001b[0m,\n",
" \u001b[32m\"retry_attempts\"\u001b[0m: \u001b[1;36m3\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"redis\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"host\"\u001b[0m: \u001b[32m\"prod-redis.company.com\"\u001b[0m,\n",
" \u001b[32m\"port\"\u001b[0m: \u001b[1;36m6379\u001b[0m,\n",
" \u001b[32m\"pool_size\"\u001b[0m: \u001b[1;36m100\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m5\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"logging\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"level\"\u001b[0m: \u001b[32m\"ERROR\"\u001b[0m,\n",
" \u001b[32m\"format\"\u001b[0m: \u001b[32m\"json\"\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"http\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"base_url\"\u001b[0m: \u001b[32m\"https://api.company.com\"\u001b[0m,\n",
" \u001b[32m\"timeout\"\u001b[0m: \u001b[1;36m30\u001b[0m,\n",
" \u001b[32m\"retry_attempts\"\u001b[0m: \u001b[1;36m3\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
"\u001b[1m}\u001b[0m\n"
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"jprint(microservice_config)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Example 2: Multi-Tenant SaaS Configuration"
]
},
{
"cell_type": "code",
"execution_count": 18,
"metadata": {},
"outputs": [],
"source": [
"# SaaS application with multiple tenants\n",
"saas_config = {\n",
" \"_defaults\": {\n",
" # Default resource limits\n",
" \"*.tenants.*.cpu_limit\": 1,\n",
" \"*.tenants.*.memory_limit\": 2, \n",
" \"*.tenants.*.storage_limit\": 10,\n",
" \n",
" # Default feature flags\n",
" \"*.tenants.*.features.analytics\": True,\n",
" \"*.tenants.*.features.api_access\": True,\n",
" \"*.tenants.*.features.custom_domain\": False,\n",
" \n",
" # Default billing\n",
" \"*.tenants.*.billing.plan\": \"basic\",\n",
" \"*.tenants.*.billing.trial_days\": 14\n",
" },\n",
" \"dev\": {\n",
" \"tenants\": {\n",
" \"test_tenant\": {\n",
" \"name\": \"Test Company\",\n",
" # Gets all defaults\n",
" \"features\": {},\n",
" \"billing\": {}\n",
" }\n",
" }\n",
" },\n",
" \"prod\": {\n",
" \"tenants\": {\n",
" \"startup_co\": {\n",
" \"name\": \"Startup Co\",\n",
" \"billing\": {\"plan\": \"startup\"}, # Override plan\n",
" # Other defaults inherited\n",
" \"features\": {},\n",
" \"billing\": {}\n",
" },\n",
" \"enterprise_corp\": {\n",
" \"name\": \"Enterprise Corp\", \n",
" \"cpu_limit\": 8, # Enterprise gets more resources\n",
" \"memory_limit\": 16,\n",
" \"storage_limit\": 1000,\n",
" \"features\": {\n",
" \"custom_domain\": True, # Enterprise feature\n",
" \"sso\": True # Additional enterprise feature\n",
" },\n",
" \"billing\": {\n",
" \"plan\": \"enterprise\",\n",
" \"trial_days\": 30 # Longer trial\n",
" }\n",
" }\n",
" }\n",
" }\n",
"}\n",
"\n",
"apply_inheritance(saas_config)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"This pattern allows you to:\n",
"- 🎯 Set sensible defaults for all tenants\n",
"- 🚀 Quickly onboard new tenants with minimal configuration\n",
"- 💰 Easily implement tiered pricing with resource overrides\n",
"- 🔧 Maintain consistent feature flags across environments"
]
},
{
"cell_type": "code",
"execution_count": 19,
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"{\n",
" \"dev\": {\n",
" \"tenants\": {\n",
" \"test_tenant\": {\n",
" \"name\": \"Test Company\",\n",
" \"features\": {\n",
" \"analytics\": true,\n",
" \"api_access\": true,\n",
" \"custom_domain\": false\n",
" },\n",
" \"billing\": {\n",
" \"plan\": \"basic\",\n",
" \"trial_days\": 14\n",
" },\n",
" \"cpu_limit\": 1,\n",
" \"memory_limit\": 2,\n",
" \"storage_limit\": 10\n",
" }\n",
" }\n",
" },\n",
" \"prod\": {\n",
" \"tenants\": {\n",
" \"startup_co\": {\n",
" \"name\": \"Startup Co\",\n",
" \"billing\": {\n",
" \"plan\": \"basic\",\n",
" \"trial_days\": 14\n",
" },\n",
" \"features\": {\n",
" \"analytics\": true,\n",
" \"api_access\": true,\n",
" \"custom_domain\": false\n",
" },\n",
" \"cpu_limit\": 1,\n",
" \"memory_limit\": 2,\n",
" \"storage_limit\": 10\n",
" },\n",
" \"enterprise_corp\": {\n",
" \"name\": \"Enterprise Corp\",\n",
" \"cpu_limit\": 8,\n",
" \"memory_limit\": 16,\n",
" \"storage_limit\": 1000,\n",
" \"features\": {\n",
" \"custom_domain\": true,\n",
" \"sso\": true,\n",
" \"analytics\": true,\n",
" \"api_access\": true\n",
" },\n",
" \"billing\": {\n",
" \"plan\": \"enterprise\",\n",
" \"trial_days\": 30\n",
" }\n",
" }\n",
" }\n",
" }\n",
"}\n",
"\n"
],
"text/plain": [
"\u001b[1m{\u001b[0m\n",
" \u001b[32m\"dev\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"tenants\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"test_tenant\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"name\"\u001b[0m: \u001b[32m\"Test Company\"\u001b[0m,\n",
" \u001b[32m\"features\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"analytics\"\u001b[0m: true,\n",
" \u001b[32m\"api_access\"\u001b[0m: true,\n",
" \u001b[32m\"custom_domain\"\u001b[0m: false\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"billing\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"plan\"\u001b[0m: \u001b[32m\"basic\"\u001b[0m,\n",
" \u001b[32m\"trial_days\"\u001b[0m: \u001b[1;36m14\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"cpu_limit\"\u001b[0m: \u001b[1;36m1\u001b[0m,\n",
" \u001b[32m\"memory_limit\"\u001b[0m: \u001b[1;36m2\u001b[0m,\n",
" \u001b[32m\"storage_limit\"\u001b[0m: \u001b[1;36m10\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"prod\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"tenants\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"startup_co\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"name\"\u001b[0m: \u001b[32m\"Startup Co\"\u001b[0m,\n",
" \u001b[32m\"billing\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"plan\"\u001b[0m: \u001b[32m\"basic\"\u001b[0m,\n",
" \u001b[32m\"trial_days\"\u001b[0m: \u001b[1;36m14\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"features\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"analytics\"\u001b[0m: true,\n",
" \u001b[32m\"api_access\"\u001b[0m: true,\n",
" \u001b[32m\"custom_domain\"\u001b[0m: false\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"cpu_limit\"\u001b[0m: \u001b[1;36m1\u001b[0m,\n",
" \u001b[32m\"memory_limit\"\u001b[0m: \u001b[1;36m2\u001b[0m,\n",
" \u001b[32m\"storage_limit\"\u001b[0m: \u001b[1;36m10\u001b[0m\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"enterprise_corp\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"name\"\u001b[0m: \u001b[32m\"Enterprise Corp\"\u001b[0m,\n",
" \u001b[32m\"cpu_limit\"\u001b[0m: \u001b[1;36m8\u001b[0m,\n",
" \u001b[32m\"memory_limit\"\u001b[0m: \u001b[1;36m16\u001b[0m,\n",
" \u001b[32m\"storage_limit\"\u001b[0m: \u001b[1;36m1000\u001b[0m,\n",
" \u001b[32m\"features\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"custom_domain\"\u001b[0m: true,\n",
" \u001b[32m\"sso\"\u001b[0m: true,\n",
" \u001b[32m\"analytics\"\u001b[0m: true,\n",
" \u001b[32m\"api_access\"\u001b[0m: true\n",
" \u001b[1m}\u001b[0m,\n",
" \u001b[32m\"billing\"\u001b[0m: \u001b[1m{\u001b[0m\n",
" \u001b[32m\"plan\"\u001b[0m: \u001b[32m\"enterprise\"\u001b[0m,\n",
" \u001b[32m\"trial_days\"\u001b[0m: \u001b[1;36m30\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
" \u001b[1m}\u001b[0m\n",
"\u001b[1m}\u001b[0m\n"
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"jprint(saas_config)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"---\n",
"\n",
"## Best Practices\n",
"\n",
"### 1. Design Patterns\n",
"\n",
"#### ✅ DO: Start with Broad Defaults, Then Specialize"
]
},
{
"cell_type": "code",
"execution_count": 20,
"metadata": {},
"outputs": [],
"source": [
"# Good: Broad defaults with specific overrides\n",
"config = {\n",
" \"_defaults\": {\n",
" \"*.memory\": 2, # Broad default\n",
" \"prod.*.memory\": 8 # Environment-specific override\n",
" },\n",
" \"dev\": {\"api\": {}, \"worker\": {}},\n",
" \"prod\": {\"api\": {}, \"worker\": {\"memory\": 16}} # Service-specific override\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"#### ❌ DON'T: Over-specify in Defaults"
]
},
{
"cell_type": "code",
"execution_count": 21,
"metadata": {},
"outputs": [],
"source": [
"# Bad: Too specific in _defaults\n",
"config = {\n",
" \"_defaults\": {\n",
" \"dev.api.memory\": 2,\n",
" \"dev.worker.memory\": 2,\n",
" \"prod.api.memory\": 8,\n",
" \"prod.worker.memory\": 8 # This defeats the purpose!\n",
" }\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"#### ✅ DO: Use Nested `_defaults` for Logical Grouping"
]
},
{
"cell_type": "code",
"execution_count": 22,
"metadata": {},
"outputs": [],
"source": [
"# Good: Logical grouping with nested _defaults\n",
"config = {\n",
" \"_defaults\": {\n",
" \"*.log_level\": \"INFO\" # Global setting\n",
" },\n",
" \"dev\": {\n",
" \"_defaults\": {\n",
" \"*.debug\": True, # Dev-specific settings\n",
" \"*.hot_reload\": True\n",
" },\n",
" \"api\": {},\n",
" \"worker\": {}\n",
" }\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 2. Path Pattern Guidelines\n",
"\n",
"#### Use Wildcards Strategically"
]
},
{
"cell_type": "code",
"execution_count": 23,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"''"
]
},
"execution_count": 23,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# ✅ Good patterns\n",
"\"*.timeout\" # All environments\n",
"\"*.database.port\" # All database configs\n",
"\"prod.*.memory\" # All prod services\n",
"\"*.services.*.cpu\" # All services in all environments\n",
"\n",
"# ❌ Avoid these patterns \n",
"\"*.*.*.*\" # Too generic\n",
"\"very.specific.deep.path.field\" # Too specific\n",
";"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"#### Establish Naming Conventions"
]
},
{
"cell_type": "code",
"execution_count": 24,
"metadata": {},
"outputs": [],
"source": [
"# ✅ Consistent naming helps pattern matching\n",
"config = {\n",
" \"_defaults\": {\n",
" \"*.database_primary.port\": 5432,\n",
" \"*.database_replica.port\": 5433,\n",
" \"*.cache_redis.port\": 6379\n",
" }\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 3. Configuration Organization\n",
"\n",
"#### Group Related Settings"
]
},
{
"cell_type": "code",
"execution_count": 25,
"metadata": {},
"outputs": [],
"source": [
"# ✅ Well-organized configuration\n",
"config = {\n",
" \"_defaults\": {\n",
" # Database cluster\n",
" \"*.database.port\": 5432,\n",
" \"*.database.pool_size\": 10,\n",
" \"*.database.timeout\": 30,\n",
" \n",
" # Caching layer\n",
" \"*.cache.ttl\": 3600,\n",
" \"*.cache.max_size\": 1000,\n",
" \n",
" # Monitoring\n",
" \"*.monitoring.enabled\": True,\n",
" \"*.monitoring.interval\": 60\n",
" }\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"#### Document Your Patterns"
]
},
{
"cell_type": "code",
"execution_count": 26,
"metadata": {},
"outputs": [],
"source": [
"config = {\n",
" \"_defaults\": {\n",
" # Resource defaults - production overrides these\n",
" \"*.memory\": 2, # GB\n",
" \"*.cpu\": 1, # cores\n",
" \n",
" # Network timeouts - keep aggressive for responsiveness\n",
" \"*.timeout\": 30, # seconds\n",
" \"*.retry_attempts\": 3, # count\n",
" \n",
" # Feature flags - enable by default, disable selectively \n",
" \"*.features.metrics\": True,\n",
" \"*.features.tracing\": True\n",
" }\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 4. Test Your Configuration Processing"
]
},
{
"cell_type": "code",
"execution_count": 27,
"metadata": {},
"outputs": [],
"source": [
"def test_config_inheritance():\n",
" config = {\n",
" \"_defaults\": {\"*.port\": 3000},\n",
" \"dev\": {\"host\": \"localhost\"},\n",
" \"prod\": {\"host\": \"prod.com\", \"port\": 8080}\n",
" }\n",
" \n",
" apply_inheritance(config)\n",
" \n",
" # Validate inheritance worked\n",
" assert config[\"dev\"][\"port\"] == 3000 # Inherited\n",
" assert config[\"prod\"][\"port\"] == 8080 # Preserved override\n",
" assert \"_defaults\" not in config # Cleaned up\n",
"\n",
"test_config_inheritance()"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 5. Error Prevention\n",
"\n",
"#### Validate Paths Before Processing"
]
},
{
"cell_type": "code",
"execution_count": 28,
"metadata": {},
"outputs": [],
"source": [
"def validate_defaults_paths(defaults_config):\n",
" \"\"\"Validate _defaults path patterns\"\"\"\n",
" for path in defaults_config.keys():\n",
" if path.endswith(\"*\"):\n",
" raise ValueError(f\"Path cannot end with '*': {path}\")\n",
" \n",
" if \"..\" in path:\n",
" raise ValueError(f\"Path cannot contain '..': {path}\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"#### Handle Missing Intermediate Keys"
]
},
{
"cell_type": "code",
"execution_count": 29,
"metadata": {},
"outputs": [],
"source": [
"# ❌ This will raise KeyError if 'database' doesn't exist\n",
"config = {\n",
" \"_defaults\": {\"*.database.port\": 5432},\n",
" \"dev\": {} # No 'database' key\n",
"}\n",
"\n",
"# ✅ Better: Ensure intermediate structures exist\n",
"config = {\n",
" \"_defaults\": {\"*.database.port\": 5432},\n",
" \"dev\": {\"database\": {}} # Provide empty database config\n",
"}"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Summary\n",
"\n",
"The Hierarchical Configuration Inheritance Pattern solves the fundamental problem of **configuration duplication** in multi-environment applications. By using `_defaults` sections and JSON path patterns, you can:\n",
"\n",
"### 🎯 **Key Benefits**\n",
"- **Eliminate Duplication**: Define common settings once\n",
"- **Reduce Errors**: Single source of truth for defaults\n",
"- **Scale Easily**: Add new environments with minimal config\n",
"- **Override Flexibly**: Keep environment-specific customizations\n",
"- **Maintain Simply**: Change defaults in one place\n",
"\n",
"### 🚀 **When to Use This Pattern**\n",
"- ✅ Multi-environment deployments (dev/staging/prod)\n",
"- ✅ Microservice configurations with shared defaults\n",
"- ✅ Multi-tenant applications with tiered features\n",
"- ✅ Configuration templates with customization points\n",
"- ✅ Any scenario with repetitive configuration data\n",
"\n",
"### 🛠️ **Getting Started**\n",
"1. Identify duplicated configuration values\n",
"2. Extract them to a `_defaults` section \n",
"3. Use `*.field` patterns for broad defaults\n",
"4. Use `env.field` patterns for specific overrides\n",
"5. Call `apply_inheritance()` to process your config\n",
"\n",
"The pattern transforms configuration management from a maintenance burden into a powerful tool for organizing and scaling your application configurations."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
"outputs": [],
"source": []
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 3 (ipykernel)",
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"name": "python3"
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"codemirror_mode": {
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"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
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