Add script to generate pycfmodel resources from CloudFormation schemas

[Jordi Soucheiron (jsoucheiron)]

Summary

Adds a CLI script that generates static pycfmodel resource classes from AWS CloudFormation schemas, plus the top 10 most common unmodeled resource types (increasing coverage from 51.9% to 71.8%).

Usage

# Generate a Lambda function resource
python scripts/generate_resource_from_schema.py AWS::Lambda::Function

# Output to the resources directory
python scripts/generate_resource_from_schema.py AWS::Lambda::Function --output-dir pycfmodel/model/resources

# Preview without writing files
python scripts/generate_resource_from_schema.py AWS::Lambda::Function --dry-run

# List all available resource types (1510 types)
python scripts/generate_resource_from_schema.py --list-types

# Generate multiple resources at once
python scripts/generate_resource_from_schema.py AWS::DynamoDB::Table AWS::SQS::Queue -o pycfmodel/model/resources

New Resource Types Added

Based on analysis of 2,211 production CloudFormation templates containing 5,285 resources:

Resource Type	Count	Cumulative Coverage
AWS::CloudWatch::Alarm	165	55.1%
AWS::IAM::InstanceProfile	146	57.8%
AWS::Route53::RecordSet	134	60.4%
AWS::SQS::Queue	125	62.7%
AWS::SNS::Topic	99	64.6%
AWS::SNS::Subscription	79	66.1%
AWS::AutoScaling::AutoScalingGroup	78	67.6%
AWS::ElasticLoadBalancingV2::Listener	78	69.0%
AWS::ElasticLoadBalancingV2::TargetGroup	75	70.5%
AWS::DynamoDB::Table	72	71.8%

Coverage improvement: 51.9% → 71.8% (1,051 additional resources now properly typed)

Generator Features

• Downloads CloudFormation schemas from AWS (cached during execution)
• Generates Properties class with proper type annotations (ResolvableStr, ResolvableGeneric, etc.)
• Generates Resource class inheriting from Resource base class
• Follows existing pycfmodel conventions (naming, structure, docstrings)
• Handles optional vs required properties correctly
• --dry-run option to preview generated code
• --list-types option to list all 1510 available AWS resource types

Example Generated Code

class SQSQueueProperties(CustomModel):
    """Properties for AWS::SQS::Queue."""

    ContentBasedDeduplication: Optional[ResolvableBool] = None
    DeduplicationScope: Optional[ResolvableStr] = None
    DelaySeconds: Optional[ResolvableInt] = None
    FifoQueue: Optional[ResolvableBool] = None
    QueueName: Optional[ResolvableStr] = None
    # ... more properties


class SQSQueue(Resource):
    """AWS SQS Queue resource."""

    Type: Literal["AWS::SQS::Queue"]
    Properties: Optional[Resolvable[SQSQueueProperties]] = None

Test plan

• Generated code compiles without errors
• Generated classes inherit from Resource correctly
• Generated classes can be instantiated with CloudFormation properties
• Generated classes support intrinsic functions (Ref, Fn::Sub, Fn::GetAtt)
• Generated classes have standard Resource attributes (DependsOn, Condition, etc.)
• Generated code matches existing pycfmodel naming conventions
• CLI options work correctly (--list-types, --dry-run, --output-dir)
• All 665 existing tests pass

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR adds a CLI script that generates static pycfmodel resource classes from AWS CloudFormation schemas, enabling permanent addition of new AWS resource types to the codebase.

Changes:

• Adds a script (generate_resource_from_schema.py) that downloads CloudFormation schemas from AWS and generates Python resource classes following pycfmodel conventions
• Includes comprehensive test coverage for the generator, validating code compilation, functionality, structure, and CLI interface
• Supports generating multiple resources with options for dry-run preview and listing all 1510+ available AWS resource types

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
scripts/generate_resource_from_schema.py	Main script implementing schema download, type conversion, and code generation functionality
tests/test_resource_generator.py	Test suite covering compilation, functionality, structure, and CLI interface of the generator

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[Copilot]

The URL construction logic is duplicated on lines 274 and 300. Extract this into a helper function to avoid code duplication.