scpz 0.3.0

Intelligently optimize AWS SCP JSONs to adhere to strict size, statement, and policy count limits.

scpz

Intelligently optimize AWS Service Control Policy (SCP) JSONs to fit within AWS's strict limits.

AWS SCP Limits

Constraint	Limit
Policy size	10,240 bytes
Statements per SCP	5
SCPs per target (account/OU)	10

Requirements

Python 3.13 or later.

Installation

pip install scpz

Or with uv (recommended):

uv tool install scpz

Usage

Optimize

# Optimize a single file in-place (original saved as policy.json.bak)
scpz optimize-cmd policy.json

# Optimize all JSON files in a directory
scpz optimize-cmd policies/

# Dry run — show diff + summary without writing
scpz optimize-cmd policy.json --dry-run

# Summary only — just show what would change
scpz optimize-cmd policy.json --summary-only

# Write to a different file
scpz optimize-cmd policy.json --output optimized.json

# Error instead of auto-splitting
scpz optimize-cmd policy.json --no-split

Validate

# Validate a single file
scpz validate policy.json

# Validate all JSON files in a directory
scpz validate policies/

Optimization Passes

scpz runs the following optimizations in order, repeating until the output stops changing (up to 5 rounds):

1. Statement merging — Combines statements that share the same Effect, Condition, and Resource into a single statement with a unioned Action list.
2. Action wildcard compression — Replaces groups of actions sharing a common prefix with wildcard patterns (e.g. s3:GetObject + s3:GetBucketPolicy → s3:Get*). Uses the bundled AWS action catalog in conservative mode to avoid scope broadening.
3. Condition merging — Deduplicates condition values and merges equivalent condition blocks.
4. Resource ARN optimization — Collapses multiple specific ARNs into wildcard patterns (e.g. role/Admin + role/ReadOnly → role/*).
5. Redundancy elimination (opt-in) — Removes statements wholly subsumed by another statement in the same policy (Action via wildcards; NotAction only when a non-empty action catalog is configured, mirroring catalog safety for NotAction compression). Enable with redundancyEliminate.enabled: true in scpz.yaml.

When a policy still exceeds limits after optimization, scpz automatically splits it into multiple SCP documents (up to 10 per target).

Configuration

Place a scpz.yaml in your project root (scpz walks up from the input file to find it). See examples/scpz.yaml for a fully-annotated reference.

apiVersion: scpz.io/v1alpha1
kind: OptimizerConfig
metadata:
  name: default
spec:
  optimizer:
    actionCompress:
      mode: conservative  # conservative | aggressive
    redundancyEliminate:
      enabled: true       # opt-in

# Print the JSON Schema for editor validation
scpz schema

Development

# Install with dev dependencies
uv sync --dev

# Run tests
uv run pytest

# Run tests with coverage
uv run pytest --cov=scpz

# Run a specific test file
uv run pytest tests/test_actions.py -v

# Regenerate the committed schema after model changes
uv run scpz schema -o schema/OptimizerConfig.json

License

MIT