Validating OCI Policies in Terraform with a CI/CD Tool

 

Introduction

Securing your Oracle Cloud Infrastructure (OCI) environment is paramount. A crucial aspect of this security is correctly defining and implementing policies that govern access to your resources. Managing these policies within Terraform configurations provides the benefits of infrastructure as code but introduces challenges in validating the syntax of the policies.

This post surface these challenges and introduces the OCI Policy Validation Tool, a GitHub custom action and CLI designed for use in CI/CD pipelines. This tool simplifies the process of checking OCI policy syntax in your Terraform workflows.

 

The Problem

Managing OCI IAM policies in Terraform often leads to the challenge that policy syntax errors only become apparent when Terraform is executed against the OCI account. Furthermore, even when we know that a policy syntax-related issue resulted in the failed execution, IAM policy complexity can make it very challenging to debug where the syntax error is that is blocking the deployment.

 

Overview of the OCI Policy Validation Tool

To address these challenges, the OCI Policy Validation Tool has been built to scan for and report on OCI IAM syntax errors in popular CI/CD pipeline platforms such as GitHub, Bitbucket, and GitLab.

The tool can be deployed as a GitHub action or in a cli mode and performs the following functions:

1. Policy Extraction

– Extracts various OCI policy expression types, including `Allow`, `Define`, `Endorse`, and `Admit`.

– Handles multiline statements, comments

-Includes a version of the IAM Policy ANTLR grammar that supports HCL variable interpolation.

2. CI/CD Integration

– Seamlessly integrates with popular CI/CD platforms like GitHub Actions, GitLab CI, and Bitbucket Pipelines.

– Supports environment variables for dynamic configuration in pipelines.

3. Flexible CLI

– Provides verbose output, recursive directory scanning, and detailed error reporting.

– Allows custom regex patterns for extracting policies tailored to your use case.

 

How It Works

The tool employs a multi-stage process for policy validation:

 

1. Terraform Parsing

– Uses custom regular expressions to parse Terraform files and extract policy statements.

– Handles complex scenarios like nested structures and multiline statements.

 

2. Validation

– Validates extracted policies against OCI syntax rules using an ANTLR-based parser that suppots HCL variable interpolation

– Provides detailed error messages for invalid policies, including the exact position of errors.

 

CLI Usage & Developer Experience

The CLI offers a rich set of options to enhance the developer experience:

 

Key Features:

– **File Paths**: Specify individual policy files or use recursive directory scanning to validate entire directories.

– **Verbosity**: Control the level of output for debugging and troubleshooting.

– **Custom Patterns**: Define custom regular expressions for extracting policies in non-standard formats.

 

Example Commands:

 

# Validate policies in a directory

policy-validation-action validate --path ./policies --verbose


# Use a custom regex pattern

policy-validation-action validate --path ./policies --pattern "statements\\s*=\\s*\\[(.*?)\\]"


# Validate specific files

policy-validation-action validate --path ./policies --files "file1.tf,file2.tf" --verbose

 

 

CI/CD Integration

The OCI Policy Validation Tool is designed to integrate seamlessly into CI/CD workflows. Here are examples for popular platforms:

 

GitHub Actions

name: Validate OCI Policies

on: [push, pull_request]


jobs:

validate:

runs-on: ubuntu-latest

steps:

- uses: actions/checkout@v3

- name: Validate policies

uses: policy-validation-action@v1

with:

path: './terraform'

extractor: 'regex'

 

 

GitLab CI

“`yaml

validate_policies:

image: node:latest

script:

– npm install -g policy-validation-action

– export POLICY_PATH=./terraform

– export POLICY_VERBOSE=true

– policy-validation-action

“`

 

Bitbucket Pipelines

“`yaml

image: node:18

 

pipelines:

default:

– step:

name: Validate Policies

script:

– npm install -g policy-validation-action

– export POLICY_PATH=./terraform

– export POLICY_VERBOSE=true

– policy-validation-action

“`

 

Example Output

 

Successful Validation

“`json

[

{

“file”: “./terraform/example.tf”,

“isValid”: true,

“statements”: [

“Allow group Administrators to manage all-resources in tenancy”

],

“errors”: []

}

]

“`

 

Validation with Errors

“`json

[

{

“file”: “./terraform/bad_example.tf”,

“isValid”: false,

“statements”: [

“Allow BadSyntax manage”

],

“errors”: [

{

“statement”: “Allow BadSyntax manage”,

“position”: 6,

“message”: “mismatched input ‘BadSyntax’ expecting {ANYUSER, RESOURCE, DYNAMICGROUP, GROUP, SERVICE}”

}

]

}

]

“`

 

Conclusion

The **OCI Policy Validation Tool** simplifies the process of securing your OCI environment by automating policy validation within your Terraform and CI/CD workflows. By catching errors early, it helps prevent misconfigurations, improves your security posture, and accelerates deployments.

 

Future Enhancements:

– Support for additional policy types (e.g., JSON-based policies).

– Deeper integration with security scanning tools.

– Enhanced error reporting with actionable suggestions.

 

We encourage you to try the tool in your CI/CD pipelines and share your feedback. Contributions are welcome!

 

Additional Resources

– **[GitHub Repository](https://github.com/gtrevorrow/policy-validation-action)**

– **[Documentation](https://github.com/gtrevorrow/policy-validation-action#readme)**

– **[OCI Policy Guidelines](https://docs.oracle.com/en-us/iaas/Content/Identity/Concepts/policies.htm)**

– **[Terraform Best Practices](https://developer.hashicorp.com/terraform/tutorials)**