Schema Validator

Note

Support JSON, YAML, TOML, and XML. I have plans to add functionality to validate .env files as well.

A flexible GitHub Action for validating JSON, YAML, and XML files against schemas. Supports both local schema files and remote schema URLs, with comprehensive validation reporting in JSON or text format.

Quick Start

- name: Checkout Repository
  uses: actions/checkout@v4

- name: Validate JSON Files
  uses: chase-roohms/schema-validator@v1
  with:
    files: |
      data/users.json
      data/products.json
      config/settings.json
    schema-file: schemas/api-schema.json

Features

Multi-Format Support: Validate JSON, YAML, TOML, and XML files
Flexible Schema Sources: Use local schema files or remote URLs
Schema Compatibility: JSON, YAML, and TOML schemas are interchangeable (all validate JSON/YAML/TOML files)
Multiple Output Formats: Generate validation reports in JSON or text format
Selective Validation: Validate specific files or scan entire repository
Built-in Pre-validation: Automatic checks for file existence, format compatibility, and schema reachability
Detailed Error Reporting: Comprehensive validation error messages
Composable: Easy integration with other GitHub Actions (artifacts, notifications, etc.)

Inputs

Input	Description	Required	Default
`files`	Newline-separated list of files to validate. If not provided, all files matching `file-format` will be validated.	No	-
`file-format`	Format of files to validate. Options: `json`, `yaml`, `toml`, `xml`. Required if `files` is not provided. Inferred from file extensions if `files` is provided.	No	-
`schema-file`	Path to local schema file. Must exist on the runner. Mutually exclusive with `schema-url`.	No¹	-
`schema-url`	URL of the schema to validate against. Will be fetched and used for validation. Mutually exclusive with `schema-file`.	No¹	-
`schema-format`	Format of the schema. Options: `json`, `yaml`, `toml`, `xml`. Will be inferred from file extension if not provided.	No	-
`output-format`	Format of validation results. Options: `json`, `text`.	No	`json`
`output-file`	Path to write validation results.	No	`${{ runner.temp }}/validation-results`

¹ Note: Exactly one of schema-file or schema-url must be provided.

Outputs

Output	Description
`validation-passed`	Boolean string (`"true"` or `"false"`) indicating whether all validations passed
`output-file`	Path to the file containing validation results

Usage Examples

Basic Examples

Validate JSON Files Against JSON Schema

- name: Checkout Repository
  uses: actions/checkout@v4

- name: Validate JSON Files
  uses: chase-roohms/schema-validator@v1
  with:
    files: |
      data/users.json
      data/products.json
      config/settings.json
    schema-file: schemas/api-schema.json

Validate YAML Files Against YAML Schema

- name: Validate YAML Configuration
  uses: chase-roohms/schema-validator@v1
  with:
    files: |
      config/app.yaml
      config/database.yaml
    schema-file: schemas/config.schema.yaml

Validate TOML Files Against TOML Schema

- name: Checkout Repository
  uses: actions/checkout@v4

- name: Validate TOML Files
  uses: chase-roohms/schema-validator@v1
  with:
    files: |
      data/users.toml
      data/products.toml
      config/settings.toml
    schema-file: schemas/api-schema.toml

Validate Mixed JSON/YAML Files

Since JSON and YAML schemas are interchangeable, you can validate both formats with a single schema:

- name: Validate Configuration Files
  uses: chase-roohms/schema-validator@v1
  with:
    files: |
      config/prod.json
      config/dev.yaml
      config/staging.yml
    schema-file: schemas/config.schema.json

Validating Specific Files

Single File Validation

- name: Validate API Response
  uses: chase-roohms/schema-validator@v1
  with:
    files: api-response.json
    schema-file: schemas/api.schema.json

Multiple Files from Different Directories

- name: Validate Data Files
  uses: chase-roohms/schema-validator@v1
  with:
    files: |
      src/data/users.json
      tests/fixtures/mock-data.json
      docs/examples/sample.json
    schema-file: schemas/data.schema.json

Auto-Discovery

Let the action find all files of a specific format in your repository:

Find and Validate All JSON Files

- name: Validate All JSON Files
  uses: chase-roohms/schema-validator@v1
  with:
    file-format: json
    schema-file: schemas/any.schema.json

Find and Validate All YAML Files

- name: Validate All YAML Files
  uses: chase-roohms/schema-validator@v1
  with:
    file-format: yaml
    schema-file: schemas/config.schema.yaml

Find and Validate All XML Files

- name: Validate All XML Files
  uses: chase-roohms/schema-validator@v1
  with:
    file-format: xml
    schema-file: schemas/document.xsd

Using Schema URLs

Fetch schemas from remote sources:

GitHub Raw Content

- name: Validate Against Remote Schema
  uses: chase-roohms/schema-validator@v1
  with:
    files: data/users.json
    schema-url: https://raw.githubusercontent.com/org/schemas/main/user.schema.json

JSON Schema Store

- name: Validate Package.json
  uses: chase-roohms/schema-validator@v1
  with:
    files: package.json
    schema-url: https://json.schemastore.org/package.json

Organization Schema Registry

- name: Validate Configuration
  uses: chase-roohms/schema-validator@v1
  with:
    files: config.yaml
    schema-url: https://schemas.example.com/v1/config.schema.json

XML Validation

XML validation uses XSD (XML Schema Definition):

Validate XML Files

- name: Validate XML Documents
  uses: chase-roohms/schema-validator@v1
  with:
    files: |
      data/document1.xml
      data/document2.xml
    schema-file: schemas/document.xsd

Validate All XML Files in Repository

- name: Validate All XML
  uses: chase-roohms/schema-validator@v1
  with:
    file-format: xml
    schema-file: schemas/standard.xsd

Output Formats

JSON Output (Default)

- name: Validate with JSON Output
  uses: chase-roohms/schema-validator@v1
  with:
    files: data/users.json
    schema-file: schemas/user.schema.json
    output-format: json
    output-file: validation-results.json

Example JSON output:

{
  "test-files/json/good_1.json": {
    "passed": true,
    "notes": ""
  },
  "test-files/json/good_2.json": {
    "passed": true,
    "notes": ""
  },
  "test-files/json/good_3.json": {
    "passed": true,
    "notes": ""
  }
}

Text Output

- name: Validate with Text Output
  uses: chase-roohms/schema-validator@v1
  with:
    files: data/users.json
    schema-file: schemas/user.schema.json
    output-format: text
    output-file: validation-results.txt

Example text output:

test-files/yaml/bad_1.yaml: not valid
-5 is less than the minimum of 0

Failed validating 'minimum' in schema['properties']['age']:
    {'type': 'integer', 'minimum': 0, 'maximum': 150}

On instance['age']:
    -5

test-files/yaml/bad_2.yaml: not valid
200 is greater than the maximum of 150

Failed validating 'maximum' in schema['properties']['age']:
    {'type': 'integer', 'minimum': 0, 'maximum': 150}

On instance['age']:
    200

Advanced Examples

Upload Validation Results as Artifact

- name: Validate Files
  id: validate
  uses: chase-roohms/schema-validator@v1
  continue-on-error: true
  with:
    files: |
      data/file1.json
      data/file2.json
    schema-file: schemas/data.schema.json
    output-format: json
    output-file: ${{ runner.temp }}/validation-results.json

- name: Upload Validation Results
  if: always()
  uses: actions/upload-artifact@v4
  with:
    name: validation-results
    path: ${{ steps.validate.outputs.output-file }}

Conditional Steps Based on Validation

- name: Validate Configuration
  id: validate-config
  uses: chase-roohms/schema-validator@v1
  continue-on-error: true
  with:
    files: config/production.yaml
    schema-file: schemas/config.schema.yaml

- name: Deploy to Production
  if: steps.validate-config.outputs.validation-passed == 'true'
  run: |
    echo "Configuration is valid, deploying..."
    # deployment steps here

- name: Notify on Failure
  if: steps.validate-config.outputs.validation-passed == 'false'
  run: |
    echo "Configuration validation failed!"
    cat ${{ steps.validate-config.outputs.output-file }}

Send Validation Report via Slack

- name: Validate API Schemas
  id: validate-schemas
  uses: chase-roohms/schema-validator@v1
  continue-on-error: true
  with:
    file-format: json
    schema-file: schemas/api.schema.json
    output-format: text
    output-file: validation-report.txt

- name: Send Report to Slack
  if: always()
  uses: slackapi/slack-github-action@v1
  with:
    payload: |
      {
        "text": "Schema Validation Results",
        "attachments": [{
          "color": "${{ steps.validate-schemas.outputs.validation-passed == 'true' && 'good' || 'danger' }}",
          "text": "${{ steps.validate-schemas.outputs.validation-passed == 'true' && 'All validations passed ✅' || 'Validation failed ❌' }}"
        }]
      }
  env:
    SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}

Create GitHub Issue on Validation Failure

- name: Validate Data Files
  id: validate
  uses: chase-roohms/schema-validator@v1
  continue-on-error: true
  with:
    file-format: json
    schema-file: schemas/data.schema.json
    output-format: text
    output-file: validation-results.txt

- name: Read Validation Results
  if: steps.validate.outputs.validation-passed == 'false'
  id: results
  run: echo "results=$(cat validation-results.txt)" >> $GITHUB_OUTPUT

- name: Create Issue
  if: steps.validate.outputs.validation-passed == 'false'
  uses: actions/github-script@v7
  with:
    script: |
      await github.rest.issues.create({
        owner: context.repo.owner,
        repo: context.repo.repo,
        title: 'Schema Validation Failed',
        body: `Schema validation failed in workflow ${context.workflow}.\n\n\`\`\`\n${{ steps.results.outputs.results }}\n\`\`\``,
        labels: ['validation-failure', 'automated']
      });

Matrix Strategy with Multiple Schemas

jobs:
  validate:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        environment: [dev, staging, prod]
        include:
          - environment: dev
            schema: schemas/dev.schema.json
          - environment: staging
            schema: schemas/staging.schema.json
          - environment: prod
            schema: schemas/prod.schema.json
    steps:
      - uses: actions/checkout@v4
      
      - name: Validate ${{ matrix.environment }} Config
        uses: chase-roohms/schema-validator@v1
        with:
          files: config/${{ matrix.environment }}.json
          schema-file: ${{ matrix.schema }}

Pull Request Comment with Results

- name: Validate Changes
  id: validate
  uses: chase-roohms/schema-validator@v1
  continue-on-error: true
  with:
    files: |
      modified-file1.json
      modified-file2.json
    schema-file: schemas/api.schema.json
    output-format: text
    output-file: validation.txt

- name: Comment PR
  if: github.event_name == 'pull_request'
  uses: actions/github-script@v7
  with:
    script: |
      const fs = require('fs');
      const results = fs.readFileSync('validation.txt', 'utf8');
      const passed = '${{ steps.validate.outputs.validation-passed }}' === 'true';
      const emoji = passed ? '✅' : '❌';
      
      await github.rest.issues.createComment({
        issue_number: context.issue.number,
        owner: context.repo.owner,
        repo: context.repo.repo,
        body: `${emoji} **Schema Validation Results**\n\n\`\`\`\n${results}\n\`\`\``
      });

Validate Generated Files from Previous Step

- name: Generate Configuration
  run: |
    # Script that generates config files
    ./scripts/generate-config.sh

- name: Validate Generated Files
  uses: chase-roohms/schema-validator@v1
  with:
    file-format: json
    schema-file: schemas/generated-config.schema.json

Multi-Stage Validation Pipeline

jobs:
  validate-dev:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Validate Dev Configs
        uses: chase-roohms/schema-validator@v1
        with:
          files: |
            config/dev/app.json
            config/dev/database.json
            config/dev/services.json
          schema-file: schemas/dev.schema.json

  validate-prod:
    runs-on: ubuntu-latest
    needs: validate-dev
    steps:
      - uses: actions/checkout@v4
      - name: Validate Prod Configs
        uses: chase-roohms/schema-validator@v1
        with:
          files: |
            config/prod/app.json
            config/prod/database.json
            config/prod/services.json
          schema-file: schemas/prod.schema.json
          
  deploy:
    runs-on: ubuntu-latest
    needs: [validate-dev, validate-prod]
    steps:
      - name: Deploy Application
        run: echo "All validations passed, deploying..."

Schema Format Compatibility

The action enforces schema format compatibility:

✅ Compatible Combinations

JSON Schema → JSON files
JSON Schema → YAML files
JSON Schema → TOML files
JSON Schema → Mixed JSON/YAML/TOML files
YAML Schema → JSON files
YAML Schema → YAML files
YAML Schema → TOML files
YAML Schema → Mixed JSON/YAML/TOML files
XSD Schema → XML files only

❌ Incompatible Combinations

XSD Schema → JSON files (will fail)
XSD Schema → YAML files (will fail)
XSD Schema → TOML files (will fail)
JSON/YAML/TOML Schema → XML files (will fail)

Why? JSON, YAML, and TOML use the same schema format (JSON Schema), so they're interchangeable. XML uses a different schema system (XSD), which is incompatible with JSON/YAML/TOML.

Error Handling

The action includes comprehensive validation checks:

Pre-validation Checks

Repository checkout verification
File existence validation
Schema file/URL accessibility
Format compatibility checks
Input parameter validation

Validation Failures

When validation fails:

The action will exit with code 1
validation-passed output will be "false"
Error details will be written to the output file
Use continue-on-error: true to prevent workflow failure

Example:

- name: Validate Files
  id: validate
  uses: chase-roohms/schema-validator@v1
  continue-on-error: true  # Don't fail the workflow
  with:
    files: data.json
    schema-file: schema.json

- name: Handle Validation Failure
  if: steps.validate.outputs.validation-passed == 'false'
  run: |
    echo "Validation failed, but workflow continues"
    cat ${{ steps.validate.outputs.output-file }}

Requirements

Repository must be checked out (use actions/checkout before this action)
Schema file must exist if using schema-file
Schema URL must be publically accessible if using schema-url

License

This action is available under the MIT License. See LICENSE for details.

Author: Chase Roohms

Issues and Contributions: Visit the GitHub repository to report issues or contribute.

Name		Name	Last commit message	Last commit date
Latest commit History 101 Commits
.github/workflows		.github/workflows
src		src
test-files		test-files
.gitignore		.gitignore
LICENSE		LICENSE
README.md		README.md
action.yml		action.yml
requirements.txt		requirements.txt

Folders and files

Latest commit

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Schema Validator

Quick Start

Features

Table of Contents

Inputs

Outputs

Usage Examples

Basic Examples

Validate JSON Files Against JSON Schema

Validate YAML Files Against YAML Schema

Validate TOML Files Against TOML Schema

Validate Mixed JSON/YAML Files

Validating Specific Files

Single File Validation

Multiple Files from Different Directories

Auto-Discovery

Find and Validate All JSON Files

Find and Validate All YAML Files

Find and Validate All XML Files

Using Schema URLs

GitHub Raw Content

JSON Schema Store

Organization Schema Registry

XML Validation

Validate XML Files

Validate All XML Files in Repository

Output Formats

JSON Output (Default)

Text Output

Advanced Examples

Upload Validation Results as Artifact

Conditional Steps Based on Validation

Send Validation Report via Slack

Create GitHub Issue on Validation Failure

Matrix Strategy with Multiple Schemas

Pull Request Comment with Results

Validate Generated Files from Previous Step

Multi-Stage Validation Pipeline

Schema Format Compatibility

✅ Compatible Combinations

❌ Incompatible Combinations

Error Handling

Pre-validation Checks

Validation Failures

Requirements

License

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