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# Sync your OpenAPI specification

Automatically pull your latest OpenAPI spec from a publicly available URL into your fern folder using the [sync-openapi GitHub Action](https://github.com/fern-api/sync-openapi). This keeps your committed spec in sync with your live API without manual updates.

## Setup

#### Configure the origin URL

Add the `origin` field to your `generators.yml` to specify where your OpenAPI spec is hosted:

**`generators.yml`**

```yml title="generators.yml"
 api:
   specs: 
     - openapi: .path/to/openapi.json               # Definition file
       overrides: .path/to-openapi-overrides.yml    # Overrides file
       origin: https://api.example.com/openapi.json # URL to fetch latest spec from
```

#### Add the GitHub Action

Create `.github/workflows/sync-openapi.yml` in your repository. This action uses [`fern api update`](/learn/cli-api-reference/cli-reference/general-commands#fern-api-update) to pull the latest version of your OpenAPI spec from the `origin` field in your `generators.yml` file.

**`.github/workflows/sync-openapi.yml`**

```yml title=".github/workflows/sync-openapi.yml"
name: Sync OpenAPI Specs # can be customized
on:                               # additional custom triggers can be configured
  workflow_dispatch:              # Manual trigger
  push:                                          
    branches:
      - main                      # Trigger on push to
  schedule:
    - cron: '0 3 * * *'           # Daily at 3:00 AM UTC
jobs:
update-from-source:
  runs-on: ubuntu-latest
  steps:
    - uses: actions/checkout@v4
      with:
        token: ${{ secrets.OPENAPI_SYNC_TOKEN }}
    - name: Update API with Fern
      uses: fern-api/sync-openapi@v2
      with:
        update_from_source: true
        token: ${{ secrets.OPENAPI_SYNC_TOKEN }}
        branch: 'update-api'
        auto_merge: false
        add_timestamp: true
```

#### Create a GitHub token

Generate a [fine-grained personal access token](https://github.com/settings/personal-access-tokens) with **Contents** and **Pull requests** read/write permissions for your repository.

#### Add to Repository Secrets

In your repository, go to `Settings > Secrets and variables > Actions`. Click **New repository secret**, name it `OPENAPI_SYNC_TOKEN`, paste your token, and click **Add secret**.

This creates daily pull requests with any API spec updates. To change the frequency, modify the `cron` schedule (see GitHub's [schedule syntax](https://docs.github.com/en/actions/reference/events-that-trigger-workflows#schedule)).

## Other use cases

If your OpenAPI spec lives in a different repository (rather than at a public URL), you can sync it to your Fern folder using explicit file mappings. See the [sync-openapi GitHub Action README](https://github.com/fern-api/sync-openapi) for this and other advanced configurations.

> Pull your latest OpenAPI Specification into your Fern Folder automatically.