A backend is JavaScript code that allows Static CMS to communicate with a service that stores content - typically a Git host like GitHub or GitLab. It provides functions that Static CMS can use to do things like read and update files using API's provided by the service.
Individual backends should provide their own configuration documentation, but there are some configuration options that are common to multiple backends. A full reference is below. Note that these are properties of the `backend` field, and should be nested under that field.
| `repo` | none | **Required** for `github`, `gitlab`, and `bitbucket` backends; ignored by `git-gateway`. Follows the pattern `[org-or-username]/[repo-name]`. |
| `api_root` | `https://api.github.com` (GitHub), `https://gitlab.com/api/v4` (GitLab), or `https://api.bitbucket.org/2.0` (Bitbucket) | The API endpoint. Only necessary in certain cases, like with GitHub Enterprise or self-hosted GitLab. |
| `site_domain` | `location.hostname` (or `cms.netlify.com` when on `localhost`) | Sets the `site_id` query param sent to the API endpoint. Non-Netlify auth setups will often need to set this for local development to work properly. |
| `base_url` | `https://api.netlify.com` (GitHub, Bitbucket) or `https://gitlab.com` (GitLab) | OAuth client hostname (just the base domain, no path). **Required** when using an external OAuth server or self-hosted GitLab. |
| `auth_endpoint` | `auth` (GitHub, Bitbucket) or `oauth/authorize` (GitLab) | Path to append to `base_url` for authentication requests. Optional. |
Anyone can write a backend, but we don't yet have a finalized and documented API. If you would like to write your own backend for a service that does not have one currently, we recommend using the [GitHub backend](https://github.com/StaticJsCMS/static-cms/tree/main/src/backends/github) as a reference for API and best practices.
