# File Server Backends

In Salt 0.12.0, the modular fileserver was introduced. This feature added the ability for the Salt Master to integrate different file server backends. File server backends allow the Salt file server to act as a transparent bridge to external resources. A good example of this is the `git` backend, which allows Salt to serve files sourced from one or more git repositories, but there are several others as well. Click here for a full list of Salt's fileserver backends.

## Enabling a Fileserver Backend

Fileserver backends can be enabled with the `fileserver_backend` option.

    fileserver_backend:
      - git

See the documentation for each backend to find the correct value to add to `fileserver_backend` in order to enable them.

## Using Multiple Backends

If `fileserver_backend` is not defined in the Master config file, Salt will use the `roots` backend, but the `fileserver_backend` option supports multiple backends. When more than one backend is in use, the files from the enabled backends are merged into a single virtual filesystem. When a file is requested, the backends will be searched in order for that file, and the first backend to match will be the one which returns the file.

    fileserver_backend:
      - roots
      - git

With this configuration, the environments and files defined in the `file_roots` parameter will be searched first, and if the file is not found then the git repositories defined in `gitfs_remotes` will be searched.

## Defining Environments

Just as the order of the values in `fileserver_backend` matters, so too does the order in which different sources are defined within a fileserver environment. For example, given the below `file_roots` configuration, if both `/srv/salt/dev/foo.txt` and `/srv/salt/prod/foo.txt` exist on the Master, then `salt://foo.txt` would point to `/srv/salt/dev/foo.txt` in the `dev` environment, but it would point to `/srv/salt/prod/foo.txt` in the `base` environment.

    file_roots:
      base:
        - /srv/salt/prod
      qa:
        - /srv/salt/qa
        - /srv/salt/prod
      dev:
        - /srv/salt/dev
        - /srv/salt/qa
        - /srv/salt/prod

Similarly, when using the `git` backend, if both repositories defined below have a `hotfix23` branch/tag, and both of them also contain the file `bar.txt` in the root of the repository at that branch/tag, then `salt://bar.txt` in the `hotfix23` environment would be served from the `first` repository.

    gitfs_remotes:
      - https://mydomain.tld/repos/first.git
      - https://mydomain.tld/repos/second.git

Note

Environments map differently based on the fileserver backend. For instance, the mappings are explicitly defined in `roots` backend, while in the VCS backends (`git`, `hg`, `svn`) the environments are created from branches/tags/bookmarks/etc. For the `minion` backend, the files are all in a single environment, which is specified by the `minionfs_env` option.

See the documentation for each backend for a more detailed explanation of how environments are mapped.