% containers-auth.json 5

# NAME
containers-auth.json - syntax for the registry authentication file

# DESCRIPTION

A file in JSON format controlling authentication against container image registries.
The primary (read/write) file is stored at `${XDG_RUNTIME_DIR}/containers/auth.json` on Linux;
on Windows and macOS, at `$HOME/.config/containers/auth.json`.

When searching for the credential for a registry, the following files will be read in sequence until the valid credential is found:
first reading the primary (read/write) file, or the explicit override using an option of the calling application.
If credentials are not present there,
the search continues in `${XDG_CONFIG_HOME}/containers/auth.json` (usually `~/.config/containers/auth.json`), `$HOME/.docker/config.json`, `$HOME/.dockercfg`.

Except for the primary (read/write) file, other files are read-only unless the user, using an option of the calling application, explicitly points at it as an override.


## FORMAT

The auth.json file stores, or references, credentials that allow the user to authenticate
to container image registries.
It is primarily managed by a `login` command from a container tool such as `podman login`,
`buildah login`, or `skopeo login`.

Each entry contains a single hostname (e.g., `docker.io`) or a namespace (e.g., `quay.io/user/image`) as a key,
and credentials in the form of a base64-encoded string as value of `auth`. The
base64-encoded string contains a concatenation of the username, a colon, and the
password.

When checking for available credentials, the relevant repository is matched
against available keys in its hierarchical order, going from most-specific to least-specific.
For example, an image pull for `my-registry.local/namespace/user/image:latest` will
result in a lookup in `auth.json` in the following order:

- `my-registry.local/namespace/user/image`
- `my-registry.local/namespace/user`
- `my-registry.local/namespace`
- `my-registry.local`

This way it is possible to setup multiple credentials for a single registry
which can be distinguished by their path.

The following example shows the values found in auth.json after the user logged in to
their accounts on quay.io and docker.io:

```
{
	"auths": {
		"docker.io": {
			"auth": "erfi7sYi89234xJUqaqxgmzcnQ2rRFWM5aJX0EC="
		},
		"quay.io": {
			"auth": "juQAqGmz5eR1ipzx8Evn6KGdw8fEa1w5MWczmgY="
		}
	}
}
```

This example demonstrates how to use multiple paths for a single registry, while
preserving a fallback for `my-registry.local`:

```
{
	"auths": {
		"my-registry.local/foo/bar/image": {
			"auth": "…"
		},
		"my-registry.local/foo": {
			"auth": "…"
		},
		"my-registry.local": {
			"auth": "…"
		},
	}
}
```

An entry can be removed by using a `logout` command from a container
tool such as `podman logout` or `buildah logout`.

In addition, credential helpers can be configured for specific registries, and the credentials-helper
software can be used to manage the credentials more securely than storing only base64-encoded credentials in `auth.json`.

When the credential helper is in use on a Linux platform, the auth.json file would contain keys that specify the registry domain, and values that specify the suffix of the program to use (i.e. everything after docker-credential-).  For example:

```
{
    "auths": {
        "localhost:5001": {}
    },
    "credHelpers": {
		"registry.example.com": "secretservice"
	}
}
```

For more information on credential helpers, please reference the [GitHub docker-credential-helpers project](https://github.com/docker/docker-credential-helpers/releases).

# SEE ALSO
    buildah-login(1), buildah-logout(1), podman-login(1), podman-logout(1), skopeo-login(1), skopeo-logout(1)

# HISTORY
Feb 2020, Originally compiled by Tom Sweeney <tsweeney@redhat.com>