Authenticating Git and image registries

This page guides you through passing Git and Docker authentication to Earthly builds, to empower related Earthly features, like GIT CLONE or FROM.

Important

This page is NOT about passing Git or Docker credentials for your own custom commands within builds. For those cases, use the RUN --secret feature.

Git authentication

A number of Earthly features use Git credentials to perform remote Git operations:

Resolving a build context when referencing remote targets
The GIT CLONE command

There are two possible ways to pass Git authentication to Earthly builds:

Via SSH agent socket (for SSH-based authentication)
Via username-password (usually for HTTPS Git URLs)

Auto authentication

Earthly defaults to an auto authentication mode, where ssh-based authentication is automatically attempted, and falls back to https-based cloning.

If you are having trouble accessing a private repository and want to use ssh-based authentication, first make sure ssh-agent is running and the SSH_AUTH_SOCK environment variable is set. If not, you can start it with eval $(ssh-agent).

Next make sure your private key has been added by running ssh-add <path to key>.

For users who want explicit control over git authentication, the following sections explain how.

SSH agent socket

Earthly uses the environment variable SSH_AUTH_SOCK to detect where the SSH agent socket is located and mounts that socket to the BuildKit daemon container. (As an exception, on Mac, Docker's compatibility SSH auth socket is used instead).

If you need to override the SSH agent socket, you can set the environment variable EARTHLY_SSH_AUTH_SOCK, or use the --ssh-auth-sock flag to point to an alternative SSH agent.

In order for the SSH agent to have the right credentials available, make sure you run ssh-add before executing Earthly builds.

Another key setting is the auth mode for the git site that hosts the repository. By default earthly automatically default to ssh authentication if the ssh auth agent is running and has at least 1 key loaded, otherwise earthly will fallback to using non-authenticated HTTPS.

Sites can be explicitly added to the earthly config file under the git section in order to override the auto-authentication mode:

git:
    git.example.com:
        auth: ssh
        user: git

Username-password authentication

Username-password based authentication can be configured in the earthly config file under the git section:

git:
    github.com:
        auth: https
        user: <username>
        password: <password>
    gitlab.com:
        auth: https
        user: <username>
        password: <password>

If no user or password are found, earthly will check for entries under ~/.netrc.

Global override via environment variables (deprecated)

Alternatively, environment variables can be set which will be override all host entries from the config file:

GIT_USERNAME
GIT_PASSWORD

However, environment variable authentication are now deprecated in favor of using the configuration file instead.

Self-hosted and private Git Repositories

Currently, github.com, gitlab.com, and bitbucket.org have been tested as SCM providers. Without any host-specific configuration, Earthly first attempts to perform a clone over SSH on the default SSH port (22), and will fallback to HTTPS, followed by HTTP. In the event access can only be established over HTTP, Earthly will refuse to send credentials due to the insecure nature of HTTP.

Earthly can be configured to use a non-standard SSH port, by using the port config option:

git:
    ghe.internal.mycompany.com:
        auth: ssh
        user: git
        port: 2222

When Earthly encounters a remote reference such as ghe.internal.mycompany.com/user/repo+some-target, the git repository will be cloned using an explicit SSH scheme, for example: git clone ssh://git@ghe.internal.mycompany.com:2222/user/repo.git.

The explicit ssh-scheme is an absolute path on the server's file-system; if the git repositories are located in a different location (e.g. /var/git/...), a prefix configuration option can be specified.

Remapping Git Repositories Paths Using Regular Expressions

The port and prefix configuration options are the preferred way to configure self-hosted git repositories; however prior to the introduction of these options, it was suggested to use a regular expression and substitution pattern:

git:
    ghe.internal.mycompany.com:
        pattern: 'ghe.internal.mycompany.com/([^/]+)/([^/]+)'
        substitute: 'ssh://git@ghe.internal.mycompany.com:22/$1/$2.git'
        auth: ssh

GitLab Subgroups

Earthly, by default, assumes git repos are stored under two levels (i.e. <org>/<path>.git). A regular expression must be configured in order to support sub groups:

git:
    gitlab.com:
        pattern: 'gitlab.com/(example-org)/([^/]+)/([^/]+)'
        substitute: 'git@gitlab.com:$1/$2/$3.git'
        auth: ssh

Where example-org is the name of your GitLab organisation. Note that the ( and ) parenthesis are required, as they are used to assign the matched value to the $1, $2, ... values.

The pattern will depend on how your subgroups are setup; if you use a mix of 2 and 3 level groupings, you will have to configure them separately:

git:
    gitlab.com/example-org/projecta:
        pattern: 'gitlab.com/(example-org)/(project-a)/([^/]+)'
        substitute: 'git@gitlab.com:$1/$2/$3.git'
        auth: ssh

    gitlab.com example-org catch-all:
        pattern: 'gitlab.com/(example-org)/([^/]+)'
        substitute: 'git@gitlab.com:$1/$2.git'
        auth: ssh

When a pattern is used, the key of the git configuration is simply used by log messages, it is not used for any matching.

Note that patterns are evaluated from the top to the bottom, subgroup specific configurations should be listed first.

Debugging tips

You can run earthly with --verbose, which will provide debugging messages to help understand how a remote earthly reference is transformed into a git URL for cloning.

You can additionally enable low-level git debugging in buildkit, by adding the following to your ~/.earthly/config.yml:

global:
  buildkit_additional_args: [ '-e', 'BUILDKIT_DEBUG_GIT=1' ]

The buildkit logs can be displayed with docker logs earthly-buildkitd.

Docker authentication

Docker credentials are used in Earthly for inheriting from private images (via FROM) and for pushing images (via SAVE IMAGE --push).

Docker authentication works automatically out of the box. It uses the same Docker libraries to infer the location of the credentials on the system and optionally invoke any necessary credentials store helper to decrypt them.

Manually

All you have to do as a user is issue the command

docker login --username <username>

before issuing earthly commands, if you have not already done so in the past. If you run into troubles, you can find out more about docker login here.

Credential Helpers

Docker can use various credential helpers to automatically generate and use credentials on your behalf. These are usually created by cloud providers to allow Docker to authenticate using the cloud providers own credentials.

You can see examples of configuring Docker to use these, and working with Earthly here: