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Remote Repositories

Dagger supports the use of HTTP and SSH protocols for accessing directories, files, and Dagger modules in remote repositories. This feature is compatible with all major Git hosting platforms such as GitHub, GitLab, BitBucket, Azure DevOps, Codeberg, and Sourcehut. Dagger supports authentication via both HTTPS (using Git credential managers) and SSH (using a unified authentication approach).

Dagger supports the following reference schemes for directory and file arguments:

ProtocolSchemeAuthenticationExample
HTTP(S)Git HTTPGit credential managerhttps://github.com/username/repo.git[#version[:subpath]]
SSHExplicitSSH keysssh://git@github.com/username/repo.git[#version[:subpath]]
SSHSCP-likeSSH keysgit@github.com:username/repo.git[#version[:subpath]]
note

The reference scheme for directory arguments is currently under discussion here and here and may change in future.

Dagger provides additional flexibility in referencing file and directory arguments through the following options:

  • Version specification: Add #version to target a particular version of the repository. This can be a tag, branch name, or full commit hash. If omitted, the default branch is used.
  • Monorepo support: Append :subpath after the version specification to access a specific subdirectory within the repository. Note that specifying a version is mandatory when including a subpath.
important

When referencing a specific subdirectory (subpath) within a repository, you must always include a version specification. The format is always #version:subpath.

Common SSH cloning patterns​

Pass a remote directory as argument​

One approach is to pre-resolve a private Git repository into a Directory object at the top-level call. This allows you to decide exactly which repository (and branch or commit) is made available to downstream modules:

dagger call clone --dir git@github.com:private/secret-repo@main

In this approach, the module simply receives a Directory object and never directly accesses your SSH agent. Refer to the cookbook for an example.

Pass the host SSH agent socket as argument​

Alternatively, you can allow a function to perform the Git clone by passing in your SSH socket:

dagger call clone-with-ssh --repository git@github.com:private/secret-repo.git \
  --ref main --sock "$SSH_AUTH_SOCK"

In this approach, the caller explicitly provides the SSH agent socket. This prevents hidden or unapproved use of SSH credentials because the module cannot complete the cloning operation without the user's approval. Refer to the cookbook for an example.

Authentication methods​

Dagger supports both HTTPS and SSH authentication for accessing remote repositories.

HTTPS authentication​

For HTTPS authentication, Dagger uses your system's configured Git credential manager. This means if you're already authenticated with your Git provider, Dagger will automatically use these credentials when needed.

The following credential helpers are supported:

  • Git Credential Manager
  • macOS Keychain
  • Windows Credential Manager
  • Custom credential helpers configured in your .gitconfig

To verify if your credentials are properly configured, try cloning a private repository (replace the placeholders below with valid values):

git clone https://github.com/USER/PRIVATE_REPOSITORY.git

If this works, Dagger will be able to use the same credentials to access your private repositories.

Credential manager configuration​

SSH authentication​

Dagger mounts the socket specified by your host's SSH_AUTH_SOCK environment variable to the Dagger Engine. This is essential for SSH refs, as most Git servers use your SSH key for authentication and tracking purposes, even when cloning public repositories.

This means that you must ensure that the SSH_AUTH_SOCK environment variable is properly set in your environment when using SSH refs with Dagger.

Read detailed instructions on setting up SSH authentication, including how to generate SSH keys, start the SSH agent, and add your keys.

Best practices​

For quick and easy referencing:

  • Copy the repository ref from your preferred Git server's UI.
  • To specify a particular version or commit, append #version (for directory arguments) or @version (for modules).
  • To target a specific directory within the repository, use the format #version:subpath (for directory arguments) or add a /subpath (for modules). Remember that the version is mandatory when specifying a subpath.
  • For private repositories:
    • HTTPS: Ensure your Git credentials are properly configured using your provider's recommended method.
    • SSH: Make sure your SSH keys are properly set up and added to the SSH agent.

Known limitations and workarounds​

This section outlines current limitations and provides workarounds for common issues. We're actively working on improvements for these areas.

Windows is not supported​

Currently, SSH refs are fully supported on UNIX-based systems (Linux and macOS). Windows support is under development. Track progress and contribute to the discussion in our GitHub issue for Windows support.

Multiple SSH keys may cause SSH forwarding to fail​

SSH forwarding may fail when multiple keys are loaded in your SSH agent. This is under active investigation in our GitHub issue. Until this is resolved, the following workaround may be used:

  1. Clear all loaded keys: ssh-add -D
  2. Add back only the required key: ssh-add /path/to/key