Git Mirror-Me (GMm)

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This CLI tool provides the ability to mirror a repository to any other git repository with optional SSH authentication. For example, it can be used with repositories on GitHub, GitLab, Bitbucket, etc.

Why “Me”? The name derives from the tool’s “ability” to default the source repository to the value computed from a GitHub action environment.


go install[email protected]


Use the provided make script by taking advantage of the build target:

make build

Tool configuration

The tool can be configured via CLI arguments and/or environment variables. Run the tool in help mode (git-mirror-me -h) to check its full description.



  • Sets the source repository for the mirror operation.
  • Can also be set via environment variables.


  • Sets the destination repository for the mirror operation.
  • Can also be set via environment variables.


  • Defines the path to the known_hosts file.
  • This is an alternative to providing the host public keys via the GMM_SSH_KNOWN_HOSTS environment variable (see below).


  • Runs the tool in debug mode.

Environment variables

This tool uses GMM_ as prefix for all the environment variables defined in its scope. That doesn’t include the ones prefixed by GITHUB_ as they are expected to be provided directly by the GitHub CI environment.


  • The source repository can be provided in three ways, listed below in the descending order of their precedence:

    • the -source-repository CLI argument
    • the GMM_SRC_REPO environment variable


  • Sets the destination repository for the mirror operation.


  • The SSH private key used for SSH authentication during git push operation.
  • Password protected SSH keys are not supported.
  • When not defined, git operations will be executed without authentication.
  • When defined, a host public key configuration is required.


  • The hosts public keys used for host validation.
  • The format needs to be based on theknown_hosts file.

Tests and Linters

Use the provided make script. For tests, a test target is provided: make test.

Linters can be executed using make lint. This make target has additional host dependencies on golangci-lint.


Contributions are more than welcome. You can send patches using GitHub pull requests.

Developer Certificate of Origin

The Developer Certificate of Origin (DCO) is a lightweight way for contributors to certify that they wrote or otherwise have the right to submit the code they are contributing to the project. Here is the full text of the DCO, reformatted for readability:

By making a contribution to this project, I certify that:

a. The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or

b. The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same open source license (unless I am permitted to submit under a different license), as indicated in the file; or

c. The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it.

d. I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project or the open source license(s) involved.

Contributors sign-off that they adhere to these requirements by adding a Signed-off-by line to commit messages.

This is my commit message

Signed-off-by: Random J Developer <[email protected]>

Git has a -s command line option to append this automatically to your commit message based on your git configuration (name and email):

$ git commit -s -m 'This is my commit message'


  • Andrei Gherzan <andrei at>


This repository is reuse compliant and it is released under the MIT license.

For convenience, a make target is provided to validate this compliance: make reuse. This make target has an additional but optional host dependency on reuse.


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