When working with private repositories in Go, fetching dependencies from private GitHub repositories requires some additional configuration. By default, go get expects public repositories, but you can instruct Go to access private ones using the GOPRIVATE environment variable.

Steps to Access Private Packages

1. Set the GOPRIVATE Environment Variable

This tells Go that the specified repository is private and should not be verified against proxy.golang.org.

export GOPRIVATE=github.com/USERNAME/REPOSITORY

Alternatively, you can add this permanently to your shell configuration file (e.g., ~/.bashrc, ~/.zshrc):

echo 'export GOPRIVATE=github.com/USERNAME/REPOSITORY' >> ~/.bashrc
source ~/.bashrc

For Windows (PowerShell):

[System.Environment]::SetEnvironmentVariable("GOPRIVATE", "github.com/USERNAME/REPOSITORY", [System.EnvironmentVariableTarget]::User)

2. Authenticate GitHub for Private Access

If your repository is private, Go needs authentication to fetch it. There are two main ways to authenticate:

Using a Personal Access Token (PAT)

  1. Generate a GitHub Personal Access Token with repo scope.
  2. Use the token in the go get command: 
git config --global url."https://YOUR_GITHUB_USERNAME:TOKEN@github.com/".insteadOf "https://github.com/"

This ensures that when Go attempts to fetch the repository, it includes your credentials.

Using SSH Keys

If you prefer SSH authentication:

  1. Generate an SSH key if you haven't already: 
ssh-keygen -t rsa -b 4096 -C "your-email@example.com"
  1. Add the key to your GitHub account under Settings > SSH and GPG keys.
  2. Configure Git to use SSH: 
git config --global url."git@github.com:".insteadOf "https://github.com/"

3. Fetch the Private Package

Now you can run:

go get -u github.com/USERNAME/REPOSITORY

or, if you need a specific module version:

go get github.com/USERNAME/REPOSITORY@v1.2.3

4. Verify the Module

To ensure that the module is recognized and properly fetched, run:

go list -m all | grep USERNAME/REPOSITORY

Conclusion

Using private packages in Go requires setting GOPRIVATE, configuring authentication, and ensuring your repository is accessible. Whether using PAT or SSH, these steps help you seamlessly integrate private dependencies into your Go projects.