In Dockerfile

RUN git config --global url.ssh://[e-mail]/.insteadOf https://github.com/
RUN go env -w GOPRIVATE=github.com/{githubusername}/*
RUN mkdir ~/.ssh
COPY id_rsa.pub /root/.ssh/id_rsa.pub
COPY known_hosts /root/.ssh/known_hosts
COPY id_rsa /root/.ssh/id_rsa

Related Errors:

> [e-mail]: Permission denied (publickey).
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.

https://docs.github.com/en/authentication/troubleshooting-ssh/error-permission-denied-publickey

`% eval "$(ssh-agent -s)"`
Agent pid 50168

`% ssh-add -l -E sha256`
The agent has no identities.

If we found the above problem, we can try this command (ref: https://stackoverflow.com/questions/26505980/github-permission-denied-ssh-add-agent-has-no-identities).
`% ssh-add ~/.ssh/id_rsa`

And then, add SSH key into github
https://docs.github.com/en/authentication/connecting-to-github-with-ssh/adding-a-new-ssh-key-to-your-github-account