I'm using go-git through a project and faced this error: [...]: author field is required.

In my Git configuration I do not specify the user.email field; here is the excerpt:

   1   │ [user]
   2   │     name = Edoardo ...
   3   │     useConfigOnly = true

This configuration forces to set user.email setting for each repo.

I went on debugging this:

• the error is triggered by

  go-git/options.go

  Lines 505 to 507 in 99457e5

  	if o.Author == nil {
  	return ErrMissingAuthor
  	}

  
  in the

  go-git/options.go

  Line 475 in 99457e5

  func (o *CommitOptions) loadConfigAuthorAndCommitter(r *Repository) error {

  
  function
• loadConfigAuthorAndCommitter is called by CommitOptions.Validate(), executed as first step in Worktree.Commit()
  

  go-git/worktree_commit.go

  Lines 21 to 24 in 99457e5

  	func (w *Worktree) Commit(msg string, opts *CommitOptions) (plumbing.Hash, error) {
  	if err := opts.Validate(w.r); err != nil {
  	return plumbing.ZeroHash, err
  	}

• loadConfigAuthorAndCommitter function first step is to load the system configurations:
  

  go-git/options.go

  Line 476 in 99457e5

  cfg, err := r.ConfigScoped(config.SystemScope)

This behaviour seems to contradicts the git documentation about Environment variables. Under Committing in Git Internals Environment variables is written:

The final creation of a Git commit object is usually done by git-commit-tree, which uses these environment variables as its primary source of information, falling back to configuration values only if these aren’t present.

(Incidentally these variables include GIT_AUTHOR_NAME and GIT_AUTHOR_EMAIL, which should override any file based configuration and I tried using to overcome the mentioned error).

Expected behaviour: go-git follows git behaviour and respects environment variables at commit time, not relying only on file based configurations

By looking at other issues I noticed aligning with what git does is important, so I would contribute a PR to change this behaviour by loading specified environment variables in loadConfigAuthorAndCommitter before system configuration and configuring author and committer accordingly to what git docs say.