Resolve hostname set in ssh config

[guruor]

Original issue in upstream repo: ruifm/gitlinker.nvim#53

Working PR for the same in upstream repo: ruifm/gitlinker.nvim#52 (Pending review)

[linrongbin16]

hi, @G0V1NDS, thanks for mention it, I'm looking into it.

[linrongbin16]

would you please help me with some details:

1. when mention alias, can you give a specific case? if it's not data-sensitive. for example it's xyz-git.
2. you propose using ssh -G to resolve host, I need to check how does the command work, if it's a better way to resolve all git remotes, or just for your use case?
3. is it running ssh -G xyz-git, or running something? I am confused about the description.

[guruor]

@linrongbin16
I just referred open issue from upstream repo. Upstream issue and PR were created by @joaodubas

I will explain how I am using ssh config. SSH allows you to configure alias for the hosts.
For example I have this alias in my ~/.ssh/config:

Host github-personal
    HostName github.com
    User git
    IdentityFile ~/.ssh/id_rsa_personal
    Compression no

I can use this alias in git remote like this:

# ❯ git remotes
origin  https://github.com/G0V1NDS/dotfiles-open.git (fetch)
origin  https://github.com/G0V1NDS/dotfiles-open.git (push)
personal        git@github-personal:G0V1NDS/dotfiles-open.git (fetch)
personal        git@github-personal:G0V1NDS/dotfiles-open.git (push)

Here origin remote is configured from regular https URL provided when cloning the repo. I configured another origin named personal using github-personal alias.
Now when I push to personal remote, git internally resolves this alias and understands that github-personal is pointing to github.com and it has to use ~/.ssh/id_rsa_personal key.

We can get the same info from ssh -G by checking the config for the configured host.
Like this:

# ❯ ssh -G github-personal | grep ^hostname
hostname github.com

Not sure ssh -G is the best approach available, got to know about this from original issue only, but I can see that is will solve a generic problem and not limited to my use case.

[linrongbin16]

hi @G0V1NDS , really thanks for your detailed example and education.

I will first do some investigation into this (since I'm not expert in git alias), make sure the solution is good for most users.

[linrongbin16]

Hi @G0V1NDS , @joaodubas,

Please use below config to map github-personal.com to github.com:

require("gitlinker").setup({
    custom_rules = function(remote_url)
        local rules = {
            {
                "^git@github-personal%.([_%.%-%w]+):([%.%-%w]+)/([_%.%-%w]+)%.git$",
                "https://github.%1/%2/%3/blob/",
            },
            {
                "^git@github-personal%.([_%.%-%w]+):([%.%-%w]+)/([_%.%-%w]+)$",
                "https://github.%1/%2/%3/blob/",
            },
        }
        for _, rule in ipairs(rules) do
            local pattern = rule[1]
            local replace = rule[2]
            if string.match(remote_url, pattern) then
                local result = string.gsub(remote_url, pattern, replace)
                return result
            end
        end
        return nil
    end,
})

---

update: since #99 , you can simply config:

require("gitlinker").setup({
  override_rules = {
    {
      "^git@github-personal%.([_%.%-%w]+):([%.%-%w]+)/([_%.%-%w]+)%.git$",
      "https://github.%1/%2/%3/blob/",
    },
    {
      "^git@github-personal%.([_%.%-%w]+):([%.%-%w]+)/([_%.%-%w]+)$",
      "https://github.%1/%2/%3/blob/",
    },
  }
})

[guruor]

@linrongbin16 Thanks for a quick solution, really appreciate it.
I was able to achieve the expected result from the override_rules with some tweaks on your suggestion.

    override_rules = {
      {
        "^git@github%-personal:([%.%-%w]+)/([_%.%-%w]+)$",
        "https://github.com/%1/%2/blob/",
      },
      {
        "^git@bitbucket%-work:([%.%-%w]+)/([_%.%-%w]+)$",
        "https://bitbucket.org/%1/%2/src/",
      },
      {
        "^git@gitlab%-work:([%.%-%w]+)/([_%.%-%w]+)$",
        "https://gitlab.com/%1/%2/blob/",
      },
    },

Tweaks made:

• My ssh alias wasn't having TLD suffix, so I had to hardcode it in substitute pattern.
• Needed to escape the hyphen in the pattern %-personal to ensure proper functionality.

I would still prefer a solution which utilises the ssh config so user won't need to define a override rule as the information is already available in ssh config.
Will see how fugitive is achieving the host identification for ssh remotes.

[guruor]

@linrongbin16 A quick look at fugitive code tells that it is achieving the same by reading the ssh config file to read information ('user', 'hostname' and 'port') which helps derive the remote url.

[linrongbin16]

hi @G0V1NDS , thanks for point that out, I will check

[joaodubas]

@linrongbin16 the solution I implemented in a PR upstream parses the result ssh -G <alias>, as can be seen in lua/gitlinker/ssh.lua.

I can open the same PR here if it makes sense.

[linrongbin16]

yeah, @joaodubas thank you!

---

seems using ssh is the correct way to get the domain.

at first I am only thinking I can use a regex thing (lua pattern) to map host to remote, but now I found it's much more complicated.

a permanent git url contains multiple components ( for example: https://github.com/neovim/neovim/blob/2e156a3b7d7e25e56b03683cc6228c531f4c91ef/src/nvim/main.c#L137-L156):

1. domain: https://github.com, this part should be resolved by ssh -G.
2. user/repo: /neovim/neovim, for this plugin it's linrongbin16/gitlinker.nvim.
3. a route: /blob ( there's another requirement want to generate the /blame url, it's also another route).
4. a git commit: /2e156a3b7d7e25e56b03683cc6228c531f4c91ef.
5. the file path: /src/nvim/main.c.
6. the line ranges: #L137-L156. and I just found that github even support columns, it looks like #L137C1-L156C10.

I am thinking how to make this thing real powerful and customizable.

[linrongbin16]

@joaodubas , oh, I forgot why this lua/gitlinker/ssh.lua not in my fork (maybe at first I didn't know what this ssh is for, so I simply delete it?)

I will patch this part back to my fork. thanks for point that!

[joaodubas]

@linrongbin16 this is the module I created to solve the issue with aliases in ssh configuration. It belongs to the PR @G0V1NDS referenced on the first message (ruifm#52)

[linrongbin16]

hi @joaodubas , @G0V1NDS ,

I'm trying to add ssh -G host in this PR: #110.

But I have some issue when testing it in my local machine. I guess I don't have a correct environment (alias git host) to test this feature, would you please help test if it's working?

Or if this feature could be tested without an alias git host environment, would you please help my testing steps (not sure if my steps have any issues):

1. set my ~/.ssh/config:

   Host github-personal.com
       HostName github.com
       User git
       IdentityFile ~/.ssh/id_rsa_personal
       Compression no
   

2. set my ~/github/linrongbin16/gitlinker.nvim/.git/config:

   [core]
        repositoryformatversion = 0
        filemode = true
        bare = false
        logallrefupdates = true
        ignorecase = true
        precomposeunicode = true
    ; [remote "origin"]
    ;   url = https://github.com/linrongbin16/gitlinker.nvim.git
    ;   fetch = +refs/heads/*:refs/remotes/origin/*
    [branch "master"]
        remote = origin
        merge = refs/heads/master
    [lfs]
        repositoryformatversion = 0
    [user]
        name = linrongbin16
        email = linrongbin16@outlook.com
    [branch "feat-routers"]
        remote = origin
        merge = refs/heads/feat-routers
    [remote "personal"]
        url = git@github-personal.com:linrongbin16/gitlinker.nvim.git
        fetch = +refs/heads/*:refs/remotes/personal/*
   

   note: the last [remote "personal"] is the test target, and I commented the [remote "origin"].

3. open the file ~/github/linrongbin16/gitlinker.nvim/lua/gitlinker.lua, and press <leader>gl, there's an error:

   

4. Here's the debug logging:

   gitlinker.log

5. looks like the error is throwed from the command:

   git rev-parse personal

   it's trying to search a git commit in current repo.

6. all below commands are failed to search the correct git commit:

   git rev-parse @{u}
   git rev-parse personal

7. this command works:

   git rev-parse HEAD

8. but it's been filtered by the check function _is_rev_in_remote (it looks like trying to verify if the git commit exists in remote host, I guess if in a correct environment that has correct alias host, this filter should be correct?):

   git branch --remotes --contains HEAD
   git branch --remotes --contains HEAD~1
   git branch --remotes --contains HEAD~2
   git branch --remotes --contains HEAD~3
   ...

   The outputs is origin/feat-routes, which cannot match the personal, the check is here:

   gitlinker.nvim/lua/gitlinker/git.lua

   Lines 242 to 258 in f094ea6

   	if _is_rev_in_remote("HEAD", remote) then
   	local head_rev = _get_rev("HEAD")
   	if head_rev then
   	return head_rev
   	end
   	end
   	-- try last 50 parent commits
   	for i = 1, 50 do
   	local revspec = "HEAD~" .. i
   	if _is_rev_in_remote(revspec, remote) then
   	local rev = _get_rev(revspec)
   	if rev then
   	return rev
   	end
   	end
   	end

[guruor]

@linrongbin16 your ssh and git config looks good to me.
I tried testing the code on local and faced multiple issues except the rev-parse issue, added the fix for those in PR comments.