I like writing blog posts, particularly about code, and I like to link to code on my repo from my blog post. I do this a lot. Until now, I’ve just been copying and pasting the full link to github. However, I ran into a problem today.

I moved a file that was referenced in a blog post. I then had to go to that blog post and update the links - this is fine if I remember the linked blog posts - but that’s not scalable.

Also:

• Finding the link on GitHub, then copying and pasting is annoying
• It worries me a little that the version they are linked to could be vastly different from what I mention on the post.

I was already trying to create permalinks using tags, but that is laborious and error prone.

What if I could get Hugo to:

• Automatically link to GitHub if the relative link is not within blog/content
• What if I could get it to link it to the file at the last commit of the post.

The last one is something to bear in mind. If I update a blog post, I’ll have to ensure that the links are still relevant.

Alternatively, let’s allow an override at the page level where you can provide a specific commit to link to:

Step 1: Enable git info

To be able to get the commit of the post, we need to enable git info

hugo.toml

1

enableGitInfo = true

Step 2: Update rendering of link

layout/_default/_markup/render-link.html

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16

{{- $linkPath := .Destination -}}                           {{/* e.g. "../scripts/tool.sh" */}}
{{- $currentPath := .Page.File.Path -}}                     {{/* e.g. "posts/foo.md" */}}
{{- $currentDir := path.Dir $currentPath -}}                {{/* e.g. "posts" */}}

{{- $combined := path.Join $currentDir $linkPath -}}        {{/* e.g. "posts/../scripts/tool.sh" */}}
{{- $resolved := path.Clean $combined -}}                   {{/* e.g. "scripts/tool.sh" */}}

{{- $fullRepoPath := path.Join "blog/content" $resolved -}} {{/* e.g. "blog/content/scripts/tool.sh" */}}

{{- $isInContent := strings.HasPrefix $fullRepoPath "blog/content/" -}}

{{- if $isInContent -}}
    <span class="unpublished">{{ $text }}</span>
{{- else -}}
    {{- $commit := or .Page.Params.link_commit .Page.GitInfo.Hash -}}
    <a href="https://github.com/drone-ah/wordsonsand/blob/{{ $commit }}/{{ $fullRepoPath }}" {{ with .Title }}title="{{ . }}"{{ end }}>{{ $text }}</a>

Bonus: Allow per-post commit override

In the above code:

1

{{- $commit := or .Page.Params.link_commit .Page.GitInfo.Hash -}}

The commit id is picked up from the page parameter link_commit, or if that doesn’t exist, from the last commit of the page.

You can therefore, set the commit to use for a post with:

1

link_commit: <custom-commit-to-link-to>

Conclusion

Necessity might be the mother of invention, but sometimes it takes a fine-tuned sense of frustration to detect minor needs.