Getting current Git commit version from within Rails app?

Question

How can I retrieve the current Git commit version from within a Ruby on Rails app?

Want to display the Git version (or maybe the last 6 letters or so) to serve as an App version.

Reactivate

Answer 1

You can invoke the git command from within your script:

commit = `git show --pretty=%H`
puts commit

Depending on your environment you may want to use the full path to the git binary, and possibly specify the GIT_DIR via an environment variable or --git-dir.

Forejudge

Learned something new today, thanks! Didn't know you could use back-quotes for shell commands. – Reactivate

I haven't used it so I can't recommend it from experience but you can use grit if you want something that's more OO. – Sybyl

Aaron, considered grit, but that's a more involved solution than my simple use. – Reactivate

Answer 2

Like @meagar said, use backticks to execute the shell command from within your app, but you may find these two commands more useful:

Full hash:

git rev-parse HEAD

First 7 characters of hash:

git rev-parse --short HEAD

Gin

I used commit = `git rev-parse HEAD`.chomp to remove the trailing newline – Iain

So, in Rails console: puts `git rev-parse HEAD` – Kandicekandinsky

Answer 3

A more robust solution would be git show --pretty=%H -q. The -q flag quiets the output.

In order to remove the newline that is part of the output, you can use chomp. For example: system('git show --pretty=%H -q').chomp

The selected answer has the potential to actually return the diff when the commit is not a merge commit. Verified on git version 2.16.2.windows.1.

Phobos

Amazing. I asked this question 7 yrs ago, and was just utilizing the answers again in a Heroku app, and you actually posted an answer at the same time. Thanks! – Reactivate

Answer 4

I presume that you want to include the app version in your HTML somewhere? The prerequisite is that you are deploying your repo with Capistrano in the default manner (you are uploading the repo, not sending up an archive file).

You can add some code to the Rails initializer as outlined here. That approach will get the SHA1 from the last commit, and make it available as an environment variable.

The other way to do it is have you Capistrano task generate a static file in the public directory with the commit SHA in it. You could include other info in this file that seems useful.

Inunction

With capistrano 3, simply read the file REVISION, in current folder. – Doorstone