Display link to current git commit deployed

[justin808]

Let's display a link to the current git commit deployed on Heroku.

There's a number of options here:

http://stackoverflow.com/questions/14583282/heroku-display-hash-of-current-commit

[robwise]

Another possible option to consider is just using JavaScript to call the GitHub API for the repo, although this assumes continuous deployment.

[justin808]

Hi @robwise, the best way to do this is to set an env var as part of a deployment script.

```#!/bin/bash
# Pass in app as either staging or production first -- must match what you seen in git remote -v
# Examples:
# ./deploy staging
# ./deploy staging --force
# ./deploy production

app=$1

shift

sha=`git rev-parse HEAD 2>/dev/null`
current_branch=`git symbolic-ref HEAD 2> /dev/null | sed -e 's/refs\/heads\///'`

# echo "current_branch is $current_branch"
# echo "sha is $sha"
# echo "app is $app"

if [ "$app" == "" ]; then
  echo "You must specify a param value for the app, such as production or staging"
  exit 1
fi

if [[ "$app" == "production" && "$current_branch" != "master" ]]; then
  echo "You can only deploy master to production!"
  exit 1
fi

echo Running:
echo git push $app $current_branch:master $@
git push $app $current_branch:master $@

echo Setting heroku config DEPLOYMENT_SHA
echo heroku config:set DEPLOYMENT_SHA=$sha --remote $app
heroku config:set DEPLOYMENT_SHA=$sha --remote $app

# Run migrations always just in case
heroku run rake db:migrate --remote $app
heroku restart --remote $app

And then add this to application.rb:

  def self.current_sha
    @sha ||= if ENV["DEPLOYMENT_SHA"].present?
               puts "Set SHA to #{ENV['DEPLOYMENT_SHA']}"
               ENV["DEPLOYMENT_SHA"]
             else
               `git rev-parse HEAD 2>/dev/null`.to_s.strip
             end
  end

And then have this in the view:

Deployed Git Commit: <%=  RailsReactTutorial.current_sha %>

[robwise]

Work in progress: #125

[justin808]

Boom!