Example
Available in Git 1.8.2 and above.
1.8
Pre-push hooks can be used to prevent a push from going though. Reasons this is helpful include: blocking accidental manual pushes to specific branches, or blocking pushes if an established check fails (unit tests, syntax).
A pre-push hook is created by simply creating a file named pre-push under .git/hooks/, and (gotcha alert), making sure the file is executable: chmod +x ./git/hooks/pre-push.
Here's an example from Hannah Wolfe that blocks a push to master:
#!/bin/bash
protected_branch='master'
current_branch=$(git symbolic-ref HEAD | sed -e 's,.*/\(.*\),\1,')
if [ $protected_branch = $current_branch ]
then
read -p "You're about to push master, is that what you intended? [y|n] " -n 1 -r < /dev/tty
echo
if echo $REPLY | grep -E '^[Yy]$' > /dev/null
then
exit 0 # push will execute
fi
exit 1 # push will not execute
else
exit 0 # push will execute
fi
Here's an example from Volkan Unsal which makes sure RSpec tests pass before allowing the push:
#!/usr/bin/env ruby
require 'pty'
html_path = "rspec_results.html"
begin
PTY.spawn( "rspec spec --format h > rspec_results.html" ) do |stdin, stdout, pid|
begin
stdin.each { |line| print line }
rescue Errno::EIO
end
end
rescue PTY::ChildExited
puts "Child process exit!"
end
# find out if there were any errors
html = open(html_path).read
examples = html.match(/(\d+) examples/)[0].to_i rescue 0
errors = html.match(/(\d+) errors/)[0].to_i rescue 0
if errors == 0 then
errors = html.match(/(\d+) failure/)[0].to_i rescue 0
end
pending = html.match(/(\d+) pending/)[0].to_i rescue 0
if errors.zero?
puts "0 failed! #{examples} run, #{pending} pending"
# HTML Output when tests ran successfully:
# puts "View spec results at #{File.expand_path(html_path)}"
sleep 1
exit 0
else
puts "\aCOMMIT FAILED!!"
puts "View your rspec results at #{File.expand_path(html_path)}"
puts
puts "#{errors} failed! #{examples} run, #{pending} pending"
# Open HTML Ooutput when tests failed
# `open #{html_path}`
exit 1
end
As you can see, there are lots of possibilities, but the core piece is to exit 0 if good things happened, and exit 1 if bad things happened. Anytime you exit 1 the push will be prevented and your code will be in the state it was before running git push....
When using client side hooks, keep in mind that users can skip all client side hooks by using the option "--no-verify" on a push. If you're relying on the hook to enforce process, you can get burned.
Documentation: https://git-scm.com/docs/githooks#_pre_push
Official Sample: https://github.com/git/git/blob/87c86dd14abe8db7d00b0df5661ef8cf147a72a3/templates/hooks--pre-push.sample
