Automatic Git commit signing with GPG on OSX

.profile

# In order for gpg to find gpg-agent, gpg-agent must be running, and there must be an env
# variable pointing GPG to the gpg-agent socket. This little script, which must be sourced
# in your shell's init script (ie, .bash_profile, .zshrc, whatever), will either start
# gpg-agent or set up the GPG_AGENT_INFO variable if it's already running.

# Add the following to your shell init to set up gpg-agent automatically for every shell
if [ -f ~/.gnupg/.gpg-agent-info ] && [ -n "$(pgrep gpg-agent)" ]; then
    source ~/.gnupg/.gpg-agent-info
    export GPG_AGENT_INFO
else
    eval $(gpg-agent --daemon --write-env-file ~/.gnupg/.gpg-agent-info)
fi

gpg-agent.conf

# Enables GPG to find gpg-agent
use-standard-socket

# Connects gpg-agent to the OSX keychain via the brew-installed
# pinentry program from GPGtools. This is the OSX 'magic sauce',
# allowing the gpg key's passphrase to be stored in the login
# keychain, enabling automatic key signing.
pinentry-program /usr/local/bin/pinentry-mac

gpg.conf

# Uncomment within config (or add this line)
use-agent

setup-gpg

# A quick outline of what must be done to get everything working.

# 1) Install the dependencies.
brew install gnupg gpg-agent pinentry-mac

# 2) Configure git to automatically gpgsign commits. This consists of
#    pointing git to your signing key ID, and then enabling commit
#    automatic signing.
git config --global user.signingkey <YOUR-SIGNING-KEY-PUB-ID>
git config --global commit.gpgsign true

# 3) Configure the GPG components (see above for relevant examples):
#    ~/.gnupg/gpg.conf
#    ~/.gnupg/gpg-agent.conf

# 4) Start the daemon and configure your shell (see above for example in .profile).
#    ~/.bash_profile | ~/.zshrc

# Don't forget to upload your public key to Github!
# https://github.com/blog/2144-gpg-signature-verification
# Note: There needs to be a three-way match on your email for Github to show
# the commit as 'verified': The commit email, github email, & the email associated with the public key

# Learn about creating a GPG key and the knowledge behind these commands here:
# https://git-scm.com/book/en/v2/Git-Tools-Signing-Your-Work