Auto-deploy system through a system of etcd locks.

deploy.sh

git fetch

# check if a deploy is necessary
checked_out=$(git rev-parse HEAD)
production=$(git rev-parse origin/production)
if [ $checked_out = $production ]; then
    echo 'Nothing to deploy. Moving on...'
    exit 0
fi

# check lock states
val=$(etcdctl get --consistent  locks/api-internal-deploy)
if [[ $? = 4 ]]; then # when lock is brand new
    echo 'Setting up lock for the first time.'
    etcdctl mk locks/api-internal-deploy '0'
elif [[ "$val" != 0 ]]; then # when the lock is not brand new
    echo 'Waiting for lock...'
    etcdctl watch locks/api-internal-deploy # wait for change
fi

# acquire the actual lock
etcdctl set --swap-with-value '0' locks/api-internal-deploy '1'
if [[ $? != 0 ]]; then
    echo 'Cannot acquire lock... EXIT.'; exit 1
fi

# finally, we can do the deploy
echo "Updating api-internal.""$1"".service..."
systemctl try-restart api-internal."$1".service
restart_code=$?

# clean up
etcdctl set locks/api-internal-deploy '0'
if [[ $restart_code != 0 ]]; then
    echo 'Failed to restart service.'; exit 1
fi
echo "Updated api-internal.""$1"".service..."