Deploy a nodejs app to AWS/DigitalOcean like yo do in heroku.

For a while now my deployment workflow has been very simple t

• Prerequisites

Install npm and pm2 in the production server and make sure they are in the system Path .

• ssh to your production server

$ ssh user@productionserver

• create deploy directory

$ mkdir my-app

• Navigate inside the deploy directory

$ cd my-app

• Initialise bare repo

$ git init --bare app.git

• Create directory for live code

$ mkdir -p deployments/production # Hold production code
$ mkdir -p deployments/test       # Hold test code

• Add post receive git hook

$ touch app.git/hooks/post-receive
$ chmod +x app.git/hooks/post-receive

Inside post-receive paste the following code snippets

#!/bin/sh
#
## store the arguments given to the script
read prevCommitSHA latestCommitSHA fullbranchName
# fullbranchName argument always comes as ref/heads/<branchName>
# and I am only interested with the last name
branch=${fullbranchName##*/}
WEBROOT="/home/ubuntu/my-app"
PROJECT="deployments"
APP="myAppName"
LOGFILE="$WEBROOT/$PROJECT/post-receive.log"
DEPLOYDIR=null
PORT=null
echo "log: $LOGFILE"
##  Record the fact that the push has been received
echo "Received Push Request at $( date +"%F %T" ) for #branch $branch"  >> $LOGFILE
echo "Checking deployment rules for project:$PROJECT, branch: $branch"
# Log the branch name
echo "---------------------------Deploy Start-------------------------------------" >> $LOGFILE
if [ $branch = "master" ]
    then
    DEPLOYDIR="$WEBROOT/$PROJECT/production"
    PORT=3000
fi
if [ $branch = "develop" ]
    then
    DEPLOYDIR="$WEBROOT/$PROJECT/test"
    PORT=5678
fi
if [ $DEPLOYDIR = null ]
    then
    echo "Received branch $branch, not deploying."
    exit
fi
pm2 stop "${APP}_${branch}" >>null
echo "Stopped server at $( date +"%F %T" )" >> $LOGFILE
echo "Deploying to $DEPLOYDIR" >> $LOGFILE
echo " - Starting code checkout"  >> $LOGFILE
GIT_WORK_TREE="$DEPLOYDIR" git checkout -f "$branch"
echo " - Finished code checkout"  >> $LOGFILE
echo " - Starting npm install" >> $LOGFILE
cd "$DEPLOYDIR"
rm -rf node_modules
npm install  >> $LOGFILE
echo " - Finished npm install"  >> $LOGFILE
echo "Restarting server using pm2 at $( date +"%F %T" )" >> $LOGFILE
PORT="$PORT" pm2 start server.js --name "${APP}_${branch}" >> $LOGFILE
echo "Restart completed at $( date +"%F %T" )"  >> $LOGFILE
cd - 1>>/dev/null
echo "---------------------------Deploy Complete---------------------------------" >> $LOGFILE
echo "Done. Run 'pm2 ls' on the server to see the process status."

• Update bashrc

As you can see inside the post-receive hook we have used npm and pm2 which must be in the PATH to avoid not-found command error during push. Despite the fact that you might already have npm and pm2 in the system path but the path environmental variables in linux servers tends to be available only in the interactively shell(e.g when you have login) and since our post receive script will run in non-interactive shell so we will have not-found command error unless we tweak the system to include environmental variables even in non-interactive shell. To do that update the bashrc file by commenting out the following lines

# If not running interactively, don't do anything
case $- in
    *i*) ;;
      *) return;;
esac

• Push

Go back to the local server and just push to the production server to see our post-receive hook in action

$ git push deploy master