Deploy Node.js using Gitlab CI pipeline

Prerequisite

Repository in Gitlab with Node.js project
Production server for which you have SSH access
Configure a folder in the server for a production Node.js server using steps from this digitalocean guide

Goal

Setup the Gitlab CI/CD pipeline to push the Node.js code to the server and deploy it whenever code is merged to master branch.

Step 1 - Clone the repository in the server using deploy token

Using a deploy token ensures that we can pull the code without the need to enter the credentials manually or save the credentials in the deploy script.

Create a deploy token for the repository or for the associated group using the steps mentioned in the documentation
Clone the repository in the production server's folder using the steps from the documentation. Make sure to use the correct repository url.

Step 2 - Give Gitlab access to your server

We are going to use Gitlab CI/CD Variables to save a private SSH key which Gitlab will use to authenticate with the server.

We are going to use SSH keys to authenticate rather than username and password as it is more secure.

This can be configured at a repository level or at a group level.
To view all the CI/CD variables of your repository,

Go to your project’s Settings > CI/CD
Expand the Variables section.

You can also view the same at a group level by first navigating to the group (Menu > Groups > Your Groups) and following the same steps.

If you already have a SSH_PRIVATE_KEY private key variable listed, you can skip this step.

To create a new variable, Select the Add Variable button and fill in the details:

Key: SSH_PRIVATE_KEY
Value: <ssh_private_key_details>. (To generate a new SSH public and private key pair, follow steps from this guide. Make sure to not accidentally overwrite any existing key pairs.)
Type: Variable
Choose other settings based on your needs

Click Add Variable to add the variable

Step 3 - Add Gitlab SSH public key to your server

Now, we need to add SSH public key to the list of authorized_keys in the production server.

SSH into your server (ssh [email protected])
Add the SSH public key to authorized_keys
```
nano ~/.ssh/authorized_keys
```
Paste the SSH public key(starts withssh-rsa) in a new line
Save the file

Step 4 - Configuring Gitlab CI/CD

Gitlab looks for .gitlab-ci.yml in the root folder of your repository for CI/CD pipeline configurations

Add a new file .gitlab-ci.yml in the root folder

before_script:
  - apt-get update -qq
  - apt-get install -qq git
  # Setup SSH deploy keys
  - "which ssh-agent || ( apt-get install -qq openssh-client )"
  - eval $(ssh-agent -s)
  - ssh-add <(echo "$SSH_PRIVATE_KEY")
  - mkdir -p ~/.ssh
  - '[[ -f /.dockerenv ]] && echo -e "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config'

deploy:
  stage: deploy
  environment:
    name: production
    url: https://example.com
  script:
    - bash deploy/deploy.sh
  only:
    - master

Update the url in the above file to your domain

Explanation

We are using the default ubuntu docker package
We install git package and then configure it to add our SSH_PRIVATE_KEY
We also configure StrictHostKeyChecking to no, to ensure git doesn't show manual prompt during initial connection.
We have setup pipeline named deploy with a single pipeline stage deploy which listens to commits on master and runs the script in deploy/deploy.sh

Step 5 - Setup the deploy script

Add a new file deploy.sh in deploy folder

#!/bin/bash

DEPLOY_SERVER=$DEPLOY_SERVER

echo "Deploying to ${DEPLOY_SERVER}"
ssh root@${DEPLOY_SERVER} 'bash' < ./deploy/server.sh

Set the CI/CD variable DEPLOY_SERVER with value domain.com for the repository using step 1.

Explanation

We set server variable
We ssh into our server and then execute code at deploy/server.sh

Step 6 - Setup the server script

Add a new file server.sh in deploy folder

# Pull code
cd /var/www/html/folder-name/
git checkout master
git pull origin master

# Build and deploy
yarn install
yarn run build
pm2 restart server

Update the folder-name in the above script to match the folder name used in the prerequisite step

Explanation

We navigate to the folder
We get the latest changes from master branch
We install dependencies and then optionally run build(incase of typescript project)
Finally we restart the pm2 server

Step 7 - Setup a Gitlab runner (One time setup)

We need a runner to run our CI/CD pipeline jobs. This step is optional if a runner is already configured for your group in Gitlab.

To setup a new Gitlab group runner

Install Gitlab Runner in any server with atleast 2GB of RAM using the steps from the documentation. The server should be separate from where Gitlab is installed for security reasons.
Go to your group's Settings > CI/CD
Expand the Runners section.
Under the Set up a group runner manually section, copy the url and token
Then register the runner in your server using steps from documentation
- Provide default image as ubuntu and empty tags
Once the runner is registered, go back to the Runners section in Gitlab to see the runner appear under Available runners section

Push the .gitlab-ci.yml and deploy/deploy.sh, deploy/server.sh files to master to start the automated deployment.

When the deployment is complete, you should see a green checkmark in the repository home page similar to

You can click the status icon to go to the pipeline and then to the individual job to see the command line output of your script

Troubleshooting

If the job is not scheduled, make sure you have setup a runner and that the runner is active. Also check the runner parameters like active, protected and tags to see if any of the conditions are incorrect.