CI-CD with Docker

Here is the step by step instructions to host a highly available website.

Pre-requisites

1. Create an account in dockerhub
2. Machine with Jenkins up and running
3. An agent with docker running
4. Install the git and java in Agent
5. Add this Agent to Jenkins with the label called docker
6. Edit the Agent's Security Group Inbound rules by allowing traffic on 8080, 8081, 8082 custom ports.

Creating Nginx Loadbalancer

Execute the following on agent

1. Create a directory called nginx and change into it.
2. Create a file called nginx.conf with following contents

upstream backend {
    server GATEWAYIP:8081;
    server GATEWAYIP:8082;
}

server {
    location / {
       proxy_pass http://backend;
    }
}

3. Get the Docker default gateway IP by running below command on docker agent.

GATEWAY=$(docker network inspect bridge | grep -i gateway | awk '{print $2}' | sed -e 's/,$//' -e 's/^"//' -e 's/"$//')

4. Replace the GATEWAYIP with the gateway ip.

sed -i 's/GATEWAYIP/'"$GATEWAY"'/g' nginx.conf

5. Confirm the GATEWAYIP is replaced with the actual ip address in nginx.conf.
6. Create a Dockerfile with following content

FROM nginx
LABEL owner=loki
LABEL desc="Nginx LoadBalancer"
RUN rm -rf /etc/nginx/conf.d/default.conf
COPY ./nginx.conf /etc/nginx/conf.d/default.conf

7. Create the docker image. Pls replace the registry with your registry

docker build -t lokeshkamalay/nginx:latest .

8. Store the image in Dockerhub

docker push lokeshkamalay/nginx:latest

Creating a Jenkins Pipeline

1. Setup a Jenkins Pipeline job with Pipeline Script from SCM
2. Choose repo as https://github.com/lokeshkamalay/tomcat_maven_app.git
3. Ensure the agent running docker is configured with the label docker
4. Create a credential with the name of docker-hub and input docker hub username and password.
5. Run the Job

Results

1. Confirm the job has run successful
2. Access your website with the Agent's Public IP on port 8080.