In the previous post, we saw how we can run more than one containers and how to route requests to them using nginx.
Of course, we had to build 3 images individually, and then run the three images in sequence to get the final ecosystem.
In this post, we'll try to combine all the steps in just one command using docker-compose.
We'll start with the same repo, where the previous post's code is checked in, clone it locally, and then setup the docker-compose yml file, and run it.
Step 1. Clone the codebase.
Clone the repo https://github.com/tirthaguha/container-reverse-proxy.
Step 2. Create the YML file
Network Drivers
Okay, so before we create the docker-compose.yml file, its important to understand how networking works in docker-compose.
Docker can create a virtual network for you to abstract the complexities of networking, and all your containers run and interact in that network. One interesting thing about this virtual network is the network driver. Based on your container ecosystem setup, the drivers can be bridge, overlay and macvlan.
In our case, since we're going to run all the containers in the same host, we're going to chose bridge network driver in our docker compose file. You may have a look into this article and learn more about docker networks
Create the docker compose file
docker-compose.yml is a file that contains all the information about the applications, their Dockerfiles and the network they are going to run in.
Here's our annotated docker-compose.yml that you need to put in your container-reverse-proxy
directory.
version: "3"
# start by defining the services
services:
# this is the first nodeJS application
nodejs_1:
# lets keep name of the image as first-app
image: first-app
# this is where the Dockerfile is compiled into an image
build:
# where is the Dockerfile kept, relative to this directory
context: ./first-app
# obviously, the Dockerfile in that directory
dockerfile: Dockerfile
# port mapping
ports:
- 3000:3000
# name of the container
container_name: first-app
# if the container crashes, it would be restarted automatically
restart: unless-stopped
# the virtual network of which this container will be a part of
networks:
- app-network
# this is the second nodeJS application
nodejs_2:
# lets keep name of the image as first-app
image: second-app
build:
# where is the Dockerfile kept, relative to this directory
context: ./second-app
dockerfile: Dockerfile
ports:
- 4000:4000
container_name: second-app
restart: unless-stopped
networks:
- app-network
# Finally, the nginx, that controlls the route
nginx-server:
image: nginx-load-balancer
build:
context: ./nginx
dockerfile: Dockerfile
ports:
- 8080:80
container_name: nginx-load-balancer
restart: unless-stopped
networks:
- app-network
# the mysterious item, network
networks:
app-network:
driver: bridge
Step 3. Run the docker-compose file
Just run
$ sudo docker-compose up -d
then go to your browser and try opening the following URLs
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