Docker for NodeJS - 2. Docker Compose Basics

• back to Docker for NodeJS

The instructor recommends that in day to day activities we should be using docker-compose YAML files instead of complex docker commands on terminal.

The first insight I had (as a DevOps Eng.), was to have a docker-compose setup for each job on a pipeline. Being able to quickly reproduce the pipeline locally.

docker-compose up

• build/pull image(s) if missing
• create volume/network/container(s)
• starts container(s) in foreground (-d to detach)
• --build to always build

docker-compose down

• stop and delete network/container(s) (keeps the volumes by default)
• use -v to delete volumes

docker-compose ...

• many commands take "service" name as option (not the container name)
• build just [re]build image(s)
• stop just stop containers, don't delete
• ps list "services"
• push images to registry
• logs same as docker CLI
• exec same as docker CLI

Assignment

clone the repo: https://github.com/BretFisher/docker-mastery-for-nodejs

# inside the repository directory...

# run through simple compose commands
cd sample-02
docker compose up
# ^c (same as `docker-compose stop`)
docker compose down
docker compose up -d # detached
docker compose ps
docker compose logs

# while app is running detached...
docker compose exec web sh
curl localhost # curl is not installed...
exit

# edit Dockerfile, add curl with apk
# RUN apk add --update curl
docker compose up -d # it won't rebuild the image

# force rebuild the image
docker compose up -d --build

# now try curl again
docker compose exec web sh
curl localhost # not it should works!
exit

# to finalize the assignment...
# inside sample-02/ dir
docker compose down