I’ve recently done some work on a personal project that I have put off for far too long. The project itself is a chat bot for moderating Telegram chat groups but this post isn’t about that project. Instead, it will focus on how I simplified setup of the development environment using Docker Compose.
I don’t have much experience with Docker or Docker Compose because in the past, I’ve used Vagrant for creating my environments. And Vagrant has been great, but over the years, I’ve run into a few issues:
virtual machines can take up to a minute to start, sometimes longer
new boxes (images) are slow to download
software versions fall out of sync with production environments
unexpected power outages have led to corrupted VMs
These issues are likely addressable in each configuration but between custom shell scripts and having so little experience with Ruby (Vagrantfiles are written in Ruby), managing it can quickly become unwieldy. Plus, Docker has become a de facto industry standard so it’s about time I learned something about it.
Ideally, this project would have a single file that makes spinning up a consistent development environment quick and painless, which is where Docker Compose comes in. A docker-compose.yml file; located in the root directory of the project, will make starting the environment as simple as running a single command; docker-compose up -d. The “-d” flag runs the containers in detached mode (the background) which frees up your terminal.
MongoDB
My first goal was to get MongoDB working with the project. This was relatively easy since the docker community maintains an official MongoDB image with an example docker-compose.yml:
# Use root/example as user/password credentials
version: ‘3.1’
services:
mongo:
image: mongo
restart: always
environment:
MONGO_INITDB_ROOT_USERNAME: root
MONGO_INITDB_ROOT_PASSWORD: example
mongo-express:
image: mongo-express
restart: always
ports:
– 8081:8081
environment:
ME_CONFIG_MONGODB_ADMINUSERNAME: root
ME_CONFIG_MONGODB_ADMINPASSWORD: example
ME_CONFIG_MONGODB_URL: mongodb://root:example@mongo:27017/
Since I wanted to start simple, I ran Node locally and connected to the MongoDB container as if it were another machine. To do that, ports needed to be exposed to the host machine. I also needed a database setup and for that same database to persist. I decided to keep the Mongo Express container as it creates a useful web interface for checking data.
version: ‘3.1’
services:
mongo:
container_name: toximongo
image: mongo
restart: always
environment:
MONGO_INITDB_ROOT_USERNAME: root
MONGO_INITDB_ROOT_PASSWORD: toxipass
MONGO_INITDB_DATABASE: toxichatdb
ports:
– 27017:27017
volumes:
– ./init-mongo.js:/docker-entrypoint-initdb.d/init-mongo.js:ro
– ./mongo-volume:/data/db
mongo-express:
container_name: toximongo-express
image: mongo-express
restart: always
ports:
– 8081:8081
environment:
ME_CONFIG_MONGODB_ADMINUSERNAME: root
ME_CONFIG_MONGODB_ADMINPASSWORD: toxipass
ME_CONFIG_MONGODB_URL: mongodb://root:toxipass@mongo:27017/toxichatdb
Some of the changes to take note of:
name containers to make them easy to differentiate and access
usernames + passwords set
expose MongoDB to local machine on port 27017
create a persistent volume at ./mongo-volume/ in the root of the project
run /docker-entrypoint-initdb.d/init-mongo.js to create a user and initialize the database
init-mongo.js is a very simple script that runs when the container is started for the first time.
db.createUser({
user: ‘root’,
pwd: ‘toxipass’,
roles: [
{
role: ‘readWrite’,
db: ‘toxichatdb’,
},
],
});
Node
After getting access to a database, the next step was to include Node. Since Node versions change frequently, its great to ensure that all developers are supporting the same version. It also simplifies getting started working on the project if a developer isn’t expected to have to install something else. This was also straightforward since there is an official image supplied by the Node JS Docker team with extensive documentation.
version: ‘3.1’
services:
node:
container_name: toxinode
image: “node:16”
user: “node”
working_dir: /home/node/app
environment:
– NODE_ENV=development
volumes:
– ./:/home/node/app
expose:
– “8080”
command: [sh, -c, “yarn && yarn start”]
mongo:
container_name: toximongo
image: mongo
restart: always
environment:
MONGO_INITDB_ROOT_USERNAME: root
MONGO_INITDB_ROOT_PASSWORD: toxipass
MONGO_INITDB_DATABASE: toxichatdb
ports:
– 27017:27017
volumes:
– ./init-mongo.js:/docker-entrypoint-initdb.d/init-mongo.js:ro
– ./mongo-volume:/data/db
mongo-express:
container_name: toximongo-express
image: mongo-express
restart: always
ports:
– 8081:8081
environment:
ME_CONFIG_MONGODB_ADMINUSERNAME: root
ME_CONFIG_MONGODB_ADMINPASSWORD: toxipass
ME_CONFIG_MONGODB_URL: mongodb://root:toxipass@toximongo:27017/toxichatdb
Again, I’ve given the container a custom name. There isn’t much else changed except for the command which issues a shell inside the container, calls Yarn to install dependencies, and then starts the application.
Summary
Since incorporating Docker Compose with this project, I’ve been impressed at the speed with which my development environment can start. This setup doesn’t include a Dockerfile but because it isn’t building custom images, I didn’t think that was necessary to include. I’m certain there are ways to improve it and I’ve got lots to learn, especially if I’d like to incorporate deploying this to production environments. If you’ve got tips or suggestions, let me know!