How to bind folders inside docker containers? - docker

Question

I have docker-compose.yml on my local machine like below:
version: "3.3"
services:
api:
build: ./api
volumes:
- ./api:/api
ports:
- 3000:3000
links:
- mysql
depends_on:
- mysql
app:
build: ./app
volumes:
- ./app:/app
ports:
- 80:80
mysql:
image: mysql:8.0.27
volumes:
- ./mysql:/var/lib/mysql
tty: true
restart: always
environment:
MYSQL_DATABASE: db
MYSQL_ROOT_PASSWORD: qwerty
MYSQL_USER: db
MYSQL_PASSWORD: qwerty
ports:
- '3306:3306'
The api is NestJS app, app, mysql - Angular and Mysql respectively. And I need to work with this one localy.
How could I make so, that any my changes will be applied without rebuilding containers every time?

Answer 1

You don't have to build an image for a development environment with your sources in it. For NestJS, and since you're using Docker (I voluntary specify this because it exists other container runtimes), you can simply run a NodeJS image from the Docker main registry: https://hub.docker.com/_/node.
You could run it with:
docker run -d -v ./app:/app node:12-alpine /app/index.js
N.B.: I choose 12-alpine for the example. I imagine the file to start your app is index.js, replace it with yours.
You must consider to install the node dependencies yourself and they must be in the ./app directory.
For docker-compose, it could look like this:
version: "3.3"
services:
app:
image: node:12-alpine
command: /app/index.js
volumes:
- ./app:/app
ports:
- "80:80"
Same way for your API project.
For a production image, it is still suggested to build the image with the sources in it.

Answer 2

Say you're working on your front-end application (app). This needs to make calls out to the other components, especially api. So you can start the things it depends on, but not the application itself
docker-compose up -d api
Update your application configuration for this different environment; if you would have proxied to http://api:3000 before, for example, you need to change this to http://localhost:3000 to connect to the container's published ports:.
Now you can develop your application totally normally, without doing anything Docker-specific.
# outside Docker, on your normal development workstation
yarn run dev
$EDITOR src/components/Foo.tsx
You might find it convenient to use environment variables for these settings that will, well, differ per environment. If you're developing the back-end code but want to attach a live UI to it, you'll either need to rebuild the container or update the front-end's back-end URL to point at the host system.
This approach also means you do not need to bind-mount your application's code into the container, and I'd recommend removing those volumes: blocks.