2.9 KiB
| website | obj |
|---|---|
| https://www.docker.com/ | application |
#refactor
Notes:
- Docker (CLI)
- Dockerfile
- Docker Swarm
Docker
Docker is a utility to pack, ship and run any application as a lightweight container. Another container engine is Podman
Dockerfile
Every container can be build from a Dockerfile.
Example
A sample Dockerfile:
FROM node:12-alpine
RUN apk add --no-cache python2 g++ make
WORKDIR /app
COPY . .
RUN yarn install --production
CMD ["node", "src/index.js"]
EXPOSE 3000
FROM defines the base image the container builds upon.
RUN runs a specific command.
WORKDIR changes working directory.
COPY copies files into the container image.
CMD is run when the container starts.
EXPOSE exposes a port to the network.
ENV sets environment variables
ENTRYPOINT specifies the executable that will run when the container starts
ARG defines build-time variables that can be passed to the docker build command with the --build-arg flag
To build a Dockerfile:
docker build -t getting-started .
Docker Compose
Docker Compose is an alternate CLI frontend for the Docker Engine, which specifies properties of containers using a docker-compose.yml YAML file rather than, for example, a script with docker run options. This is useful for setting up reoccuring services that are use often and/or have complex configurations.
Example
version: "3.7"
services:
app:
build: ./app
ports:
- 3000:3000
volumes:
- ./:/app
environment:
MYSQL_HOST: mysql
MYSQL_USER: root
MYSQL_PASSWORD: secret
MYSQL_DB: todos
mysql:
image: mysql:5.7
volumes:
- todo-mysql-data:/var/lib/mysql
environment:
MYSQL_ROOT_PASSWORD: secret
MYSQL_DATABASE: todos
Every container is defined within the services.
Ports Forwards and Volumes are defined in their respective ports and volumes.
Everything inside environment is passed as a environment variable.
Containers can use a prebuild image (image: image:tag) or build one from scratch (build: ./dir)
Usage
docker-compose -f docker-compose.yml up # Start services
docker-compose -f docker-compose.yml down # Stop services
docker-compose -f docker-compose.yml build # Rebuild services
docker-compose -f docker-compose.yml pull # Pull images
Docker Swarm
Current versions of Docker include swarm mode for natively managing a cluster of Docker Engines called a swarm. Use the Docker CLI to create a swarm, deploy application services to a swarm, and manage swarm behavior.
Usage
# Create a swarm
docker swarm init --advertise-addr <MANAGER-IP>
# Get a join command on manager
docker swarm join-token worker
# Join a swarm
docker swarm join --token <TOKEN> <MANAGER-IP>:2377
# View node info
docker node ls