105 lines
2.9 KiB
Markdown
105 lines
2.9 KiB
Markdown
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---
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website: https://www.docker.com/
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obj: application
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---
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#refactor
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---
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Notes:
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- Docker (CLI)
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- Dockerfile
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- Docker Swarm
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---
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# Docker
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[Docker](https://www.docker.com/) is a utility to pack, ship and run any application as a lightweight container. Another container engine is [Podman](Podman.md)
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## Dockerfile
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Every container can be build from a `Dockerfile`.
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### Example
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A sample `Dockerfile`:
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```dockerfile
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FROM node:12-alpine
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RUN apk add --no-cache python2 g++ make
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WORKDIR /app
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COPY . .
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RUN yarn install --production
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CMD ["node", "src/index.js"]
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EXPOSE 3000
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```
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`FROM` defines the base image the container builds upon.
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`RUN` runs a specific command.
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`WORKDIR` changes working directory.
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`COPY` copies files into the container image.
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`CMD` is run when the container starts.
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`EXPOSE` exposes a port to the network.
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`ENV` sets environment variables
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`ENTRYPOINT` specifies the executable that will run when the container starts
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`ARG` defines build-time variables that can be passed to the `docker build` command with the `--build-arg` flag
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To build a `Dockerfile`:
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```shell
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docker build -t getting-started .
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```
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## Docker Compose
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[Docker Compose](https://docs.docker.com/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.
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### Example
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```yaml
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version: "3.7"
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services:
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app:
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build: ./app
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ports:
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- 3000:3000
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volumes:
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- ./:/app
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environment:
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MYSQL_HOST: mysql
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MYSQL_USER: root
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MYSQL_PASSWORD: secret
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MYSQL_DB: todos
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mysql:
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image: mysql:5.7
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volumes:
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- todo-mysql-data:/var/lib/mysql
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environment:
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MYSQL_ROOT_PASSWORD: secret
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MYSQL_DATABASE: todos
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```
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Every container is defined within the `services`.
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Ports Forwards and Volumes are defined in their respective `ports` and `volumes`.
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Everything inside `environment` is passed as a environment variable.
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Containers can use a prebuild image (`image: image:tag`) or build one from scratch (`build: ./dir`)
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### Usage
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```shell
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docker-compose -f docker-compose.yml up # Start services
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docker-compose -f docker-compose.yml down # Stop services
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docker-compose -f docker-compose.yml build # Rebuild services
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docker-compose -f docker-compose.yml pull # Pull images
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```
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## Docker Swarm
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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.
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### Usage
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```shell
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# Create a swarm
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docker swarm init --advertise-addr <MANAGER-IP>
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# Get a join command on manager
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docker swarm join-token worker
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# Join a swarm
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docker swarm join --token <TOKEN> <MANAGER-IP>:2377
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# View node info
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docker node ls
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```
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