Skip to content

Latest commit

 

History

History
291 lines (206 loc) · 8.06 KB

docker.md

File metadata and controls

291 lines (206 loc) · 8.06 KB
Raw

Docker

Docker is a platform that uses containers to package software and its depencies into a light and isolated environment

Key Terms

Container

A lightweight, standalone, and executable software package that includes everything needed to run a piece of software
or
An isolated process in a machine that can contain an application and all its necessary dependencies. Isolated filesystems provided by an image
Each container should do one thing and do it well
**********

Context

A specific environment where Docker operates and performs actions. Similar to a BE(Boot Environment) has the exact rules, settings, and configurations/conditions needed by the app.
The configuration and settings for Docker to interact with different container env_ Examples: local Docker install, remote Docker host, or a cloud-based container service like AWS ECS or kubernetes.
**********

Volumes

Map specific filesystem path on local machine to the container for persistent data
Named Volumes: Bucket of data. Docker maintains the physical location on the disk. End user names only needs to remember the name of the volume
Bind Mounts: We control the exact mountpoint on the host. Can be used to persist data or more often to provide additional data inst containers.
**********

Image

A template of a container's filesystem. It has everything needed to run the application - all dependencies,configuration, scripts, binaries, etc.
Also has it's own configuration stored like env vars
**********

Environment variables

A default command to run on other metadata
**********

Tags

Giving it a unique name and version to be easily identifiable and allows others to pull specific version **********

Network

Provides a way for containers to communicate with each other in a virtual network environment. If two containers are on the same network, they can talk to each other. If they aren't, they can't.
network alias are assigned as a more descriptive name for containers to use when communicating with one another.
**********

Getting Started

COMMAND

``
-
**********

See all Docker images

docker images
**********

See docker image history

docker image history <img> --no-trunc See the layers in the image untruncated **********

Build docker image

docker build -t <image_name>:<tag> <path_to_docker_file>
-t name for the image
-f <path to docker file>
**********

See all containers running and not running

docker ps -a
-a show all containers
**********

Run docker compose file

docker compose <action> up
down Tear down containers
-d detached **********

Create and run a container

docker run --name <name> <image>:<version>

-d detached mode running container in the background
-p map port of x of the host to port y in the container
--rm remove container when stopped
-v <volume_name_or_absolute_path>:<cntner_pth> Will created named volume if not already created
-w <working_directory> sets the container present working directory where the command will run from -e Set environment variables for the container
--network <network_name> Connects container to specific docker network
--network-alias <cntnr_alias> Assigns additional alias to a container when connected to a network. An alternative name other containers can refer to the container.
<optional_corresponding_interprt> <optional_cmnd> command to run on container <username>/<repo_name> Can include the user and the repo of that user you want to pull an image from instead of <image>:<version>
<optional_interprt> <optional_cmnd> command to be ran in the container example: bash -c "echo Hello!" | sh -c "echo Hello! | python /path/to/your/project.py
Example

docker run -dp 3000:3000 -v todo-db:/etc/todos getting-started

docker run -dp 3000:3000 \
    -w /app -v "$(pwd):/app" \
    node:18-alpine \
    sh -c "yarn install && yarn run dev"

**********

Rename a container

docker rename <og_name> <new_name>

**********

Start Docker container

docker start <container>
-i interactive
**********

Stop Docker container

docker stop <container>

**********

Delete the container

docker rm <container_name_or_id>
-f forcefully stop the container if running and then delete it

**********

Container logs

docker logs -f <container_name_or_id> <container_name_or_id> optional can show logs of all containers
-f Follow log output

Advanced

Creating network

docker network <action>
create <network_name>
inspect see network info
ls see list of networks
**********

Volume

docker volume <action>
create <name_volume>
inspect see info of volume
ls see list of volumes
**********

Execute a command into a container

docker exec <container> <command>
-i interactive. Keep STDIN open even when unattached
-t Allocate a pseudo-TTY(emulation of a physical terminal) Example:
docker exec -it 56a714cded3b /bin/bash open an interactive session with a pseudo-TTY pointing to the shell intrepeter /bin/bash
docker exec 56a714cded3b cat /data.txt
**********

Create a tag for an existing docker image

docker tag <image name>:<optional_tag> <YOUR-USER-NAME>/<repo name>
**********

Push docker image into Docker hub repo

docker push <username>/<image_name>:<optinal_tag>

**********

Change the environment where Docker operates

docker scout <action> <image>
cves <img1> Display CVEs (Common Vulnerabilities and Exposures) identified in an image quickview <img1> Quick overview of an image compare <img1> <img2> compare two images and display differences
recommendations Display available base image updates and remediation recommendations **********

Change the environment where Docker operates

docker context create ecs myecscontext

**********

Configs

Docker Image file

A docker file defines the configuration and instructions for building a docker container image
The file is named Dockerfile

FROM <base_image>
WORKDIR <working_dir_on_container>
ADD <path_of_local_file_to_add> <path_on_cntnr_to_save_file>

Docker Compose file

Defines the configuration of multiple containers in one file. Define and share multi-container applications.
docker-compose.yml

services: #list of services/containers we want to run
  <service_name_(app)>: # The name will automatically become a network alias
    image: node:18-alpine
    container_name: bless #if name is not specified it will default to: <project-name>_<service-name>_<replica-number>
    command: sh -c "yarn install && yarn run dev"
    ports:
      - 3000:3000
    working_dir: /app
    volumes:
      - ./:/app
    environment:
      MYSQL_HOST: mysql
      MYSQL_USER: root
      MYSQL_PASSWORD: secret
      MYSQL_DB: todos

  <service_name_(mysql)>:
    image: mysql:8.0
    volumes: # Named volumes are not automatically created in docker compose file like cli
      - todo-mysql-data:/var/lib/mysql
    environment: 
      MYSQL_ROOT_PASSWORD: secret
      MYSQL_DATABASE: todos

volumes: #need to define the volume in the top-level
  todo-mysql-data: #only providing volume name will use default options

Processes

Sharing an App

  1. Create an image
  2. Test image and create a container
  3. Upload image to Docker Hub
    a. Create repo b. Tag image
    c. Push image

**********

Images

nginx
mysql:8.0
node
python:3
nicolaka/netshoot
useful for troubleshooting or debugging networking issues.

**********

Links

Docker tutorial
Play with Docker
Docker CLI