docker-quickref.md

Show docker version

Syntax:

docker version

List images

Syntax:

docker image ls 

List containers

List all running containers

Syntax:

docker container ls 

List all containers including stopped

Syntax:

docker container ls --all

Download image

docker image pull diamol/ch02-hello-diamol-web

Build image

docker image build --tag web-ping .
or
docker image build -t web-ping .

Skip cache while building

docker build -t <tag> --pull --no-cache -f <dockerfile> .

Clean system

Stop all and remove all containers (Linux):

docker ps -aq | xargs docker stop | xargs docker rm

Remove all containers (Windows, PowerShell):

docker rm @(docker ps -aq)	

Remove all images (Linux):

docker image rm -f $(docker image ls -f reference='diamol/*' -q)

Remove all containers (Linux):

docker container rm -f $(docker container ls -aq)

or (for non-running only)

docker rm $(docker ps -q -f status=exited)

Remove all containers (Windows Batch):

FOR /f "tokens=*" %i IN ('docker ps -a -q') DO docker rm %i	

Prune system

Remove all unused objects except volumes and containers:

docker system prune

Remove all unused objects with volumes:

docker system prune --volumes

Remove all unused objects with volumes and stopped containers:

docker system prune --volumes -a

Remove all unused volumes:

docker volume prune

Remove all unused images:

docker image prune

Remove all stopped containers:

docker container prune

Remove all stopped containers older than 24 hours:

docker container prune --filter "until=24h"

Remove unused networks

docker network prune

Execution modes

interactive mode:

docker container run -it --tty diamol/base

detached mode:

docker container run --detach --publish 8088:80 diamol/ch02-hello-diamol-web
or
docker container run -d --name web-ping diamol/ch03-web-ping

start stopped container:

docker container start --attach <container-id>
ex. docker container start --attach f1

Pass settings to container during start

docker container run -d --env TARGET=google.com diamol/ch03-web-ping
or
docker container run -d -e TARGET=google.com diamol/ch03-web-ping

List all containers

Syntax:

docker ps -a

Stop container

docker stop <container-id>

Run container from image

docker container run --name <container-name> -d -p <published-port> --network <network-name> <image-name>
ex. docker container run --name iotd -d -p 800:80 --network nat image-of-the-day

Execute commands

Execute shell

Syntax:

docker exec -it <container> bash
or
docker exec -it <container> /bin/bash
or
docker exec -it <container> /bin/sh

Example:

docker exec -it 881 bash
or
docker run -it my-image:v1 sh

Run command inside container

Syntax:

docker container exec <container-id> <command>

or for Windows:

docker container exec <container-id> cmd /C "<command>"

Example (Linux):

docker container exec 74f86665f0fd ls

Example (Windows):

docker container exec 86b cmd /s /c dir C:\usr\local\apache2\htdocs
docker container exec 86b cmd /C "dir C:\data"

Info on image

Show commands used to build the image

Syntax:

docker image history <image-name>

Example:

docker image history diamol/ch03-web-ping

Info on container

Show detailed info about container

Syntax:

docker container inspect <container-id>

Example:

docker container inspect c0

Show logs

Syntax:

docker container logs <container-id>
or
docker container logs <container-name>

Example:

docker container logs c0

Copy files from host to container (running or stopped)

Syntax:

docker container cp <source-path> <container-id>:<target-path>

Example:

docker container cp index.html 86b:/usr/local/apache2/htdocs/index.html

Copy files from container (running or stopped) to host

Syntax:

docker container cp <container-id>:<source-path> <target-path>

Example:

docker container cp rn1:/random/number.txt number1.txt 

Save changes

Save container changes

Syntax:

docker container commit <container-id>

Example:

docker container commit 881	

// or (creates new container)	
docker container commit ch03lab ch03-lab-soln

Network

Overview

The host networking driver only works on Linux hosts, and is not supported on Docker Desktop for Mac, Docker Desktop for Windows, or Docker EE for Windows Server.

Create network

Syntax:

docker network create <network-name>

Example:

docker network create nat

Use network

docker container run --name <container-name> -d -p <published-port> --network <network-name> <image-name>
ex. docker container run --name iotd -d -p 800:80 --network nat image-of-the-day

Note:

• on Windows, when you need to use "nat" network it is possible user will not be able to create it for Windows containers
  • "nat" is predefined network on Windows
  • see also: Windows container network drivers
• on Linux, you can use any name, "nat" is recommended for compatibility with Windows

Remove network

Syntax:

docker network rm <network-name>

Example (Linux):

docker network rm nat

Volumes

List mount points for container

docker container inspect --format '{{.Mounts}}'	todo1

List all existing volumes in system

docker volume ls		

Create volume manually:

docker volume create <volume-id>

Attach manually created volume:

docker container run -d -p <port-mapping> -v <volume-name>:<container-path> --name <image-name>		
ex. docker container run -d -p 8011:80 -v todo-list:/data --name todo-v1		

Attach volume from another container:

docker container run -d -p 8011:80 --volumes-from todo1 /diamol/ch06-todo-list

List volume contents

docker run --rm -i -v=<volume-name>:<tmp-path> busybox find <tmp-path>
ex. docker run --rm -i -v=ch06-lab:/tmp/myvolume busybox find /tmp/myvolume

Mounted directories

Mount host directory as container directory

docker container run (...) --mount type=bind,source=$source,target=$target[,readonly]

Mount volume as directory

 docker run -d --name=<container-name> --mount source=<volume-name>,destination=<container-path> <image-name>
 ex. docker run -d --name=nginxtest --mount source=nginx-vol,destination=/usr/share/nginx/html nginx:latest

Publishing

Login

Login action is required in order to publish images.

Syntax:

docker login --username <registry-user-name>

Example:

docker login --username myuser

Tag image for publishing

Image must be tagged with account id in order to be published in the repository.

Syntax:

docker image tag <input-image-name> <account-id>/<image-reference>:<version-id>

Example:

docker image tag image-gallery myuser/image-gallery:v1	

List image references

To list image references with a given name:

Syntax:

docker image ls --filter reference=<image-reference> --filter reference='*/<image-reference>'

Example:

docker image ls --filter reference=image-gallery --filter reference='*/image-gallery'

Publish image in remote repository

Syntax:

docker image push <account-id>/<image-name>:<image-version>

Example:

docker image push myuser/image-gallery:v1

Publish image in local repository

Syntax:

docker image push <host>:<port>/<account-id>/<image-name>:<image-version>

Example:

docker image push localhost:5000/myuser/image-gallery:v1

Download image from remote repository

Syntax:

docker pull <image-name>:<version-id>

Example:

docker pull alpine:edge

Download image from local repository

Syntax:

docker pull <host>:<port>/<image-name>:<version-id>

Example:

docker pull localhost:5000/alpine

Download all tags for a given image

Syntax:

docker pull --all-tags <image-name>

Example:

docker pull --all-tags alpine	

Export/import

Export container to a tarball file

Syntax:

docker export <container_ID> > <file_name>

Example:

docker export 3673f8996e1a > helloworld.tar	

Import image from a tarball file

Syntax:

docker import <archive_name> <Image_name>
or
cat <archive_name> | docker import - <image_name>

Example:

docker import helloworld.tar my-imported-img:v1

Save/load

Save

Syntax:

docker save <image-name> > <file-name>.tar

Example:

docker save verse_gapminder > verse_gapminder.tar

Load

Load image from a file

Syntax:

docker load --input <input-file>.tar

Example:

docker load --input verse_gapminder.tar

Local registry

Overview

See: https://docs.docker.com/registry/deploying/

Start

docker run -d -p 5000:5000 --restart=always --name registry registry:2

Tag

Tag image for local registry:

docker tag diamol/ch03-web-ping localhost:5000/ch03-web-ping

Push

Push image to local registry:

docker push localhost:5000/ch03-web-ping

Stop

docker container stop registry

Remove registry container

docker container stop registry && docker container rm -v registry

Security scanning

Run scan:

docker scout cves <image-name>

Dockerfile

Command syntax

Define base image

FROM ubuntu:latest

Define environment variable

It can be passed to container with default value:

ENV TARGET="my.blog.com"

or

ENV TARGET="my.blog.com" \
	METHOD="HEAD" \
	INTERVAL="3000"

Copy file from host to image

• syntax:

  COPY

• example:

  COPY app.js .

RUN command

Makes changes and performs implicit commit.

RUN command - shell form (uses sh as default shell):

RUN apk add --no-cache openssh-client

RUN command - exec form (can use different shell):

RUN ["/bin/bash", "-c", "echo hello"]

SHELL command - change default shell

HEALTHCHECK - status check

Syntax:

HEALTHCHECK CMD <command>

Example:

HEALTHCHECK CMD curl --fail http://localhost/health

CMD for startup check

Syntax:

CMD <check-command> && \
  <run-command>

Example:

CMD curl --fail http://localhost/health && \
  dotnet numbers.dll

Optimizations

List of possible optimizations:

• join ENV commands into one
• move CMD command up, closer to FROM
• keep frequently changed commands / data at the bottom

Multi-stage builds

Dockerfile can have several FROM steps, each step can use a different image.

Steps can have a name as follows:

FROM <base-image> as <step-name>
ex. FROM diamol/maven as builder 

Steps can generate files which can be used in next steps as follows:

COPY --from=<source-step-name> <source-path> <target-path>
ex. COPY --from=builder /usr/src/iotd/target/iotd.jar .	

To define volume for container

VOLUME /data	

Docker Compose

Commands

Run all services from specific file

docker compose -f docker-compose-mysql.yml up -d

Run joined definition from two or more files

docker compose -f docker-compose.yml -f docker-compose.admin.yml up -d

Run specific service from specific file

docker compose -f docker-compose.yml -f docker-compose.admin.yml run backup_db

Build and run

docker-compose up -d

Build and run, rebuild images defined inside compose

docker-compose up -d --build

Skip cache while rebuildimg

docker-compose rm -f
docker-compose pull
docker-compose up --build --force-recreate -d

Stop and destroy

docker-compose down

Stop

docker-compose stop

Full stop (with clean)

docker stop $(docker ps -aq)
docker rm $(docker ps -aq)

Start

docker-compose start

Scale one of services

docker-compose up -d --scale <service-name>=<required-number-of-instances>
ex. docker-compose up -d --scale iotd=3

Docker Compose file

Access other dockerized services from container:

• Use http://host.docker.internal:8080/
• instead of http://localhost:8080/

REST API:

Overview: https://docs.docker.com/registry/spec/api/

Url:

http://localhost:5000/v2

Get repository list:

GET http://localhost:5000/v2/_catalog

Get image tag list:

GET http://localhost:5000/v2/<name>/tags/list	
ex. http://localhost:5000/v2/ch03-web-ping/tags/list	

Get tag manifest info:

GET http://localhost:5000/v2/<name>/manifests/<reference>
ex. http://localhost:5000/v2/ch03-web-ping/manifests/latest

Docker Secrets

See:

• Using Docker Secrets With Docker Compose
• Manage sensitive data with Docker secrets

Docker Configs

See: Store configuration data using Docker Configs

Clean time drift from docker engine (Windows, WSL)

Run:

wsl --shutdown
wsl

Monitor performance

List running containers

docker ps

Show performance stats of all containers

docker stats

Show performance inside container:

docker container top <container-id>

example:

docker container top c0

Show usage statistics (mem, cpu, io)

docker container stats <container-id>

example:

docker container stats c0

Show storage used by all images and containers

docker system df