Docker Command Cheatsheet

To build a docker image from Dockerfile

docker build

To pull a docker image

docker pull

To run a docker image

docker run

Find docker version

docker version 
docker -v

Find docker installation details and how many containers currently running on docker host

docker info

Execute a command in docker container

docker run docker/whalesay cowsay Hello World

Login to a docker container with interactive shell

docker run -it ubuntu bash 

Login to a docker container with interactive shell as root user

docker run -u 0 -it ubuntu bash 

List all the images from local docker repository

docker images 

Search the image name called debian from the docker hub image repository

docker search debian 

Pull the debian image from docker hub image repository

docker pull debian

List details about the debian image, like ID, Tag, Creation Date, Container configuration

docker inspect debian

Will show history of each layer that was added to the debain docker image

docker history debian 

Save nginx image in tar format)

docker save nginx -o nginx.tar
docker load -i ./nginx.tar 

Delete a docker image

Search for the image alpine

docker images alpine 

Delete the alpine image

docker rmi alpine 

Delete all docker images

docker rmi $(docker images -q)

Indentify dangling docker images

docker images -f "dangling=true"

Delete all dangling images

docker rmi $(docker images -f "dangling=true" -q)

How to tag an image during build

docker build myimage -t"myfirstimage:latest"
docker images myfirstimage

List all containers running and terminated

docker ps -a

Run a docker image as a container instance

docker run fedora /bin/echo 'Hello World'

Run a docker container with interactive shell

docker run -it fedora /bin/bash

Detach or a container and run in background

docker run -d ubuntu /bin/sh -c "while true; do echo current date and time is: $(date); sleep 10; done"
docker ps
docker logs <docker hash id>

Login to a docker container instance

docker exec -it <container hash id> /bin/bash

Steps to create a Docker Image

Step 1:

Create Dockerfile

cat myimage/Dockerfile
FROM ubuntu
RUN echo "my first image" >/tmp/first.txt

Step 2:

Build the image from Dockerfile

docker build myimage

Step 3:

Check if the image is created

docker images | grep <docker image hashid from step2>

Step 4:

Create a container instance

docker run -it <docker image hashid from step2>

How to stop and remove a container instance

Step 1:

First stop the container instance

docker stop <container hash id>

Step 2:

Remove the container

docker rm <container hash id>

How do I remove all containers

docker stop $(docker ps -a -q)
docker rm $(docker ps -a -q)
docker ps -a

Steps to create a NGINX Docker Instance.

Step 1:

cat DockerFile
FROM: nginx:latest
MAINTENER Naresh Padiyar
ADD ./index.html /usr/share/nginx/html/index.html 
EXPOSE 80

cat index.html
<h1> welcome to Dockerizing app !<h1>

Step 2:

docker build .

Step 3:

docker images

Step 4:

docker run -p 80:80 -d <docker hash id from step 3>

Step 5:

curl localhost:80

How do I run a C Program

docker pull gcc
docker pull ubuntu:latest

docker run -it ubuntu /bin/bash
apt-get update
aget-get install gcc
cat >hello.c
int main() { printf("hello world\n”); }
gcc -w hello.c
./a.out

How do I run a Java program

Step 1:

cat Dockerfile
FROM java:latest
COPY . /usr/src/
WORKDIR /usr/src/
RUN javac hello.java
CMD ["java","hello"]

cat hello.java
call hello {
	public static void main(String []args) {
	System.out.println("Hello World");
	}
}

Step 2:

docker build . -t"myjavaapp:latest"

Step 3:

docker images

Step 4:

docker run myjavaapp

How to push images to docker hub ?

docker tag myjavaapp nareshpadiyar/myfirstjavaprog:latest
docker push nareshpadiyar/myfirstjavaprog:latest

How to pull images from docker hub and run a container instance ?

docker pull nareshpadiyar/myfirstjavaprog:latest
docker images
docker run nareshpadiyar/myfirstjavaprog

Docker Best practises

1. Explicitly use --rm to remove the conatiner from file system else the filesystem will still be occupied.

2. Remove dangling images using "docker rmi $(docker images -f "dnagling=true" -q)"

Containers will have volumes. when container is removed, the volumes will not be removed.

3. If the volumes also need to be removed, we have to use -v option, as in:

docker rm -v <<sha>>