Docker Container Management

Introduction

Docker container management involves tasks such as creating, starting, stopping, and removing containers, as well as monitoring and troubleshooting container performance and health

Some Basic Commands Hands-on

docker

👉 This will show us some options that we can use and also some of the management commands

docker search hello-world

👉 This will search for the 'hello-world' images from dockerhub

docker pull hello-world

👉 This will pull the latest hello-world image from the dockerhub

docker images

👉 This will show us pulled images

docker run --name hello1 -it hello-world

👉 This command creates and starts a new Docker container using the hello-world image

💡 'hello1' is the container name and '-it' enables interactive mode but '-it' shouldn't be used as it is for developing or debugging only as it enables us to interact with the container's shell

In the above case, as the 'hello-world' image doesn't have any shell to be interacted with, it automatically pushes us back to our Linux terminal. To check any running container process

docker ps

👉 This will show us nothing as the 'hello1' container was stopped immediately

But we can see previous container using

docker ps -a

👉 This will show us 'hello1' container and at what time it exited

Now let's use the -d option to run a docker container

docker run --name hello2 -d hello-world

👉 This will show us the container ID and quit itself

💡 The 'hello-world' image is designed to automatically quit itself after its processing. -d option indicates the container to run in the background

If we want to delete these exited containers,

docker rm <first-four-digits-of-container-ID>

# OR

docker rm <container-name>

To remove the hello-world image

docker rmi hello-world

We can confirm this using docker images commmand

Next, we can try creating a container

docker create --name myWEB nginx:latest

👉 create command simply 'creates' the container and doesn't run it while the run command creates and run the container

💡 run is a shortcut for the docker create and docker start commands combined

We can also check the status using the ps -a that will show us the container status as 'Created'

docker start myWEB

👉 This will start the container and we can see the process using docker ps

What if we want to delete this container?

docker rm myWEB
Error response from daemon: You cannot remove a running container

We can either stop the container first and delete it or force delete it using

docker rm -f myWEB

Finally removing the nginx image

docker rmi nginx:latest

Another test we can do using an ubuntu image

docker run -it --name ubuntu_1 ubuntu:bionic

👉 This will allow us to connect to ubuntu shell automatically

So what if we want to exit from the ubuntu image terminal while keeping the container running?

✨ We will use CTRL + P + Q

We can confirm that our container is running even after returning to our own terminal using docker ps

To return to the container shell

docker attach <container-name>

We can also pause and unpause the container

docker pause ubuntu_1

docker unpause ubuntu_1

Stopping a container

docker stop ubuntu_1

Killing a container

docker kill ubuntu_1

👉 This is force stop

To remove all Docker containers that are currently stopped

docker rm $(docker ps -a -q)

Now what if we don't apply a custom name for our container

docker run --rm -it ubuntu:bionic

👉 The --rm option automatically removes the container when we 'exit' from the container

We can also change the container name

docker rename <current-container-name> <new-custom-container-name>

To inspect a container or an image

docker inspect <container-name> 

# OR

docker inspect <image-name>

✍ In this post I walked through some of the basic docker container commands that are beginner friendly