Docker - Container usage | From Zen to Code

Manage containers
Monitoring a container:
References

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Manage containers

Listing containers

docker container ls

To list all containers:
```
docker container ls -a
```
To list all containers and size (-s option):
```
docker container ls -sa
```

Run container

To start new container interactively from an image with its Tag Name or Image ID:
```
docker container run <TagName|ImageID>
```
This command always starts a new container, use docker container start <TagName|ImageID> to start an exixting stopped one.
Example of start and attach to an Alpin linux operating system:
```
docker run -it --rm alpine /bin/ash
```
- -i, --interactive: Remain the STDIN accessible.
- -t, --tty: Allocate a pseudo-tty, bind it on this container.
- --rm: Automatically delete the container when it exits.
- /bin/ash: To run the application /bin/ash inside the container, without this option, Docker will run /bin/sh by default.
Execute a command: To run an additional command in existing container.
```
docker container exec <TagName|ImageID> <command>
```
Publish a container’s port(s) to the host (-p, --publish)
```
docker run -p 127.0.0.1:80:8080/tcp <TagName|ImageID>
```
This binds the TCP port 80 on 127.0.0.1 from the host to the port ` 8080` from the container.
Expose a port or a range of ports
```
docker run --expose 80 my_ubuntu /bin/bash
```
This exposes port 80 of the conatiner without publishing the port to the host system’s interfaces.

Set evnironment variable (-e, --env, --env-file)

docker run -e FOO=bar --env-file ./env.list <TagName|ImageID> /bin/bash

This connect port 3000 between container and host and set host’s environment variable http_proxy to container.
```
docker container run -e http_proxy -e https_proxy -p 3000:3000 <TagName|ImageID>
```

Start container

Wake up an exited container:
```
docker container start <TagName|ImageID>
```
Instead of using a full container ID, we can use just the first few characters, as long as they are uniquely identifying a container.
Attach to a stoped container:
```
docker container start -ai CONTAINER
```
- -a, --attach: Attach STDOUT/STDERR and forward signals.
- -i, --interactive: Attach to container’s STDIN.

Stop containers:

dokcer stop CONTAINER

# Stop All containers
docker stop $(docker ps -aq)

# Stop specific container
docker stop $(docker ps -aq --filter name="my_container")

docker ps -aq will listing all the containers with container ID.

Keep a container busy living

Option 1.

Use docker run with -t option:

docker run -td IMAGE

-d: Run container in background and print container ID.
-t, --tty: Allocate a pseudo-TTY.

Option 2.

A Docker container is supposed to be built with only one process running.

As the container will exit when the process itself exits, there’s a way to keep a ubuntu container busy by continuously printing nothing to the system blackhole /dev/null:

docker run -d ubuntu tail -f /dev/null

Pause & Unpause

To suspends all processes in the specified containers.
```
docker pause CONTAINER [CONTAINER...]
```

Attach to a running container

Examples:

$ docker attach CONTAINER
$ docker exec -it CONTAINER /bin/bash

Remove containers

docker rm [OPTIONS] CONTAINER [CONTAINER...]

Options:

-f, --force: Force remove a container even it’s running.
-v, --volumes: Remove anonymous volumes associated with the container.

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Monitoring a container:

Display the running processes of a container

To list processes that running inside of the specific container.

docker top CONTAINER

Display detailed information from containers

docker container inspect [OPTIONS] CONTAINER [CONTAINER...]

To shows the IP address of the container:
```
docker container inspect --format '{{ .NetworkSettings.IPAddress }}' CONTAINER
```
- -f, --format: Format the output using the given Go template.

Display a live stream of container(s) resource usage statistics

docker stats

Quick port check

docker container port CONTAINER

Fetch the logs of a container

docker logs [OPTIONS] CONTAINER

Note: This command is only functional for containers that are started with the json-file or journald loggin driver.

Options:

--follow: To continue streaming the new output from the container’s STDOUT and STDERR.
--timestamps: To add an RFC3339Nano timestamp, for example 2021-02-12T08:32:48.001607450Z to each log entry.

References

Docker official reference documentation

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