- A non-interactive container
- Run a container in the background
- List running containers
- Starting more containers
- Viewing only the last container started
- View only the IDs of the containers
- Combining flags
- View the logs of a container
- View only the tail of the logs
- Follow the logs in real time
- Stop our container
- Stopping our containers
- Killing the remaining containers
- List stopped containers
Our first containers were interactive.
We will now see how to:
- Run a non-interactive container.
- Run a container in the background.
- List running containers.
- Check the logs of a container.
- Stop a container.
- List stopped containers.
A non-interactive container
We will run a small custom container.
This container just displays the time every second.
$ docker run jpetazzo/clock Fri Feb 20 00:28:53 UTC 2015 Fri Feb 20 00:28:54 UTC 2015 Fri Feb 20 00:28:55 UTC 2015 ...
- This container will run forever.
- To stop it, press
- Docker has automatically downloaded the image
- This image is a user image, created by
- We will hear more about user images (and other types of images) later.
Run a container in the background
Containers can be started in the background, with the
-d flag (daemon mode):
$ docker run -d jpetazzo/clock 47d677dcfba4277c6cc68fcaa51f932b544cab1a187c853b7d0caf4e8debe5ad
- We don't see the output of the container.
- But don't worry: Docker collects that output and logs it!
- Docker gives us the ID of the container.
List running containers
How can we check that our container is still running?
docker ps, just like the UNIX
ps command, lists running processes.
$ docker ps CONTAINER ID IMAGE ... CREATED STATUS ... 47d677dcfba4 jpetazzo/clock ... 2 minutes ago Up 2 minutes ...
Docker tells us:
- The (truncated) ID of our container.
- The image used to start the container.
- That our container has been running (
Up) for a couple of minutes.
- Other information (COMMAND, PORTS, NAMES) that we will explain later.
Starting more containers
Let's start two more containers.
$ docker run -d jpetazzo/clock 57ad9bdfc06bb4407c47220cf59ce21585dce9a1298d7a67488359aeaea8ae2a
$ docker run -d jpetazzo/clock 068cc994ffd0190bbe025ba74e4c0771a5d8f14734af772ddee8dc1aaf20567d
docker ps correctly reports all 3 containers.
Viewing only the last container started
When many containers are already running, it can be useful to see only the last container that was started.
This can be achieved with the
-l ("Last") flag:
$ docker ps -l CONTAINER ID IMAGE ... CREATED STATUS ... 068cc994ffd0 jpetazzo/clock ... 2 minutes ago Up 2 minutes ...
View only the IDs of the containers
Many Docker commands will work on container IDs:
If we want to list only the IDs of our containers (without the other columns
or the header line),
we can use the
-q ("Quiet", "Quick") flag:
$ docker ps -q 068cc994ffd0 57ad9bdfc06b 47d677dcfba4
We can combine
-q to see only the ID of the last container started:
$ docker ps -lq 068cc994ffd0
At a first glance, it looks like this would be particularly useful in scripts.
However, if we want to start a container and get its ID in a reliable way,
it is better to use
docker run -d, which we will cover in a bit.
View the logs of a container
We told you that Docker was logging the container output.
Let's see that now.
$ docker logs 068 Fri Feb 20 00:39:52 UTC 2015 Fri Feb 20 00:39:53 UTC 2015 ...
- We specified a prefix of the full container ID.
- You can, of course, specify the full ID.
logscommand will output the entire logs of the container.
(Sometimes, that will be too much. Let's see how to address that.)
View only the tail of the logs
To avoid being spammed with eleventy pages of output,
we can use the
$ docker logs --tail 3 068 Fri Feb 20 00:55:35 UTC 2015 Fri Feb 20 00:55:36 UTC 2015 Fri Feb 20 00:55:37 UTC 2015
- The parameter is the number of lines that we want to see.
Follow the logs in real time
Just like with the standard UNIX command
tail -f, we can
follow the logs of our container:
$ docker logs --tail 1 --follow 068 Fri Feb 20 00:57:12 UTC 2015 Fri Feb 20 00:57:13 UTC 2015 ^C
- This will display the last line in the log file.
- Then, it will continue to display the logs in real time.
Stop our container
There are two ways we can terminate our detached container.
- Killing it using the
- Stopping it using the
The first one stops the container immediately, by using the
The second one is more graceful. It sends a
and after 10 seconds, if the container has not stopped, it
KILL signal cannot be intercepted, and will
forcibly terminate the container.
Stopping our containers
Let's stop one of those containers:
$ docker stop 47d6 47d6
This will take 10 seconds:
- Docker sends the TERM signal;
- the container doesn't react to this signal (it's a simple Shell script with no special signal handling);
- 10 seconds later, since the container is still running, Docker sends the KILL signal;
- this terminates the container.
Killing the remaining containers
Let's be less patient with the two other containers:
$ docker kill 068 57ad 068 57ad
kill commands can take multiple container IDs.
Those containers will be terminated immediately (without the 10 seconds delay).
Let's check that our containers don't show up anymore:
$ docker ps
Nota Bene :
To kill all the remainings containers :
$ docker kill $(docker ps -q)
List stopped containers
We can also see stopped containers, with the
$ docker ps -a CONTAINER ID IMAGE ... CREATED STATUS 068cc994ffd0 jpetazzo/clock ... 21 min. ago Exited (137) 3 min. ago 57ad9bdfc06b jpetazzo/clock ... 21 min. ago Exited (137) 3 min. ago 47d677dcfba4 jpetazzo/clock ... 23 min. ago Exited (137) 3 min. ago 5c1dfd4d81f1 jpetazzo/clock ... 40 min. ago Exited (0) 40 min. ago b13c164401fb ubuntu ... 55 min. ago Exited (130) 53 min. ago