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How to use Podman to get information about your containers
Use the podman ps command to get size, resource consumption, and other information about your containers.
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Mylene2401. Pixabay
Podman is a daemon-less engine for developing, managing, and running Open Container Initiative (OCI)-compliant containers. This is the second article in a series about using Podman based on things I do in my real work environment. In my previous article, I showed you how to start containers quickly and easily using the familiar interface of shell scripting.
In this article, I'll demonstrate how to get insight into running containers. If you want to follow along with this article, first run the shell scripts I used in the "Setting things up" section of the first article in this series.
Get information about running containers
The main command to print out information about the running containers is podman ps. Or, if you're running containers inside pods, podman pod ps has the same purpose. Here are the full options for these commands:
$ podman ps --help
List containers
Description:
Prints out information about the containers
Usage:
podman ps [options]
Examples:
podman ps -a
podman ps -a --format "{{.ID}} {{.Image}} {{.Labels}} {{.Mounts}}"
podman ps --size --sort names
Options:
-a, --all Show all the containers, default is only running containers
--external Show containers in storage not controlled by Podman
-f, --filter strings Filter output based on conditions given
--format string Pretty-print containers to JSON or using a Go template
-n, --last int Print the n last created containers (all states) (default -1)
-l, --latest Act on the latest container podman is aware of
Not supported with the "--remote" flag
--no-trunc Display the extended information
--ns Display namespace information
-p, --pod Print the ID and name of the pod the containers are associated with
-q, --quiet Print the numeric IDs of the containers only
-s, --size Display the total file sizes
--sort choice Sort output by: command, created, id, image, names, runningfor, size, status
--sync Sync container state with OCI runtime
-w, --watch uint Watch the ps output on an interval in seconds
$ podman pod ps --help
List pods
Description:
List all pods on system including their names, ids and current state.
Usage:
podman pod ps [options]
Aliases:
ps, ls, list
Options:
--ctr-ids Display the container UUIDs. If no-trunc is not set they will be truncated
--ctr-names Display the container names
--ctr-status Display the container status
-f, --filter strings Filter output based on conditions given
--format string Pretty-print pods to JSON or using a Go template
-l, --latest Act on the latest container podman is aware of
Not supported with the "--remote" flag
--no-trunc Do not truncate pod and container IDs
--ns Display namespace information of the pod
-q, --quiet Print the numeric IDs of the pods only
--sort string Sort output by created, id, name, or number (default "created")
Because I'm running both a standalone container and a pod with two containers in it, I'll use both commands to show some slight differences between them. I'll start exploring by running podman ps and podman pod ps:
$ podman ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
055fc7959f58 docker.io/library/wordpress apache2-foregroun... 3 minutes ago Up 3 minutes ago 0.0.0.0:8080->80/tcp wordpress
5bd37169ce0d docker.io/library/mysql mysqld 3 minutes ago Up 3 minutes ago 0.0.0.0:8080->80/tcp mysql
f8750c81cdb8 k8s.gcr.io/pause:3.2 3 minutes ago Up 3 minutes ago 0.0.0.0:8080->80/tcp a061ffe41575-infra
7c4c01d99ccc docker.io/library/httpd httpd-foreground 2 hours ago Up 36 minutes ago 0.0.0.0:8081->80/tcp httpd
$ podman pod ps
POD ID NAME STATUS CREATED INFRA ID # OF CONTAINERS
a061ffe41575 blog Running 3 minutes ago f8750c81cdb8 3
For more detail on the commands' output, check their official documentation (podman ps and podman pod ps). To get more detailed information about your running containers, you can change the output format to use JSON or Go:
$ podman ps --format json
[
{
"Command": [
"apache2-foreground"
],
"Created": 1638753466,
"CreatedAt": "7 minutes ago",
"Exited": false,
"ExitedAt": -62135596800,
"ExitCode": 0,
"Id": "055fc7959f58921ef11119b44b1d250558272b523765e639a5e5c3aa2ad3d2a0",
"Image": "docker.io/library/wordpress",
"ImageID": "054741915cf1ee661d897b168fe70ce3c35bcf49234d21035654a1f03c143412",
"IsInfra": false,
"Labels": null,
"Mounts": [
"/var/www/html"
],
"Names": [
"wordpress"
[...]
To get information about the namespaces your containers are using, try the --namespace option (-ns for short):
$ podman ps --namespace
CONTAINER ID NAMES PID CGROUPNS IPC MNT NET PIDNS USERNS UTS
055fc7959f58 wordpress 11246 4026531835 4026532957 4026532961 4026532842 4026532962 4026531837 4026532956
5bd37169ce0d mysql 11145 4026531835 4026532957 4026532959 4026532842 4026532960 4026531837 4026532956
f8750c81cdb8 a061ffe41575-infra 11123 4026531835 4026532957 4026532955 4026532842 4026532958 4026531837 4026532956
7c4c01d99ccc httpd 6016 4026531835 4026532839 4026532837 4026532893 4026532840 4026531837 4026532838
$ podman pod ps --ns
POD ID NAME STATUS CREATED INFRA ID <no value> <no value> # OF CONTAINERS
a061ffe41575 blog Running 9 minutes ago f8750c81cdb8 machine.slice
To find which pods your containers are running in, use the --pod option (or -p for short)
$ podman ps --pod
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES POD ID PODNAME
055fc7959f58 docker.io/library/wordpress apache2-foregroun... 11 minutes ago Up 11 minutes ago 0.0.0.0:8080->80/tcp wordpress a061ffe41575 blog
5bd37169ce0d docker.io/library/mysql mysqld 11 minutes ago Up 11 minutes ago 0.0.0.0:8080->80/tcp mysql a061ffe41575 blog
f8750c81cdb8 k8s.gcr.io/pause:3.2 11 minutes ago Up 11 minutes ago 0.0.0.0:8080->80/tcp a061ffe41575-infra a061ffe41575 blog
7c4c01d99ccc docker.io/library/httpd httpd-foreground 2 hours ago Up 43 minutes ago 0.0.0.0:8081->80/tcp httpd
The output shows that two of my three running containers are within a pod called "blog."
Get container size
You can also sort your running containers' output by different values, like size or creation time. To get the size of a container, use the --size option (-s for short), and you can sort with the --sort option, along with the value you want to sort by:
$ podman ps --size --sort size
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES SIZE
f8750c81cdb8 k8s.gcr.io/pause:3.2 15 minutes ago Up 15 minutes ago 0.0.0.0:8080->80/tcp a061ffe41575-infra 0B (virtual 683kB)
7c4c01d99ccc docker.io/library/httpd httpd-foreground 2 hours ago Up 47 minutes ago 0.0.0.0:8081->80/tcp httpd 2B (virtual 143MB)
5bd37169ce0d docker.io/library/mysql mysqld 15 minutes ago Up 15 minutes ago 0.0.0.0:8080->80/tcp mysql 7B (virtual 515MB)
055fc7959f58 docker.io/library/wordpress apache2-foregroun... 15 minutes ago Up 15 minutes ago
You can sort by any heading. For instance, this sorts by creation time:
$ podman ps --sort created
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
7c4c01d99ccc docker.io/library/httpd httpd-foreground 2 hours ago Up 46 minutes ago 0.0.0.0:8081->80/tcp httpd
055fc7959f58 docker.io/library/wordpress apache2-foregroun... 14 minutes ago Up 14 minutes ago 0.0.0.0:8080->80/tcp wordpress
5bd37169ce0d docker.io/library/mysql mysqld 14 minutes ago Up 14 minutes ago 0.0.0.0:8080->80/tcp mysql
f8750c81cdb8 k8s.gcr.io/pause:3.2 14 minutes ago Up 14 minutes ago
Another option is to specify only the columns that you want to see in the output:
$ podman ps --all --format "{{.Names}} {{.Ports}} {{.Mounts}} {{.Status}}"
wordpress 0.0.0.0:8080->80/tcp [/var/www/html] Up 18 minutes ago
mysql 0.0.0.0:8080->80/tcp [/var/lib/mysql] Up 18 minutes ago
a061ffe41575-infra 0.0.0.0:8080->80/tcp [] Up 18 minutes ago
httpd 0.0.0.0:8081->80/tcp [/usr/local/apache2/htdocs] Up 51 minutes ago
You can tailor the output from pod containers by selecting only container IDs, names, or status:
$ podman pod ps --ctr-ids
POD ID NAME STATUS CREATED INFRA ID <no value>
a061ffe41575 blog Running 20 minutes ago f8750c81cdb8 055fc7959f58,5bd37169ce0d,f8750c81cdb8
$ podman pod ps --ctr-names
POD ID NAME STATUS CREATED INFRA ID <no value>
a061ffe41575 blog Running 20 minutes ago f8750c81cdb8 wordpress,mysql,a061ffe41575-infra
$ podman pod ps --ctr-status
POD ID NAME STATUS CREATED INFRA ID <no value>
a061ffe41575 blog Running 20 minutes ago f8750c81cdb8 running,running,running
Get resources being used by containers
To get resource-consumption information about your running containers, retrieve their stats:
$ podman stats
ID NAME CPU % MEM USAGE / LIMIT MEM % NET IO BLOCK IO PIDS
055fc7959f58 wordpress 0.01% 135.7MB / 2.047GB 6.63% 1.065MB / 671.2kB 2.212MB / 16.38kB 11
5bd37169ce0d mysql 0.38% 546.1MB / 2.047GB 26.69% 1.065MB / 671.2kB 229.4kB / 626MB 40
7c4c01d99ccc httpd 0.02% 12.57MB / 2.047GB 0.61% 4.914kB / 12.67kB -- / -- 82
f8750c81cdb8 a061ffe41575-infra -- 204.8kB / 2.047GB 0.01% 1.065MB / 671.2kB -- / --
$ podman pod stats
POD CID NAME CPU % MEM USAGE/ LIMIT MEM % NET IO BLOCK IO PIDS
a061ffe41575 055fc7959f58 wordpress 2.10% 135.7MB / 2.047GB 6.63% 1.065MB / 671.2kB 2.212MB / 16.38kB 11
a061ffe41575 5bd37169ce0d mysql 9.67% 546.1MB / 2.047GB 26.69% 1.065MB / 671.2kB 229.4kB / 626MB 40
a061ffe41575 f8750c81cdb8 a061ffe41575-infra 1.80% 204.8kB / 2.047GB 0.01% 1.065MB / 671.2kB -- / -- 1
Show all containers
The podman ps and podman pod ps commands show only the running containers. To list all containers, regardless of their status, use the --all, or -a for short, parameter. In this example, I pause my httpd container before monitoring and then unpause it to demonstrate the different output:
$ podman pause httpd
7c4c01d99cccf70a0c42ebdba458afb8be6d1563de3a91c99519213a4d8654af
$ podman ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
055fc7959f58 docker.io/library/wordpress apache2-foregroun... 30 minutes ago Up 30 minutes ago 0.0.0.0:8080->80/tcp wordpress
5bd37169ce0d docker.io/library/mysql mysqld 30 minutes ago Up 30 minutes ago 0.0.0.0:8080->80/tcp mysql
f8750c81cdb8 k8s.gcr.io/pause:3.2 30 minutes ago Up 30 minutes ago 0.0.0.0:8080->80/tcp a061ffe41575-infra
$ podman ps --all
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
055fc7959f58 docker.io/library/wordpress apache2-foregroun... 30 minutes ago Up 30 minutes ago 0.0.0.0:8080->80/tcp wordpress
5bd37169ce0d docker.io/library/mysql mysqld 30 minutes ago Up 30 minutes ago 0.0.0.0:8080->80/tcp mysql
f8750c81cdb8 k8s.gcr.io/pause:3.2 30 minutes ago Up 30 minutes ago 0.0.0.0:8080->80/tcp a061ffe41575-infra
7c4c01d99ccc docker.io/library/httpd httpd-foreground 2 hours ago paused 0.0.0.0:8081->80/tcp httpd
$ podman unpause httpd
7c4c01d99cccf70a0c42ebdba458afb8be6d1563de3a91c99519213a4d8654af
$ podman ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
055fc7959f58 docker.io/library/wordpress apache2-foregroun... 31 minutes ago Up 31 minutes ago 0.0.0.0:8080->80/tcp wordpress
5bd37169ce0d docker.io/library/mysql mysqld 31 minutes ago Up 31 minutes ago 0.0.0.0:8080->80/tcp mysql
f8750c81cdb8 k8s.gcr.io/pause:3.2 31 minutes ago Up 31 minutes ago 0.0.0.0:8080->80/tcp a061ffe41575-infra
7c4c01d99ccc docker.io/library/httpd httpd-foreground 2 hours ago Up About an hour ago 0.0.0.0:8081->80/tcp httpd
Podman for maximum flexibility
There are more options to explore in the podman ps and podman stats toolset. Try them out to familiarize yourself with the outputs. As you do, you'll become comfortable with the commands, and you'll be able to decide what suits your ongoing needs best.
Podman is gaining more and more followers as a convenient and flexible tool for managing containers and images. Understanding how to use it for things such as listing running containers gives you an advantage in managing containers.
In my next article, I'll explore how to get your container's external internet protocol (IP) address. Until then, you can learn more about Podman from 10 Podman guides to do more with containers in 2022, Top 10 container guides for sysadmins, and of course, Podman.io.
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Topics:
Podman
Containers
Alexon Oliveira
Alexon has been working as a Senior Technical Account Manager at Red Hat since 2018, working in the Customer Success organization focusing on Infrastructure and Management, Integration and Automation, Cloud Computing, and Storage Solutions. More about me
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