cAdvisor support

[kanyi]

cAdvisor as datasource. That will be a big help of monitoring containers in Monitorix.

[mikaku]

is this is related to #313?

[kanyi]

Yes. cAdvisor can create more detailed statistics for containers, but yes, basically the same.

[mikaku]

I'd like to avoid using third party tools that might be difficult to install in all systems. I mean, I'd prefer using podman to get the statistics.

In this aspect, and as I already said in #313, I'm not familiarized with podman or containers in general. So, I'm pretty lost when trying to get stats of running containers using the root user, when the containers are being ran using another user (which will be the common case).

Can you, please, share a list of useful commands that Monitorix can run to get general container statistics?
That would get me an idea to develop the new module container.pm.

[kanyi]

Sorry but I don't use podman until now. I wil check it, and figure out these command is working or not. But, maybe this is help for you.

The normal docker stat command but separated the values:
docker stats --format "table {{.Container}}\t{{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}\t{{.NetIO}}\t{{.BlockIO}}\t{{.MemPerc}}\t{{.PIDs}}"

The last 2 values (MemPerc and PIDs) works only linux systems.
The trick about running docker command, under linux you have a GID name is docker, not only a user. So every user who is in these docker group can run all of the docker commands without any other privileges. I your case, under linux, the monitorix user is added to docker group you can read the stats and run docker commands.

[mikaku]

As I read it, podman and docker are very similar tools, they share almost the same options and syntax. Moreover, I discovered that I can install the package podman-docker on Fedora to emulate Docker CLI using Podman.

So, I just ran your command and I got the following:

$  docker stats --format "table {{.Container}}\t{{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}\t{{.NetIO}}\t{{.BlockIO}}\t{{.MemPerc}}\t{{.PIDs}}"
<no value>  NAME        CPU %       MEM USAGE / LIMIT  NET IO      BLOCK IO    MEM %       PI DS
Error: template: stats:1:13: executing "stats" at <.Container>: can't evaluate field Container in type containers.containerStats
$

No stats.

Then I checked the processes with containers using docker and I see the same output as with podman:

$ docker ps -a
Emulate Docker CLI using podman. Create /etc/containers/nodocker to quiet msg.
CONTAINER ID  IMAGE                             COMMAND     CREATED            STATUS                     PORTS       NAMES
6725ce9cb235  docker.io/library/busybox:latest  sh          About an hour ago  Exited (0) 51 minutes ago              compassionate_bose
$ 

[kanyi]

Looks podman can not recognize the {{.Container}} variable. - That's true https://docs.podman.io/en/latest/markdown/podman-stats.1.html So here is a difference, in docker and podman. :-)
I think this work, under podman (this is working for me Debian 11, Docker 20.10):
You can leave the table this is only for headers.
docker stats --format "{{.ID}}\t{{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}\t{{.NetIO}}\t{{.BlockIO}}\t{{.MemPerc}}\t{{.PIDs}}"

[mikaku]

Still no stats.

Moreover, the command does not return. It keeps refreshing which ruins the chance to get stats.
Monitorix runs under the root user, if that user cannot get Docker/Podman generic (all users) stats then this will be hard to implement.

[kanyi]

For me, the root user can run a docker stats command without any problem.
For you maybe podman stats -a --no-stream ?

[kanyi]

Oh, and Docker has an API interface, more detailed statistics. In this case you have to know the container ID, but I don't think is a problem monitoring only the given ID's and not all of the containers.

Access API information as follows for a JSON stream in every second:
curl -v --unix-socket /var/run/docker.sock \ http://localhost/containers/CONTAINER_ID/stats
Substitute CONTAINER_ID with the actual ID of the container being inspected.

But in this case you have a "little" more work: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/building_running_and_managing_containers/assembly_using-the-container-tools-api_building-running-and-managing-containers