Prefix for Docker-Container Hosts, Hostname translation for piggyback

Troubleshooting
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#1

Hello there,

I ran into a big problem while testing out checkmk on my servers.
I want to monitor a lot of Docker-Containers as single Hosts and because I have a lot of different Hosts running the same Docker-Containers I had problems with the rule “Hostname translation for piggybacked Hosts”.
With this rule you can change the name of the piggyback/subdirectory that is created for every single container into something different, and then you can rename the Host as well, so that you have a better structure in your Webinterface.
But like I said if you have a container with the same name as the one you already have, but on a different server, you will get the problem that checkmk can not distinguish these two from another.
And I really don’t want to use a workaround here, for example renaming every directory that contains compose files specific to the used server.

So my question is: Is there a way or a rule I can use to create specific name prefixes for every child host (docker container) my parent Host has? So that I can then distinguish them all from another and monitor each one ?
Here is an example of my current situation:
I have 3 parent hosts: vm-01, vm-02, vm-03.
Every parent host has 2 docker-containers running, they are all called “tools_portainer” and “my_nginx” on all 3 hosts.
I tried creating the hostname translation rule, so that “tools_portainer” is changed to “vm-01_portainer” and “my_nginx” to “vm-01_nginx”.
The problem is that I can now only monitor the two containers from my vm-01, because checkmk can not find my “tools_portainer” and “my_nginx” from vm-02 or vm-02 anymore.

Like I said I am looking for a certain rule or anything similar, that automatically renames the child hosts “tools_portainer” and “my_nginx” to something regarding their parent host.
I would like to have “vm-01_portainer”, “vm-02_portainer” etc.

And I can not change the containers name directly on the server, because that would be an ugly workaround and I use the same .yml file on all servers and it would only make things even more complicated.

Thanks for reading, I am looking forward to help :wink:

#2

This should really be a feature of the dynamic configuration daemon or even the mk_docker.py agent plugin, but currently is not.

You can create multiple rules in “Hostname translation for piggybacked Hosts” for each Docker node (assign every single rule to a differen Docker node host). With this and the regex replacement you can create individual prefixes for the container hosts.

#3

Hey sorry for the late reply, thank you for your suggestion, but I found a nice workaround.
I added “hostname_name” as a third option in the mk_docker.py file where it would otherwise only be “name” or “long”. To get the hostname I simply used os.gethostname().

Just thought you’d like to know, take care :wink:

1 Like
#4

That would make a nice pull request for the github repo.