Use service labels and average value in docker Swarm mode

[UnclePhil]

Description

When we are using Docker SwarmMode with possible multiple replica for each services, we need to be linked to the service in place of container instance.
In this case we need to define the label at the service level (service/deploy/labels) to obtain one effective link to the service and the widget data must use the average value of all replica in the service.

This is a little bit more complicated but more effective.

Other

No response

[nacholopez2022]

would be very usefull when using dhcp bridge networks the service discovery should "discover" the container bridge ip without passing url label 😅

[hugosxm]

@shamoon Hi, i think this is the way to solve my problem.

The new swarm check is very nice when i do the config via the services.yaml. It show the number of container as expected. But when trying to discover the config via labels it does not work.

I tried this :

labels:
  homepage.group: Services
  homepage.name: Prometheus node-exporter
  homepage.icon: https://Prometheus_software_logo.svg.png
  homepage.ping: http://prometheus.xxx.net:9100/
  homepage.href: http://prometheus.xxx.net:9100/
  homepage.description: Linux node metrics
  homepage.container: prometheus_node-exporter

This kind of work, but it shows x entry in the dashboard and of course I only want one. And if i put the labels in the deploy section, it does not show at all...

I know i'm not supposed to use the homepage.container label but it was to test things...

[hugosxm]

@shamoon, just realized something else, when using label and swarm mode, if a service is not running of the node with from the socket is exposed, homepage won't find it ! I tried that by forcing the placement like this :

      placement:
        constraints:
          - "node.hostname==docker-manager"

I use socket proxy container so the socket is in fact available on all my swarm nodes

[rkokkelk]

This is how homepage determines services, e.g. via container labels instead of service labels. With normal deployments with docker this is no issue, with swarm it is. Service labels (Service:Servicename:deploy:labels) of all running services are only available on manager nodes, however container labels (Service:Servicename:labels) are only available on the nodes which actually run the containers.

Unfortunately, homepage currently, does not check service deploy labels. E.g. in the current implementation it is not possible to use homepage service detection with docker swarm.

You can 'make' it work by constraining the containers you want the services to be detected from on the same host as the homepage container and create container labels. However, this totally defeats the use of docker swarm so it is not really a benefit.

[UnclePhil]

The answer is not very difficult
Something like this is working perfectly on my own dashboard used only in swarm cluster (https://github.com/UnclePhil/xfeed )

Have a look at https://github.com/UnclePhil/xfeed/blob/master/src/GetFeed.js

      if (mode == "swarm") {
              logger.info('Xfeeder request swarm services')
                    //const servicesJson =  GetFeed.getSwarmServices();
                    GetFeed.getSwarmServices().then(servicesJson => {
                       servicesJson.forEach(function (service) {
                            logger.debug("Analyze :" +service.Spec.Name)
                            if (service.Spec != null && service.Spec.Labels != null) {
                                logger.debug("swarm Labels found")
....

And in the docker.yaml you know that you are on swarm

my-docker:
  socket: /var/run/docker.sock
  swarm: true

[rkokkelk]

I've created a PR #1571 which implements this exact functionality for detecting the labels for a docker swarm instance. Hopefully it will get merged soon.

[UnclePhil]

I've seen it.... after i write my comment. Hope it will be merged. Le mer. 7 juin 2023, 22:03, RoyK ***@***.***> a écrit :

…

I've created a PR #1571 <#1571> which implements this exact functionality for detecting the labels for a docker swarm instance. Hopefully it will get merged soon. — Reply to this email directly, view it on GitHub <#1255 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AADTDEYQ67K6J7UW5VA56GDXKDNCHANCNFSM6AAAAAAYZ6FOGY> . You are receiving this because you authored the thread.Message ID: ***@***.***>

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