missing-container-metrics

README

Missing Container Metrics - metrics cadvisor won't give you

STATUS: stable, maintained

cadvisor is great, but missing a few important metrics, that every serious devops person wants to know about. This is a secondary process to export all the missing Prometheus metrics:

• OOM-kill
• number of container restarts
• last exit code

[!NOTE]
cadvisor now implemented some of those features, but there are some issues, for example:

• https://github.com/google/cadvisor/issues/3015

This was motivated by hunting down a OOM kills in a large Kubernetes cluster. It's possible for containers to keep running, even after a OOM-kill, if a sub-process got affect for example. Without this metric, it becomes much more difficult to find the root cause of the issue.

True story; after this was deployed, a recurring OOM-kill in Fluentd was quickly discovered on one of the nodes. It turns out that the resource limits were set too low to process logs on that node. Logs were not being forwarded because the Fluentd worker process kept being OOM-kill and then restarted by the main process. A fix was then deployed 10 minutes later.

Supported Container Runtimes

• Docker
• Containerd

Kubernetes 1.20 has deprecated Docker container runtime, so we have added support for Containerd since the version 0.21.0 of missing-container-metrics. Both options should cover most of common use cases (EKS, GKE, K3S, Digital Ocean Kubernetes, ...).

Deployment

Kubernetes

The easiest way of installing missing-container-metrics in your kubernetes cluster is using our helm chart.

Docker

$ docker run -d -p 3001:3001 -v /var/run/docker.sock:/var/run/docker.sock ghcr.io/wonderland-platform/missing-container-metrics:1.0.0-rc3

Usage

Exposes metrics about Docker/Containerd containers. Every metric contains following labels:

Exposed Metrics

Each of those metrics, are published with the labels from the next section.

container_restarts (counter)

Number of restarts of the container.

container_ooms (counter)

Number of OOM kills for the container. This covers OOM kill of any process in the container cgroup.

container_last_exit_code (gauge)

Last exit code of the container.

Labels

docker_container_id

Full id of the container.

container_short_id

First 6 bytes of the Docker container id.

container_id

Container id represented in the same format as in metrics of kubernetes pods - prefixed with docker:// and containerd:// depending on the container runtime. This enables easy joins in Prometheus to kube_pod_container_info metric.

name

Name of the container.

image_id

Image id represented in the same format as in metrics of k8s pod. This enables easy joins in Prometheus to kube_pod_container_info metric.

pod

If io.kubernetes.pod.name label is set on the container, it's value will be set as the pod label in the metric

namespace

If io.kubernetes.pod.namespace label is set on the container, it's value will be set as the namespace label of the metric.

Together with pod, this label is useful in the context of Kubernetes deployments, to determine namespace/pod to which the container is part of. One can see it as a shortcut to joining with the kube_pod_container_info metric to determine those values.

Contributing

Contributions are welcome, send your issues and PRs to this repo.

Releasing

1. Push tag with new version: E.g.: git tag -a -m "Version 1.0.0" v1.0.0 && git push origin 1.0.0
2. Wait for release of new container image
3. Update helm chart with new image version: Edit charts/missing-container-metrics/Chart.yaml
4. Merge helm chart update PR to main branch

License

MIT - Copyright Dragan Milic and contributors