container_memory_usage_bytes by deployment name

Question

Given a kubernetes cluster with:

1. prometheus
2. node-exporter
3. kube-state-metrics

I like to use the metric container_memory_usage_bytes but select by deployment_name instead of pod.

Selectors like container_memory_usage_bytes{pod_name=~"foo-.+"} if the deployment_name=foo are great as long there is not a deployment with deployment_name=foo-bar.

The same I'd like to achieve with the metric kube_pod_container_resource_limits_memory_bytes.

Is there a way to achieve this?

Answer 1

TL;DR

There is no straightforward way to query prometheus by a deployment-name.

You can query memory usage of a specific deployment by using deployment's labels.

Used query:

sum(
  kube_pod_labels{label_app=~"ubuntu.*"} * on (pod) group_right(label_app) container_memory_usage_bytes{namespace="memory-testing", container=""}
  ) 
  by (label_app)

There is an awesome article which explains the concepts behind this query. I encourage you to read it:

• Medium.com: Amimahloof: Kubernetes promql prometheus cpu aggregation walkthrough

I've included an explanation with example below.

---

The selector mentioned in the question: container_memory_usage_bytes{pod_name=~"foo-.+"}

.+ - match any string but not an empty string

with pods like:

• foo-12345678-abcde - will match (deployment foo)
• foo-deployment-98765432-zyxzy - will match (deployment foo-deployment)

As shown above it will match for both pods and for both deployments.

For more reference:

• Prometheus.io: Docs: Prometheus: Querying: Basics

---

As mentioned earlier, you can use labels from your deployment to pinpoint the resource used by your specific deployment.

Assuming that:

• There are 2 deployments in memory-testing namespace:
  • ubuntu with 3 replicas
  • ubuntu-additional with 3 replicas
• Above deployments have labels the same as their names (they can be different):
  • app: ubuntu
  • app: ubuntu-additional
• Kubernetes cluster version 1.18.X

Why do I specify Kubernetes version?

Kubernetes 1.16 will remove the duplicate pod_name and container_name metric labels from cAdvisor metrics. For the 1.14 and 1.15 release all pod, pod_name, container and container_name were available as a grace period.

• Github.com: Kubernetes: Metrics Overhaul

This means that you will need to substitute the parameters like:

• pod with pod_name
• container with container_name

To deploy Prometheus and other tools to monitor the cluster I used: Github.com: Coreos: Kube-prometheus

The pods in ubuntu deployment are configured to generate artificial load (stress-ng). This is done to show how to avoid situation where the used resources are doubled.

The resources used by pods in memory-testing namespace:

$ kubectl top pod --namespace=memory-testing
NAME                                 CPU(cores)   MEMORY(bytes)   
ubuntu-5b5d6c56f6-cfr9g              816m         280Mi           
ubuntu-5b5d6c56f6-g6vh9              834m         278Mi            
ubuntu-5b5d6c56f6-sxldj              918m         288Mi           
ubuntu-additional-84bdf9b7fb-b9pxm   0m           0Mi             
ubuntu-additional-84bdf9b7fb-dzt72   0m           0Mi             
ubuntu-additional-84bdf9b7fb-k5z6w   0m           0Mi     

If you were to query Prometheus with below query:

container_memory_usage_bytes{namespace="memory-testing", pod=~"ubuntu.*"}

You would get output similar to one below (it's cut to show only one pod for example purposes, by default it would show all pods with ubuntu in name and in memory-testing namespace):

container_memory_usage_bytes{endpoint="https-metrics",id="/kubepods/besteffort/podb96dea39-b388-471e-a789-8c74b1670c74",instance="192.168.0.117:10250",job="kubelet",metrics_path="/metrics/cadvisor",namespace="memory-testing",node="node1",pod="ubuntu-5b5d6c56f6-cfr9g",service="kubelet"} 308559872
container_memory_usage_bytes{container="POD",endpoint="https-metrics",id="/kubepods/besteffort/podb96dea39-b388-471e-a789-8c74b1670c74/312980f90e6104d021c12c376e83fe2bfc524faa4d4cee6553182d0fa2e007a1",image="k8s.gcr.io/pause:3.2",instance="192.168.0.117:10250",job="kubelet",metrics_path="/metrics/cadvisor",name="k8s_POD_ubuntu-5b5d6c56f6-cfr9g_memory-testing_b96dea39-b388-471e-a789-8c74b1670c74_0",namespace="memory-testing",node="node1",pod="ubuntu-5b5d6c56f6-cfr9g",service="kubelet"} 782336
container_memory_usage_bytes{container="ubuntu",endpoint="https-metrics",id="/kubepods/besteffort/podb96dea39-b388-471e-a789-8c74b1670c74/1b93889a3e7415ad3fa040daf89f3f6bc77e569d85069de518267666ede8e21c",image="ubuntu@sha256:55cd38b70425947db71112eb5dddfa3aa3e3ce307754a3df2269069d2278ce47",instance="192.168.0.117:10250",job="kubelet",metrics_path="/metrics/cadvisor",name="k8s_ubuntu_ubuntu-5b5d6c56f6-cfr9g_memory-testing_b96dea39-b388-471e-a789-8c74b1670c74_0",namespace="memory-testing",node="node1",pod="ubuntu-5b5d6c56f6-cfr9g",service="kubelet"} 307777536

In this point you will need to choose which metric you will be using. In this example I used the first one. For more of a deep dive please take a look on this articles:

• Blog.freshtracks.io: A deep dive into kubernetes metrics part 3 container resource metrics
• Ianlewis.org: Almighty pause container

If we were to aggregate this metrics with sum (QUERY) by (pod) we would have in fact doubled our reported used resources.

Dissecting the main query:

container_memory_usage_bytes{namespace="memory-testing", container=""}

Above query will output records with used memory metric for each pod. The container=""parameter is used to get only one record (mentioned before) which does not have container parameter.

kube_pod_labels{label_app=~"ubuntu.*"}

Above query will output record with pods and it's labels with regexp of ubuntu.*

kube_pod_labels{label_app=~"ubuntu.*"} * on (pod) group_right(label_app) container_memory_usage_bytes{namespace="memory-testing", container=""}

Above query will match the pod from kube_pod_labels with pod of container_memory_usage_bytes and add the label_app to each of the records.

sum (kube_pod_labels{label_app=~"ubuntu.*"} * on (pod) group_right(label_app) container_memory_usage_bytes{namespace="memory-testing", container=""}) by (label_app)

Above query will sum the records by label_app.

After that you should be able to get the query that will sum the used memory by a label (and in fact a Deployment).

---

As for:

The same I'd like to achieve with the metric kube_pod_container_resource_limits_memory_bytes.

You can use below query to get the memory limit for the deployment tagged with labels as in previous example, assuming that each pod in a deployment is having the same limits:

kube_pod_labels{label_app="ubuntu-with-limits"} * on (pod) group_right(label_app) kube_pod_container_resource_limits_memory_bytes{namespace="memory-testing", pod=~".*"}

You can apply functions like avg(),mean(),max() on this query to get the single number that will be your memory limit:

avg(kube_pod_labels{label_app="ubuntu-with-limits"} * on (pod) group_right(label_app) kube_pod_container_resource_limits_memory_bytes{namespace="memory-testing", pod=~".*"}) by (label_app)

Your memory limits can vary if you use VPA. In that situation you could show all of them simultaneously or use the avg() to get the average for all of the "deployment".

---

As a workaround to above solutions you could try to work with regexp like below:

container_memory_usage_bytes{pod=~"^ubuntu-.{6,10}-.{5}"}