Checking kubernetes pod CPU and memory
KubernetesKubernetes Problem Overview
I am trying to see how much memory and CPU is utilized by a kubernetes pod. I ran the following command for this:
kubectl top pod podname --namespace=default
I am getting the following error:
W0205 15:14:47.248366 2767 top_pod.go:190] Metrics not available for pod default/podname, age: 190h57m1.248339485s
error: Metrics not available for pod default/podname, age: 190h57m1.248339485s
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What do I do about this error? Is there any other way to get CPU and memory usage of the pod?
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I saw the sample output of this command which shows CPU as 250m. How is this to be interpreted?
-
Do we get the same output if we enter the pod and run the linux
top
command?
Kubernetes Solutions
Solution 1 - Kubernetes
> CHECK WITHOUT METRICS SERVER or ANY THIRD PARTY TOOL
If you want to check pods cpu/memory usage without installing any third party tool then you can get memory and cpu usage of pod from cgroup.
- Go to pod's exec mode
kubectl exec -it pod_name -- /bin/bash
- Go to
cd /sys/fs/cgroup/cpu
for cpu usage runcat cpuacct.usage
- Go to
cd /sys/fs/cgroup/memory
for memory usage runcat memory.usage_in_bytes
Make Sure you have added the resources section (requests and limits) to deployment so that it can calculate the usage based on cgroup and container will respect the limits set on pod level > > NOTE: This usage is in bytes. This can vary upon pod usage and these values changes frequently.
Solution 2 - Kubernetes
kubectl top pod <pod-name> -n <fed-name> --containers
FYI, this is on v1.16.2
Solution 3 - Kubernetes
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As described in the docs, you should install metrics-server
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250m means 250 milliCPU, The CPU resource is measured in CPU units, in Kubernetes, is equivalent to:
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1 AWS vCPU
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1 GCP Core
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1 Azure vCore
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1 Hyperthread on a bare-metal Intel processor with Hyperthreading
> Fractional values are allowed. A Container that requests 0.5 CPU is > guaranteed half as much CPU as a Container that requests 1 CPU. You > can use the suffix m to mean milli. For example 100m CPU, 100 > milliCPU, and 0.1 CPU are all the same. Precision finer than 1m is not > allowed. > > CPU is always requested as an absolute quantity, never as a relative > quantity; 0.1 is the same amount of CPU on a single-core, dual-core, > or 48-core machine.
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No,
kubectl top pod podname
shows metrics for a given pod, Linuxtop
andfree
runs inside a Container and report metrics based on Linux system reporting based on the information stored in the virtual filesystem/proc/
, they are not aware of the cgroup where it runs.
There are more details on these links:
Solution 4 - Kubernetes
Use k9s for a super easy way to check all your resources' cpu and memory usage.
Solution 5 - Kubernetes
You need to run metric server to make below commands working with correct data:
- kubectl get hpa
- kubectl top node
- kubectl top pods
Without metric server: Go into the pod by running below command:
- kubectl exec -it pods/{pod_name} sh
- cat /sys/fs/cgroup/memory/memory.usage_in_bytes
You will get memory usage of pod in bytes.
Solution 6 - Kubernetes
A quick way to check CPU/Memory is by using the following kubectl command. I found it very useful.
kubectl describe PodMetrics <pod_name>
replace
kubectl get pod
Solution 7 - Kubernetes
Not sure why it's not here
- To see all pods with time alive -
kubectl get pods --all-namespaces
- To see memory and CPU -
kubectl top pods --all-namespaces
Solution 8 - Kubernetes
As heapster is deprecated and will not be releasing any future releases, you should go with installing metrics-server
You can install metrics-server in following way:
- Clone the metrics-server github repo:
git clone https://github.com/kubernetes-incubator/metrics-server.git
Edit the deploy/1.8+/metrics-server-deployment.yaml
file and add following section just after command
section:
- command:
- /metrics-server
- --metric-resolution=30s
- --kubelet-insecure-tls
- --kubelet-preferred-address-types=InternalIP
3. Run the following command: kubectl apply -f deploy/1.8+
It will install all the requirements you need for metrics server.
For more info, please have a look at my following answer:
Solution 9 - Kubernetes
To check the usage of individual pods in Kubernetes type the following commands in terminal
$
docker ps | grep
This will give your list of running containers in Kubernetes To check CPU and memory utilization using
$
docker stats
CONTAINER_ID NAME CPU% MEM USAGE/LIMIT MEM% NET_I/O BLOCK_I/O PIDS
Solution 10 - Kubernetes
An alternative approach without having to install the metrics server.
It requires you to currently install crictl into Worker Nodes where pods are installed. There is Kubernetes task defined in official doc.
Once, you have installed it properly you can use the below commands. (I had to use sudo in my case, but, probably may not be required depending on your Kubernetes Cluster install)
- Find your container id of the pod
sudo crictl ps
- use stats to get CPU and RAM
sudo crictl stats <CONTAINERID>
Sample output for reference:
CONTAINER CPU % MEM DISK INODES
873f04b6cef94 0.50 54.16MB 28.67kB 8
Solution 11 - Kubernetes
you need to deploy heapster or metric server to see the cpu and memory usage of the pods
Solution 12 - Kubernetes
In case you are using minikube, you can enable the metrics-server addon; this will show the information in the dashboard.
Solution 13 - Kubernetes
If you exec into your pod, using sh or bash, you can run the top
command which will give you some stats about resource utilisation that updates every few moments.
Solution 14 - Kubernetes
You can use API as defined here:
For example:
kubectl -n default get --raw /apis/metrics.k8s.io/v1beta1/namespaces/default/pods/nginx-7fb5bc5df-b6pzh | jq
{
"kind": "PodMetrics",
"apiVersion": "metrics.k8s.io/v1beta1",
"metadata": {
"name": "nginx-7fb5bc5df-b6pzh",
"namespace": "default",
"selfLink": "/apis/metrics.k8s.io/v1beta1/namespaces/default/pods/nginx-7fb5bc5df-b6pzh",
"creationTimestamp": "2021-06-14T07:54:31Z"
},
"timestamp": "2021-06-14T07:53:54Z",
"window": "30s",
"containers": [
{
"name": "nginx",
"usage": {
"cpu": "33239n",
"memory": "13148Ki"
}
},
{
"name": "git-repo-syncer",
"usage": {
"cpu": "0",
"memory": "6204Ki"
}
}
]
}
Where nginx-7fb5bc5df-b6pzh is pod's name.
Pay attention CPU is measured in nanoCPUs where 1x10E9 nanoCPUs = 1 CPU
Solution 15 - Kubernetes
If you use Prometheus operator or VictoriaMetrics operator for Kubernetes monitoring, then the following PromQL queries can be used for determining per-container, per-pod and per-node resource usage:
- Per-container memory usage in bytes:
sum(container_memory_usage_bytes{container!~"POD|"}) by (namespace,pod,container)
- Per-container CPU usage in CPU cores:
sum(rate(container_cpu_usage_seconds_total{container!~"POD|"}[5m])) by (namespace,pod,container)
- Per-pod memory usage in bytes:
sum(container_memory_usage_bytes{container!=""}) by (namespace,pod)
- Per-pod CPU usage in CPU cores:
sum(rate(container_cpu_usage_seconds_total{container!=""}[5m])) by (namespace,pod)
- Per-node memory usage in bytes:
sum(container_memory_usage_bytes{container!=""}) by (node)
- Per-node CPU usage in CPU cores:
sum(rate(container_cpu_usage_seconds_total{container!=""}[5m])) by (node)
- Per-node memory usage percentage:
100 * (
sum(container_memory_usage_bytes{container!=""}) by (node)
/ on(node)
kube_node_status_capacity{resource="memory"}
)
- Per-node CPU usage percentage:
100 * (
sum(rate(container_cpu_usage_seconds_total{container!=""}[5m])) by (node)
/ on(node)
kube_node_status_capacity{resource="cpu"}
)