I have a Kubernetes cluster running in minikube, I want to filter out all Logstash pods via Kubernetes API. Kubernetes API documentation is a bit confusing, I did some research and found out that I can use something like this, but I have been unsuccessful so far:
localhost:8000/api/v1/namespaces/default/pods?labelSelector=logstash
any ideas how to retrieve this? Any help would be really appreciated.
any ideas how to retrieve this?
Since labels are defined in <name>=<value> pairs you need to supply both, as described in the documentation (see the API section)
As an example, supposing you have:
namepace: default
labels on pods you want to select:
role=ops
application=logstash
kubectl proxy runs on localhost:8000
Then your api call would look like this:
curl localhost:8000/api/v1/namespaces/default/pods?labelSelector=role%3Dops,application%3Dlogstash
Related
I am studying "kubectl describe" sourcecodes at https://github.com/kubernetes/kubectl/blob/master/pkg/describe/describe.go
However, I still could not figure out how "kubectl decsribe [CRD]" works (as in which function/functions are called).
I am a Go newbie, so would like to get some pointers please. Thanks.
I have read describePod function and understand how it works more or less, but still could not figure out how "kubectl describe [CRD]" works.
The "kubectl describe " function can be found in the command-line interface (CLI) of Kubernetes, specifically in the "kubectl" tool. "kubectl" is used to manage and interact with a Kubernetes cluster and its resources.
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Kubectl describe command helps to view the entire information about the kubernetes resources like Pods,deployments,services,nodes,jobs etc.
By using CRD(Custom Resource Definition) you can do CRUD operations like create, update, get and delete commands to access the resources. To use CRD we need to use the API groups.
Example:
Suppose you specify an API group as example.crd.com, which means you can issue the get, list, create, update, and delete commands to access the custom resources under the API group example.crd.com.
You can use kubectl describe crd <crd_name> to get a description of the CRD.
For more information refer this official doc
Try this similar SO’s SO1 and SO2 for more information
Is it possible for a pod to act like a spawner? When someone calls the api service in the first pod, it should spawn a new pod. This seems like a very simple thing but I cant really figure out where to look in the docs. Someone already mentioned using operators but I dont really see how that would aid me.
Im currenlty migrating a project which uses docker as a spawner to create other dockers. I somehow need this principle to work in kubernetes pods.
Kind regards
Have you looked into Kubespawner part of JupyterHub ?
I have been trying to find alternatives to Kubespawner and Kubernetes Operators might be the answer. https://kubernetes.io/docs/concepts/extend-kubernetes/operator/
GL
How can we obtain the gke pod counts running in the cluster? I found there are ways to get node count but we needed pod count as well. it will be better if we can use something with no logging needed in gcp operations.
You can do it with Kubernetes Python Client library as shown in this question, posted by Pradeep Padmanaban C, where he was looking for more effective way of doing it, but his example is actually the best what you can do to perform such operation as there is no specific method which would allow you just to count pods without retrieving their entire json manifests:
from kubernetes import client , config
config.load_kube_config()
v1= client.CoreV1Api()
ret_pod = v1.list_pod_for_all_namespaces(watch=False)
print(len(ret_pod.items))
You can also use a different method, which allows to retrieve pods only from specific namespace e.g.:
list_namespaced_pod("default")
In kubectl way you can do it as follows (as proposed here by RammusXu):
kubectl get pods --all-namespaces --no-headers | wc -l
You can directly access the kubernetes API using a restful API call. You will need to make sure you provide the authentication token in your call by including a bearer token.
Once you are able to query the api server directly, you can use GET <master_endpoint>/api/v1/pods to list all the pods in the cluster. You can also search for specific namespaces by specifying the namespace /api/v1/namespaces/<namespace>/pods.
Keep in mind that the kubectl cli tool is just a wrapper for API calls, each kubectl command will form a RESTful API call in a similar format to the one listed above, so any interaction you have with the cluster using kubectl can also be achieved through RESTful API calls
I have installed a K8S cluster on laptop using Kubeadm and VirtualBox. It seems a bit odd that the cluster has to be up and running to see the documentation as shown below.
praveensripati#praveen-ubuntu:~$ kubectl explain pods
Unable to connect to the server: dial tcp 192.168.0.31:6443: connect: no route to host
Any workaround for this?
See "kubectl explain — #HeptioProTip"
Behind the scenes, kubectl just made an API request to my Kubernetes cluster, grabbed the current Swagger documentation of the API version running in the cluster, and output the documentation and object types.
Try kubectl help as an offline alternative, but that won't be as complete (limite to kubectl itself).
So the rather sobering news is that AFAIK there's not out-of-the box way how to do it, though you could totally write a kubectl plugin (it has become rather trivial now in 1.12). But for now, the best I can offer is the following:
# figure out which endpoint kubectl uses to retrieve docs:
$ kubectl -v9 explain pods
# from above I learn that in my case it's apparently
# https://192.168.64.11:8443/openapi/v2 so let's curl that:
$ curl -k https://192.168.64.11:8443/openapi/v2 > resources-docs.json
From here you can, for example, use jq to query for the descriptions. It's not as nice as a proper explain, but kinda is a good enough workaround until someone writes an docs offline query kubectl plugin.
The 'explain' documentation lives in the kube-apiserver and its resource definitions. Hence the need to connect to it through kubectl explain to get any docs. This is different from the standard very basic cli help from kubectl where it's in the kubectl Golang code.
So no workaround really other than setting up a dummy Kubernetes cluster and have kubectl point to it. Please note that CRDs help might not be available since they live in the deployed CRDs themselves.
My objective is to fetch the time series of a metric for a pod running on a kubernetes cluster on GKE using the Stackdriver TimeSeries REST API.
I have ensured that Stackdriver monitoring and logging are enabled on the kubernetes cluster.
Currently, I am able to fetch the time series of all the resources available in a cluster using the following filter:
metric.type="container.googleapis.com/container/cpu/usage_time" AND resource.labels.cluster_name="<MY_CLUSTER_NAME>"
In order to fetch the time series of a given pod id, I am using the following filter:
metric.type="container.googleapis.com/container/cpu/usage_time" AND resource.labels.cluster_name="<MY_CLUSTER_NAME>" AND resource.labels.pod_id="<POD_ID>"
This filter returns an HTTP 200 OK with an empty response body. I have found the pod ID from the metadata.uid field received in the response of the following kubectl command:
kubectl get deploy -n default <SERVICE_NAME> -o yaml
However, when I use the Pod ID of a background container spawned by GKE/Stackdriver, I do get the time series values.
Since I am able to see Stackdriver metrics of my pod on the GKE UI, I believe I should also get the metric values using the REST API.
My doubts/questions are:
Am I fetching the Pod ID of my pod correctly using kubectl?
Could there be some issue with my cluster setup/service deployment due to which I'm unable to fetch the metrics?
Is there some other way in which I can get the time series of my pod using the REST APIs?
I wouldn't rely on kubectl get deploy for pod ids. I would get them with something like kubectl -n default get pods | grep <prefix-for-your-pod> | awk '{print $1}'
I don't think so, but the best way to find out is opening a support ticket with GCP if you have any doubts.
Not that I'm aware of, Stackdriver is the monitoring solution in GCP. Again, you can check with GCP support. There are other tools that you can use to get metrics from Kubernetes like Prometheus. There are multiple guides on the web on how to set it up with Grafana on k8s. This is one for example.
Hope it helps!
Am I fetching the Pod ID of my pod correctly using kubectl?
You could use JSONpath as output with kubectl, in this case iterating over the Pods and fetching the metadata.name and metadata.uid fields:
kubectl get pods -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.metadata.uid}{"\n"}{end}'
which will output something like this:
nginx-65899c769f-2j775 d4fr5t6-bc2f-11e8-81e8-42010a84011f
nginx2-77b5c9d48c-7qlps 4f5gh6r-bc37-11e8-81e8-42010a84011f
Could there be some issue with my cluster setup/service deployment due to which I'm unable to fetch the metrics?
As #Rico mentioned in his answer, contacting the GCP support could be a way forward if you don't get further with the troubleshooting, see below.
Is there some other way in which I can get the time series of my pod using the REST APIs?
You could use the APIs Explorer or the Metrics Explorer from within the Stackdriver portal. There's some good troubleshooting tips here with a link to the APIs Explorer. In the Stackdriver Metrics Explorer it's fairly easy to reassemble the filter you've used using dropdown lists to choose e.g. a particular pod_id.
Taken from the Troubleshooting the Monitoring guide (linked above) regarding an empty HTTP 200 response on filtered queries:
If your API call returns status code 200 and an empty response, there
are several possibilities:
If your call uses a filter, then the filter might not have matched anything. The filter match is case-sensitive. To resolve filter
problems, start by specifying only one filter component, such as
metric.type, and see if you get results. Add the other filter
components one-by-one.
If you are working with a custom metric, you might not have specified the project where your custom metric is defined.*
I found this link when reading through the documentation of the Monitoring API. That link will get you to the APIs Explorer with some pre-filled fields, change these accordingly and add your own filter.
I have not tested more using the REST API at the moment but hopefully this could get you forward.