I am writing a bash script and I need the kubectl command to get all the namespace in my cluster based on a particular label.
kubectl get ns -l=app=backend
When I run the command above I get:
no resources found
only the pods in the ns have that label. wondering if there's a way I can manipulate kubectl to output only the ns of the pods that have that label
You can combine a few commands to do something like:
kubectl get pods -A -l app=backend -o json |
jq -r '.items[]|.metadata.namespace' |
sort -u
This gets a list of all pods in all namespaces that match the label selector; uses jq to extract the namespace name from each pod, and then uses sort -u to produce a unique list.
You can actually do this without jq by using the go-template output format, but for me that always means visiting the go template documentation:
kubectl get pods -A -l app=backend \
-o go-template='{{range .items}}{{.metadata.namespace}}{{"\n"}}{{end}}' |
sort -u
This is the output with custom-columns
$ kubectl -n web get pod -ocustom-columns="Name:.metadata.name,Image:.spec.containers[0].image"
Name Image
mysql-0 myrepo.mydomain.com/mysql:5.7
mysql-1 myrepo.mydomain.com/mysql:5.7
mysql-2 myrepo.mydomain.com/mysql:5.7
This is the output with jsonpath for single pod
$ kubectl -n web get pod -o jsonpath="{..metadata.name}:{..spec.containers[0].image}" mysql-0
mysql-0:myrepo.mydomain.com/mysql:5.7
This is the output with jsonpath for multiple pods
$ kubectl -n web get pod -o jsonpath="{..metadata.name}:{..spec.containers[0].image}"
mysql-0 mysql-1 mysql-2:myrepo.mydomain.com/mysql:5.7 myrepo.mydomain.com/mysql:5.7 myrepo.mydomain.com/mysql:5.7
Now how to combine this into a single column or word, something like this, using -ocustom-columns or -ojsonpath
mysql-0=myrepo.mydomain.com/mysql:5.7
mysql-1=myrepo.mydomain.com/mysql:5.7
mysql-2=myrepo.mydomain.com/mysql:5.7
Using kubectl using plain jsonpath:
kubectl get pod -n <namespace> -o jsonpath='{range .items[*]}{.metadata.name}={.spec.containers[*].image}{"\n"}{end}'
Example:
kubectl get pod -n default -o jsonpath='{range .items[*]}{.metadata.name}={.spec.containers[*].image}{"\n"}{end}'
nginx-0=nginx
nginx-1=nginx
nginx-2=nginx
Here range feature is used to loop over all the pods:
{range items[*]} ...<LOGIC HERE>... {end}
Between the range block(As described above), use the jsonpath, notice the = sign is used as per our requirement.
{.metadata.name}={.spec.containers[*].image}{"\n"}
I often run tasks like:
Read the log of the service X
or
Attach a shell inside the service Y
I always use something in my history like:
kubectl logs `kubectl get pods --no-headers -o custom-columns=":metadata.name" | grep <partial_name>`
or
kubectl exec -it `kubectl get pods --no-headers -o custom-columns=":metadata.name" | grep <partial_name>` bash
Do you know if kubectl has already something in place for this? Or should I create my own set of aliases?
Kubernetes instances are loosely coupled by the means of labels (key-value pairs). Because of that Kubernetes provides various functionalities that can help you to operate on sets of objects based on labels.
In case you have several pods of the same service good chances that they are managed by some ReplicaSet with the use of some specific label. You should see it if you run:
kubectl get pods --show-labels
Now for aggregating logs for instance you could use label selector like:
kubectl logs -l key=value
For more info please see: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/ .
added to my .zshconfig
sshpod () {
kubectl exec --stdin --tty `kubectl get pods --no-headers -o custom-columns=":metadata.name" | grep ${1} | head -n 1` -- /bin/bash
}
usage
sshpod podname
this
finds all pods
greps needed name
picks the first
sshs into the pod
You can go access a pod by its deployment/service/etc:
kubectl exec -it svc/foo -- bash
kubectl exec -it deployment/bar -- bash
Kubernetes will pick a pod that matches the criteria and send you to it.
You can enable shell autocompletion. Kubectl provides this support for Bash and Zsh which will save you a lot of typing (you will use TAB to get the suggestion/completion).
Kuberentes documentations has a great set of information about how to enable autocompletion under Optional kubectl configurations. It covers Bash on Linux, Bash on MacOS and Zsh.
I know I can get the pods using:
kubectl get pods -n "namespace", and also to retrieve a json output
I'm trying to expand to get the pods name, the associated images, and a label attribute called 'base'. Also the date when I retrieve this information.
You can try this using yaml output.
kubectl get pods --all-namespaces -o yaml| egrep "name:|image:"
This will give you name of pod and image which is there for running the pod.
OR
kubectl get pods --all-namespaces -o jsonpath="{.items[*].spec.containers[*].image}"
This command will give you all images which are there in all pods.
If you found this is difficult then use,
kubectl get pod --all-namespaces
Check which pods image you need to find then use,
kubectl describe pod <pod_name> -n <namespace>
For reference use Link
Here you can find the description of kubectl get command.
What are you looking for is this:
output o Output format. One of:
json|yaml|wide|name|custom-columns=...|custom-columns-file=...|go-template=...|go-template-file=...|jsonpath=...|jsonpath-file=...
See custom columns
[http://kubernetes.io/docs/user-guide/kubectl-overview/#custom-columns],
golang template [http://golang.org/pkg/text/template/#pkg-overview]
and jsonpath template [http://kubernetes.io/docs/user-guide/jsonpath].
For example:
List a pod identified by type and name specified in "pod.yaml" in JSON
output format:
kubectl get -f pod.yaml -o json
Adjust by using the flags that you need from there.
Please let me know if that helped.
You can try jsonpath to retrieve the values for json output.
kubectl get po --all-namespaces -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.spec.containers[0].image}{"\t"}{.metadata.labels.k8s-app}{"\n"}{end}'
probably you can write shell script and achieve this. first try to get all running pods across all namespaces using:
kubectl get pods -all-namespaces
and then iterate over each pod and execute following command:
kubectl describe pods <name of pod>
In the describe command you can get all information that you are looking for.
I am looking to list all the containers in a pod in a script that gather's logs after running a test. kubectl describe pods -l k8s-app=kube-dns returns a lot of info, but I am just looking for a return like:
etcd
kube2sky
skydns
I don't see a simple way to format the describe output. Is there another command? (and I guess worst case there is always parsing the output of describe).
Answer
kubectl get pods POD_NAME_HERE -o jsonpath='{.spec.containers[*].name}'
Explanation
This gets the JSON object representing the pod. It then uses kubectl's JSONpath to extract the name of each container from the pod.
You can use get and choose one of the supported output template with the --output (-o) flag.
Take jsonpath for example,
kubectl get pods -l k8s-app=kube-dns -o jsonpath={.items[*].spec.containers[*].name} gives you etcd kube2sky skydns.
Other supported output output templates are go-template, go-template-file, jsonpath-file. See http://kubernetes.io/docs/user-guide/jsonpath/ for how to use jsonpath template. See https://golang.org/pkg/text/template/#pkg-overview for how to use go template.
Update: Check this doc for other example commands to list container images: https://kubernetes.io/docs/tasks/access-application-cluster/list-all-running-container-images/
Quick hack to avoid constructing the JSONpath query for a single pod:
$ kubectl logs mypod-123
a container name must be specified for pod mypod-123, choose one of: [etcd kubesky skydns]
I put some ideas together into the following:
Simple line:
kubectl get po -o jsonpath='{range .items[*]}{"pod: "}{.metadata.name}{"\n"}{range .spec.containers[*]}{"\tname: "}{.name}{"\n\timage: "}{.image}{"\n"}{end}'
Split (for readability):
kubectl get po -o jsonpath='
{range .items[*]}
{"pod: "}
{.metadata.name}
{"\n"}{range .spec.containers[*]}
{"\tname: "}
{.name}
{"\n\timage: "}
{.image}
{"\n"}
{end}'
How to list BOTH init and non-init containers for all pods
kubectl get pod -o="custom-columns=NAME:.metadata.name,INIT-CONTAINERS:.spec.initContainers[*].name,CONTAINERS:.spec.containers[*].name"
Output looks like this:
NAME INIT-CONTAINERS CONTAINERS
helm-install-traefik-sjts9 <none> helm
metrics-server-86cbb8457f-dkpqm <none> metrics-server
local-path-provisioner-5ff76fc89d-vjs6l <none> local-path-provisioner
coredns-6488c6fcc6-zp9gv <none> coredns
svclb-traefik-f5wwh <none> lb-port-80,lb-port-443
traefik-6f9cbd9bd4-pcbmz <none> traefik
dc-postgresql-0 init-chmod-data dc-postgresql
backend-5c4bf48d6f-7c8c6 wait-for-db backend
if you want a clear output of which containers are from each Pod
kubectl get po -l k8s-app=kube-dns \
-o=custom-columns=NAME:.metadata.name,CONTAINERS:.spec.containers[*].name
To get the output in the separate lines:
kubectl get pods POD_NAME_HERE -o jsonpath='{range .spec.containers[*]}{.name}{"\n"}{end}'
Output:
base-container
sidecar-0
sidecar-1
sidecar-2
If you use json as output format of kubectl get you get plenty details of a pod. With json processors like jq it is easy to select or filter for certain parts you are interested in.
To list the containers of a pod the jq query looks like this:
kubectl get --all-namespaces --selector k8s-app=kube-dns --output json pods \
| jq --raw-output '.items[].spec.containers[].name'
If you want to see all details regarding one specific container try something like this:
kubectl get --all-namespaces --selector k8s-app=kube-dns --output json pods \
| jq '.items[].spec.containers[] | select(.name=="etcd")'
Use below command:
kubectl get pods -o=custom-columns=PodName:.metadata.name,Containers:.spec.containers[*].name,Image:.spec.containers[*].image
To see verbose information along with configmaps of all containers in a particular pod, use this command:
kubectl describe pod/<pod name> -n <namespace name>
Use below command to see all the information of a particular pod
kubectl get pod <pod name> -n <namespace name> -o yaml
For overall details about the pod try following command to get the container details as well
kubectl describe pod <podname>
I use this to display image versions on the pods.
kubectl get pods -o=jsonpath='{range .items[*]}{"\n"}{.metadata.name}{":\t"}{range .spec.containers[*]}{.image}{end}{end}' && printf '\n'
It's just a small modification of script from here, with adding new line to start next console command on the new line, removed commas at the end of each line and listing only my pods, without service pods (e.g. --all-namespaces option is removed).
There are enough answers here but sometimes you want to see a deployment object pods' containers and initContainers. To do that;
1- Retrieve the deployment name
kubectl get deployment
2- Retrieve containers' names
kubectl get deployment <deployment-name> -o jsonpath='{.spec.template.spec.containers[*].name}'
3- Retrieve initContainers' names
kubectl get deployment <deployment-name> -o jsonpath='{.spec.template.spec.initContainers[*].name}'
Easiest way to know the containers in a pod:
kubectl logs -c -n