I'm trying to get metadata for a given kubernetes resource. Similar to a describe for a REST end-point.
Is there a kubectl to get all possible things that I could provide for any k8s resource ?
For example for the deployment resource, it could be something like this.
apiVersion: apps/v1
kind: Deployment
metadata:
name: <type:String>
<desc: name for the deployment>
namespace: <type:String>
<desc: Valid namespace>
annotations:
...
Thanks in advance !
You can use the kubectl explain CLI command:
This command describes the fields associated with each supported API
resource. Fields are identified via a simple JSONPath identifier:
<type>.<fieldName>[.<fieldName>]
Add the --recursive flag to display all of the fields at once without descriptions. Information about each field is retrieved from the server in OpenAPI format.
Example to view all Deployment associated fields:
kubectl explain deployment --recursive
You can dig into specific fields:
kubectl explain deployment.spec.template
You can also rely on Kubernetes API Reference Docs.
Are you familiar with OpenApi/Swagger? Try to open the following file in swagger-ui https://raw.githubusercontent.com/kubernetes/kubernetes/master/api/openapi-spec/swagger.json
If you have a live kubernetes api available the file should be available under /openapi/v2 like they describe here: https://kubernetes.io/docs/concepts/overview/kubernetes-api/#openapi-and-swagger-definitions
Related
Due to Kubernetes removing deprecated API I am trying to figure out an apiVersion of resources in a cluster and came across the following behavior.
When requesting definition for specific deployment, it reports an old api version:
> kubectl get deployment/some-deployment -o yaml
apiVersion: extensions/v1beta1
kind: Deployment
...
Bud when requesting it for all resources api version reported as new for the same resource:
> kubectl get all -o yaml
...
- apiVersion: apps/v1
kind: Deployment
...
Same goes when checking selfLink in metadata:
kubectl get all -o=custom-columns=NAME:.metadata.name,API-version:.metadata.selfLink
and
kubectl get deployment/some-deployment -o=custom-columns=NAME:.metadata.name,API-version:.metadata.selfLink
How should this be interpreted?
Kubernetes version is 1.15.7.
Quoted from here
kubectl get deployment foo is ambiguous, since the server has deployments in multiple api groups. When a resource exists in multiple api groups, kubectl uses the first group listed in discovery docs published by the server which contains the resource. For backwards compatibility, that is the extensions api group.
If you want to ensure you get a deployment in the apps api group, fully qualify the resource you are requesting by running kubectl get deployments.apps test-nginx
If you want a specific version, like v1, in the apps api group, include that as well: kubectl get deployments.v1.apps test-nginx
Also from here
What stored version is used for?
It is the serialized version in etcd. Whenever you fetch an object, the api server reads it from etcd, converts it into an internal version, then converts it to the version you requested.
So, If you run
$ kubectl get deployments nginx -o name
deployment.extensions/nginx
As you can see requested version for above command is deployment.extensions
And If you run
$ kubectl get all -o name
...
deployment.apps/nginx
The requested version is deployment.apps. so, it returns the version with apps/v1
Ref: https://github.com/kubernetes/kubernetes/issues/58131
I am creating namespace using kubectl with yaml. The following is my yaml configuration
apiVersion: v1
kind: Namespace
metadata:
name: "slackishapp"
labels:
name: "slackishapp"
But, when I run kubectl create -f ./slackish-namespace-manifest.yaml, I got an error like the following
error: SchemaError(io.k8s.api.autoscaling.v2beta2.PodsMetricStatus): invalid object doesn't have additional properties.
What goes wrong on my yaml? I am reading about it on the documentation as well. I don't see any difference with my configuration.
There is nothing wrong with your yaml but I suspect you have the wrong version of kubectl.
kubectl needs to be within 1 minor from the cluster you are using as described here.
You can check your versions with
kubectl version
Download the kubectl.exe on https://kubernetes.io/docs/tasks/tools/install-kubectl/#before-you-begin then replace it on Program Files\Docker\Docker\resources\bin if you have docker desktop
Like Andreas Wederbrand said, it is a version problem.
As a workaround, try to create your namespace within imperative mode
kubectl create ns slackishapp && kubectl label ns slackishapp name=slackishapp
And then compare existing yaml with one you have written in order to check what is missing
kubectl get ns slackishapp -o yaml --export
I have deployed a Kubernetes service and when I query to get the Deployment $ kubectl get deployments, I can see the Deployment.
the json of the Deployment looks like below --
apiVersion: v1
kind: Deployment
metadata:
name: test
spec:
replicas: 1
template:
metadata:
labels:
app: test
release: testRelease
customProp: xyz
My question is how can I frame a query by which I can get the Deployment by specifying the 'customProp' value. Does kubectl support to pass a jsonpath as part of the query? so that I can pass a json path like jsonpath='{$.spec.template.metadata.labels.customProp}' and value against this jsonPath as 'xyz'.
This is what I am thinking to execute:
$ kubectl get deployments -n <namespace> <json path query>
However not sure how to frame the json path query and pass along with $kubectl get deployments.
Kubectl does support query feature, you can use below query
kubectl get pods --selector=customProp=xyz
Kubectl also supports JSON path expressions too, to get more details, follow the link. You can write query following the syntax shown on the link.
Yes, one can query to the kube-apiserver for a resource using jsonpath. Run following command to get what you want:
$ kubectl get deploy test -o=jsonpath='{.spec.template.metadata.labels.customProp}'
For more usage, see https://kubernetes.io/docs/reference/kubectl/jsonpath.
Add a label to your deployment object. Then with below command to query specific deployment
kubectl get deploy - l labelname=labelvalue
To get deployed image name as a string, you can choose from any attribute in deployment yaml.
kubectl get deploy/${image.name} -o jsonpath="{..image}"
Forgive my ignorance but I can't seem to find a way of using a yaml file to deploy a single container pod (read: kind: Pod). It appears the only way to do it is to use a deployment yaml file (read: kind: Deployment) with a replica of 1.
Is there really no way?
Why I ask is because it would be nice to put everything in source control, including the one off's like databases.
It would be awesome if there was a site with all the available options you can use in a yaml file (like vagrant's vagrantfile). There isn't one, right?
Thanks!
You should be able to find pod yaml files easily. For example, the documentation has an example of a Pod being created.
apiVersion: v1
kind: Pod
metadata:
name: hello-world
spec: # specification of the pod's contents
restartPolicy: Never
containers:
- name: hello
image: "ubuntu:14.04"
command: ["/bin/echo", "hello", "world"]
One thing to note is that if a deployment or a replicaset created a resource on your behalf, there is no reason why you couldn't do the same.
kubectl get pod <pod-name> -o yaml should give you the YAML spec of a created pod.
There is Kubernetes charts, which serves as a repository for configuration surrounding complex applications, using the helm package manager. This would serve you well for deploying more complex applications.
Never mind, figured it out. It's possible. You just use the multi-container yaml file (example found here: https://kubernetes.io/docs/user-guide/pods/multi-container/) but only specify one container.
I'd tried it before but had inadvertently mistyped the yaml formatting.
Thanks rubber ducky!
I have defined a Deployment for my app:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: myapp-deployment
spec:
replicas: 2
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: 172.20.34.206:5000/myapp_img:2.0
ports:
- containerPort: 8080
Now, if I want update my app's image 2.0 to 3.0, I do this:
$ kubectl edit deployment/myapp-deployment
vim is open. I change the image version from 2.0 to 3.0 and save.
How can it be automated? Is there a way to do it just running a command? Something like:
$ kubectl edit deployment/myapp-deployment --image=172.20.34.206:5000/myapp:img:3.0
I thought using Kubernetes API REST but I don't understand the documentation.
You could do it via the REST API using the PATCH verb. However, an easier way is to use kubectl patch. The following command updates your app's tag:
kubectl patch deployment myapp-deployment -p \
'{"spec":{"template":{"spec":{"containers":[{"name":"myapp","image":"172.20.34.206:5000/myapp:img:3.0"}]}}}}'
According to the documentation, YAML format should be accepted as well. See Kubernetes issue #458 though (and in particular this comment) which may hint at a problem.
There is a set image command which may be useful in simple cases
Update existing container image(s) of resources.
Possible resources include (case insensitive):
pod (po), replicationcontroller (rc), deployment (deploy), daemonset (ds), job, replicaset (rs)
kubectl set image (-f FILENAME | TYPE NAME) CONTAINER_NAME_1=CONTAINER_IMAGE_1 ... CONTAINER_NAME_N=CONTAINER_IMAGE_N
http://kubernetes.io/docs/user-guide/kubectl/kubectl_set_image/
$ kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1
deployment "nginx-deployment" image updated
http://kubernetes.io/docs/user-guide/deployments/
(I would have posted this as a comment if I had enough reputation)
Yes, as per http://kubernetes.io/docs/user-guide/kubectl/kubectl_patch/ both JSON and YAML formats are accepted.
But I see that all the examples there are using JSON format.
Filed https://github.com/kubernetes/kubernetes.github.io/issues/458 to add a YAML format example.
I have recently built a tool to automate deployment updates when new images are available, it works with Kubernetes and Helm:
https://github.com/rusenask/keel
You only have to label your deployments with Keel policy like keel.sh/policy=major to enable major version updates, more info in the readme. Works similarly with Helm, no additional CLI/UI required.