kyaml

Print clean YAML of a live object, ready to reuse.

Synopsis

kyaml [-n NAMESPACE] [-o FILE] [--status] [--no-namespace] KIND/NAME [-- kubectl options]
kyaml [options] KIND NAME

Description

kubectl get -o yaml prints an object the way the cluster stores it, not the way you wrote it. Half of it is bookkeeping. There are managedFields, which can run to hundreds of lines, and there is the status block. On top of that come the uid, resourceVersion, creationTimestamp and generation, and the last-applied annotation that holds a second copy of the whole object as JSON. Apply that output to another namespace or cluster and some of it fails, since a uid or resourceVersion from one cluster means nothing in another.

kyaml runs kubectl get -o yaml and removes what the cluster added. The rest is the object as a person would write it, with its labels, annotations of your own, and the spec. You can read it, diff it against the file in git, or save it and apply it somewhere else.

kyaml only reads the cluster. It writes a file only with -o, and never over a file that exists.

Options

The object is KIND/NAME as kubectl writes it, such as deploy/api, svc/api or configmap/app-config, or the same as two words. Any short name kubectl knows works, since kyaml hands it to kubectl as it is.

What it removes

An annotations: block left empty after that goes too. Every other field stays as the cluster printed it, including defaults it filled in, such as progressDeadlineSeconds or sessionAffinity. Those apply cleanly.

Pass-through

Options after -- go to kubectl get.

$ kyaml deploy/api -- --context kind-kind

Needs

kubectl. The filter is built in and uses awk, so no YAML tool is needed.

Examples

A Deployment, ready to reuse

$ kyaml -n shop deploy/api
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: api
  name: api
  namespace: shop
spec:
  progressDeadlineSeconds: 600
  replicas: 2
  selector:
    matchLabels:
      app: api
  template:
    metadata:
      labels:
        app: api
    spec:
      containers:
      - image: registry.example.com/api:2.3.0
        name: api
        ports:
        - containerPort: 8080
          protocol: TCP

What it took out

$ kyaml -v -n shop deploy/api > api.yaml
+ kubectl get deploy/api -n shop -o yaml
kyaml: removed deployment.kubernetes.io/revision, kubectl.kubernetes.io/last-applied-configuration, creationTimestamp, generation, managedFields (8 lines), resourceVersion, uid, status

The + and kyaml: lines go to stderr, so the file holds only the YAML.

Save a Service to a file

$ kyaml -v -n shop svc/api -o api-svc.yaml
+ kubectl get svc/api -n shop -o yaml
kyaml: removed creationTimestamp, resourceVersion, uid, clusterIP, clusterIPs, status
kyaml: wrote api-svc.yaml, 23 lines
$ kyaml -n shop svc api -o api-svc.yaml
kyaml: api-svc.yaml exists, pick another name or move it away first
$ echo $?
4

Move an object to another namespace

$ kyaml --no-namespace -n shop svc/api | head -8
apiVersion: v1
kind: Service
metadata:
  annotations:
    example.com/owner: shop-team
  labels:
    app: api
  name: api
$ kyaml --no-namespace -n shop svc/api | kubectl apply -n staging -f -

Only the annotation you wrote yourself is left.

Keep the status

$ kyaml --status -n shop svc/api | tail -3
  type: ClusterIP
status:
  loadBalancer: {}

Mistakes

$ kyaml -n shop api
kyaml: give a kind and a name, for example deploy/api or svc/api
Try 'kyaml --help' for the options.
$ kyaml -n shop deploy/nope
kyaml: no deploy/nope in shop. List them with: kubectl get deploy -n shop
$ kyaml pizza/x
kyaml: the cluster has no resource type pizza. List them with: kubectl api-resources

Troubleshooting

kubectl apply of the file says the object has been modified

The file still has a resourceVersion. That happens only when the field sits somewhere kyaml does not look, such as inside a List. Delete the line and apply again.

The Service in the new cluster gets a different IP

That is on purpose. kyaml drops clusterIP so the new cluster picks a free address. A headless Service is the exception. It keeps clusterIP: None, since without it the copy would get an address and stop being headless.

The output still has fields you did not write

The cluster fills in defaults, such as terminationMessagePath or dnsPolicy. They are valid and apply cleanly, so kyaml leaves them.

Exit status

See also

ksecret, yamlcheck, kubectl-get(1), kubectl-apply(1)