I'd like to show entries that have .metadata.labels.app set to "myapp"value.

Command:

kubectl get pods -o go-template --template="{{range .items}}{{if eq .metadata.labels.app "myapp"}}{{.metadata.name}} {{end}}{{end}}"

It gives an error:

output:1: function "myapp" not defined

The structures look like this:

- apiVersion: v1
  kind: Pod
  metadata:
    creationTimestamp: 2017-09-15T08:18:26Z
    generateName: myapp-2830765207-
    labels:
      app: myapp
      pod-template-hash: "2830765207"
    name: myapp-2830765207-dh359
    namespace: default

I haven't used kubetcl before, but I am familiar with shell commands in general, from which I can tell you one thing that's going wrong, and maybe that's all you need. (I'm also somewhat familiar with Go templates, and your string comparison looks fine to me.) By using double quotes around your template and within your template, you're actually closing the string you're passing in as the template at the first double quote in "myapp". Using single quotes around the template should help:

kubectl get pods -o go-template --template='{{range .items}}{{if eq .metadata.labels.app "myapp"}}{{.metadata.name}} {{end}}{{end}}'