Consider using go embed to keep object definitions in YAMLs rather than in Go code

[rojkov]

Currently in the operator we construct DaemonSet objects directly as a Go structure:

ds := &apps.DaemonSet{
    ObjectMeta: metav1.ObjectMeta{...},
    Spec: apps.DaemonSetSpec{...},
}

This way we end up with very long though simple functions and this prevents us from enabling some linter checks like funlen.

Evaluate moving object definitions to YAML files and generating Go files with go-bindata the way it's done in OpenShift operators: https://github.com/openshift/cluster-ingress-operator/tree/master/pkg/manifests.

Try to annotate the generated go-bindata files with buildtags so that linter checks don't go crazy: e.g. generate debug and release versions of the Go files and enable linter checks only for the debug version.

[mythi]

@rojkov https://golang.org/pkg/embed/

[rojkov]

Nice new feature. Looks cleaner than go-bindata

[mythi]

@rojkov I gave it a try using tips from this blog post

package main

import (
	_ "embed"
	"fmt"
	"sigs.k8s.io/yaml"
	apps "k8s.io/api/apps/v1"

)
var (
    //go:embed deployments/qat_plugin/base/intel-qat-plugin.yaml
    b []byte
    s = func() (s apps.DaemonSet) {
	   err := yaml.Unmarshal(b, &s)
	   if err != nil {
		   panic(err)
	   }
	   return
    }()
)

func main() {
    fmt.Printf("s: %#v\n", s)
}

[mythi]

Updated the title: Go embed likely better option than go-bindata.

[rojkov]

Moving the Go code to YAML files may enable us to add the funlen check to .golangci.yaml.

[mythi]

@bart0sh one problem to solve first is how to make embed to find the YAMLs because the embedded files must be under same dir hierarcy (and symlinks are not allowed) as the code that embeds them.

[pohly]

In PMEM-CSI, we treat our deploy directory as a Go package. That package then embeds the YAML files and exports them with a suitable API.

[bart0sh]

@mythi it worked this way: #747
We can either symlink embed.go for other plugins or just copy this file as it should be identical for all of them.

[mythi]

@bart0sh this looks good to me (and thanks @pohly!)

We can either symlink embed.go for other plugins or just copy this file as it should be identical for all of them.

or have deployments/embed.go that pulls in all devices?

[bart0sh]

@mythi thanks. that's even better as yamls do not always cooperate with that simple wildcard pattern. will do.