✨ feat: Accessing old object on watchEvent

[mhkarimi1383]

Overview

By using OldObject input from K8s we will have access to oldObject when modified

What this PR does / why we need it

Closes #515
I need this here: mhkarimi1383/reflector#3

Sometimes we need to have access to older object specially if we are managing our own CRD

Special notes for your reviewer

[mhkarimi1383]

I don't know if I have updated docs correctly, Also in Delete event we can fill OldObject instead of Object, Since we can Called removed object 'old'

[mhkarimi1383]

@nabokihms Can you review this?

[nabokihms]

@mhkarimi1383 yes, sure. I've just put it in the queue.

[nabokihms]

I left a couple of suggestions. One more thing is that the unit test is also required for the feature.

[mhkarimi1383]

I will add unit test for that later on, I have not worked with Golang unit tests alot :)

Can you give me a context of how should I test this thing? I mean testing the input and output is good enough or I have to do a more advaced test

[mhkarimi1383]

@nabokihms Hi, I have fixed linter and unit test error.!

The only left thing is the feature unit tests :)

[mhkarimi1383]

@nabokihms

Any updates on this? My project development blocked 😕

[mhkarimi1383]

@nabokihms
What is this error?

pkg/kube_events_manager/resource_informer.go:302: File is not `gci`-ed with --skip-generated -s standard,default,prefix(github.com/flant/) (gci)

[nabokihms]

Suggested change

	"oldObject": {
	"apiVersion": "apps/v1",
	"kind": "DaemonSet",
	"metadata": {
	"name": "flannel",
	"namespace": "d8-flannel"
	},
	"spec": {
	"selector": {
	"matchLabels": {
	"app": "flannel"
	}
	},
	"template": {
	"metadata": {
	"labels": {
	"app": "flannel",
	"tier": "old-node"
	}
	},
	"spec": {
	"containers": [
	{
	"args": [
	"--ip-masq",
	"--kube-subnet-mgr"
	],
	"image": "flannel:v0.11",
	"name": "kube-flannel",
	"securityContext": {
	"privileged": true
	}
	}
	],
	"hostNetwork": true,
	"imagePullSecrets": [
	{
	"name": "registry"
	}
	],
	"terminationGracePeriodSeconds": 5
	}
	},
	"updateStrategy": {
	"type": "RollingUpdate"
	}
	}
	},

This is not the right doc. The doc is about Kubernetes object modification, not about binding contexts.
The right doc is here https://github.com/flant/shell-operator/blob/main/docs/src/HOOKS.md#kubernetes-binding-context-example

[nabokihms]

I fixed the linter, but PR doesn't work because there are other parts missing.

For example, to finally see an old object in a hook, this file requires changes as well
https://github.com/flant/shell-operator/blob/main/pkg/hook/binding_context/binding_context.go

And probably this one

shell-operator/pkg/hook/controller/kubernetes_bindings_controller.go

Lines 294 to 329 in 1d4c4d9

	func ConvertKubeEventToBindingContext(kubeEvent KubeEvent, link *KubernetesBindingToMonitorLink) []BindingContext {
	bindingContexts := make([]BindingContext, 0)
	switch kubeEvent.Type {
	case TypeSynchronization:
	bc := BindingContext{
	Binding: link.BindingConfig.BindingName,
	Type: kubeEvent.Type,
	Objects: kubeEvent.Objects,
	}
	bc.Metadata.JqFilter = link.BindingConfig.Monitor.JqFilter
	bc.Metadata.BindingType = OnKubernetesEvent
	bc.Metadata.IncludeSnapshots = link.BindingConfig.IncludeSnapshotsFrom
	bc.Metadata.Group = link.BindingConfig.Group
	bindingContexts = append(bindingContexts, bc)
	case TypeEvent:
	for _, kEvent := range kubeEvent.WatchEvents {
	bc := BindingContext{
	Binding: link.BindingConfig.BindingName,
	Type: kubeEvent.Type,
	WatchEvent: kEvent,
	Objects: kubeEvent.Objects,
	}
	bc.Metadata.JqFilter = link.BindingConfig.Monitor.JqFilter
	bc.Metadata.BindingType = OnKubernetesEvent
	bc.Metadata.IncludeSnapshots = link.BindingConfig.IncludeSnapshotsFrom
	bc.Metadata.Group = link.BindingConfig.Group
	bindingContexts = append(bindingContexts, bc)
	}
	}
	return bindingContexts
	}

One more thing, without adding tests, we will not be able to merge the PR.