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Add a WithValueTranslator option to Reconciller. #6

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Merged
merged 5 commits into from
May 25, 2021
Merged

Add a WithValueTranslator option to Reconciller. #6

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ff139a1
Add a WithValueTranslator option to Reconciller.
porridge May 20, 2021
bb22d60
lint
porridge May 20, 2021
bf32ac6
:facepalm:
porridge May 20, 2021
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porridge May 24, 2021
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todo
porridge May 25, 2021
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8 changes: 8 additions & 0 deletions pkg/reconciler/internal/values/values.go
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Original file line number Diff line number Diff line change
Expand Up @@ -68,3 +68,11 @@ func (v *Values) ApplyOverrides(in map[string]string) error {
}

var DefaultMapper = values.MapperFunc(func(v chartutil.Values) chartutil.Values { return v })

var DefaultTranslator = values.TranslatorFunc(func(u *unstructured.Unstructured) (chartutil.Values, error) {
internalValues, err := FromUnstructured(u)
if err != nil {
return chartutil.Values{}, err
}
return internalValues.Map(), err
})
23 changes: 20 additions & 3 deletions pkg/reconciler/reconciler.go
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Expand Up @@ -61,6 +61,7 @@ const uninstallFinalizer = "uninstall-helm-release"
type Reconciler struct {
client client.Client
actionClientGetter helmclient.ActionClientGetter
valueTranslator values.Translator
valueMapper values.Mapper
eventRecorder record.EventRecorder
preHooks []hook.PreHook
Expand Down Expand Up @@ -362,8 +363,20 @@ func WithPostHook(h hook.PostHook) Option {
}
}

// WithValueTranslator is an Option that configures a function that translates a
// custom resource to the values passed to Helm.
// Use this if you need to customize the logic that translates your custom resource to Helm values.
func WithValueTranslator(t values.Translator) Option {
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Could you mention the difference to the Mapper? It could get confusing as they have similar use-cases.

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+1, reading this PR I don't really understand why a custom translator is required in addition to the mapper. Things that come to mind:

  • access to metadata (name, ...) and status fields
  • ability to use Go types by converting the *unstructured.Unstructured into the Go type for a CR.

However, having translator + mapper seems confusing. Perspectively, I think it would make more sense to introduce translator as the first-class citizen, and drop the valueMapper field. WithValueMapper could then return a function that sets the valueTranslator accordingly (relying on FromUnstructured).

Or am I completely off, and the difference is actually whether it gets executed pre/post the application of overrides?

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@porridge porridge May 24, 2021 •
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@SimonBaeumer added a couple of sentences.

@misberner the rationale is in the PR description:

This lets the user inject code which produces helm values based on the fetched object itself (unlike Mapper which can only see Values).
This way the custom code can convert the object to a typed one and work with proper structs rather than a tree of maps to interface{}.

Basically it is so that we can have write type-safe code at least to read the CRs.

I'd agree about dropping the Mapper API eventually, but:

  • it's out of scope of this PR, I'm trying to diverge from upstream as little as possible,
  • in general it would need more discussion with upstream, for example there are also these ApplyOverrides and CoalesceValues steps in getValues which I don't fully understand, so there might be use cases where Mapper is a better tool

return func(r *Reconciler) error {
r.valueTranslator = t
return nil
}
}

// WithValueMapper is an Option that configures a function that maps values
// from a custom resource spec to the values passed to Helm
// from a custom resource spec to the values passed to Helm.
// Use this if you want to apply a transformation on the values obtained from your custom resource, before
// they are passed to Helm.
func WithValueMapper(m values.Mapper) Option {
return func(r *Reconciler) error {
r.valueMapper = m
Expand Down Expand Up @@ -522,14 +535,15 @@ func (r *Reconciler) Reconcile(ctx context.Context, req ctrl.Request) (res ctrl.
}

func (r *Reconciler) getValues(obj *unstructured.Unstructured) (chartutil.Values, error) {
crVals, err := internalvalues.FromUnstructured(obj)
vals, err := r.valueTranslator.Translate(obj)
if err != nil {
return chartutil.Values{}, err
}
crVals := internalvalues.New(vals)
if err := crVals.ApplyOverrides(r.overrideValues); err != nil {
return chartutil.Values{}, err
}
vals := r.valueMapper.Map(crVals.Map())
vals = r.valueMapper.Map(crVals.Map())
vals, err = chartutil.CoalesceValues(r.chrt, vals)
if err != nil {
return chartutil.Values{}, err
Expand Down Expand Up @@ -736,6 +750,9 @@ func (r *Reconciler) addDefaults(mgr ctrl.Manager, controllerName string) {
if r.eventRecorder == nil {
r.eventRecorder = mgr.GetEventRecorderFor(controllerName)
}
if r.valueTranslator == nil {
r.valueTranslator = internalvalues.DefaultTranslator
}
if r.valueMapper == nil {
r.valueMapper = internalvalues.DefaultMapper
}
Expand Down
13 changes: 13 additions & 0 deletions pkg/values/values.go
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Expand Up @@ -18,8 +18,11 @@ package values

import (
"helm.sh/helm/v3/pkg/chartutil"
"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
)

// TODO: Consider deprecating Mapper and overrides in favour of Translator.

type Mapper interface {
Map(chartutil.Values) chartutil.Values
}
Expand All @@ -29,3 +32,13 @@ type MapperFunc func(chartutil.Values) chartutil.Values
func (m MapperFunc) Map(v chartutil.Values) chartutil.Values {
return m(v)
}

type Translator interface {
Translate(unstructured *unstructured.Unstructured) (chartutil.Values, error)
}

type TranslatorFunc func(*unstructured.Unstructured) (chartutil.Values, error)

func (t TranslatorFunc) Translate(u *unstructured.Unstructured) (chartutil.Values, error) {
return t(u)
}