[GitHub] [camel-k] astefanutti commented on a change in pull request #1861: WIP: Add podTrait to specify customPodTemplateSpec

[GitBox <gi...@apache.org>]

astefanutti commented on a change in pull request #1861:
URL: https://github.com/apache/camel-k/pull/1861#discussion_r580414494



##########
File path: pkg/trait/pod.go
##########
@@ -0,0 +1,196 @@
+/*
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements.  See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to You under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package trait
+
+import (
+	"fmt"
+	v1 "github.com/apache/camel-k/pkg/apis/camel/v1"
+	"github.com/ghodss/yaml"
+	v12 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/util/json"
+
+	//"github.com/ghodss/yaml"
+	//	cmd "github.com/apache/camel-k/pkg/cmd"
+
+	appsv1 "k8s.io/api/apps/v1"
+)
+
+// The Pod trait allows to modify the custom PodTemplateSpec resource for the Integration pods
+//
+// +camel-k:trait=pdb
+type podTrait struct {
+	BaseTrait `property:",squash"`
+	Template  string `property:"template"`
+}
+
+func newPodTrait() Trait {
+	return &podTrait{
+		BaseTrait: NewBaseTrait("pod", 1800),
+	}
+}
+
+func (t *podTrait) Configure(e *Environment) (bool, error) {
+	if t.Enabled == nil || !*t.Enabled {
+		return false, nil
+	}
+
+	if t.Template == "" {
+		return false, fmt.Errorf("template must be specified")
+	}
+
+	if _, err := t.parseTemplate(); err != nil {
+		return false, err
+	}
+
+	return e.IntegrationInPhase(
+		v1.IntegrationPhaseDeploying,
+		v1.IntegrationPhaseRunning,
+	), nil
+}
+
+func (t *podTrait) Apply(e *Environment) error {
+	var deployment *appsv1.Deployment
+
+	e.Resources.VisitDeployment(func(d *appsv1.Deployment) {
+		if d.Name == e.Integration.Name {
+			deployment = d
+		}
+	})
+
+	modifiedTemplate, err := t.mergeIntoTemplateSpec(deployment.Spec.Template, []byte(t.Template))
+	if err != nil {
+		return err
+	}
+	deployment.Spec.Template = modifiedTemplate
+	return nil
+}
+
+func (t *podTrait) parseTemplate() (*v12.PodTemplateSpec, error) {
+	var template *v12.PodTemplateSpec
+
+	if err := yaml.Unmarshal([]byte(t.Template), &template); err != nil {
+		return nil, err
+	}
+	return template, nil
+
+}
+
+func (t *podTrait) mergeIntoTemplateSpec(template v12.PodTemplateSpec, changesBytes []byte) (mergedTemplate v12.PodTemplateSpec, err error) {

Review comment:
       I think we are implementing what strategic merge patch functionally does. Before making the decision to implement the merging strategy ourselves, I think we have to assess whether we could re-use Kubernetes strategic merge patch:
   
   https://github.com/kubernetes/apimachinery/blob/10b38829b6211c0d672e14a126479221312d3368/pkg/util/strategicpatch/patch.go#L812
   
   Among the multiple benefits that could provide re-using strategic merge patch from Kubernetes, I see:
   - Leveraging the default `patchStrategy` field tag
   - Ability to specify replace directives




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