Add support for env in podtemplate

This will help to specificy env default, env at pipelinerun
and taskrun level. Env in pod template at taskrun and pipelinerun
level will take precedence over one defined in step and stepTemplate

Env at pipelinerun and taskrun level will override the
default podtemplate

Fix tektoncd#1606

docs/podtemplates.md

@@ -49,6 +49,10 @@ Pod templates support fields listed in the table below.
 			<td><code>volumes</code></td>
 			<td>Specifies a list of volumes that containers within the Pod can mount. This allows you to specify a volume type for each <code>volumeMount</code> in a <code>Task</code>.</td>
 		</tr>
+        <tr>
+			<td><code>envs</code></td>
+			<td>Specifies a list of environments that all containers within the Pod will be populated</td>
+		</tr>
 		<tr>
 			<td><code>runtimeClassName</code></td>
 			<td>Specifies the <a href=https://kubernetes.io/docs/concepts/containers/runtime-class/>runtime class</a> for the Pod.</td>

examples/v1beta1/taskruns/podtemplate-env.yaml

@@ -0,0 +1,15 @@
+apiVersion: tekton.dev/v1beta1
+kind: TaskRun
+metadata:
+  generateName: podtemplate-env-
+spec:
+  podTemplate:
+    env:
+      - name: MY_VAR1
+        value: foo
+  taskSpec:
+    steps:
+      - image: ubuntu
+        script: |
+          #!/usr/bin/env bash
+          [[ $MY_VAR1 == foo ]]

pkg/apis/pipeline/pod/template.go

@@ -52,6 +52,12 @@ type Template struct {
 	// +patchStrategy=merge,retainKeys
 	Volumes []corev1.Volume `json:"volumes,omitempty" patchStrategy:"merge,retainKeys" patchMergeKey:"name" protobuf:"bytes,1,rep,name=volumes"`
 
+	// List of environment variables that can be provided to the containers belonging to the pod.
+	// +optional
+	// +patchMergeKey=name
+	// +patchStrategy=merge,retainKeys
+	Env []corev1.EnvVar `json:"env,omitempty" patchStrategy:"merge,retainKeys" patchMergeKey:"name" protobuf:"bytes,1,rep,name=env"`
+
 	// RuntimeClassName refers to a RuntimeClass object in the node.k8s.io
 	// group, which should be used to run this pod. If no RuntimeClass resource
 	// matches the named class, the pod will not be run. If unset or empty, the

pkg/apis/pipeline/v1beta1/swagger.json

@@ -31,6 +31,15 @@
           "description": "EnableServiceLinks indicates whether information about services should be injected into pod's environment variables, matching the syntax of Docker links. Optional: Defaults to true.",
           "type": "boolean"
         },
+        "env": {
+          "description": "List of environment variables that can be provided to the containers belonging to the pod.",
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/v1.EnvVar"
+          },
+          "x-kubernetes-patch-merge-key": "name",
+          "x-kubernetes-patch-strategy": "merge,retainKeys"
+        },
         "hostNetwork": {
           "description": "HostNetwork specifies whether the pod may use the node network namespace",
           "type": "boolean"

pkg/pod/pod.go

@@ -217,6 +217,30 @@ func (b *Builder) Build(ctx context.Context, taskRun *v1beta1.TaskRun, taskSpec
 		podTemplate = *taskRun.Spec.PodTemplate
 	}
 
+	// Add envs specified in podtemplate to all step containers
+	// Envs specified in podtemplate should take precedence over
+	// the one specified in step and step template
+	for i, _ := range stepContainers {
+		envs := updateAndMergeEnv(stepContainers[i].Env, podTemplate.Env)
+		stepContainers[i].Env = envs
+	}
+
+	// Add envs specified in podtemplate to all sidecar containers
+	// Envs specified in podtemplate should take precedence over
+	// the one specified in sidecar and step template
+	for i, _ := range sidecarContainers {
+		envs := updateAndMergeEnv(sidecarContainers[i].Env, podTemplate.Env)
+		sidecarContainers[i].Env = envs
+	}
+
+	// Add envs specified in podtemplate to all initContainers
+	// Envs specified in podtemplate should take precedence over
+	// the one specified in init and step template
+	for i, _ := range initContainers {
+		envs := updateAndMergeEnv(initContainers[i].Env, podTemplate.Env)
+		initContainers[i].Env = envs
+	}
+
 	// Add podTemplate Volumes to the explicitly declared use volumes
 	volumes = append(volumes, taskSpec.Volumes...)
 	volumes = append(volumes, podTemplate.Volumes...)
@@ -403,3 +427,22 @@ func shouldAddReadyAnnotationOnPodCreate(ctx context.Context, sidecars []v1beta1
 	cfg := config.FromContextOrDefaults(ctx)
 	return !cfg.FeatureFlags.RunningInEnvWithInjectedSidecars
 }
+
+// updateAndMergeEnv will merge two slices of env
+// precedence will be given to second input if exist with same name key
+func updateAndMergeEnv(containerenvs []corev1.EnvVar, podtemplateEnvs []corev1.EnvVar) []corev1.EnvVar {
+	for _, env := range podtemplateEnvs {
+		var updated bool
+		for i, _ := range containerenvs {
+			if env.Name == containerenvs[i].Name {
+				containerenvs[i].Value = env.Value
+				containerenvs[i].ValueFrom = env.ValueFrom
+				updated = true
+			}
+		}
+		if !updated {
+			containerenvs = append(containerenvs, env)
+		}
+	}
+	return containerenvs
+}