Initial Implementation of conditionals

docs/conditions.md

@@ -0,0 +1,50 @@
+# Conditions
+
+This document defines `Conditions` and their capabilities.
+
+*NOTE*: This feature is currently a WIP being tracked in [#1137](https://github.com/tektoncd/pipeline/issues/1137)
+
+---
+
+- [Syntax](#syntax)
+  - [Check](#check)
+- [Examples](#examples)
+
+## Syntax
+
+To define a configuration file for a `Condition` resource, you can specify the
+following fields:
+
+- Required:
+  - [`apiVersion`][kubernetes-overview] - Specifies the API version, for example
+    `tekton.dev/v1alpha1`.
+  - [`kind`][kubernetes-overview] - Specify the `Condition` resource object.
+  - [`metadata`][kubernetes-overview] - Specifies data to uniquely identify the
+    `Condition` resource object, for example a `name`.
+  - [`spec`][kubernetes-overview] - Specifies the configuration information for
+    your `Condition` resource object. In order for a `Condition` to do anything,
+    the spec must include:
+    - [`check`](#check) - Specifies a container that you want to run for evaluating the condition 
+
+[kubernetes-overview]:
+  https://kubernetes.io/docs/concepts/overview/working-with-objects/kubernetes-objects/#required-fields
+
+### Check
+
+The `check` field is required. You define a single check to define the body of a `Condition`. The 
+check must specify a container image that adheres to the [container contract](./container-contract.md). The container image 
+runs till completion. The container must exit successfully i.e. with an exit code 0 for the 
+condition evaluation to be successful. All other exit codes are considered to be a condition check
+failure.
+
+## Examples
+
+For complete examples, see
+[the examples folder](https://github.com/tektoncd/pipeline/tree/master/examples).
+
+---
+
+Except as otherwise noted, the content of this page is licensed under the
+[Creative Commons Attribution 4.0 License](https://creativecommons.org/licenses/by/4.0/),
+and code samples are licensed under the
+[Apache 2.0 License](https://www.apache.org/licenses/LICENSE-2.0).

docs/pipelines.md

@@ -45,6 +45,8 @@ following fields:
       - [`retries`](#retries) - Used when the task is wanted to be executed if
         it fails. Could a network error or a missing dependency. It does not
         apply to cancellations.
+      - [`conditions`](#conditions) - Used when a task is to be executed only if the specified
+        conditons are evaluated to be true.
 
 [kubernetes-overview]:
   https://kubernetes.io/docs/concepts/overview/working-with-objects/kubernetes-objects/#required-fields
@@ -285,6 +287,28 @@ In this example, the task "build-the-image" will be executed and if the first
 run fails a second one would triggered. But, if that fails no more would
 triggered: a max of two executions.
 
+
+#### conditions
+
+Sometimes you will need to run tasks only when some conditions are true. The `conditions` field 
+allows you to list a series of references to [`Conditions`](./conditions.md) that are run before the task
+is run. If all of the conditions evaluate to true, the task is run. If any of the conditions are false,
+the Task is not run. Its status.ConditionSucceeded is set to False with the reason set to  `ConditionCheckFailed`.
+However, unlike regular task failures, condition failures do not automatically fail the entire pipeline 
+run -- other tasks that are not dependent on the task (via `from` or `runAfter`) are still run.
+
+```yaml
+tasks:
+  - name: conditional-task
+    taskRef:
+      name: build-push
+    conditions:
+      - conditionRef: my-condition
+```
+
+In this example, `my-condition` refers to a [Condition](#conditions) custom resource. The `build-push` 
+task will only be executed if the condition evaluates to true. 
+
 ## Ordering
 
 The [Pipeline Tasks](#pipeline-tasks) in a `Pipeline` can be connected and run

examples/pipelineruns/conditional-pipelinerun.yaml

@@ -0,0 +1,68 @@
+apiVersion: tekton.dev/v1alpha1
+kind: Condition
+metadata:
+  name: always-true
+spec:
+ check:
+    image: alpine
+    command: ["/bin/sh"]
+    args: ['-c', 'exit 0']
+---
+apiVersion: tekton.dev/v1alpha1
+kind: PipelineResource
+metadata:
+  name: pipeline-git
+spec:
+  type: git
+  params:
+    - name: revision
+      value: master
+    - name: url
+      value: https://github.com/tektoncd/pipeline
+---
+apiVersion: tekton.dev/v1alpha1
+kind: Task
+metadata:
+  name: list-files
+spec:
+  inputs:
+    resources:
+      - name: workspace
+        type: git
+  steps:
+    - name: run-ls
+      image: ubuntu
+      command: ["/bin/bash"]
+      args: ['-c', 'ls -al ${inputs.resources.workspace.path}']
+---
+apiVersion: tekton.dev/v1alpha1
+kind: Pipeline
+metadata:
+  name: list-files-pipeline
+spec:
+  resources:
+    - name: source-repo
+      type: git
+  tasks:
+    - name: list-files-1
+      taskRef:
+        name: list-files
+      conditions:
+        - conditionRef: "always-true"
+      resources:
+        inputs:
+          - name: workspace
+            resource: source-repo
+---
+apiVersion: tekton.dev/v1alpha1
+kind: PipelineRun
+metadata:
+  name: demo-condtional-pr
+spec:
+  pipelineRef:
+    name: list-files-pipeline
+  serviceAccount: 'default'
+  resources:
+    - name: source-repo
+      resourceRef:
+        name: pipeline-git

pkg/apis/pipeline/register.go

@@ -16,12 +16,25 @@ limitations under the License.
 
 package pipeline
 
-// GroupName is the Kubernetes resource group name for Pipeline types.
 const (
-	GroupName            = "tekton.dev"
-	TaskLabelKey         = "/task"
-	TaskRunLabelKey      = "/taskRun"
-	PipelineLabelKey     = "/pipeline"
-	PipelineRunLabelKey  = "/pipelineRun"
+	// GroupName is the Kubernetes resource group name for Pipeline types.
+	GroupName = "tekton.dev"
+
+	// TaskLabelKey is used as the label identifier for a task
+	TaskLabelKey = "/task"
+
+	// TaskRunLabelKey is used as the label identifier for a TaskRun
+	TaskRunLabelKey = "/taskRun"
+
+	// PipelineLabelKey is used as the label identifier for a Pipeline
+	PipelineLabelKey = "/pipeline"
+
+	// PipelineRunLabelKey is used as the label identifier for a PipelineRun
+	PipelineRunLabelKey = "/pipelineRun"
+
+	// PipelineRunLabelKey is used as the label identifier for a PipelineTask
 	PipelineTaskLabelKey = "/pipelineTask"
+
+	// ConditionCheck is used as the label identifier for a ConditionCheck
+	ConditionCheckKey = "/conditionCheck"
 )

pkg/apis/pipeline/v1alpha1/condition_types.go

@@ -98,3 +98,13 @@ func NewConditionCheck(tr *TaskRun) *ConditionCheck {
 	cc := ConditionCheck(*tr)
 	return &cc
 }
+
+// IsDone returns true if the ConditionCheck's status indicates that it is done.
+func (cc *ConditionCheck) IsDone() bool {
+	return !cc.Status.GetCondition(apis.ConditionSucceeded).IsUnknown()
+}
+
+// IsSuccessful returns true if the ConditionCheck's status indicates that it is done.
+func (cc *ConditionCheck) IsSuccessful() bool {
+	return cc.Status.GetCondition(apis.ConditionSucceeded).IsTrue()
+}

pkg/apis/pipeline/v1alpha1/condition_types_test.go

@@ -0,0 +1,55 @@
+/*
+ Copyright 2019 The Tekton Authors
+
+ Licensed 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 v1alpha1_test
+
+import (
+	"testing"
+
+	corev1 "k8s.io/api/core/v1"
+	"knative.dev/pkg/apis"
+
+	"github.com/tektoncd/pipeline/pkg/apis/pipeline/v1alpha1"
+	tb "github.com/tektoncd/pipeline/test/builder"
+)
+
+func TestConditionCheck_IsDone(t *testing.T) {
+	tr := tb.TaskRun("", "", tb.TaskRunStatus(tb.StatusCondition(
+		apis.Condition{
+			Type:   apis.ConditionSucceeded,
+			Status: corev1.ConditionFalse,
+		},
+	)))
+
+	cc := v1alpha1.ConditionCheck(*tr)
+	if !cc.IsDone() {
+		t.Fatal("Expected conditionCheck status to be done")
+	}
+}
+
+func TestConditionCheck_IsSuccessful(t *testing.T) {
+	tr := tb.TaskRun("", "", tb.TaskRunStatus(tb.StatusCondition(
+		apis.Condition{
+			Type:   apis.ConditionSucceeded,
+			Status: corev1.ConditionTrue,
+		},
+	)))
+
+	cc := v1alpha1.ConditionCheck(*tr)
+	if !cc.IsSuccessful() {
+		t.Fatal("Expected conditionCheck status to be done")
+	}
+}

pkg/reconciler/v1alpha1/pipelinerun/controller.go

@@ -22,6 +22,7 @@ import (
 
 	pipelineclient "github.com/tektoncd/pipeline/pkg/client/injection/client"
 	clustertaskinformer "github.com/tektoncd/pipeline/pkg/client/injection/informers/pipeline/v1alpha1/clustertask"
+	conditioninformer "github.com/tektoncd/pipeline/pkg/client/injection/informers/pipeline/v1alpha1/condition"
 	pipelineinformer "github.com/tektoncd/pipeline/pkg/client/injection/informers/pipeline/v1alpha1/pipeline"
 	resourceinformer "github.com/tektoncd/pipeline/pkg/client/injection/informers/pipeline/v1alpha1/pipelineresource"
 	pipelineruninformer "github.com/tektoncd/pipeline/pkg/client/injection/informers/pipeline/v1alpha1/pipelinerun"
@@ -54,6 +55,7 @@ func NewController(
 	pipelineRunInformer := pipelineruninformer.Get(ctx)
 	pipelineInformer := pipelineinformer.Get(ctx)
 	resourceInformer := resourceinformer.Get(ctx)
+	conditionInformer := conditioninformer.Get(ctx)
 	timeoutHandler := reconciler.NewTimeoutHandler(ctx.Done(), logger)
 
 	opt := reconciler.Options{
@@ -72,6 +74,7 @@ func NewController(
 		clusterTaskLister: clusterTaskInformer.Lister(),
 		taskRunLister:     taskRunInformer.Lister(),
 		resourceLister:    resourceInformer.Lister(),
+		conditionLister:   conditionInformer.Lister(),
 		timeoutHandler:    timeoutHandler,
 	}
 	impl := controller.NewImpl(c, c.Logger, pipelineRunControllerName)