Add timeout setting to Steps

This feature allows a Task author to specify a timeout for a Step.
An example use case is when a Task author would like to execute a
Step for setting up an execution environment. One may expect this
Step to execute within a few seconds. If the execution time takes
longer than expected one may rather want to fail fast than wait
for the TaskRun timeout to abort the TaskRun
(example by @imjasonh).

Closes tektoncd#1690

Author: Peaorl

cmd/entrypoint/main.go

@@ -17,6 +17,7 @@ limitations under the License.
 package main
 
 import (
+	"context"
 	"flag"
 	"log"
 	"os"
@@ -40,6 +41,7 @@ var (
 	terminationPath     = flag.String("termination_path", "/tekton/termination", "If specified, file to write upon termination")
 	results             = flag.String("results", "", "If specified, list of file names that might contain task results")
 	waitPollingInterval = time.Second
+	timeout             = flag.String("timeout", "", "If specified, sets timeout for step")
 )
 
 func main() {
@@ -78,7 +80,16 @@ func main() {
 		log.Printf("non-fatal error copying credentials: %q", err)
 	}
 
-	if err := e.Go(); err != nil {
+	// Add timeout to context if a non-zero timeout is specified for a step
+	ctx := context.Background()
+	timeoutContext, _ := time.ParseDuration(*timeout)
+	var cancel context.CancelFunc
+	if timeoutContext != time.Duration(0) {
+		ctx, cancel = context.WithTimeout(ctx, timeoutContext)
+		defer cancel()
+	}
+
+	if err := e.Go(ctx); err != nil {
 		switch t := err.(type) {
 		case skipError:
 			log.Print("Skipping step because a previous step failed")

cmd/entrypoint/runner.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"os"
 	"os/exec"
 	"os/signal"
@@ -19,7 +20,7 @@ type realRunner struct {
 
 var _ entrypoint.Runner = (*realRunner)(nil)
 
-func (rr *realRunner) Run(args ...string) error {
+func (rr *realRunner) Run(ctx context.Context, args ...string) error {
 	if len(args) == 0 {
 		return nil
 	}
@@ -33,7 +34,7 @@ func (rr *realRunner) Run(args ...string) error {
 	signal.Notify(rr.signals)
 	defer signal.Reset()
 
-	cmd := exec.Command(name, args...)
+	cmd := exec.CommandContext(ctx, name, args...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
 	// dedicated PID group used to forward signals to

cmd/entrypoint/runner_test.go

@@ -1,9 +1,11 @@
 package main
 
 import (
+	"context"
 	"os"
 	"syscall"
 	"testing"
+	"time"
 )
 
 // TestRealRunnerSignalForwarding will artificially put an interrupt signal (SIGINT) in the rr.signals chan.
@@ -14,9 +16,23 @@ func TestRealRunnerSignalForwarding(t *testing.T) {
 	rr := realRunner{}
 	rr.signals = make(chan os.Signal, 1)
 	rr.signals <- syscall.SIGINT
-	if err := rr.Run("sleep", "3600"); err.Error() == "signal: interrupt" {
+	if err := rr.Run(context.Background(), "sleep", "3600"); err.Error() == "signal: interrupt" {
 		t.Logf("SIGINT forwarded to Entrypoint")
 	} else {
 		t.Fatalf("Unexpected error received: %v", err)
 	}
 }
+
+// TestRealRunnerTimeout tests whether cmd is killed after time.Second even though it's supposed to sleep for an hour.
+func TestRealRunnerTimeout(t *testing.T) {
+	rr := realRunner{}
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	// For seconds and higher time units, err.Error() returns "signal: killed".
+	// For microseconds and lower time units, err.Error() returns "context deadline exceeded".
+	if err := rr.Run(ctx, "sleep", "3600"); err.Error() == "signal: killed" || err.Error() == "context deadline exceeded" {
+		t.Logf("Timeout observed")
+	} else {
+		t.Fatalf("Unexpected error received: %v", err)
+	}
+}

docs/tasks.md

@@ -241,7 +241,24 @@ steps:
     #!/usr/bin/env bash
     /bin/my-binary
 ```
+#### Specifying a timeout
 
+A step can specify a `timeout` field. If the `Step` execution time exceeds the specified timeout, the `Step` and consequently the entire `TaskRun` is canceled.
+An accompanying error message is output under `status.conditions.message`.
+
+The format for a timeout is a duration string as specified in the [Go time package](https://golang.org/src/time/format.go?s=40541:40587#L1364) (e.g. 1s or 1ms).
+
+The example `Step` below is supposed to sleep for 60 seconds but will be canceled by the specified 5 second timeout.
+```yaml
+steps:
+  - name: willTimeout
+    image: ubuntu
+    script: | 
+      #!/usr/bin/env bash
+      echo "I am supposed to sleep for 60 seconds!"
+      sleep 60
+    timeout: 5s
+``` 
 ### Specifying `Parameters`
 
 You can specify parameters, such as compilation flags or artifact names, that you want to supply to the `Task` at execution time.

examples/v1beta1/taskruns/step-timeout.yaml

@@ -0,0 +1,14 @@
+kind: TaskRun
+apiVersion: tekton.dev/v1beta1
+metadata:
+  generateName: timeout-test-
+spec:
+  taskSpec:
+    steps:
+      - name: wait
+        image: ubuntu
+        script: | 
+          #!/usr/bin/env bash
+          echo "I am supposed to sleep for 60 seconds!"
+          sleep 60
+        timeout: 5s

go.mod

@@ -3,10 +3,11 @@ module github.com/tektoncd/pipeline
 go 1.13
 
 require (
+	cloud.google.com/go/storage v1.8.0
 	contrib.go.opencensus.io/exporter/stackdriver v0.13.1 // indirect
 	github.com/GoogleCloudPlatform/cloud-builders/gcs-fetcher v0.0.0-20191203181535-308b93ad1f39
 	github.com/cloudevents/sdk-go/v2 v2.1.0
-	github.com/docker/cli v0.0.0-20200210162036-a4bedce16568 // indirect
+	github.com/docker/cli v0.0.0-20200303162255-7d407207c304 // indirect
 	github.com/ghodss/yaml v1.0.0
 	github.com/google/go-cmp v0.4.1
 	github.com/google/go-containerregistry v0.1.1
@@ -18,12 +19,16 @@ require (
 	github.com/mailru/easyjson v0.7.1-0.20191009090205-6c0755d89d1e // indirect
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/pkg/errors v0.9.1
-	github.com/tektoncd/plumbing v0.0.0-20200430135134-e53521e1d887
+	github.com/tektoncd/plumbing v0.0.0-20200217163359-cd0db6e567d2
 	go.opencensus.io v0.22.4
 	go.uber.org/zap v1.15.0
 	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d
 	golang.org/x/text v0.3.3 // indirect
+	golang.org/x/tools v0.0.0-20200731060945-b5fad4ed8dd6 // indirect
 	gomodules.xyz/jsonpatch/v2 v2.1.0
+	google.golang.org/api v0.25.0
+	gopkg.in/yaml.v2 v2.3.0 // indirect
+	gotest.tools/v3 v3.0.2 // indirect
 	k8s.io/api v0.17.6
 	k8s.io/apimachinery v0.17.6
 	k8s.io/client-go v11.0.1-0.20190805182717-6502b5e7b1b5+incompatible