Declarative application specifications for Fission (#422)

This change enables users to have declarative specifications for Fission resources. Users can specify their "app" in a set of spec files, and use a new fission CLI command to "apply" these specs to a running cluster.

The new "spec" CLI also includes archiving of local source files, and a file watcher that re-builds archives and uploads them on file changes, and a package build watcher that waits for package builds on the CLI. 

A "--spec" option is also added to "function create", and will be added to other resources in future changes.  This option causes a YAML to be outputted to the specs directory instead of the resource being created on the cluster.

The CLI "fission spec --help" outputs usage information.

fission/buildwatch.go

@@ -0,0 +1,120 @@
+/*
+Copyright 2016 The Fission 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 main
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	"github.com/fission/fission"
+	"github.com/fission/fission/controller/client"
+	"github.com/fission/fission/crd"
+)
+
+type (
+	// packageBuildWatcher is used to watch a set of in-progress builds.
+	packageBuildWatcher struct {
+		// fission client
+		fclient *client.Client
+
+		// set of packages already printed, ensures we don't duplicate the notifications
+		finished map[string]bool
+
+		// set of metadata in the app spec.  packages outside this set should be ignored.
+		pkgMeta map[string]metav1.ObjectMeta
+	}
+)
+
+func makePackageBuildWatcher(fclient *client.Client) *packageBuildWatcher {
+	return &packageBuildWatcher{
+		fclient:  fclient,
+		finished: make(map[string]bool),
+		pkgMeta:  make(map[string]metav1.ObjectMeta),
+	}
+}
+
+func (w *packageBuildWatcher) addPackages(pkgMeta map[string]metav1.ObjectMeta) {
+	for k, v := range pkgMeta {
+		w.pkgMeta[k] = v
+	}
+}
+
+func (w *packageBuildWatcher) watch(ctx context.Context) {
+	for {
+		// non-blocking check if we're cancelled
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
+
+		// poll list of packages (TODO: convert to watch)
+		pkgs, err := w.fclient.PackageList()
+		checkErr(err, "Getting list of packages")
+
+		// find packages that (a) are in the app spec and (b) have an interesting
+		// build status (either succeeded or failed; not "none")
+		keepWaiting := false
+		buildpkgs := make([]crd.Package, 0)
+		for _, pkg := range pkgs {
+			_, ok := w.pkgMeta[mapKey(&pkg.Metadata)]
+			if !ok {
+				continue
+			}
+			if pkg.Status.BuildStatus == fission.BuildStatusNone {
+				continue
+			}
+			if pkg.Status.BuildStatus == fission.BuildStatusPending ||
+				pkg.Status.BuildStatus == fission.BuildStatusRunning {
+				keepWaiting = true
+			}
+			buildpkgs = append(buildpkgs, pkg)
+		}
+
+		// print package status, and error logs if any
+		for _, pkg := range buildpkgs {
+			k := pkgKey(&pkg)
+			if _, printed := w.finished[k]; printed {
+				continue
+			}
+			if pkg.Status.BuildStatus == fission.BuildStatusFailed {
+				w.finished[k] = true
+				fmt.Printf("--- Build FAILED: ---\n%v\n------\n", pkg.Status.BuildLog)
+			} else if pkg.Status.BuildStatus == fission.BuildStatusSucceeded {
+				w.finished[k] = true
+				fmt.Printf("--- Build SUCCEEDED ---\n")
+				if len(pkg.Status.BuildLog) > 0 {
+					fmt.Printf("%v\n------\n", pkg.Status.BuildLog)
+				}
+			}
+		}
+
+		// if there are no builds running, we can stop polling
+		if !keepWaiting {
+			return
+		}
+		time.Sleep(time.Second)
+	}
+}
+
+func pkgKey(pkg *crd.Package) string {
+	// packages are mutable so we want to keep track of them by resource version
+	return fmt.Sprintf("%v:%v:%v", pkg.Metadata.Name, pkg.Metadata.Namespace, pkg.Metadata.ResourceVersion)
+}