Merge pull request #65 from wanjunlei/java

support multiple functions in one pod

Author: benjaminhuo

builders/java/README.md

@@ -3,7 +3,7 @@
 Use the follow command to build a java builder.
 
 ```shell
-hack/build.sh --with-stack --java-version < java_version > --docker-registry < registry >
+hack/build.sh java --with-stack --java-version < java_version > --docker-registry < registry >
 ```
 
 This command will create three image:

cmd/java/functions_framework/main.go

@@ -65,16 +65,9 @@ func buildFn(ctx *gcp.Context) error {
 
 	ctx.SetFunctionsEnvVars(layer)
 
-	// Use javap to check that the class is indeed in the classpath we just determined.
-	// On success, it will output a description of the class and its public members, which we discard.
-	// On failure it will output an error saying what's wrong (usually that the class doesn't exist).
-	// Success here doesn't guarantee that the function will execute. It might not implement one of the
-	// required interfaces, for example. But it eliminates the commonest problem of specifying the wrong target.
-	// We use an ExecUser* method so that the time taken by the javap command is counted as user time.
-	target := os.Getenv(env.FunctionTarget)
-	if _, err := ctx.ExecWithErr([]string{"javap", "-classpath", classpath, target}, gcp.WithUserAttribution); err != nil {
-		// The javap error output will typically be "Error: class not found: foo.Bar".
-		return gcp.UserErrorf("build succeeded but did not produce the class %q specified as the function target: %s", target, (*err).Error())
+	// Check that the classes are indeed in the classpath we just determined.
+	if !checkTargets(ctx, classpath) {
+		return gcp.UserErrorf("build succeeded but did not produce the target classes")
 	}
 
 	launcherSource := filepath.Join(ctx.BuildpackRoot(), "launch.sh")
@@ -85,6 +78,26 @@ func buildFn(ctx *gcp.Context) error {
 	return nil
 }
 
+// checkTargets use javap to check that the class is indeed in the classpath we just determined.
+// On success, it will output a description of the class and its public members, which we discard.
+// On failure it will output an error saying what's wrong (usually that the class doesn't exist).
+// Success here doesn't guarantee that the function will execute. It might not implement one of the
+// required interfaces, for example. But it eliminates the commonest problem of specifying the wrong target.
+// We use an ExecUser* method so that the time taken by the javap command is counted as user time.
+func checkTargets(ctx *gcp.Context, classpath string) bool {
+	targets := strings.Split(os.Getenv(env.FunctionTarget), ",")
+	success := true
+	for _, target := range targets {
+		cmd := []string{"javap", "-classpath", classpath, target}
+		if _, err := ctx.ExecWithErr(cmd, gcp.WithUserAttribution); err != nil {
+			// The javap error output will typically be "Error: class not found: foo.Bar".
+			success = false
+		}
+	}
+
+	return success
+}
+
 func createLauncher(ctx *gcp.Context, launcherSource, launcherTarget string) {
 	launcherContents := ctx.ReadFile(launcherSource)
 	ctx.WriteFile(launcherTarget, launcherContents, 0755)