GAE standard: allow passing entrypoint and shorten service names (#47)

- For some reason, app.yaml can't be used to override `entrypoint`. I think this is because of the way terraform calls the GAE admin API. Instead, allow passing it so individual languages can override if needed.
- The service name was too long. Service name becomes the DNS name and IDNA specifies they should have no "label" (part between dots) longer than 64 characters. This was causing issues with Flask.

Author: aabmass

e2e_testing.go

@@ -63,8 +63,9 @@ type GaeCmd struct {
 }
 
 type GaeStandardCmd struct {
-	Runtime   string `arg:"required" help:"The language runtime for the instrumented test server, used in naming the service"`
-	AppSource string `arg:"required" help:"The full path of the zip file that contains the source code to run in GAE"`
+	Runtime    string `arg:"required" help:"The language runtime for the instrumented test server, used in naming the service"`
+	AppSource  string `arg:"required" help:"The full path of the zip file that contains the source code to run in GAE"`
+	Entrypoint string `help:"Optional entrypoint to control how GAE starts the application. See https://cloud.google.com/appengine/docs/standard/reference/app-yaml#entrypoint"`
 }
 
 type CloudRunCmd struct {

setupgaestandard.go

@@ -35,8 +35,9 @@ func SetupGaeStandard(
 		args.TestRunID,
 		gaeStandardTfDir,
 		map[string]string{
-			"runtime":   args.GaeStandard.Runtime,
-			"appsource": args.GaeStandard.AppSource,
+			"runtime":    args.GaeStandard.Runtime,
+			"appsource":  args.GaeStandard.AppSource,
+			"entrypoint": args.GaeStandard.Entrypoint,
 		},
 		logger,
 	)

tf/gae-standard/gae-standard.tf

@@ -21,7 +21,7 @@ resource "google_app_engine_standard_app_version" "test_service" {
 
   version_id = "v1"
   project    = var.project_id
-  service    = "test-standard-service-${var.runtime}-${terraform.workspace}"
+  service    = "standard-${var.runtime}-${terraform.workspace}"
   runtime    = var.runtime
 
   deployment {
@@ -32,9 +32,9 @@ resource "google_app_engine_standard_app_version" "test_service" {
     }
   }
 
-  // Required, but leave empty to fall back to the runtime default
+  // Required, but if variable is unset (empty string), fall back to the runtime default
   entrypoint {
-    shell = ""
+    shell = var.entrypoint
   }
 
   env_variables = {
@@ -84,6 +84,11 @@ variable "runtime" {
   type = string
 }
 
+variable "entrypoint" {
+  type = string
+  default = ""
+}
+
 output "pubsub_info" {
   value       = module.pubsub.info
   description = "Info about the request/response pubsub topics and subscription to use in the test"

tf/gae/gae.tf

@@ -20,7 +20,7 @@
 resource "google_app_engine_flexible_app_version" "test_service" {
   version_id = "v1"
   project    = var.project_id
-  service    = "test-service-${var.runtime}-${terraform.workspace}"
+  service    = "flex-${var.runtime}-${terraform.workspace}"
   runtime    = "custom"
 
   deployment {