doc: Upgrade the crashpad-home App Engine app to the Go 1.11 runtime

App Engine’s Go 1.9 runtime is no longer functional. See
https://cloud.google.com/appengine/docs/deprecations and
https://cloud.google.com/appengine/docs/standard/go111/go-differences.

Note that this doesn’t migrate away from the App Engine SDK per
https://cloud.google.com/appengine/docs/standard/go111/go-differences#migrating-appengine-sdk,
as this service does use App Engine APIs. Newer Go runtimes are
available, currently including 1.12, 1.13, and a beta version of 1.14,
but 1.12 and newer do not support App Engine APIs per
https://cloud.google.com/appengine/docs/standard/go112/go-differences,
so this upgrade targets the Go 1.11 runtime.

Change-Id: Ia9c28cfb1abe5f226ae8c07de90cd2e9b6e19a48
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2328805
Commit-Queue: Mark Mentovai <mark@chromium.org>
Reviewed-by: Scott Graham <scottmg@chromium.org>

doc/appengine/README

@@ -1,39 +1,51 @@
 This is the App Engine app that serves https://crashpad.chromium.org/.
 
-To work on this app, obtain the App Engine SDK for Go from
-https://cloud.google.com/appengine/docs/go/download. Unpacking it produces a
-go_appengine directory. This may be added to your $PATH for convenience,
-although it is not necessary.
+To work on this app, obtain the following packages:
+
+ - Go, from https://golang.org/dl/. This is only necessary for local development
+   and testing. The directory containing the “go” executable, such as
+   /usr/local/go/bin, must appear in $PATH. It does not appear critical for the
+   Go version used to match the Go runtime version used (for example, these
+   instructions were tested with Go 1.14 locally but a Go 1.11 runtime when
+   deployed), but if problems are encountered, it would be wise to use the same
+   version for both local development and AppEngine deployment.
+ - The Google Cloud SDK from, https://cloud.google.com/sdk/docs. This is
+   necessary for both local development and for AppEngine deployment. Unpacking
+   this package produces a google-cloud-sdk directory, whose bin child directory
+   may be added to $PATH for convenience, although this is not strictly
+   necessary.
 
 The commands in this README are expected to be run from the directory containing
-app.yaml.
+it. $GOPATH must also be set to include this directory:
 
-The App Engine SDK for Go provides App Engine packages at the “appengine” import
-path, but not the newer “google.golang.org/appengine” path. The Crashpad app
-uses the newer paths. See
-https://github.com/golang/appengine#2-update-import-paths and
-https://code.google.com/p/googleappengine/issues/detail?id=11670.  To make these
-available, obtain a Go release from https://golang.org/dl/, and run:
-
-$ GOROOT=…/go_appengine/goroot GOPATH=…/go_appengine/gopath go get -d
+% export GOPATH="$(go env GOPATH):$(pwd)"
 
 To test locally:
 
-$ …/go_appengine/goapp serve
+% go get -d crashpad-home
+% …/google-cloud-sdk/bin/dev_appserver.py src/crashpad-home
 
 Look for the “Starting module "default" running at: http://localhost:8080” line,
-which tells you the URL of the local running instance of the app.
+which tells you the URL of the local running instance of the app. Test
+http://localhost:8080/ and http://localhost:8080/doxygen to ensure that they
+work.
 
 To deploy:
 
-$ version=$(git rev-parse --short=12 HEAD)
-$ [[ -n "$(git status --porcelain)" ]] && version+=-dirty
-$ …/go_appengine/goapp deploy -version "${version}"
+% version=$(git rev-parse --short=12 HEAD)
+% [[ -n "$(git status --porcelain)" ]] && version+=-dirty
+% …/google-cloud-sdk/bin/gcloud app deploy \
+      --project=crashpad-home --version="${version}" --no-promote \
+      "$(pwd)/src/crashpad-home"
 
-Note that app.yaml does not name a “version” to encourage you to use a git hash
-as the version, as above.
+(Note: the $(pwd) is necessary for “gcloud app deploy” to recognize that the
+application is in GOPATH, putting it into “GOPATH mode”. This normally happens
+correctly on its own even with a relative path, but will fail for relative
+paths when $(pwd) is a symbolic link. Using an absolute path here will save you
+from this frustration, freeing you up to undoubtedly experience other
+frustrations.)
 
 Activate a newly-deployed version by visiting the App Engine console at
-https://appengine.google.com/deployment?&app_id=s~crashpad-home, selecting it,
-and choosing “Make Default”. It is also possible to delete old versions from
-this page when they are no longer needed.
+https://console.cloud.google.com/appengine/versions?project=crashpad-home,
+selecting it, and choosing “Migrate Traffic”. It is also possible to delete old
+versions from this page when they are no longer needed.

doc/appengine/app.yaml

@@ -1,8 +0,0 @@
-application: crashpad-home
-runtime: go
-api_version: go1
-
-handlers:
-- url: /.*
-  script: _go_app
-  secure: always

doc/appengine/src/crashpad-home/app.yaml

@@ -0,0 +1,20 @@
+# Copyright 2015 The Crashpad Authors. All rights reserved.
+#
+# 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.
+
+runtime: go111
+
+handlers:
+- url: /.*
+  script: auto
+  secure: always

doc/appengine/src/crashpad-home/main.go

@@ -12,8 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package crashpad mirrors crashpad documentation from Chromium’s git repo.
-package crashpad
+package main
 
 import (
 	"encoding/base64"
@@ -31,6 +30,10 @@ import (
 	"google.golang.org/appengine/urlfetch"
 )
 
+func main() {
+	appengine.Main()
+}
+
 func init() {
 	http.HandleFunc("/", handler)
 }