internal: reintroduce legacy appengine build constraints (#3850)

.travis.yml

@@ -30,11 +30,13 @@ before_install:
 install:
   - try3() { eval "$*" || eval "$*" || eval "$*"; }
   - try3 'if [[ "${GO111MODULE}" = "on" ]]; then go mod download; else make testdeps; fi'
+  - if [[ -n "${GAE}" ]]; then source ./install_gae.sh; make testappenginedeps; fi
   - if [[ -n "${VET}" ]]; then ./vet.sh -install; fi
 
 script:
   - set -e
   - if [[ -n "${TESTEXTRAS}" ]]; then examples/examples_test.sh; interop/interop_test.sh; make testsubmodule; exit 0; fi
   - if [[ -n "${VET}" ]]; then ./vet.sh; fi
+  - if [[ -n "${GAE}" ]]; then make testappengine; exit 0; fi
   - if [[ -n "${RACE}" ]]; then make testrace; exit 0; fi
   - make test

Makefile

@@ -23,6 +23,12 @@ testsubmodule: testdeps
 	cd security/advancedtls && go test -cpu 1,4 -timeout 7m google.golang.org/grpc/security/advancedtls/...
 	cd security/authorization && go test -cpu 1,4 -timeout 7m google.golang.org/grpc/security/authorization/...
 
+testappengine: testappenginedeps
+	goapp test -cpu 1,4 -timeout 7m google.golang.org/grpc/...
+
+testappenginedeps:
+	goapp get -d -v -t -tags 'appengine appenginevm' google.golang.org/grpc/...
+
 testdeps:
 	go get -d -v -t google.golang.org/grpc/...
 
@@ -48,6 +54,8 @@ vetdeps:
 	deps \
 	proto \
 	test \
+	testappengine \
+	testappenginedeps \
 	testdeps \
 	testrace \
 	updatedeps \

install_gae.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+TMP=$(mktemp -d /tmp/sdk.XXX) \
+&& curl -o $TMP.zip "https://storage.googleapis.com/appengine-sdks/featured/go_appengine_sdk_linux_amd64-1.9.68.zip" \
+&& unzip -q $TMP.zip -d $TMP \
+&& export PATH="$PATH:$TMP/go_appengine"

internal/credentials/syscallconn_appengine.go

@@ -0,0 +1,30 @@
+// +build appengine
+
+/*
+ *
+ * Copyright 2018 gRPC 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 credentials
+
+import (
+	"net"
+)
+
+// WrapSyscallConn returns newConn on appengine.
+func WrapSyscallConn(rawConn, newConn net.Conn) net.Conn {
+	return newConn
+}