adservice: export logs with the Stackdriver Logging library

This commit exports logs from the adservice directly to Stackdriver using the
Stackdriver Logging library.  Using the Stackdriver Logging library instead of
unstructured logging gives more control over setting fields such as severity.
This change can also be used to enable OpenCensus log correlation
(https://github.com/census-instrumentation/opencensus-java/tree/master/contrib/log_correlation/stackdriver).

src/adservice/build.gradle

@@ -54,7 +54,8 @@ dependencies {
                 "io.grpc:grpc-services:${grpcVersion}",
                 "io.prometheus:simpleclient_httpserver:${prometheusVersion}"
 
-        runtime "io.opencensus:opencensus-impl:${opencensusVersion}",
+        runtime "com.google.cloud:google-cloud-logging:1.45.0",
+                "io.opencensus:opencensus-impl:${opencensusVersion}",
                 "io.netty:netty-tcnative-boringssl-static:2.0.8.Final"
     }
 }
@@ -106,6 +107,7 @@ task adService(type: CreateStartScripts) {
     applicationName = 'AdService'
     outputDir = new File(project.buildDir, 'tmp')
     classpath = jar.outputs.files + project.configurations.runtime
+    defaultJvmOpts = ["-Djava.util.logging.config.file=./src/main/resources/logging.properties"]
 }
 
 task adServiceClient(type: CreateStartScripts) {
@@ -113,6 +115,7 @@ task adServiceClient(type: CreateStartScripts) {
     applicationName = 'AdServiceClient'
     outputDir = new File(project.buildDir, 'tmp')
     classpath = jar.outputs.files + project.configurations.runtime
+    defaultJvmOpts = ["-Djava.util.logging.config.file=./src/main/resources/logging.properties"]
 }
 
 applicationDistribution.into('bin') {

src/adservice/src/main/resources/logging.properties

@@ -0,0 +1,12 @@
+# This configuration file is based on the example at
+# https://github.com/GoogleCloudPlatform/java-docs-samples/blob/master/logging/jul/src/main/resources/logging.properties
+
+.level = INFO
+
+io.grpc.netty.level=INFO
+sun.net.level=INFO
+
+handlers=com.google.cloud.logging.LoggingHandler
+
+com.google.cloud.logging.LoggingHandler.formatter=java.util.logging.SimpleFormatter
+java.util.logging.SimpleFormatter.format=%3$s: %5$s%6$s