Authentication to Google Compute Engine example

compute.groovy

// compile 'com.github.groovy-wslite:groovy-wslite:1.1.0'
// compile 'com.google.apis:google-api-services-compute:v1-rev29-1.19.0'
// compile 'com.google.http-client:google-http-client-jackson2:1.19.0'
// compile 'com.google.oauth-client:google-oauth-client-jetty:1.19.0'

import com.google.api.services.compute.Compute
import com.google.api.services.compute.model.*
import wslite.rest.ContentType
import wslite.http.HTTPClient
import wslite.rest.RESTClient

final int tm = 10000 // ms
@Lazy volatile HTTPClient httpClient = new HTTPClient().with { connectTimeout = readTimeout = tm; it }
@Lazy volatile RESTClient metadata = new RESTClient('http://metadata/computeMetadata/v1', httpClient)

Compute initGCEServiceAccount() {
    // https://developers.google.com/compute/docs/authentication
    // we use GCE Service Account by querying metadata server for an access token
    // Alternative: Developer Service Account https://code.google.com/p/google-api-java-client/wiki/OAuth2#Service_accounts
    // see Scala example below
    def initializer = new com.google.api.client.http.HttpRequestInitializer() {
        @Override
        void initialize(com.google.api.client.http.HttpRequest request) {
            request.headers.setAuthorization(
                metadata.get(path: '/instance/service-accounts/default/token',
                    headers: [ 'X-Google-Metadata-Request': 'true' ], accept: ContentType.JSON)
                .json.with { "$token_type $access_token" })
        }
    }
    new com.google.api.services.compute.Compute.Builder(
            com.google.api.client.googleapis.javanet.GoogleNetHttpTransport.newTrustedTransport(),
            com.google.api.client.json.jackson2.JacksonFactory.getDefaultInstance(), initializer)
        .setApplicationName("${grailsApplication.metadata.'app.name'}/${grailsApplication.metadata.'app.version'}")
        .build()
}

// Full Oauth2 flow using usual Google user account - on first use, a prompt will be
// issued on the console to perform a manual interaction with Google in browser.
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport
import com.google.api.client.json.jackson2.JacksonFactory
import com.google.api.client.util.store.FileDataStoreFactory
import com.google.api.services.compute.Compute
import com.google.api.services.compute.ComputeScopes
@Lazy static volatile Compute compute = {
    // http://samples.google-api-java-client.googlecode.com/hg/compute-engine-cmdline-sample/instructions.html
    // hg clone https://code.google.com/p/google-api-java-client.samples/
    // alternatively we may use https://code.google.com/p/google-api-java-client/wiki/ClientLogin (deprecated)
    //   more info:
    // https://code.google.com/p/google-api-java-client/wiki/DeveloperGuide
    // https://developers.google.com/resources/api-libraries/documentation/compute/v1/java/latest/
    // http://javadoc.google-api-java-client.googlecode.com/hg/1.19.0/index.html
    def http = GoogleNetHttpTransport.newTrustedTransport()
    def dataStore = new FileDataStoreFactory(new java.io.File(System.getProperty("user.home"), (windows() ? "AppData/Local" : ".cache") + "/myapp_google_compute_engine"))
    def json = JacksonFactory.getDefaultInstance()
    def secret = GoogleClientSecrets.load(json, new InputStreamReader(getClass().getResourceAsStream("/client_secret.json")))
    def flow = new GoogleAuthorizationCodeFlow.Builder(http, json, secret, [ ComputeScopes.COMPUTE ]).setDataStoreFactory(dataStore).build()
    def credential = new AuthorizationCodeInstalledApp(flow, new LocalServerReceiver()).authorize("user")
    new Compute.Builder(http, json, null).setApplicationName("MyApp/1.0").setHttpRequestInitializer(credential).build()
} ()

compute.scala

libraryDependencies ++= Seq(
  "com.google.apis" % "google-api-services-compute" % "v1-rev55-1.20.0",
  "com.google.http-client" % "google-http-client-jackson2" % "1.20.0",
  "org.bouncycastle" % "bcpkix-jdk15on" % "1.52"
)


import java.io.{StringReader, InputStreamReader}

import com.google.api.client.googleapis.auth.oauth2.{GoogleClientSecrets, GoogleCredential}
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport
import com.google.api.client.json.jackson2.JacksonFactory
import com.google.api.services.compute.{ComputeScopes, Compute}
import org.bouncycastle.asn1.pkcs.PrivateKeyInfo
import org.bouncycastle.openssl.PEMParser
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter

object GceApiClient {
  val project = "my-project-id"
  val compute = {
    import collection.JavaConversions._
    val creds = "/project-service-account.json" // Google Developers Console >> APIs & auth >> Credentials >> Create new Client ID >> Service Account
    val http = GoogleNetHttpTransport.newTrustedTransport()
    val json = JacksonFactory.getDefaultInstance()
    val auth = GoogleClientSecrets.load(json, new InputStreamReader(this.getClass.getResourceAsStream(creds)))
    val key = new PEMParser(new StringReader(auth.get("private_key").asInstanceOf[String])).readObject().asInstanceOf[PrivateKeyInfo]
    val jcak = new JcaPEMKeyConverter().getPrivateKey(key)
    val initializer = new GoogleCredential.Builder().setTransport(http)
      .setJsonFactory(json)
      .setServiceAccountId(auth.get("client_email").asInstanceOf[String])
      .setServiceAccountScopes(List(ComputeScopes.COMPUTE))
      .setServiceAccountPrivateKey(jcak)
      .build()
    new Compute.Builder(http, json, initializer).setApplicationName("ACP/3.0").build()
  }
}


GceApiClient.compute.zones().list(GceApiClient.project).execute()