Quickstart: Create and deploy an HTTP Cloud Run function by using Java
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    Create and deploy an HTTP Cloud Run function by using Java (1st gen)

    This guide takes you through the process of writing a Cloud Run function using the Java runtime. There are two types of Cloud Run functions:

    • An HTTP function, which you invoke from standard HTTP requests.
    • An event-driven function, which you use to handle events from your Cloud infrastructure, such as messages on a Pub/Sub topic, or changes in a Cloud Storage bucket.

    The document shows how to create a simple HTTP function and build it using either Maven or Gradle .

    Before you begin

    1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

    2. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

      Go to project selector

    3. Verify that billing is enabled for your Google Cloud project .

    4. Enable the Cloud Functions and Cloud Build APIs.

      Enable the APIs

    5. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

      Go to project selector

    6. Verify that billing is enabled for your Google Cloud project .

    7. Enable the Cloud Functions and Cloud Build APIs.

      Enable the APIs

    8. Install and initialize the Google Cloud SDK .
    9. Update and install gcloud components: 
      gcloud  
components  
update
    10. Prepare your development environment.

      Go to the Java setup guide

    Create a function

    This section describes how to create a function.

    Maven

    1. Create a directory on your local system for the function code:

      Linux or Mac OS X:

         
 mkdir 
  
 ~/ 
 helloworld 
  
 cd 
  
 ~/ 
 helloworld

      Windows:

         
 mkdir 
  
 % 
 HOMEPATH 
 % 
 \ 
 helloworld 
  
 cd 
  
 % 
 HOMEPATH 
 % 
 \ 
 helloworld

    2. Create the project structure to contain the source directory and source file.

        mkdir 
  
 - 
 p 
  
 src 
 / 
 main 
 / 
 java 
 / 
 functions 
 touch 
  
 src 
 / 
 main 
 / 
 java 
 / 
 functions 
 / 
 HelloWorld 
 . 
 java

    3. Add the following contents to the HelloWorld.java file:

        package 
  
 functions 
 ; 
 import 
  
 com.google.cloud.functions.HttpFunction 
 ; 
 import 
  
 com.google.cloud.functions.HttpRequest 
 ; 
 import 
  
 com.google.cloud.functions.HttpResponse 
 ; 
 import 
  
 java.io.BufferedWriter 
 ; 
 import 
  
 java.io.IOException 
 ; 
 public 
  
 class 
 HelloWorld 
  
 implements 
  
 HttpFunction 
  
 { 
  
 // Simple function to return "Hello World" 
  
 @Override 
  
 public 
  
 void 
  
 service 
 ( 
 HttpRequest 
  
 request 
 , 
  
 HttpResponse 
  
 response 
 ) 
  
 throws 
  
 IOException 
  
 { 
  
 BufferedWriter 
  
 writer 
  
 = 
  
 response 
 . 
 getWriter 
 (); 
  
 writer 
 . 
 write 
 ( 
 "Hello World!" 
 ); 
  
 } 
 }

      This example function outputs the greeting "Hello World!"

    Gradle

    1. Create a directory on your local system for the function code:

      Linux or Mac OS X:

         
 mkdir 
  
 ~/ 
 helloworld 
 - 
 gradle 
  
 cd 
  
 ~/ 
 helloworld 
 - 
 gradle

      Windows:

         
 mkdir 
  
 % 
 HOMEPATH 
 % 
 \ 
 helloworld 
 - 
 gradle 
  
 cd 
  
 % 
 HOMEPATH 
 % 
 \ 
 helloworld 
 - 
 gradle

    2. Create the project structure to contain the source directory and source file.

         
 mkdir 
  
 - 
 p 
  
 src 
 / 
 main 
 / 
 java 
 / 
 functions 
  
 touch 
  
 src 
 / 
 main 
 / 
 java 
 / 
 functions 
 / 
 HelloWorld 
 . 
 java

    3. Add the following contents to the HelloWorld.java file:

        package 
  
 functions 
 ; 
 import 
  
 com.google.cloud.functions.HttpFunction 
 ; 
 import 
  
 com.google.cloud.functions.HttpRequest 
 ; 
 import 
  
 com.google.cloud.functions.HttpResponse 
 ; 
 import 
  
 java.io.BufferedWriter 
 ; 
 import 
  
 java.io.IOException 
 ; 
 public 
  
 class 
 HelloWorld 
  
 implements 
  
 HttpFunction 
  
 { 
  
 // Simple function to return "Hello World" 
  
 @Override 
  
 public 
  
 void 
  
 service 
 ( 
 HttpRequest 
  
 request 
 , 
  
 HttpResponse 
  
 response 
 ) 
  
 throws 
  
 IOException 
  
 { 
  
 BufferedWriter 
  
 writer 
  
 = 
  
 response 
 . 
 getWriter 
 (); 
  
 writer 
 . 
 write 
 ( 
 "Hello World!" 
 ); 
  
 } 
 }

      This example function outputs the greeting "Hello World!"

    Specify dependencies

    The next step is to set up dependencies:

    Maven

    Change directory to the helloworld directory you created above, and create a pom.xml file:

       
 cd 
  
 ~/ 
 helloworld 
  
 touch 
  
 pom 
 . 
 xml

    To manage dependencies using Maven, specify the dependencies in the <dependencies> section inside the pom.xml file of your project. For this exercise, copy the following contents into your pom.xml file.

     < project 
  
 xmlns 
 = 
 "http://maven.apache.org/POM/4.0.0" 
  
 xmlns 
 : 
 xsi 
 = 
 "http://www.w3.org/2001/XMLSchema-instance" 
  
 xsi 
 : 
 schemaLocation 
 = 
 "http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" 
>  
< modelVersion>4 
 .0.0 
< / 
 modelVersion 
>  
< groupId>com 
 . 
 example 
 . 
 functions 
< / 
 groupId 
>  
< artifactId>functions 
 - 
 hello 
 - 
 world 
< / 
 artifactId 
>  
< version>1 
 .0.0 
 - 
 SNAPSHOT 
< / 
 version 
>  
< properties 
>  
< maven 
 . 
 compiler 
 . 
 target>11 
< / 
 maven 
 . 
 compiler 
 . 
 target 
>  
< maven 
 . 
 compiler 
 . 
 source>11 
< / 
 maven 
 . 
 compiler 
 . 
 source 
>  
< / 
 properties 
>  
< dependencies 
>  
< !-- 
  
 Required 
  
 for 
  
 Function 
  
 primitives 
  
 -- 
>  
< dependency 
>  
< groupId>com 
 . 
 google 
 . 
 cloud 
 . 
 functions 
< / 
 groupId 
>  
< artifactId>functions 
 - 
 framework 
 - 
 api 
< / 
 artifactId 
>  
< version>1 
 .1.0 
< / 
 version 
>  
< scope>provided 
< / 
 scope 
>  
< / 
 dependency 
>  
< / 
 dependencies 
>  
< build 
>  
< plugins 
>  
< plugin 
>  
< !-- 
  
 Google 
  
 Cloud 
  
 Functions 
  
 Framework 
  
 Maven 
  
 plugin 
  
 This 
  
 plugin 
  
 allows 
  
 you 
  
 to 
  
 run 
  
 Cloud 
  
 Functions 
  
 Java 
  
 code 
  
 locally 
 . 
  
 Use 
  
 the 
  
 following 
  
 terminal 
  
 command 
  
 to 
  
 run 
  
 a 
  
 given 
  
 function 
  
 locally 
 : 
  
 mvn 
  
 function 
 : 
 run 
  
 - 
 Drun 
 . 
 functionTarget 
 = 
 your 
 . 
 package 
 . 
 yourFunction 
  
 -- 
>  
< groupId>com 
 . 
 google 
 . 
 cloud 
 . 
 functions 
< / 
 groupId 
>  
< artifactId>function 
 - 
 maven 
 - 
 plugin 
< / 
 artifactId 
>  
< version>0 
 .11.0 
< / 
 version 
>  
< configuration 
>  
< functionTarget>functions 
 . 
 HelloWorld 
< / 
 functionTarget 
>  
< / 
 configuration 
>  
< / 
 plugin 
>  
< / 
 plugins 
>  
< / 
 build 
>
< / 
 project 
>

    See helloworld for a complete sample based on Maven.

    Gradle

    Change directory to the helloworld-gradle directory you created above, and create a build.gradle file:

       
 cd 
  
 ~/ 
 helloworld 
 - 
 gradle 
  
 touch 
  
 build 
 . 
 gradle

    To manage dependencies using Gradle, specify the dependencies in the build.gradle file of your project. For this exercise, copy the following contents into your build.gradle file. Note that this build.gradle file includes a custom task to help you run functions locally .

      apply 
  
 plugin 
 : 
  
 ' 
 java 
 ' 
 repositories 
  
 { 
  
 jcenter 
 () 
  
 mavenCentral 
 () 
 } 
 configurations 
  
 { 
  
 invoker 
 } 
 dependencies 
  
 { 
  
 // Every function needs this dependency to get the Functions Framework API. 
  
 compileOnly 
  
 ' 
 com 
 . 
 google 
 . 
 cloud 
 . 
 functions 
 : 
 functions 
 - 
 framework 
 - 
 api 
 : 
 1.1.0 
 ' 
  
 // To run function locally using Functions Framework's local invoker 
  
 invoker 
  
 ' 
 com 
 . 
 google 
 . 
 cloud 
 . 
 functions 
 . 
 invoker 
 : 
 java 
 - 
 function 
 - 
 invoker 
 : 
 1.3.1 
 ' 
  
 // These dependencies are only used by the tests. 
  
 testImplementation 
  
 ' 
 com 
 . 
 google 
 . 
 cloud 
 . 
 functions 
 : 
 functions 
 - 
 framework 
 - 
 api 
 : 
 1.1.0 
 ' 
  
 testImplementation 
  
 ' 
 junit 
 : 
 junit 
 : 
 4.13.2 
 ' 
  
 testImplementation 
  
 ' 
 com 
 . 
 google 
 . 
 truth 
 : 
 truth 
 : 
 1.4.0 
 ' 
  
 testImplementation 
  
 ' 
 org 
 . 
 mockito 
 : 
 mockito 
 - 
 core 
 : 
 5.10.0 
 ' 
 } 
 // Register a "runFunction" task to run the function locally 
 tasks 
 . 
 register 
 ( 
 "runFunction" 
 , 
  
 JavaExec 
 ) 
  
 { 
  
 main 
  
 = 
  
 ' 
 com 
 . 
 google 
 . 
 cloud 
 . 
 functions 
 . 
 invoker 
 . 
 runner 
 . 
 Invoker 
 ' 
  
 classpath 
 ( 
 configurations 
 . 
 invoker 
 ) 
  
 inputs 
 . 
 files 
 ( 
 configurations 
 . 
 runtimeClasspath 
 , 
  
 sourceSets 
 . 
 main 
 . 
 output 
 ) 
  
 args 
 ( 
  
 ' 
 -- 
 target 
 ' 
 , 
  
 project 
 . 
 findProperty 
 ( 
 ' 
 run 
 . 
 functionTarget 
 ' 
 ) 
  
 ? 
 : 
  
 '' 
 , 
  
 ' 
 -- 
 port 
 ' 
 , 
  
 project 
 . 
 findProperty 
 ( 
 ' 
 run 
 . 
 port 
 ' 
 ) 
  
 ? 
 : 
  
 8080 
  
 ) 
  
 doFirst 
  
 { 
  
 args 
 ( 
 ' 
 -- 
 classpath 
 ' 
 , 
  
 files 
 ( 
 configurations 
 . 
 runtimeClasspath 
 , 
  
 sourceSets 
 . 
 main 
 . 
 output 
 ). 
 asPath 
 ) 
  
 } 
 }

    See helloworld-gradle for a complete sample based on Gradle.

    Build and test locally

    Before deploying the function, you can build and test it locally:

    Maven

    Run the following command to confirm that your function builds:

      mvn 
  
 compile

    Another option is to use the mvn package command to compile your Java code, run any tests, and package the code up in a JAR file within the target directory. You can learn more about the Maven build lifecycle here .

    To test the function, run the following command:

      mvn 
  
 function 
 : 
 run

    Gradle

    Run the following command to confirm that your function builds:

      gradle 
  
 build

    To test the function, run the following command:

      gradle 
  
 runFunction 
  
 - 
 Prun 
 . 
 functionTarget 
 = 
 functions 
 . 
 HelloWorld

    If testing completes successfully, it displays the URL you can visit in your web browser to see the function in action: http://localhost:8080/ . You should see a Hello World! message.

    Alternatively, you can send requests to this function using curl from another terminal window:

      curl 
  
 localhost 
 : 
 8080 
 # 
  
 Output 
 : 
  
 Hello 
  
 World 
 !

    Deploy the function

    Maven

    To deploy the function with an HTTP trigger, run the following command in the helloworld directory:

    gcloud  
functions  
deploy  
my-first-function  
--no-gen2  
--entry-point  
functions.HelloWorld  
--runtime  
java17  
--trigger-http  
--memory  
512MB  
--allow-unauthenticated
     where my-first-function is the registered name by which your function will be identified in the Google Cloud console, and --entry-point specifies your function's fully qualified class name (FQN).

    Gradle

    To deploy the function with an HTTP trigger, run the following command in the helloworld-gradle directory:

    gcloud  
functions  
deploy  
my-first-function  
--no-gen2  
--entry-point  
functions.HelloWorld  
--runtime  
java17  
--trigger-http  
--memory  
512MB  
--allow-unauthenticated
     where my-first-function is the registered name by which your function will be identified in the Google Cloud console, and --entry-point specifies your function's fully qualified class name (FQN).

    Test the deployed function

    1. When the function finishes deploying, take note of the httpsTrigger.url property or find it using the following command:

      gcloud  
functions  
describe  
my-first-function
       It should look like this: 
      https:// GCP_REGION 
- PROJECT_ID 
.cloudfunctions.net/my-first-function

    2. Visit this URL in your browser. You should see a Hello World! message.

    View logs

    Logs for Cloud Run functions are viewable using the Google Cloud CLI, and in the Cloud Logging UI.

    Use the command-line tool

    To view logs for your function with the gcloud CLI, use the logs read command, followed by the name of the function:

    gcloud  
functions  
logs  
 read 
  
my-first-function

    The output should resemble the following:

    LEVEL  
NAME  
EXECUTION_ID  
TIME_UTC  
LOG
D  
my-first-function  
k2bqgroszo4u  
 2020 
-07-24  
 18 
:18:01.791  
Function  
execution  
started
D  
my-first-function  
k2bqgroszo4u  
 2020 
-07-24  
 18 
:18:01.958  
Function  
execution  
took  
 168 
  
ms,  
finished  
with  
status  
code:  
 200 
...

    Use the Logging dashboard

    You can also view logs for Cloud Run functions from the Google Cloud console .
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