A Java action is a Java program with a method called main
that has the exact signature as follows:
public static com.google.gson.JsonObject main(com.google.gson.JsonObject);
For example, create a Java file called Hello.java
with the following content:
import com.google.gson.JsonObject; public class Hello { public static JsonObject main(JsonObject args) { String name = "stranger"; if (args.has("name")) name = args.getAsJsonPrimitive("name").getAsString(); JsonObject response = new JsonObject(); response.addProperty("greeting", "Hello " + name + "!"); return response; } }
In order to compile, test and archive Java files, you must have a JDK 8 installed locally.
Then, compile Hello.java
into a JAR file hello.jar
as follows:
javac Hello.java
jar cvf hello.jar Hello.class
Note: google-gson must exist in your Java CLASSPATH when compiling the Java file.
You need to specify the name of the main class using --main
. An eligible main class is one that implements a static main
method as described above. If the class is not in the default package, use the Java fully-qualified class name, e.g., --main com.example.MyMain
.
If needed you can also customize the method name of your Java action. This can be done by specifying the Java fully-qualified method name of your action, e.q., --main com.example.MyMain#methodName
To use as a docker action:
wsk action update helloJava hello.jar --main Hello --docker openwhisk/java8action
This works on any deployment of Apache OpenWhisk
To use on a deployment of OpenWhisk that contains the runtime as a kind:
wsk action update helloJava hello.jar --main Hello --kind java:8
Action invocation is the same for Java actions as it is for Swift and JavaScript actions:
wsk action invoke --result helloJava --param name World
{ "greeting": "Hello World!" }
./gradlew java8:distDocker
This will produce the image whisk/java8action
Build and Push image
docker login ./gradlew java8:distDocker -PdockerImagePrefix=$prefix-user -PdockerRegistry=docker.io
Deploy OpenWhisk using ansible environment that contains the kind java:8
Assuming you have OpenWhisk already deploy localy and OPENWHISK_HOME
pointing to root directory of OpenWhisk core repository.
Set ROOTDIR
to the root directory of this repository.
Redeploy OpenWhisk
cd $OPENWHISK_HOME/ansible ANSIBLE_CMD="ansible-playbook -i ${ROOTDIR}/ansible/environments/local" $ANSIBLE_CMD setup.yml $ANSIBLE_CMD couchdb.yml $ANSIBLE_CMD initdb.yml $ANSIBLE_CMD wipe.yml $ANSIBLE_CMD openwhisk.yml
Or you can use wskdev
and create a soft link to the target ansible environment, for example:
ln -s ${ROOTDIR}/ansible/environments/local ${OPENWHISK_HOME}/ansible/environments/local-java wskdev fresh -t local-java
Install dependencies from the root directory on $OPENWHISK_HOME repository
pushd $OPENWHISK_HOME ./gradlew install podd $OPENWHISK_HOME
Using gradle to run all tests
./gradlew :tests:test
Using gradle to run some tests
./gradlew :tests:test --tests *ActionContainerTests*
Using IntelliJ:
To use as docker action push to your own dockerhub account
docker tag whisk/java8action $user_prefix/java8action docker push $user_prefix/java8action
Then create the action using your the image from dockerhub
wsk action update helloJava hello.jar --main Hello --docker $user_prefix/java8action
The $user_prefix
is usually your dockerhub user id.