Google Cloud Functions

Google Cloud Functions in Java should be packaged as an Uber JAR. To be deployed, the JAR should be placed in a directory that must not contain any other JAR.

DEPLOYMENT_DIR=deployment

Packaging

The maven-shade-plugin is used to build the Uber JAR. While configuring it in the pom.xml is the recommended way to use it, here we execute it from the command line to keep the pom.xml file agnostic to the cloud provider.

mvn package shade:shade

# This is the Maven "target" directory
BUILD_DIR=$(mvn help:evaluate -Dexpression=project.build.directory -q -DforceStdout)

# The Maven shade plugin adds the "original-" prefix to the non-shaded JAR.
# Here we select the shaded JAR which does not have this prefix.
JAR_FILE=$(ls ${BUILD_DIR} | grep '.jar$' | grep -v '^original')

# the Uber JAR is copied into the deployment directory
mkdir -p ${BUILD_DIR}/${DEPLOYMENT_DIR}
cp ${BUILD_DIR}/${JAR_FILE} ${BUILD_DIR}/${DEPLOYMENT_DIR}/${JAR_FILE}

Deployment

The Google Cloud documentation describes all the possible ways to deploy your function.

For example, using the gcloud CLI:

gcloud functions deploy ${FUNCTION_NAME} \
    --region ${REGION} \
    --entry-point fr.axelop.agnosticserverlessfunctions.FunctionInvoker \
    --source ${BUILD_DIR}/${DEPLOYMENT_DIR} \
    --runtime java11 \
    --trigger-http \
    --gen2

The entrypoint class is always fr.axelop.agnosticserverlessfunctions.FunctionInvoker.