Multipart Dockerfile to download Open Policy Agent into an AWS Lambda

Dockerfile

# Pull latest static opa executable image
FROM openpolicyagent/opa:latest-static AS opa-stage

# Start lambda image
FROM public.ecr.aws/lambda/java:11

ARG OPA_INSTALL_PATH=${LAMBDA_TASK_ROOT}/opa
ARG OPA_EXECUTABLE_PATH=${OPA_INSTALL_PATH}/opa

COPY --from=opa-stage /opa ${OPA_INSTALL_PATH}/
RUN chmod +x ${OPA_EXECUTABLE_PATH}

# Copy function code and runtime dependencies from Gradle layout
COPY build/explode ${LAMBDA_TASK_ROOT}

# Tell lambda where the handler lives
CMD [ "example.lambda.JavaLambdaHandler" ]