Building Using the Pack CLI

Cloud Functions runs user code in containers created using Google's Cloud Native buildpacks. You can create these containers yourself and run them locally using Docker and the pack tool.

Note: if you're interested in running functions locally without containerization, see Running Functions with Function Frameworks.

Introduction Video

In this video, Matt introduces Buildpacks on Google Cloud:

Setup

Before proceeding, make sure you have the pack tool and Docker installed.

Building your function

Selecting a signature type

In order to build your function, you'll first have to determine your function's signature type. The Functions Frameworks support three different signature types for incoming events:

Function type	Signature type	Description	Runtimes
HTTP-triggered functions	http	Functions that receive and respond to HTTP requests.	All
Background functions	event	Cloud Functions-specific event format	Java, Node, Go, and Python
CloudEvent functions	cloudevent	Industry-standard event format	Ruby and .NET.

Building your function

To build your function into a portable Docker container using buildpacks, use the pack build command shown below. Replace the following variables:

• YOUR_FUNCTION_SIGNATURE_TYPE should be your function's signature type (as shown in the table above)
• YOUR_FUNCTION_NAME with the entry-point of your function
• YOUR_BUILDPACK_IMAGE_NAME with the name you wish to give the resulting container

Node.js

  pack build \
  --builder gcr.io/buildpacks/builder:v1 \
  --env GOOGLE_RUNTIME=nodejs \
  --env GOOGLE_FUNCTION_SIGNATURE_TYPE=YOUR_FUNCTION_SIGNATURE_TYPE \
  --env GOOGLE_FUNCTION_TARGET=YOUR_FUNCTION_NAME \
  YOUR_BUILDPACK_IMAGE_NAME

Python

  pack build \
  --builder gcr.io/buildpacks/builder:v1 \
  --env GOOGLE_RUNTIME=python \
  --env GOOGLE_FUNCTION_SIGNATURE_TYPE=YOUR_FUNCTION_SIGNATURE_TYPE \
  --env GOOGLE_FUNCTION_TARGET=YOUR_FUNCTION_NAME \
  YOUR_BUILDPACK_IMAGE_NAME

Go

  pack build \
  --builder gcr.io/buildpacks/builder:v1 \
  --env GOOGLE_RUNTIME=go \
  --env GOOGLE_FUNCTION_SIGNATURE_TYPE=YOUR_FUNCTION_SIGNATURE_TYPE \
  --env GOOGLE_FUNCTION_TARGET=YOUR_FUNCTION_NAME \
  YOUR_BUILDPACK_IMAGE_NAME

Java

  pack build \
  --builder gcr.io/buildpacks/builder:v1 \
  --env GOOGLE_RUNTIME=java \
  --env GOOGLE_FUNCTION_SIGNATURE_TYPE=YOUR_FUNCTION_SIGNATURE_TYPE \
  --env GOOGLE_FUNCTION_TARGET=YOUR_FUNCTION_NAME \
  YOUR_BUILDPACK_IMAGE_NAME

Note: Java functions use [PACKAGE_NAME].[CLASS_NAME] as an entry-point value.

C#

  pack build \
  --builder gcr.io/buildpacks/builder:v1 \
  --env GOOGLE_RUNTIME=dotnet \
  --env GOOGLE_FUNCTION_SIGNATURE_TYPE=YOUR_FUNCTION_SIGNATURE_TYPE \
  --env GOOGLE_FUNCTION_TARGET=YOUR_FUNCTION_NAME \
  YOUR_BUILDPACK_IMAGE_NAME

Note: .NET functions use their class name as an entry-point value.

Ruby

  pack build \
  --builder gcr.io/buildpacks/builder:v1 \
  --env GOOGLE_RUNTIME=ruby \
  --env GOOGLE_FUNCTION_SIGNATURE_TYPE=YOUR_FUNCTION_SIGNATURE_TYPE \
  --env GOOGLE_ENTRYPOINT=YOUR_FUNCTION_NAME \
  YOUR_BUILDPACK_IMAGE_NAME

This command packages your function into a runnable Docker container that can process HTTP requests matching one of the signature types specified in the table above.

Running the image as a container

Use the following command to run your container:

docker run --rm -p 8080:8080 YOUR_BUILDPACK_IMAGE_NAME

Calling your function

See the calling running functions page for instructions on how to interact with your locally-running function.