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.

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

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

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.