Deploying Functions

This guide covers how to deploy your Ruby functions written with the Functions Framework. Functions can be deployed to Google Cloud Functions, Google's Functions-as-a-service (FaaS) product, to Google Cloud Run. Google's container-based serverless environment, or to any KNative-based environment. For more information about the Framework as a whole, see the Overview Guide.

Before you begin

To deploy to Google Cloud, whether to Cloud Functions or Cloud Run, you'll need a Google Cloud project with billing enabled. Go to the Google Cloud console, create a project (or select an existing project), and ensure billing is enabled.

Additionally, install the Google Cloud SDK if you haven't done so previously.

Deploying to Cloud Functions

Google Cloud Functions is Google's scalable pay-as-you-go Functions-as-a-Service (FaaS) environment that can run your function with zero server management. The Functions Framework is designed especially for functions that can be hosted on Cloud Functions.

You can run Ruby functions on Google Cloud Functions by selecting the ruby26 runtime or ruby27 runtime to use a recent release of Ruby 2.6 or Ruby 2.7. Support for Ruby 3.0 is forthcoming.

Deploying and updating your function

Before you can deploy to Cloud Functions, make sure your bundle, and in particular your Gemfile.lock file, is up to date. The easiest way to do this is to bundle install or bundle update and run your local tests prior to deploying. Cloud Functions will not accept your function unless an up-to-date Gemfile.lock is present.

Also, make sure your source file (which defines your function) is called app.rb. The Functions Framework lets you choose a function source file, but Cloud Functions currently requires you to use app.rb.

Decide which function in the source file to invoke, that is, the name that you used when writing the function. This is called the target. (Note that if you did not specify a name for the function, it defaults to the name function.)

Choose a Cloud Functions name for your function. The name identifies this function deployment (e.g. in the cloud console) and is also part of the function's default URL. (Note: the name and the target do not have to be the same value.)

Then, issue the gcloud command to deploy:

gcloud functions deploy $YOUR_FUNCTION_NAME \
    --project=$YOUR_PROJECT_ID \
    --runtime=ruby27 \
    --trigger-http \
    --entry-point=$YOUR_FUNCTION_TARGET

The --entry-point= flag can be omitted if the target has the same value as the name. Additionally, the --project flag can be omitted if you've set your default project using gcloud config set project.

If your function handles events rather than HTTP requests, you'll need to replace --trigger-http with a different trigger. For details, see the reference documentation for gcloud functions deploy.

To update your deployment, just redeploy using the same function name.

Configuring Cloud Functions deployments

The Functions Framework provides various configuration parameters, described in Running a Functions Server. If you want to set any of these parameters beyond the source file and target, you must set environment variables. For example, to limit logging to WARN level and above, set FUNCTION_LOGGING_LEVEL to WARN when deploying:

gcloud functions deploy $YOUR_FUNCTION_NAME --project=$YOUR_PROJECT_ID \
  --runtime=ruby27 --trigger-http --source=$YOUR_FUNCTION_SOURCE \
  --entry-point=$YOUR_FUNCTION_TARGET \
  --set-env-vars=FUNCTION_LOGGING_LEVEL=WARN

Consult the table in Running a Functions Server for a list of the environment variables that can be set.

Deploying to Cloud Run

Google Cloud Run is Google's managed compute platform for deploying and scaling containerized applications quickly and securely. It can run any container-based workload, including a containerized function.

Cloud Run has a hosted fully-managed option that runs on Google's infrastructure and monitors and scales your application automatically, and a self-managed or on-prem option called Cloud Run for Anthos that runs atop Kubernetes. Both flavors use the same general interface and can run functions in the same way. This tutorial is written for the managed option, but it should not be difficult to adapt it if you have an Anthos installation.

Building an image for your function

Before you can deploy to Cloud Run, make sure your bundle, and in particular your Gemfile.lock file, is up to date. The easiest way to do this is to bundle install or bundle update and run your local tests prior to deploying. The configuration used in the Dockerfile below will not accept your function unless an up-to-date Gemfile.lock is present.

First, build a Docker image containing your function. Following is a simple Dockerfile that you can use as a starting point. Feel free to adjust it to the needs of your project:

FROM ruby:2.7
WORKDIR /app
COPY . .
RUN gem install --no-document bundler \
    && bundle config --local frozen true \
    && bundle config --local without "development test" \
    && bundle install
ENTRYPOINT ["bundle", "exec", "functions-framework-ruby"]

You can test your image locally using the steps described under Running a Functions Server.

When your Dockerfile is ready, you can use Cloud Build to build it and store the image in your project's container registry.

gcloud builds submit --tag=gcr.io/$YOUR_PROJECT_ID/$YOUR_APP_NAME:$YOUR_BUILD_ID .

You must use your project ID, but you can choose an app name and build ID. The command may ask you for permission to enable the Cloud Build API for the project if it isn't already enabled.

Because you provide your own Docker image when deploying to Cloud Run, you can use any version of Ruby supported by the Functions Framework, from 2.5 through 3.0.

Deploying an image to Cloud Run

To deploy to Cloud Run, specify the same image URL that you built above. For example:

gcloud run deploy $YOUR_APP_NAME --project=$YOUR_PROJECT_ID \
  --image=gcr.io/$YOUR_PROJECT_ID/$YOUR_APP_NAME:$YOUR_BUILD_ID \
  --platform=managed --allow-unauthenticated --region=us-central1 \
  --set-env-vars=FUNCTION_SOURCE=$YOUR_SOURCE,FUNCTION_TARGET=$YOUR_TARGET

You can omit the --project flag if you've already set it as the default with gcloud config set project.

The command may ask you for permission to enable the Cloud Run API for the project, if it isn't already enabled.

At the end of the deployment process, the command will display the hostname for the Cloud Run service. You can use that hostname to send test requests to your deployed function.

Configuring Cloud Run deployments

Note that our Dockerfile's entrypoint did not pass any source file or target name to the Functions Framework. If these are not specified, the Framework will use the source ./app.rb and the target function by default. To use different values, you need to set the appropriate environment variables when deploying, as illustrated above with the FUNCTION_SOURCE and FUNCTION_TARGET variables.

Source and target are not the only configuration parameters available. The various parameters, along with their environment variables, are described in Running a Functions Server. Any of these can be specified in the --set-env-vars flag when you deploy to Google Cloud Run.

It is also possible to "hard-code" configuration into the Dockerfile, by setting environment variables in the Dockerfile, or adding flags to the entrypoint. However, it is often better practice to keep your Dockerfile "generic", and set configuration environment variables during deployment, so that you do not need to rebuild your Docker image every time you want to change configuration.