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How-to Guide: Deploy your function to Cloud Run

This guide shows how to deploy a C++ function handling HTTP requests to Cloud Run.

WARNING: The development version of this document may not work with the released version of the functions framework. Please use this document as it appears in the corresponding release if you are using a released version of the library. In particular, buildpacks use the latest release.

Pre-requisites

This guide assumes you are familiar with Google Cloud, and that you have a GCP project with Cloud Run enabled. If needed, consult:

Verify the docker tool is functional on your workstation:

docker run hello-world
# Output: Hello from Docker! and then some more informational messages.

If needed, use the online instructions to download and install this tool. This guide assumes that you have configured sudoless docker. If you prefer replace all docker commands below with sudo docker.

Verify the pack tool is functional on our workstation. These instructions were tested with v0.17.0, although they should work with newer versions. Some commands may not work with older versions.

pack version
# Output: a version number, e.g., 0.17.0+git-d9cb4e7.build-2045

In this guide we will be using this function:

#include <google/cloud/functions/function.h>
#include <nlohmann/json.hpp>

namespace gcf = ::google::cloud::functions;

gcf::HttpResponse hello_world_http_impl(gcf::HttpRequest request) {
  auto greeting = [r = std::move(request)] {
    auto request_json = nlohmann::json::parse(r.payload(), /*cb=*/nullptr,
                                              /*allow_exceptions=*/false);
    if (request_json.count("name") && request_json["name"].is_string()) {
      return "Hello " + request_json.value("name", "World") + "!";
    }
    return std::string("Hello World!");
  };

  return gcf::HttpResponse{}
      .set_header("content-type", "text/plain")
      .set_payload(greeting());
}

gcf::Function hello_world_http() {
  return gcf::MakeFunction(hello_world_http_impl);
}

Getting the code for this example

This example is included in the Functions Framework for C++ source code repository. Download this code as usual:

cd $HOME
git clone https://github.com/GoogleCloudPlatform/functions-framework-cpp

The rest of this guide will assume you are issuing commands in the framework's clone:

cd $HOME/functions-framework-cpp

Building a Docker image

⚠️ This will automatically download and compile the functions framework and all its dependencies. Consequently, the first build of a function may take several minutes (and up to an hour) depending on the performance of your workstation. Subsequent builds cache many binary artifacts, but these caches are not shared across functions, so plan accordingly.

Set the GOOGLE_CLOUD_PROJECT shell variable to the project id of your GCP project, and use the [Google Cloud buildpack] builder to create a docker image containing your function:

GOOGLE_CLOUD_PROJECT=... # put the right value here
pack build \
    --builder gcr.io/buildpacks/builder:v1 \
    --env GOOGLE_FUNCTION_TARGET=hello_world_http \
    --path examples/site/hello_world_http \
   "gcr.io/${GOOGLE_CLOUD_PROJECT}/gcf-cpp-hello-world-http"

Push this new container image to Google Container Registry:

docker push "gcr.io/${GOOGLE_CLOUD_PROJECT}/gcf-cpp-hello-world-http:latest"

Deploy to Cloud Run

To deploy this image in Cloud Run use this command. You need to select a Cloud Run region for your deployment. We will use us-central1 in this guide:

Set the active project:

gcloud config set project ${GOOGLE_CLOUD_PROJECT}
gcloud run deploy gcf-cpp-hello-world-http \
    --image="gcr.io/${GOOGLE_CLOUD_PROJECT}/gcf-cpp-hello-world-http:latest" \
    --region="us-central1" \
    --platform="managed" \
    --allow-unauthenticated

Send a request to your function

Find out what URL was assigned to your function, and use curl to send a request:

HTTP_SERVICE_URL=$(gcloud run services describe \
    --platform="managed" \
    --region="us-central1" \
    --format="value(status.url)" \
    gcf-cpp-hello-world-http)

curl -H "Authorization: Bearer $(gcloud auth print-identity-token)" "${HTTP_SERVICE_URL}"
# Output: Hello World!

Cleanup

Delete the Cloud Run deployment:

gcloud run services delete gcf-cpp-hello-world-http \
    --region="us-central1" \
    --platform="managed"

And the container image:

gcloud container images delete \
    "gcr.io/${GOOGLE_CLOUD_PROJECT}/gcf-cpp-hello-world-http:latest"