Using HTTP/2 (services)

For Cloud Run services, Cloud Run by default downgrades HTTP/2 requests to HTTP/1 when those requests are sent to the container. If you want to explicitly set your service to use HTTP/2 end-to-end, with no such downgrading, you can configure it for HTTP/2. This page shows how to do the configuration.

For more information on invoking services using HTTP, refer to Invoking with an HTTPS Request.

Before you configure

Your Cloud Run service must handle requests in HTTP/2 cleartext (h2c) format, because TLS is still terminated automatically by Cloud Run.

To confirm that your service supports h2c requests, test the service locally using this cURL command:

curl -i --http2-prior-knowledge http://localhost:PORT

Setting and updating HTTP/2 end-to-end

Any configuration change leads to the creation of a new revision. Subsequent revisions will also automatically get this configuration setting unless you make explicit updates to change it.

You can specify the use of HTTP/2 end-to-end using the Cloud console, the gcloud command line, or a YAML file when you create a new service or deploy a new revision:

Console

Go to Cloud Run
Click Create Service if you are configuring a new service you are deploying to. If you are configuring an existing service, click on the service, then click Edit and Deploy New Revision.
If you are configuring a new service, fill out the initial service settings page as desired, then click Next > Container, Variables & Secrets, Connections, Security to reach the service configuration page.
Click the Connections tab.
Select the checkbox Enable http/2 connections
Click Create or Deploy.

Command line

You can update a given service to use HTTP/2 by using the following command:

gcloud run services update SERVICE --use-http2

Replace SERVICE with the name of your service.

You can also set your service to use HTTP/2 during deployment using the command:

gcloud run deploy --image IMAGE_URL --use-http2

Replace IMAGE_URL with a reference to the container image, for example, us-docker.pkg.dev/cloudrun/container/hello:latest

YAML

You can download and view existing service configuration using the gcloud run services describe --format export command, which yields cleaned results in YAML format. You can then modify the fields described below and upload the modified YAML using the gcloud run services replace command. Make sure you only modify fields as documented.

To view and download the configuration:

gcloud run services describe SERVICE --format export > service.yaml

Update ports with the nameh2c and containerPort with the port of your choice, as shown belows:
```
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: SERVICE
spec:
  template:
    metadata:
      name: REVISION
    spec:
      containers:
      - image: IMAGE_URL
        ports:
        - name: h2c
          containerPort: 8080
```
Replace
- SERVICE with the name of your Cloud Run service
- IMAGE_URL with a reference to the container image, for example, us-docker.pkg.dev/cloudrun/container/hello:latest
- REVISION with a new revision name or delete it (if present). If you supply a new revision name, it must meet the following criteria:
  - Starts with SERVICE-
  - Contains only lowercase letters, numbers and -
  - Does not end with a -
  - Does not exceed 63 characters
Replace the service with its new configuration using the following command:
```
gcloud run services replace service.yaml
```

View http/2 settings

To view the current http/2 settings for your Cloud Run service:

Console

Go to Cloud Run
Click the service you are interested in to open the Service details page.
Click the Revisions tab.
In the details panel at the right, the http/2 setting is listed under the Connections tab.

Command line

Use the following command:
```
gcloud run services describe SERVICE
```
Locate the http/2 setting in the returned configuration.