This page describes a few things you need to know to get started in developinga service for Cloud Run.

Code requirements

You must meet the following requirements when you develop a service:

• The service must listen for requests.You canconfigure the porton which requests are sent.Inside Cloud Run instances, the value of thePORTenvironment variable always reflects the port to which requests are sent.Your code should check for the existence of thisPORT environmentvariable and if it is present, should listen on it to maximize portability.
• The service must bestateless. It cannot rely on a persistentlocal state.
• If the service performs background activities outside the scope of requesthandling it must use theinstance-based billingsetting in order to have CPU allocated outside of the standard request cycle.
• If your service uses NFS, it must use thesecond generation execution environment.

You can find more details about these constraints in theContainer runtime contract.

Programming language support

Cloud Run source deployment conveniently supports multiplelanguage runtimes, each ofwhich is available through container base images provided byGoogle Cloud's buildpacks. You can also use other programming languages orframeworks, as long as the source code is in an OCI-compliant image.

Thebuild and deploy quickstartsprovides samples in many popular languages.

Using a web server

You can use a web server to listen on the required port, and to process androute incoming requests. For example, Node.js developers can useExpress.js, Python developers can useFlask, Ruby developers can useSinatra, and so forth.

Containerizing your code

SeeContainerize your code fordetails.

Design Cloud Run apps with Gemini assistance

This product or feature is subject to the "Pre-GA Offerings Terms" in the General Service Terms section of theService Specific Terms. Pre-GA products and features are available "as is" and might have limited support. For more information, see thelaunch stage descriptions.

You can get AI-powered help fromGemini Cloud Assist chat todesign applications optimally. With Gemini Cloud Assist, you candiscover the most suitable configurations and strategies for deploying yourapplications on Cloud Run, ensuring efficient resourceutilization and seamless operation.

To use Gemini Cloud Assist from the Google Cloud console, dothe following:

1. Ensure that Gemini Cloud Assist is set up for your Google Cloud user account and project.

2. Set up your Cloud Run development environmentin your Google Cloud project and ensure you have the appropriatedeployment permissions.

3. Go to the Cloud Run page in the Google Cloud console.

   Go to Cloud Run

4. In the console toolbar, select a Google Cloud project. Use a projectassociated with a project ID you submitted after you were granted access toGemini Cloud Assist.

5. ClicksparkOpen or close Gemini AI chat.

   The Gemini panel opens.

6. If necessary, clickAccept if you agree to the terms.

7. If you have a question about a specific application, provide context bygoing to the page that shows your resource before asking your question. Whengenerating a response, Gemini includes information about thecurrent console page and project.

8. Enter a prompt in theGemini panel.

   The following table provide some example prompts for usingGemini Cloud Assist with Cloud Run.

   Prompt	Type of response
   "I want to design a Node.js app on Cloud Run. What's the recommended approach and what do I need to know?"	Summary of containerizing your app, structuring your node.js app, and the deployment process.
   "What permission do I need to deploy a Cloud Run app?"	List of required permissions and roles.
   "I want to deploy a three-tier web application using Cloud Run"	General outline of the steps to design a three-tier web app.
   "How do I migrate my App Engine app to Cloud Run"	High-level overview of key steps for preparing your Cloud Run development environment, and some key differences between both products. Links to an example tutorial that can be used to customize the solution to meet your specific needs.
   "What is the gcloud CLI command for updating the min instance setting to 2 for my Cloud Run service 'example-service'"	Suggested gcloud CLI command for updating the min instances setting.
   "How do I update my service account for my Cloud Run servicehello-world"	Suggested gcloud CLI command for updating the service account.
   "Show me an example of building a generative AI app on Cloud Run with LangChain"	Steps for creating an example app using Cloud Run with LangChain.
   "Generate a Terraform config using thegoogle_cloud_run_v2_service resource for a Cloud Run service that sets the billing setting to instance-based billing"	Suggested Terraform configuration for updating the billing setting.

For more details, see the following resources:

• Learn how towrite better prompts.
• Learn how to use theGemini Cloud Assist panel.
• ReadUse Gemini for AI assistance and development.
• Learnhow Gemini for Google Cloud uses your data.

What's next

• Once you have your service code and Dockerfile, you shouldbuild a container image then continue iteratinginlocal testing.
• If you are migrating an existing web application, seeMigrating Your Service to Cloud Run.
• For best practices for designing, implementing, testing, and deploying aCloud Run service, see theDevelopment tips.