Write Cloud Run functions
Cloud Run functions supports writing source code in a number of programming languages. The language runtime you choose and the type of function you want to write determine how to structure your code and implement your function. This page provides an overview of the types of Cloud Run functions and expectations for source code.
Types of Cloud Run functions
There are two types of Cloud Run functions:
HTTP functions, which handle HTTP requests and use HTTP triggers. See Write HTTP functions for information about implementing HTTP functions.
Event-driven functions, which handle events from your cloud environment and use event triggers as described in Cloud Run functions triggers. See Write event-driven functions for information about implementing event-driven functions.
Use an HTTP function when you need your function to have a URL endpoint and respond to HTTP requests, such as for webhooks. Use an event-driven function when your function should be triggered directly in response to events within your Google Cloud project, such as messages on a Pub/Sub topic or changes in a Cloud Storage bucket.
Source directory structure
In order for Cloud Run functions to locate your function definition, each language runtime has requirements for structuring your source code. The basic directory structure for a function in each runtime is shown below.
Node.js
The basic directory structure for Node.js functions is as follows:
. ├── index.js └── package.json
By default, Cloud Run functions attempts to load source code from a file
named index.js
at the root of your function directory. To specify a different
main source file, use the main
field in your package.json
file.
Your package.json
file must also include the
Functions Framework for Node.js
as a dependency:
{
"main": "index.js",
"dependencies": {
"@google-cloud/functions-framework": "^3.0.0"
}
}
The code in your main file must define your function entry point and can import other code and Node.js modules as normal. The main file can also define multiple function entry points that can be deployed separately.
Python
The basic directory structure for Python functions is as follows:
. ├── main.py └── requirements.txt
Cloud Run functions loads source code from a file named main.py
at the
root of your function directory. Your main file must be named main.py
.
Your requirements.txt
file must include the
Functions Framework for Python
as a dependency:
functions-framework==3.*
The code in your main.py
file must define your
function entry point and can import other code and external
dependencies as normal. The main.py
file can also define multiple function
entry points that can be deployed separately.
Go
The basic directory structure for Go functions is as follows:
. ├── myfunction.go └── go.mod
Your function must be in a Go package at the root of your project. The package
and its source files can have any name, except your function cannot be in
package main
. If you need a main
package, for example for local testing,
you can create one in a subdirectory:
. ├── myfunction.go ├── go.mod └── cmd/ └── main.go
Your go.mod
file must include the
Functions Framework for Go
as a dependency:
module example.com/my-module
require (
github.com/GoogleCloudPlatform/functions-framework-go v1.5.2
)
The code in your root package must define your function entry point and can import other code from subpackages and dependencies as normal. Your package can also define multiple function entry points that can be deployed separately.
Java
The basic directory structure for Java functions is as follows:
. ├── pom.xml └── src/ └── main/ └── java/ └── MyFunction.java
Your Java source files must be under the src/main/java/
directory and can have
any name. If your source files declare a package, add an extra directory under
src/main/java
with the name of the package:
. ├── pom.xml └── src/ └── main/ └── java/ └── mypackage/ └── MyFunction.java
We recommend putting associated tests under a src/test/java/
subdirectory.
Your pom.xml
file must include the
Functions Framework for Java
as a dependency:
...
<dependency>
<groupId>com.google.cloud.functions</groupId>
<artifactId>functions-framework-api</artifactId>
<version>1.0.4</version>
</dependency>
...
The code in your source files must define your function entry point and can import other code and external dependencies as normal. Your source files can also define multiple function entry points that can be deployed separately.
C#
The basic directory structure for .NET functions is as follows:
. ├── MyFunction.cs └── MyProject.csproj
You can structure your projects as you would any other .NET source code. Your source files can have any name.
Your project file must include the Functions Framework for .NET as a dependency:
...
<PackageReference Include="Google.Cloud.Functions.Hosting" Version="1.0.0" />
...
The code in your source files must define your function entry point and can import other code and external dependencies as normal. Your source files can also define multiple function entry points that can be deployed separately.
You can also use the Cloud Run functions template package for .NET to generate the required files.
Ruby
The basic directory structure for Ruby functions is as follows:
. ├── app.rb ├── Gemfile └── Gemfile.lock
Cloud Run functions loads source code from a file named app.rb
at the
root of your function directory. Your main file must be named app.rb
.
Your Gemfile
file must include the
Functions Framework for Ruby
as a dependency:
source "https://rubygems.org"
gem "functions_framework", "~> 1.0"
The code in your app.rb
file must define your
function entry point and can import other code and external
dependencies as normal. The app.rb
file can also define multiple function
entry points that can be deployed separately.
PHP
The basic directory structure for PHP functions is as follows:
. ├── index.php └── composer.json
Cloud Run functions loads source code from a file named index.php
at the
root of your function directory. Your main file must be named index.php
.
Your composer.json
file must include the
Functions Framework for PHP
as a dependency:
{
"require": {
"google/cloud-functions-framework": "^1.1"
}
}
The code in your index.php
file must define your
function entry point and can import other code and external
dependencies as normal. The index.php
file can also define multiple function
entry points that can be deployed separately.
If you are thinking of grouping multiple functions into a single project, be aware that every function may end up sharing the same set of dependencies. However, some of the functions may not need all of the dependencies.
Where possible, we recommend splitting up large multi-function codebases and putting each function in its own top-level directory as shown above, with its own source and project configuration files. This approach minimizes the number of dependencies required for a particular function, which in turn reduces the amount of memory your function needs.
Function entry point
Your source code must define an entry point for your function, which is the particular code that is executed when the Cloud Run function is invoked. You specify this entry point when you deploy your function.
How you define the entry point depends on the language runtime you use. For some languages, the entry point is a function, whereas for others the entry point is a class. To learn more about defining entry points and implementing Cloud Run functions in different languages, see Write HTTP functions and Write event-driven functions.
Dependencies
You can manage dependencies using standard tools for each runtime. For more information, see the appropriate page:
- Specifying dependencies in Node.js
- Specifying dependencies in Python
- Specifying dependencies in Go
- Specifying dependencies in Java
- Specifying dependencies in .NET
- Specifying dependencies in Ruby
- Specifying dependencies in PHP
Next steps
- Learn how to write HTTP functions.
- Learn how to write event-driven functions.
- Learn about Cloud Run functions triggers.