Introduction:
Google Cloud Functions is a serverless platform that allows you to run your code in response to specific events, such as a change in a database or a new file uploaded to Cloud Storage. One of the benefits of Cloud Functions is that you can deploy and test your code locally before deploying it to the cloud. In this blog post, we will discuss how to deploy and test your Cloud Functions locally using the open source Functions Framework.
Cloud Functions builds upon the open source Functions Framework:
Cloud Functions is built on top of the open source Functions Framework, which is a command-line tool that allows you to write, test, and deploy your functions locally. The Functions Framework also provides a local development environment that simulates the same environment as the cloud, making it easy to test your functions before deploying them.
A real-world example:
Let’s say you have a function that is triggered by a new file being uploaded to Cloud Storage. Your function processes the file and then writes the processed data to a Firestore database. To test this function locally, you would use the Functions Framework to create a local development environment that simulates the Cloud Storage and Firestore services. You can then write test data to the local Cloud Storage and check that the data is written correctly to the local Firestore.
Codes:
Here is an example of how you would write a function using the Functions Framework:
const functions = require('@google-cloud/functions-framework');
exports.processFile = functions.storage.object().onFinalize(async (object) => {
// code to process the file
// code to write data to Firestore
});
How to run a Cloud Function locally:
To run a Cloud Function locally, you can use the following command:
functions-framework --target=processFile
This will start the local development environment and run your function. You can then write test data to the local Cloud Storage to trigger your function and check that the data is written correctly to the local Firestore.
How to invoke a Cloud Function with an Eventarc event locally:
Cloud Functions can also be triggered by events from other services, such as Eventarc. To test a function that is triggered by an Eventarc event locally, you can use the functions-framework-eventarc package to simulate the event.
const eventarc = require('functions-framework-eventarc');
exports.myFunction = eventarc.event().onCloudEvent(async (event) => {
// code to handle the event
});
eventarc.emit({
eventType: 'example.event',
resource: 'projects/my-project/locations/us-central1/eventTypes/example.event'
});
How to use the same permissions as if it were deployed in the Cloud:
When you run your function locally, it will not have access to the same permissions as it would have when it is deployed in the cloud. To grant your function the same permissions as if it were deployed in the cloud, you can use the functions-framework-env package to set environment variables that correspond to the permissions of your function in the cloud.
const functionsEnv = require('functions-framework-env');
exports.myFunction = functionsEnv.cloudFunction(async (req, res) => {
// code to handle the event
});
How to fetch secrets stored remotely from Secret manager:
Cloud Functions also allows you to securely store and retrieve secrets, such as database credentials, using Secret Manager. To test a function that uses secrets stored in Secret Manager locally, you can use the functions-framework-secrets package to fetch the secrets and set them as environment variables.
const functionsSecrets = require('functions-framework-secrets');
exports.myFunction = functionsSecrets.cloudFunction(async (req, res) => {
const secrets = functionsSecrets.get();
// code to use the secrets
});
How to set Breakpoints in Visual Studio Code within a local Cloud Function:
When debugging a local Cloud Function, you can use Visual Studio Code to set breakpoints in your code and step through it. To do this, you will need to install the “Cloud Functions for Firebase” extension in Visual Studio Code. Once the extension is installed, you can set breakpoints and start debugging your function by clicking on the “Debug” button in the sidebar.
Wrapping up and conclusion:
In this blog post, we discussed how to deploy and test your Cloud Functions locally using the open source Functions Framework. By using the Functions Framework, you can create a local development environment that simulates the same environment as the cloud, making it easy to test your functions before deploying them. Additionally, we discussed how to invoke a Cloud Function with an Eventarc event locally, how to use the same permissions as if it were deployed in the cloud, how to fetch secrets stored remotely from Secret Manager and how to set breakpoints in Visual Studio Code within a local Cloud Function. By following these best practices, you can improve the development process of your Cloud Functions and make sure that they are working as expected before deploying them to the cloud.
