Azure Functions with Blob Trigger

Important

For a general information about building and deploying Azure Functions with Spring Cloud Function, consult the Azure Adapter documentation.

The Blob storage trigger starts a function when a new or updated blob is detected. The blob contents are provided as input to the function.

The Blob storage binding is part of an extension bundle, specified in your host.json file.

Usage

For local Azure Storage development you need Azurite emulator. For the emulator you can run a docker container (see below) or use the Visual-Studio-Code extension.

Here is how to start the Azure emulator as docker container:

docker run --name azurite --rm -p 10000:10000 -p 10001:10001 -p 10002:10002 mcr.microsoft.com/azure-storage/azurite

Package Staging folder

Use the script below to package your staging folder:

./mvnw clean package

Run Azure Functions locally

Use the script below to run the function locally.

./mvnw azure-functions:run

Use the Azure Storage Explorer to access the Emulator Storage Account.

Under the Blob Containers create 3 new containers: test-trigger, test-input, test-output. Then upload the src/test/resource/sample.txt file into the test-input and the test-trigger folders in this order.

The appearance of the sample.txt file in the test-trigger folder triggers the blobTest function handler, that would look up for a file with the same name (because we used the {name} convention in the @BlobInput path) from the test-input folder. Later is passed through the auto-wired uppercase service and the result is saved in the test-output folder. Verify that the newly created file in test-output is in capitalized letters.

Deploy Azure Functions to Azure Cloud

Make sure you are logged in your Azure account.

az login

then build and deploy

./mvnw clean package
./mvnw azure-functions:deploy

Debug locally

Run the function in debug mode.

./mvnw azure-functions:run -DenableDebug

Alternatively and the JAVA_OPTS value to your local.settings.json like this:

{
	"IsEncrypted": false,
	"Values": {
		...
		"FUNCTIONS_WORKER_RUNTIME": "java",
		"JAVA_OPTS": "-Djava.net.preferIPv4Stack=true -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=127.0.0.1:5005"
	}
}

For VSCode remote debug use configuration like this:

{
	"version": "0.2.0",
	"configurations": [
		{
			"type": "java",
			"name": "Attach to Remote Program",
			"request": "attach",
			"hostName": "localhost",
			"port": "5005"
		},
	    ...
	]
}