== Azure Functions with Blob Trigger
IMPORTANT: For a general information about building and deploying `Azure Functions` with Spring Cloud Function, consult the https://docs.spring.io/spring-cloud-function/docs/current/reference/html/azure.html[Azure Adapter] documentation.
The Blob storage trigger starts a function when a new or updated blob is detected. The blob contents are provided as https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-storage-blob-input?tabs=in-process%2Cextensionv5&pivots=programming-language-java[input] to the function.
The Blob storage binding is part of an https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-register#extension-bundles[extension bundle], specified in your https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-storage-blob?tabs=in-process%2Cextensionv5%2Cextensionv3&pivots=programming-language-java#install-bundle[host.json] file.
=== Usage
For local Azure Storage development you need https://learn.microsoft.com/en-us/azure/storage/common/storage-use-azurite?tabs=visual-studio[Azurite emulator].
For the emulator you can run a docker container (see below) or use the https://learn.microsoft.com/en-us/azure/storage/common/storage-use-azurite?tabs=visual-studio-code[Visual-Studio-Code extension].
Here is how to start the `Azure emulator` as docker container:
[source,shell]
----
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:
[source,shell]
----
./mvnw clean package
----
==== Run Azure Functions locally
Use the script below to run the function locally.
[source,shell]
----
./mvnw azure-functions:run
----
Use the https://azure.microsoft.com/en-us/products/storage/storage-explorer/[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.
[source,shell]
----
az login
----
then build and deploy
[source,shell]
----
./mvnw clean package
./mvnw azure-functions:deploy
----
==== Debug locally
Run the function in debug mode.
[source,shell]
----
./mvnw azure-functions:run -DenableDebug
----
Alternatively and the `JAVA_OPTS` value to your `local.settings.json` like this:
[source,json]
----
{
"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:
[source,json]
----
{
"version": "0.2.0",
"configurations": [
{
"type": "java",
"name": "Attach to Remote Program",
"request": "attach",
"hostName": "localhost",
"port": "5005"
},
...
]
}
----
