Ballerina Azure Functions Extension

Annotation based Azure Functions extension implementation for Ballerina.

Azure Setup

• An Azure "Function App" needs to be created in a given resource group with the following requirements
  • Runtime stack - "Java 11"
  • Hosting operating system - "Windows" (default; Linux is not supported in Azure for custom handlers at the moment)

Supported Annotations:

@azure_functions:Function

Custom 'host.json'

A custom host.json file for the functions deployment can be optionally provided by placing a 'host.json' file in the current working directory where the bal build is done. The required host.json properties are provided/overridden by the values derived from the source code by the compiler extension.

Usage Sample:

import ballerina/uuid;
import ballerinax/azure_functions as af;

// HTTP request/response with no authentication
@af:Function
public function hello(@af:HTTPTrigger { authLevel: "anonymous" } string payload) 
                      returns @af:HTTPOutput string|error {
    return "Hello, " + payload + "!";
}

// HTTP request to add data to a queue
@af:Function
public function fromHttpToQueue(af:Context ctx, 
            @af:HTTPTrigger {} af:HTTPRequest req, 
            @af:QueueOutput { queueName: "queue1" } af:StringOutputBinding msg) 
            returns @af:HTTPOutput af:HTTPBinding {
    msg.value = req.body;
    return { statusCode: 200, payload: "Request: " + req.toString() };
}

// A message put to a queue is copied to another queue
@af:Function
public function fromQueueToQueue(af:Context ctx, 
        @af:QueueTrigger { queueName: "queue2" } string inMsg,
        @af:QueueOutput { queueName: "queue3" } af:StringOutputBinding outMsg) {
    ctx.log("In Message: " + inMsg);
    ctx.log("Metadata: " + ctx.metadata.toString());
    outMsg.value = inMsg;
}

// A blob added to a container is copied to a queue
@af:Function
public function fromBlobToQueue(af:Context ctx, 
        @af:BlobTrigger { path: "bpath1/{name}" } byte[] blobIn,
        @af:BindingName { } string name,
        @af:QueueOutput { queueName: "queue3" } af:StringOutputBinding outMsg) 
        returns error? {
    outMsg.value = "Name: " + name + " Content: " + blobIn.toString();
}

// HTTP request to read a blob value
@af:Function
public function httpTriggerBlobInput(@af:HTTPTrigger { } af:HTTPRequest req, 
                    @af:BlobInput { path: "bpath1/{Query.name}" } byte[]? blobIn)
                    returns @af:HTTPOutput string {
    int length = 0;
    if blobIn is byte[] {
        length = blobIn.length();
    }
    return "Blob: " + req.query["name"].toString() + " Length: " + 
            length.toString() + " Content: " + blobIn.toString();
}

// HTTP request to add a new blob
@af:Function
public function httpTriggerBlobOutput(@af:HTTPTrigger { } af:HTTPRequest req, 
        @af:BlobOutput { path: "bpath1/{Query.name}" } af:StringOutputBinding bb)
        returns @af:HTTPOutput string|error {
    bb.value = req.body;
    return "Blob: " + req.query["name"].toString() + " Content: " + 
            bb?.value.toString();
}

// Sending an SMS
@af:Function
public function sendSMS(@af:HTTPTrigger { } af:HTTPRequest req, 
                        @af:TwilioSmsOutput { fromNumber: "+12069845840" } 
                                              af:TwilioSmsOutputBinding tb)
                        returns @af:HTTPOutput string {
    tb.to = req.query["to"].toString();
    tb.body = req.body.toString();
    return "Message - to: " + tb?.to.toString() + " body: " + tb?.body.toString();
}

public type Person record {
    string id;
    string name;
    string country;
};

// CosmosDB record trigger
@af:Function
public function cosmosDBToQueue1(@af:CosmosDBTrigger { 
        connectionStringSetting: "CosmosDBConnection", databaseName: "db1",
        collectionName: "c1" } Person[] req, 
        @af:QueueOutput { queueName: "queue3" } af:StringOutputBinding outMsg) {
    outMsg.value = req.toString();
}

@af:Function
public function cosmosDBToQueue2(@af:CosmosDBTrigger { 
        connectionStringSetting: "CosmosDBConnection", databaseName: "db1", 
        collectionName: "c2" } json req,
        @af:QueueOutput { queueName: "queue3" } af:StringOutputBinding outMsg) {
    outMsg.value = req.toString();
}

// HTTP request to read CosmosDB records
@af:Function
public function httpTriggerCosmosDBInput1(
            @af:HTTPTrigger { } af:HTTPRequest httpReq, 
            @af:CosmosDBInput { connectionStringSetting: "CosmosDBConnection", 
                databaseName: "db1", collectionName: "c1", 
                id: "{Query.id}", partitionKey: "{Query.country}" } json dbReq)
                returns @af:HTTPOutput string|error {
    return dbReq.toString();
}

@af:Function
public function httpTriggerCosmosDBInput2(
            @af:HTTPTrigger { } af:HTTPRequest httpReq, 
            @af:CosmosDBInput { connectionStringSetting: "CosmosDBConnection", 
                databaseName: "db1", collectionName: "c1", 
                id: "{Query.id}", partitionKey: "{Query.country}" } Person? dbReq)
                returns @af:HTTPOutput string|error {
    return dbReq.toString();
}

@af:Function
public function httpTriggerCosmosDBInput3(
        @af:HTTPTrigger { route: "c1/{country}" } af:HTTPRequest httpReq, 
        @af:CosmosDBInput { connectionStringSetting: "CosmosDBConnection", 
        databaseName: "db1", collectionName: "c1", 
        sqlQuery: "select * from c1 where c1.country = {country}" } 
        Person[] dbReq)
        returns @af:HTTPOutput string|error {
    return dbReq.toString();
}

// HTTP request to write records to CosmosDB
@af:Function
public function httpTriggerCosmosDBOutput1(
    @af:HTTPTrigger { } af:HTTPRequest httpReq, @af:HTTPOutput af:HTTPBinding hb) 
    returns @af:CosmosDBOutput { connectionStringSetting: "CosmosDBConnection", 
                                 databaseName: "db1", collectionName: "c1" } json {
    json entry = { id: uuid:createType1AsString(), name: "Saman", country: "Sri Lanka" };
    hb.payload = "Adding entry: " + entry.toString();
    return entry;
}

@af:Function
public function httpTriggerCosmosDBOutput2(
        @af:HTTPTrigger { } af:HTTPRequest httpReq, 
        @af:HTTPOutput af:HTTPBinding hb) 
        returns @af:CosmosDBOutput { 
            connectionStringSetting: "CosmosDBConnection", 
            databaseName: "db1", collectionName: "c1" } json {
    json entry = [{ id: uuid:createType1AsString(), name: "John Doe A", country: "USA" }, 
                  { id: uuid:createType1AsString(), name: "John Doe B", country: "USA" }];
    hb.payload = "Adding entries: " + entry.toString();
    return entry;
}

@af:Function
public function httpTriggerCosmosDBOutput3(
                    @af:HTTPTrigger { } af:HTTPRequest httpReq) 
                    returns @af:CosmosDBOutput { 
                        connectionStringSetting: "CosmosDBConnection", 
                        databaseName: "db1", collectionName: "c1" } Person[] {
    Person[] persons = [];
    persons.push({id: uuid:createType1AsString(), name: "Jack", country: "UK"});
    persons.push({id: uuid:createType1AsString(), name: "Will", country: "UK"});
    return persons;
}

// A timer function which is executed every 10 seconds.
@af:Function
public function queuePopulationTimer(
            @af:TimerTrigger { schedule: "*/10 * * * * *" } json triggerInfo, 
            @af:QueueOutput { queueName: "queue4" } af:StringOutputBinding msg) {
    msg.value = triggerInfo.toString();
}

The output of the bal build is as follows:

$ bal build azure_functions_deployment.bal 
Compiling source
        azure_functions_deployment.bal

Generating executables
        azure_functions_deployment.jar
        @azure_functions:Function: hello, fromHttpToQueue, fromQueueToQueue, fromBlobToQueue, httpTriggerBlobInput, httpTriggerBlobOutput, sendSMS, cosmosDBToQueue1, cosmosDBToQueue2, httpTriggerCosmosDBInput1, httpTriggerCosmosDBInput2, httpTriggerCosmosDBInput3, httpTriggerCosmosDBOutput1, httpTriggerCosmosDBOutput2, httpTriggerCosmosDBOutput3, queuePopulationTimer