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Serverless Apache OpenWhisk Plugin

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This plugin enables support for the Apache OpenWhisk platform within the Serverless Framework.

Getting Started

Register account with Apache OpenWhisk

Before you can deploy your service to Apache OpenWhisk, you need to have an account registered with the platform.

Set up account credentials

Account credentials for OpenWhisk can be provided through a configuration file or environment variables. This plugin requires the API endpoint, namespace and authentication credentials.

Do you want to use a configuration file for storing these values? Please follow the instructions for setting up the OpenWhisk command-line utility. This tool stores account credentials in the .wskprops file in the user's home directory. The plugin automatically extracts credentials from this file at runtime. No further configuration is needed.

Do you want to use environment variables for credentials? Use the following environment variables to be pass in account credentials. These values override anything extracted from the configuration file.

Install Serverless Framework

$ npm install --global serverless

This framework plugin requires Node.js runtime version 6.0 or above.

Create Service From Template

Using the create command, you can create an example service from the following template.

serverless create --template openwhisk-nodejs --path my_service
cd my_service
npm install

More service examples are available in the serverless-examples repository.

Using a self-hosted version of the platform?

Ensure you set the ignore_certs option in the serverless.yaml prior to deployment.

provider:
  name: openwhisk
  ignore_certs: true

Deploy Service

The sample service from the template can be deployed without modification.

serverless deploy

If the deployment succeeds, the following messages will be printed to the console.

$ serverless deploy
Serverless: Packaging service...
Serverless: Compiling Functions...
Serverless: Compiling API Gateway definitions...
Serverless: Compiling Rules...
Serverless: Compiling Triggers & Feeds...
Serverless: Deploying Functions...
Serverless: Deployment successful!

Service Information
platform:	openwhisk.ng.bluemix.net
namespace:	_
service:	my_service

actions:
my_service-dev-hello

triggers:
**no triggers deployed***

rules:
**no rules deployed**

endpoints:
**no routes deployed**

web-actions:
**no web actions deployed**

Test Service

Use the invoke command to test your newly deployed service.

$ serverless invoke --function hello
{
    "payload": "Hello, World!"
}
$ serverless invoke --function hello --data '{"name": "OpenWhisk"}'
{
    "payload": "Hello, OpenWhisk!"
}

Add the -v or --verbose flag to show more invocation details, e.g. activation id and duration details.

$ serverless invoke --function hello -v
=> action (<ACTION_NAME>) activation (<ID>) duration: 96ms (init: 83ms, wait: 35ms)
{
    "payload": "Hello, OpenWhisk!"
}

Writing Functions - Node.js

Here's an index.js file containing an example handler function.

function main(params) {
  const name = params.name || 'World';
  return {payload:  'Hello, ' + name + '!'};
};

exports.main = main;

Modules should return the function handler as a custom property on the global exports object.

In the serverless.yaml file, the handler property is used to denote the source file and module property containing the serverless function.

functions:
  my_function:
    handler: index.main

Request Properties

OpenWhisk executes the handler function for each request. This function is called with a single argument, an object containing the request properties.

function main(params) {
  const parameter = params.parameter_name;
  ...
};

Function Return Values

The handler must return an object from the function call. Returning undefined or null will result in an error. If the handler is carrying out an asynchronous task, it can return a Promise.

// synchronous return
function main () {
  return { payload: "..." }
}

// asychronous return
function main(args) {
  return new Promise(function(resolve, reject) {
    setTimeout(function() {
      resolve({ done: true });
     }, 2000);
  })
}

If you want to return an error message, return an object with an error property with the message. Promise values that are rejected will be interpreted as runtime errors.

// synchronous return
function main () {
  return { error: "..." }
}

// asychronous return
function main(args) {
  return new Promise(function(resolve, reject) {
    setTimeout(function() {
      reject("error message");
     }, 2000);
  })
}

Using NPM Modules

NPM modules must be installed locally in the node_modules directory before deployment. This directory will be packaged up in the deployment artefact. Any dependencies included in node_modules will be available through require() in the runtime environment.

OpenWhisk provides a number of popular NPM modules in the runtime environment. Using these modules doesn't require them to be included in the deployment package. See this list for full details of which modules are available.

const leftPad = require("left-pad")

function pad_lines(args) {
    const lines = args.lines || [];
    return { padded: lines.map(l => leftPad(l, 30, ".")) }
};

exports.handler = pad_lines;

Writing Functions - PHP

Here's an index.php file containing an example handler function.

<?php
function main(array $args) : array
{
    $name = $args["name"] ?? "stranger";
    $greeting = "Hello $name!";
    echo $greeting;
    return ["greeting" => $greeting];
}

In the serverless.yaml file, the handler property is used to denote the source file and function name of the serverless function.

functions:
  my_function:
    handler: index.main
    runtime: php

Request Properties

OpenWhisk executes the handler function for each request. This function is called with a single argument, an associative array containing the request properties.

function main(array $args) : array
{
    $name = $args["name"] ?? "stranger";
    ...
}

Function Return Values

The handler must return an associative array from the function call.

func main(args: [String:Any]) -> [String:Any] {
	...
    return ["foo" => $bar];
}

If you want to return an error message, return an object with an error property with the message.

Writing Functions - Python

Here's an index.py file containing an example handler function.

def endpoint(params):
    name = params.get("name", "stranger")
    greeting = "Hello " + name + "!"
    print(greeting)
    return {"greeting": greeting}

In the serverless.yaml file, the handler property is used to denote the source file and module property containing the serverless function.

functions:
  my_function:
    handler: index.endpoint
    runtime: python:3

Request Properties

OpenWhisk executes the handler function for each request. This function is called with a single argument, a dictionary containing the request properties.

def endpoint(params):
    name = params.get("name", "stranger")
    ...

Function Return Values

The handler must return a dictionary from the function call.

def endpoint(params):
    ...
    return {"foo": "bar"}

If you want to return an error message, return an object with an error property with the message.

Writing Functions - Ruby

Here's an hello.rb file containing an example handler function.

def main(args)
  name = args["name"] || "stranger"
  greeting = "Hello #{name}!"
  puts greeting
  { "greeting" => greeting }
end

In the serverless.yaml file, the handler property is used to denote the source file and function name of the serverless function.

functions:
  my_function:
    handler: hello.main
    runtime: ruby

Request Properties

OpenWhisk executes the handler function for each request. This function is called with a single argument, which is a hash containing the request properties.

def main(args)
  name = args["name"] || "stranger"
  ...

Function Return Values

The handler must return a hash from the function call.

def main(args)
  ...
  { "greeting" => greeting }
end

If you want to return an error message, return an error property string in the return hash.

Writing Functions - Swift

Here's an index.swift file containing an example handler function.

func main(args: [String:Any]) -> [String:Any] {
    if let name = args["name"] as? String {
      return [ "greeting" : "Hello \(name)!" ]
    } else {
      return [ "greeting" : "Hello stranger!" ]
    }
}

In the serverless.yaml file, the handler property is used to denote the source file and module property containing the serverless function.

functions:
  my_function:
    handler: index.main
    runtime: swift

Request Properties

OpenWhisk executes the handler function for each request. This function is called with a single argument, a dictionary containing the request properties.

func main(args: [String:Any]) -> [String:Any] {
    let prop = args["prop"] as? String
}

Function Return Values

The handler must return a dictionary from the function call.

func main(args: [String:Any]) -> [String:Any] {
	...
    return ["foo": "bar"]
}

If you want to return an error message, return an object with an error property with the message.

Codable Support

Swift 4 runtimes support Codable types to handle the converting between JSON input parameters and response types to native Swift types.

struct Employee: Codable {
  let id: Int?
  let name: String?
}
// codable main function
func main(input: Employee, respondWith: (Employee?, Error?) -> Void) -> Void {
    // For simplicity, just passing same Employee instance forward
    respondWith(input, nil)
}

Pre-Compiled Swift Binaries

OpenWhisk supports creating Swift actions from a pre-compiled binary. This reduces startup time for Swift actions by removing the need for a dynamic compilation step.

In the serverless.yaml file, the handler property can refer to the zip file containing a binary file produced by the build.

functions:
  hello:
    handler: action.zip

Compiling a single Swift file to a binary can be handled using this Docker command with the OpenWhisk Swift runtime image. main.swift is the file containing the swift code and action.zip is the zip archive produced.

docker run -i openwhisk/action-swift-v4.2 -compile main < main.swift > action.zip

Swift packages containing multiple source files with a package descriptor (Package.swift ) can be built using the following command.

zip - -r * | docker run -i openwhisk/action-swift-v4.2 -compile main > action.zip

Writing Functions - Java

Here's an src/main/java/HelloWorld.java file containing an example handler function.

import com.google.gson.JsonObject;

public class HelloWorld {

  public static JsonObject main(JsonObject args) throws Exception {

    final String name = args.getAsJsonPrimitive("name").getAsString();

    final JsonObject response = new JsonObject();
    response.addProperty("greeting", "Hello " + name + "!");

    return response;
  }
}

Here is a simple pom.xml file that will allow you to use Maven to build it. You will notice that gson is excluded from the uberjar. That is because OpenWhisk already provides this dependency.

<project>
 <modelVersion>4.0.0</modelVersion>
 <groupId>hello</groupId>
 <artifactId>hello-world</artifactId>
 <version>1.0</version>

 <dependencies>
  <dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.8.2</version>
  </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>3.1.0</version>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
            <configuration>
              <minimizeJar>true</minimizeJar>
              <artifactSet>
                <excludes>
                  <exclude>com.google.code.gson:gson</exclude>
                </excludes>
              </artifactSet>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
 </project>

In the serverless.yaml file (see below), the handler property is the uberjar produced by calling mvn clean package, a colon, and then the fully qualified class name of the class with the main function. If you do not provide a class name after the jar, it will look for a class in the default package called Main.

service: my-java-service
provider:
  name: openwhisk
  runtime: java
functions:
  hello:
    handler: target/hello-world-1.0.jar:HelloWorld
plugins:
  - serverless-openwhisk

Request Properties

OpenWhisk executes the handler function for each request. This function is called with a single argument, a com.google.gson.JsonObject containing the request properties.

import com.google.gson.JsonObject;

public class MyActionClass {
  public static JsonObject main(JsonObject args) throws Exception
  {
    final String name = args.getAsJsonPrimitive("name").getAsString();
    ...
  }
}

Function Return Values

The handler must return an com.google.gson.JsonObject from the function call.

import com.google.gson.JsonObject;

public class MyActionClass {
  public static JsonObject main(JsonObject args) throws Exception
  {
    ...
    final JsonObject response = new JsonObject();
    response.addProperty("greeting", "Hello " + name + "!");

    return response;
  }
}

If you want to return an error message, throw an exception.

Writing Functions - Binary

OpenWhisk supports executing a compiled binary for the function handler. Using a Python wrapper, the file will be invoked within the openwhisk/dockerskeleton Docker container.

The binary must be compiled for the correct platform architecture and only link to shared libraries installed in the openwhisk/dockerskeleton runtime.

In the serverless.yaml file, the handler property is used to denote the binary file to upload.

functions:
  my_function:
    handler: bin_file
    runtime: binary

Request Properties

OpenWhisk executes the binary file for each request. Event parameters are streamed to stdio as a JSON object string.

Function Return Values

The handler must write a JSON object string with the response parameters to stdout before exiting.

If you want to return an error message, return an object with an error property with the message.

Custom Runtime Images

OpenWhisk actions can use custom Docker images as the runtime environment. This allows extra packages, libraries or tools to be pre-installed in the runtime environment. Using a custom runtime image, with extra libraries and dependencies built-in, is useful for overcoming the maximum deployment size on actions.

Images must implement the API used by the platform to interact with runtime environments. Images must also be available on Docker Hub. OpenWhisk does not support private Docker registries.

OpenWhisk publishes the existing runtime images on Docker Hub. Using these images in the FROM directive in the Dockerfile is an easy way to create new images compatible with the platform.

In the serverless.yaml file, the image property is used to denote the custom runtime image.

functions:
  my_function:
    handler: source.js
    runtime: nodejs
    image: dockerhub_user/image_name

Node.js, Swift, Python and Binary runtimes support using a custom image property.

Writing Functions - Docker

OpenWhisk supports creating actions from public images on Docker Hub without handler files. These images are expected to support the platform API used to instantiate and invoke serverless functions.

All necessary files for execution must be provided within the image. Local source files will not be uploaded to the runtime environment.

In the serverless.yaml file, the handler property is used to denote the image label.

functions:
  my_function:
    handler: repo/image_name
    runtime: docker

Working With Packages

OpenWhisk provides a concept called "packages" to manage related actions. Packages can contain multiple actions under a common identifier in a namespace. Configuration values needed by all actions in a package can be set as default properties on the package, rather than individually on each action.

Packages are identified using the following format: /namespaceName/packageName/actionName.

Rules and triggers can not be created within packages.

Implicit Packages

Actions can be assigned to packages by setting the function name with a package reference.

functions:
  foo:
    handler: handler.foo
    name: "myPackage/foo"
  bar:
    handler: handler.bar
    name: "myPackage/bar"

In this example, two new actions (foo & bar) will be created using the myPackage package.

Packages which do not exist will be automatically created during deployments. When using the remove command, any packages referenced in the serverless.yml will be deleted.

Explicit Packages

Packages can also be defined explicitly to set shared configuration parameters. Default package parameters are merged into event parameters for each invocation.

functions:
  foo:
    handler: handler.foo
    name: "myPackage/foo"

resources:
  packages:
    myPackage:
      name: optionalCustomName
      parameters:
        hello: world

Explicit packages support the following properties: name, parameters, annotations, services and shared.

Binding Packages

OpenWhisk also supports "binding" external packages into your workspace. Bound packages can have default parameters set for shared actions.

For example, binding the /whisk.system/cloudant package into a new package allows you to set default values for the username, password and dbname properties. Actions from this package can then be invoked with having to pass these parameters in.

Define packages explicitly with a binding parameter to use this behaviour.

resources:
  packages:
    mySamples:
      binding: /whisk.system/cloudant
      parameters:
        username: bernie
        password: sanders
        dbname: vermont

For more details on package binding, please see the documentation here.

Binding Services (IBM Cloud Functions)

This feature requires the IBM Cloud CLI and IBM Cloud Functions plugin to be installed.

IBM Cloud Functions supports automatic binding of service credentials to actions using the CLI.

Bound service credentials will be passed as the __bx_creds parameter in the invocation parameters.

This feature is also available through the serverless.yaml file using the bind property for each function.

functions:
  my_function:
    handler: file_name.handler    
    bind:
      - service:
          name: cloud-object-storage
          instance: my-cos-storage

The service configuration supports the following properties.

If the instance or key properties are missing, the first available instance and key found will be used.

Binding services removes the need to manually create default parameters for service keys from platform services.

More details on binding service credentials to actions can be found in the official documentation and this blog post.

Packages defined in the resources section can bind services using the same configuration properties.

resources:
  packages:
    myPackage:
      bind:
        - service:
            name: cloud-object-storage
            instance: my-cos-storage

Runtime Configuration Properties

The following OpenWhisk configuration properties are supported for functions defined in the serverless.yaml file.

functions:
  my_function:
    handler: file_name.handler_func
    name: "custom_function_name"
    runtime: 'runtime_label' // defaults to nodejs:default
    namespace: "..." // defaults to user-provided credentials
    memory: 256 // 128 to 512 (MB).
    timeout: 60 // 0.1 to 600 (seconds)
    concurrency: 1 // 1 to 500, default is 1
    parameters:
      foo: bar // default parameters
    annotations:
      foo: bar // action annotations
    bind:
      - service:
          name: cloud-object-storage
          instance: my-cos-storage

Writing Sequences

OpenWhisk supports a special type of serverless function called sequences.

These functions are defined from a list of other serverless functions. Upon invocation, the platform executes each function in series. Request parameters are passed into the first function in the list. Each subsequent function call is passed the output from the previous step as input parameters. The last function's return value is returned as the response result.

Here's an example of the configuration to define a sequence function, composed of three other functions.

functions:
  my_function:
    sequence:
      - parse_input
      - do_some_algorithm
      - construct_output

Sequence functions do not have a handler file defined. If you want to refer to functions not defined in the serverless project, use the fully qualified identifier e.g. /namespace/package/action_name

Connecting HTTP Endpoints

Functions can be bound to public URL endpoints using the API Gateway service. HTTP requests to configured endpoints will invoke functions on-demand. Requests parameters are passed as function arguments. Function return values are serialised as the JSON response body.

HTTP endpoints for functions can be configured through the serverless.yaml file.

functions:
  my_function:
    handler: index.main
    events:
      - http: GET /api/greeting

HTTP event configuration also supports using explicit parameters.

functions:
  my_function:
    handler: index.main
    events:
      - http:
          method: GET
          path: /api/greeting
          resp: http

API Gateway hosts serving the API endpoints will be shown during deployment.

$ serverless deploy
...
endpoints:
GET https://xxx-gws.api-gw.mybluemix.net/service_name/api/greeting --> service_name-dev-my_function

Calling the configured API endpoints will execute the deployed functions.

$ http get https://xxx-gws.api-gw.mybluemix.net/api/greeting?user="James Thomas"
HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Date: Mon, 19 Dec 2016 15:47:53 GMT

{
    "message": "Hello James Thomas!"
}

Functions exposed through the API Gateway service are automatically converted into Web Actions during deployment. The framework secures Web Actions for HTTP endpoints using the require-whisk-auth annotation. If the require-whisk-auth annotation is manually configured, the existing annotation value is used, otherwise a random token is automatically generated.

URL Path Parameters

The API Gateway service supports path parameters in user-defined HTTP paths. This allows functions to handle URL paths which include templated values, like resource identifiers.

Path parameters are identified using the {param_name} format in the URL path. The API Gateway sends the full matched path value in the __ow_path field of the event parameters.

functions:
  retrieve_users:
    handler: users.get
    events:
      - http:
          method: GET
          path: /users/{id}
          resp: http

This feature comes with the following restrictions:

CORS Support

API Gateway endpoints automatically include CORS headers for all endpoints under the service base path. This property can be disabled by manually configuring the resources.apigw.cors property.

resources:
    apigw:
        cors: false

Application Authentication

API endpoints can be protected by API keys with a secret or API keys alone.

Setting the HTTP headers used to pass keys and secrets automatically enables API Gateway authentication.

This parameter configures the HTTP header containing the API key. Without the additional secret header, authentication uses an API key alone.

resources:
    apigw:
        auth:
            key: API-Key-Header

Adding the secret header parameter enables authentication using keys with secrets.

resources:
    apigw:
        auth:
            key: API-Key-Header
            secret: API-Key-Secret-Header

See the API Gateway configuration panel to manage API keys and secrets after authentication is enabled.

Application Authentication with OAuth

API endpoints can also be protected by an external OAuth providers.

OAuth tokens must be included as the Authorization header of each API request. Token will be validated with the specified token provider. If the token is invalid, requests are rejected with response code 401.

The following OAuth providers are supported: IBM Cloud App ID, Google, Facebook and Github.

resources:
  apigw:
    oauth:
      provider: app-id || google || facebook || github

If the app-id provider is selected, the tenant identifier must be provided as an additional configuration token. This can be retrieved from the tenantId property of provisioned service credentials for the instance

resources:
  apigw:
    oauth:
      provider: app-id
      tenant: uuid

Application Authentication with keys (and secrets) and OAuth support are mutually exclusive configuration options.

Rate Limiting

API Gateways endpoints support rate limiting to reject excess traffic. When rate limiting is enabled, API calls falling outside of the limit will be rejected and response code 429 will be returned.

Rate limiting is on a per-key basis and application authentication (without oauth) must be enabled.

The leaky bucket algorithm is used to prevent sudden bursts of invocations of APIs. If the limit is set as 10 calls per minute, users will be restricted to 1 call every 6 seconds (60/10 = 6).

resources:
  apigw:
    rate_limit:
      rate: 100
      unit: minute || second || hour || day

Base Path

All API Gateway endpoints defined as HTTP events in the serverless.yml are deployed under the default base path (/). This basepath can be configured explicitly using the following parameter.

resources:
  apigw:
    basepath: /api

API Name

The service name is used as the API identifier in the API Gateway swagger files. This can be configured explicitly using the following parameter.

resources:
  apigw:
    name: my-api-name

Exporting Web Actions

Functions can be turned into "web actions" which return HTTP content without use of an API Gateway. This feature is enabled by setting an annotation (web-export) in the configuration file.

functions:
  my_function:
    handler: index.main
    annotations:
      web-export: true

Functions with this annotation can be invoked through a URL template with the following parameters.

https://{APIHOST}/api/v1/web/{USER_NAMESPACE}/{PACKAGE}/{ACTION_NAME}.{TYPE}

Return values from the function are used to construct the HTTP response. The following parameters are supported.

  1. headers: a JSON object where the keys are header-names and the values are string values for those headers (default is no headers).
  2. code: a valid HTTP status code (default is 200 OK).
  3. body: a string which is either plain text or a base64 encoded string (for binary data).

Here is an example of returning HTML content:

function main(args) {
    var msg = "you didn&#39;t tell me who you are."
    if (args.name) {
        msg = `hello ${args.name}!`
    }
    return {body:
       `<html><body><h3><center>${msg}</center></h3></body></html>`}
}

Here is an example of returning binary data:

function main() {
   let png = <base 64 encoded string>
   return {
      headers: { "Content-Type": "image/png" },
      body: png };
}

Functions can access request parameters using the following environment variables.

  1. __ow_method - HTTP method of the request.
  2. __ow_headers - HTTP request headers.
  3. __ow_path - Unmatched URL path of the request.
  4. __ow_body - Body entity from request.
  5. __ow_query - Query parameters from the request.

Full details on this feature are available in this here.

Scheduled Invocations

Functions can be set up to fire automatically using the alarm package. This allows you to invoke functions with preset parameters at specific times (12:00 each day) or according to a schedule (every ten minutes).

Scheduled invocation for functions can be configured through the serverless.yaml file.

The schedule event configuration is controlled by a string, based on the UNIX crontab syntax, in the format cron(X X X X X). This can either be passed in as a native string or through the rate parameter.

functions:
  my_function:
    handler: index.main
    events:
      - schedule: cron(* * * * *) // fires each minute.

This above example generates a new trigger (${service}_crawl_schedule_trigger) and rule (${service}_crawl_schedule_rule) during deployment.

Other schedule event parameters can be manually configured, e.g trigger or rule names.

functions:
  aggregate:
    handler: statistics.handler
    events:
      - schedule:
          rate: cron(0 * * * *) // call once an hour
          trigger: triggerName
          rule: ruleName
          max: 10000 // max invocations, default: 1000, max: 10000
          params: // event params for invocation
            hello: world

IBM Message Hub Events

IBM Bluemix provides an "Apache Kafka"-as-a-Service called IBM Message Hub. Functions can be connected to fire when messages arrive on Kafka topics.

IBM Message Hub instances can be provisioned through the IBM Bluemix platform. OpenWhisk on Bluemix will export Message Hub service credentials bound to a package with the following name:

/${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1

Rather than having to manually define all the properties needed by the Message Hub trigger feed, you can reference a package to use instead. Credentials from the referenced package will be used when executing the trigger feed.

Developers only need to add the topic to listen to for each trigger.

# serverless.yaml
functions:
    index:
        handler: users.main
        events:
            - message_hub:
                package: /${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
                topic: my_kafka_topic

The plugin will create a trigger called ${serviceName}_${fnName}_messagehub_${topic} and a rule called ${serviceName}_${fnName}_messagehub_${topic}_rule to bind the function to the message hub events.

The trigger and rule names created can be set explicitly using the trigger andrule parameters.

Other functions can bind to the same trigger using the inline trigger event referencing this trigger name.

# serverless.yaml
functions:
    index:
        handler: users.main
        events:
            - message_hub:
                package: /${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
                topic: my_kafka_topic
                trigger: log_events
                rule: connect_index_to_kafka
     another:
        handler: users.another
        events:
            - trigger: log_events

Using Manual Parameters

Parameters for the Message Hub event source can be defined explicitly, rather than using pulling credentials from a package.

# serverless.yaml
functions:
    index:
        handler: users.main
        events:
            - message_hub:
                topic: my_kafka_topic
                brokers: afka01-prod01.messagehub.services.us-south.bluemix.net:9093
                user: USERNAME
                password: PASSWORD
                admin_url:  https://kafka-admin-prod01.messagehub.services.us-south.bluemix.net:443
                json: true
                binary_key: true
                binary_value: true

topic, brokers, user, password and admin_url are mandatory parameters.

Cloudant DB Events

IBM Cloudant provides a hosted NoSQL database, based upon CouchDB, running on IBM Bluemix. Functions can be connected to events fired when the database is updated. These events use the CouchDB changes feed to follow database modifications.

IBM Cloudant instances can be provisioned through the IBM Bluemix platform. OpenWhisk on Bluemix will export Cloudant service credentials bound to a package with the following name:

/${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1

Rather than having to manually define all the properties needed by the Cloudant trigger feed, you can reference a package to use instead. Credentials from the referenced package will be used when executing the trigger feed.

Developers only need to add the database name to follow for modifications.

# serverless.yaml
functions:
    index:
        handler: users.main
        events:
            - cloudant:
                package: /${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
                db: my_db_name

The plugin will create a trigger called ${serviceName}_${fnName}_cloudant_${topic} and a rule called ${serviceName}_${fnName}_cloudant_${topic}_rule to bind the function to the Cloudant update events.

The trigger and rule names created can be set explicitly using the trigger andrule parameters.

Other functions can bind to the same trigger using the inline trigger event referencing this trigger name.

Using Manual Parameters

Parameters for the Cloudant event source can be defined explicitly, rather than using pulling credentials from a package.

# serverless.yaml
functions:
    index:
        handler: users.main
        events:
            - cloudant: // basic auth example
                host: xxx-yyy-zzz-bluemix.cloudant.com
                username: USERNAME
                password: PASSWORD
                db: db_name
			- cloudant: // iam auth example
                host: xxx-yyy-zzz-bluemix.cloudant.com
                iam_api_key: IAM_API_KEY
                db: db_name

username and password or iam_api_key parameters can be used for authentication.

Adding Optional Parameters

The following optional feed parameters are also supported:

# serverless.yaml
functions:
    index:
        handler: users.main
        events:
            - cloudant:
                ...
                max: 10000
                query:
                   status: new
                filter: mailbox/by_status

Custom Event Triggers

Functions are connected to event sources in OpenWhisk using triggers and rules. Triggers create a named event stream within the system. Triggers can be fired manually or connected to external data sources, like databases or message queues.

Rules set up a binding between triggers and serverless functions. With an active rule, each time a trigger is fired, the function will be executed with the trigger payload.

Event binding for functions can be configured through the serverless.yaml file.

functions:
  my_function:
    handler: index.main
    events:
      - trigger: my_trigger

This configuration will create a trigger called servicename-my_trigger with an active rule binding my_function to this event stream.

Customising Rules

Rule names default to the following format servicename-trigger-to-action. These names be explicitly set through configuration.

functions:
  my_function:
    handler: index.main
    events:
      - trigger:
        name: "my_trigger"
        rule: "rule_name"

Customing Triggers

Triggers can be defined as separate resources in the serverless.yaml file. This allows you to set up trigger properties like default parameters.

functions:
  my_function:
    handler: index.main
    events:
      - trigger: my_trigger

resources:
  triggers:
    my_trigger:
      parameters:
        hello: world

Trigger Feeds

Triggers can be bound to external event sources using the feed property. OpenWhisk provides a catalogue of third-party event sources bundled as packages.

This example demonstrates setting up a trigger which uses the /whisk.system/alarms/alarm feed. The alarm feed will fire a trigger according to a user-supplied cron schedule.

resources:
  triggers:
    alarm_trigger:
      parameters:
        hello: world
      feed: /whisk.system/alarms/alarm
      feed_parameters:
        cron: '*/8 * * * * *'

Commands

The following serverless commands are currently implemented for the OpenWhisk provider.