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Getting started with OpenWhisk

OpenWhisk is an Apache Incubator Project. It is an open source implementation of a distributed, event-driven compute service. You can run it on your own hardware on-prem, or in the cloud. When running in the cloud you could use PaaS version of the OpenWhisk provided by IBM Bluemix cloud, or you can provision it yourself into Bluemix IaaS, or other IaaS clouds, such as Amazon AWS, Microsoft Azure, Google GCP, etc.

OpenWhisk runs application logic in response to events or direct invocations from web or mobile apps over HTTP. Events can be provided from Bluemix services like Cloudant and from external sources. Developers can focus on writing application logic, and creating actions that are executed on demand. The benefits of this new paradigm are that you do not longer need to explicitly provision servers and worry about auto-scaling, high availability, updates, maintenance and pay for hours of processor time when your server is running, but not serving requests. Your code gets called whenever there is an HTTP call, database state change, or other type of event that triggers the execution of your code. You get billed by request or per millisecond of execution time, not per hour of JVM regardless whether that VM was doing useful work or not.

This programming model is perfect match for microservices, mobile, IoT and many other apps – you get inherent auto-scaling and load balancing out of the box without having to manually configure clusters, load balancers, http plugins, etc. If you happen to run on IBM Bluemix cloud, you also get zero administration benefit. All you need to do is to provide the code you want to execute and give it to your cloud vendor. The rest is “magic”. Good introduction into the serverless programming model is available on Martin Fowler's blog.

For more details about how OpenWhisk works, see System overview. Official project website can be found here.

Setting up the OpenWhisk CLI

  • Building OpenWhisk from a cloned repository will result in the generation of the command line interface. The generated CLIs will be located in openwhisk/bin/go-cli/. There will be an executable CLI located in the mentioned directory that will run on the operating system, and CPU architecture on which it was built. Executables for other operating system, and CPU architectures are located in the following directories: openwhisk/bin/go-cli/mac, openwhisk/bin/go-cli/linux, openwhisk/bin/go-cli/windows.

  • To download the CLI from an existing deployment, you will need to download the CLI using the deployment's base URL. A list of downloadable CLIs for various operating systems, and CPU architectures can be obtained from the following location {BASE URL}/cli/go/download. The {BASE URL} is the OpenWhisk API hostname or IP address (e.g.,

There are three properties to configure the CLI with:

  1. API host (name or IP address) for the OpenWhisk deployment you want to use.
  2. Authorization key (username and password) which grants you access to the OpenWhisk API.
  3. Namespace where your OpenWhisk assets are stored.

The CLI will usually have an API host already set. You can check its value with wsk property get --apihost.

If you know your authorization key and namespace, you can configure the CLI to use them. Otherwise you will need to provide one or both for most CLI operations.

wsk property set [--apihost <openwhisk_baseurl>] --auth <username:password> --namespace <namespace>

The API host is set automatically when you build the CLI for your environment. A guest account is available in local installations with an authorization key located in ansible/files/auth.guest and the namespace guest. To configure the CLI to use the guest account, you can run the following command from your openwhisk directory:

./bin/wsk property set --namespace guest --auth `cat ansible/files/auth.guest`

To verify your CLI setup, try creating and running an action.

Setting up the deprecated OpenWhisk CLI (Python based)

  • The OpenWhisk command line interface (CLI) requires Python 2.7.

  • If you cloned the OpenWhisk repository, you will find the CLI in openwhisk/bin/wsk.

  • Otherwise, download the CLI from an existing deployment. You will need to know the base URL for the deployment you want to use and install it using pip.

sudo pip install --upgrade https://{BASE URL}/openwhisk-0.1.0.tar.gz [--trusted-host {BASE URL}]

The {BASE URL} is the OpenWhisk API hostname or IP address (e.g., The --trusted-host option allows you to download the CLI from a host with a self-signed (i.e., untrusted) certificate.

Using the OpenWhisk CLI

After you have configured your environment, you can begin using the OpenWhisk CLI to do the following:

Configure the CLI to use an HTTPS proxy

The CLI can be setup to use an HTTPS proxy. To setup an HTTPS proxy, an environment variable called HTTPS_PROXY must 
be created. The variable must be set to the address of the HTTPS proxy, and its port using the following format: {PROXY IP}:{PROXY PORT}.

Using OpenWhisk from an iOS app

You can use OpenWhisk from your iOS mobile app or Apple Watch by using the OpenWhisk iOS SDK. For more details, refer to the iOS documentation.

Using REST APIs with OpenWhisk

After your OpenWhisk environment is enabled, you can use OpenWhisk with your web apps or mobile apps with REST API calls. For more details about the APIs for actions, activations, packages, rules, and triggers, see the OpenWhisk API documentation.

OpenWhisk Hello World example

To get started with OpenWhisk, try the following JavaScript code example.

 * Hello world as an OpenWhisk action.
function main(params) {
    var name = || 'World';
    return {payload:  'Hello, ' + name + '!'};

To use this example, follow these steps:

  1. Save the code to a file. For example, hello.js.

  2. From the OpenWhisk CLI command line, create the action by entering this command:

    $ wsk action create hello hello.js
  3. Then, invoke the action by entering the following commands.

    $ wsk action invoke hello --blocking --result

    This command outputs:

        "payload": "Hello, World!"
    $ wsk action invoke hello --blocking --result --param name Fred

    This command outputs:

        "payload": "Hello, Fred!"

You can also use the event-driven capabilities in OpenWhisk to invoke this action in response to events. Follow the alarm service example to configure an event source to invoke the hello action every time a periodic event is generated.

System details

You can find additional information about OpenWhisk in the following topics: