Run a Wallaroo Application

In this section, we're going to run an example Wallaroo application. By the time you are finished, you'll have validated that your environment is set up and working correctly. If you haven't already completed the install from source instructions or the install with Wallaroo Up instructions, please do so before continuing.

There are a few Wallaroo support applications that you'll be interacting with for the first time:

  • Our Metrics UI allows you to monitor the performance and health of your applications.
  • Data receiver is designed to capture TCP output from Wallaroo applications.
  • Machida or Machida3, our programs for running Wallaroo Python 2.7 and Python 3.5+ applications, respectively.

You're going to set up our "Alerts" example application. We will use an internal generator source to generate simulated inputs into the system. Data receiver will receive the output, and our Metrics UI will be running so you can observe the overall performance.

The Metrics UI process will be run in the background. The other two processes (data_receiver and Wallaroo) will run in the foreground. We recommend that you run each process in a separate terminal.

Starting new shells

For each Shell you're expected to setup, you'd have to run the following to configure the Wallaroo environment:

cd ~/wallaroo-tutorial/wallaroo-0.6.0
source bin/activate

This command will set up the environment variables for running Wallaroo Applications.

Let's get started!

Since Wallaroo is a distributed application, its components need to run separately, and concurrently, so that they may connect to one another to form the application cluster. For this example, you will need 4 separate terminal shells to run the metrics UI, run a sink, run the Alerts application, and eventually, to send a cluster shutdown command.

Shell 1: Start the Metrics UI

To start the Metrics UI run:

metrics_reporter_ui start

You can verify it started up correctly by visiting http://localhost:4000.

If you need to restart the UI, run:

metrics_reporter_ui restart

When it's time to stop the UI, run:

metrics_reporter_ui stop

If you need to start the UI after stopping it, run:

metrics_reporter_ui start

Shell 2: Run Data Receiver

We'll use Data Receiver to listen for data from our Wallaroo application.

data_receiver --listen --no-write --ponythreads=1 --ponynoblock

Data Receiver will start up and receive data without creating any output. By default, it prints received data to standard out, but we are giving it the --no-write flag which results in no output.

Shell 3: Run the "Alerts" Application

First, we will need to set up the PYTHONPATH environment variable. Machida needs to be able to find the the module that defines the application. In order to do that, set and export the PYTHONPATH environment variable like this:

export PYTHONPATH="$HOME/wallaroo-tutorial/wallaroo-0.6.0/examples/python/alerts_stateful:$PYTHONPATH"

Now that we have Machida set up to run the "Alerts" application, and the metrics UI and something it can send output to up and running, we can run the application itself by executing the following command (remember to use the machida3 executable instead of machida if you are using Python 3.X):

machida --application-module alerts \
  --out --metrics --control \
  --data --name worker-name --external \
  --cluster-initializer --ponythreads=1 --ponynoblock

This tells the "Alerts" application that it should write outgoing data to port 5555, and send metrics data to port 5001.

Check Out Some Metrics

First Look

Once the application has successfully initialized, the internal test generator source will begin simulating inputs into the system. If you visit the Metrics UI, the landing page should show you that the "Alerts" application has successfully connected.

Landing Page

If your landing page resembles the one above, the "Alerts" application has successfully connected to the Metrics UI.

Now, let's have a look at some metrics. By clicking on the "Alerts" link, you'll be taken to the "Application Dashboard" page. On this page you should see metric stats for the following:

  • a single pipeline: Alerts
  • a single worker: Initializer
  • a single computation: check transaction total

Application Dashboard Page

You'll see the metric stats update as data continues to be processed in our application.

You can then click into one of the elements within a category to get to a detailed metrics page for that element. If we were to click into the check transaction total computation, we'll be taken to this page:

Computation Detailed Metrics page

Feel free to click around and get a feel for how the Metrics UI is set up and how it is used to monitor a running Wallaroo application. If you'd like a deeper dive into the Metrics UI, have a look at our Monitoring Metrics with the Monitoring Hub section.


Shell 4: Cluster Shutdown

You can shut down the cluster with this command at any time:


You can shut down Data Receiver by pressing Ctrl-c from its shell.

You can shut down the Metrics UI with the following command:

metrics_reporter_ui stop

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