Lab 1.5: Building Imperative Workflows with Postman Collections¶
As you have seen in the previous labs, we can use the Collections and Folders
features of the Postman client to group REST requests logically. Additionally,
as you’ve seen most of the examples so far have consisted of executing a
sequence of REST request to achieve some outcome.
In this lab, we will use a feature in Postman called the Collection Runner
(Runner) to execute a sequence of REST requests. Using the Runner we can
rapidly prototype REST requests into an Imperative Workflow that can be
executed without user intervention.
The purpose of this exercise is to provide an example of how new workflows can
be built from scratch or existing workflows can be modified.
Additionally, we will use some Postman Javascript Tests to programmatically
populate environment variables with the output of our workflow.
The collection we will run in this task will populate some environment
variables with various data about the BIG-IP system. First, let’s examine
the Environment Variables that are currently set. Click the icon
in the top right of the Postman window. Notice that there are no variables
starting with the name lab1.5_:
Click the Lab1.5-BuildingImperativeWorkflows folder to expand it
Click the Step1:GetBIG-IPSoftwareVersion request. Click the
Tests tab and examine the Javascript code and comments:
The Javascript code in the Test script will populate an environment variable
based on the response from the BIG-IP system.
Click the Runner button at the top left of your Postman window:
Select the F5Programmability:Class1 Collection then the
Lab1.5-BuildingImperativeWorkflows folder. Next, be sure the
environment is set to F5Programmability:Class1:
Your Runner window should look like:
As you can see from the screenshot or your own Collection Runner screen, we
will be sending 3 requests (Steps 1-3 in Lab 1.5). Each request has a
unit test implemented in JavaScript to ensure it’s ok to continue to the
next request when using the Collection Runner. The Runner will step through
each request unless one of the tests fails.
Click the Run Lab 1.5 - Buil… button
The results window will now populate. You will see each request in the
folder is sent and its associated test results are displayed on the screen.
The last request in the folder includes some Javascript code to dump the
results to the screen:
Next, switch back to the main Postman window. Click the button
again and examine the environment variables. Notice that three new variables
starting with the name lab1.5_ have been populated. You may need to scroll
down to see these variables:
Note
It is normal for the values of Software Version, CPU Count and Base
MAC Address to be different from the screenshot(s).
In this lab, we demonstrated running a simple Imperative Workflow using the
Postman Collection Runner. In subsequent labs, we will expand on this simple
use case to perform more complex functions. As you continue through the labs,
be sure to take time to explore the details of the requests being sent. The
Postman Collection used in this class can also serve as a starting point for
building your own collections or modifying existing ones.
As we move through the rest of this module you will see the complexity involved
in building Imperative Workflows. While these types of workflows are incredibly
powerful, they are also time-consuming to build from scratch. As we move into
Module 2 you will see the importance of leveraging Abstraction
and Declarative Interfaces to minimize the amount of time spent on building
Imperative Workflows.
icon
in the top right of the Postman window. Notice that there are no variables
starting with the name 
