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Pass Data Between Steps

Pass Data Between Steps

Overview

Rundeck offers powerful Runbook Automation. Most Runbooks are complicated, multi-step processes.

This guide will show various examples of how to share data from one step to another through the use of Log Filters.

Note: If you haven't followed the Exercise Steps in the Tutorial we encourage starting with that walk-through.

Type of Variables

When a Job step is executed, it has a set of context variables that you can access in the Job step. There are several sets of context variables, including: the Job context job, the Node context node, the Option context option, and the Step Data Context data.

Click here for more documentation on: Context Variables

Other Terminology

These are some key terms we'll be using throughout this tour in addition to terms used in our Terminology documentation.

Log Filters

Log Filters are applied to a Job step to act on the output from that step. Certain Job Filters can set variables based on information in the log output. There is a separate guide (coming soon) to cover different types of Log Filters and how they are used.

RegEx

Log Filters use Regular Expression syntax (RegEx) to collect information from the log output. Familiarity with Regex will be key to successfully gathering data from your own job steps. You will not need to know it for these Exercises.

Exercises Intro

As part of the Welcome Projects we have built some example jobs to highlight how variables can be passed from one job step to another. For more information about the Welcome Projects check out the Learning Overview.

It's important to note that Node Steps (steps run against nodes) and Workflow Steps (steps run from the Rundeck server) store variables differently. The examples will also show how to use the variables from different types of steps and highlight common trouble spots.

Important Exercise Prerequisite

If you are new to Rundeck, we recommend finishing the exercises in the Getting Started Tutorial first. Terminology and actions in the following exercise will assume you have completed that Tutorial.

Using Input Option Variables

Input Option are values that are provided at the start of running a job. They may be represented as a form on the Job Execution page or populated by a Webhook or other call.

  1. Open the Jobs section in the Welcome Project.
  2. Expand the Variables > Variables in Job Steps folders.
  3. Edit the Using Input Options in command and scripts job.
  4. On the Workflow tab under Options Click the input_key option entry.
  5. The Option Name is input and the Option Label is My Input
  6. To reference this variable Job Steps will use ${option.input_key} and Script Steps would use @option.input_key@

Using Step Data Variables

Step Data variables are data gathered using Log Filters and stored in memory while the job is running. (See the Log Filters How To for specifics on each type).

How Step Data variables are referenced in Jobs depend on a few things:

  • The type of Job Step we are running (Node Step vs. Workflow Step)
  • Whether the variable is being accessed from a Command Step or a Script

Job Step Types

There are two types of Job Steps.

  • Node Steps: These are steps that are run against every node associated with this job.
  • Workflow Steps: These steps are run from the Rundeck server without being associated to a specific node.

This is important to keep in mind because when a job is run against more than one node a variable may have multiple entries, one for each node it was run against.

Command Steps vs Scripts

Referencing variables from Command Steps use a different syntax than referencing them from within a Script. Most Job Steps are Command Steps and will follow a format of: ${data.MyKeyName}. Scripts will reference variables by enclosing them in @ symbols: @data.MyKeyName@

  1. Open the Jobs section in the Welcome Project.
  2. Expand the Variables > Variables in Job Steps folders.
  3. Edit the Using Step Data Variables job.
  4. Job Step 1 is executing a simple hostname command and capturing that output with a Log Filter. The Log Filter sets the variable name to MyKeyName.
  5. Job Step 2 is an example of a Node Command Step using data from Step 1 by calling ${data.MyKeyName}.
  6. Job Step 3 is an example of a Node Script Step using data from Step 1 by calling @data.MyKeyName@.

Node vs Workflow Steps (Multi-Node Example)

The Using Step Data Variables job in the previous section was configured to only execute against the Rundeck Server. To highlight the difference when running against multiple nodes, let's run the Multi-Node Example job and explore its output and configuration.

Note: It is recommended to configure multiple Nodes as detailed in the Getting Started Tutorial.

  1. Open the Jobs section in the Welcome Project.
  2. Expand the Variables > Variables in Job Steps folders.
  3. Run the Multi-Node Example Job
  4. Note that the code within the job is exactly the same as the Using Step Data Variables job we ran with one added step.
  5. Since there are now multiple nodes that the Command and Script steps are run against we will see more output than before.
  6. Each Node will have different output for the hostname command. This is because those job steps are Node Steps. Each step output line will have a node associated with it on the right. (If you are in Log Output view look for the blue text)

A common sticking point is when Workflow Steps need to use a variable value from a Node Step.

Accessing the variable from the node would need to be called using ${data.MyKeyName@hostname} to get the specific value. Note the @hostname portion of that string.

If your job is run against a single node it is also possible to use the * character ${data.MyKeyName*}. The * is used in Step 4 but as you can see in the output when used on jobs with multiple nodes the variables are joined with a comma ,. If you want to use a character other than ,, you can add it after the * like ${data.MyKeyName*;} which will separate all values with ;.

Using Other Context Variables

Using other Context variables follows the same format.

To see what variables might be available check out the list here: Context Variables Documentationopen in new window

To check variable values during your workflow use the Workflow Step titled Log Data Step.