Creating Flows¶

This section covers how to create your Azkaban flows using Azkaban Flow 2.0. Flow 1.0 will be deprecated in the future.

Flow 2.0 Basics¶

Step 1:¶

Create a simple file called flow20.project. Add azkaban-flow-version to indicate this is a Flow 2.0 Azkaban project:

azkaban-flow-version: 2.0

Step 2:¶

Create another file called basic.flow. Add a section called nodes, which will contain all the jobs you want to run. You need to specify name and type for all the jobs. Most jobs will require the config section as well. We will talk more about it later. Below is a simple example of a command job.

nodes:
  - name: jobA
    type: command
    config:
      command: echo "This is an echoed text."

Step 3:¶

Select the two files you’ve already created and right click to compress them into a zip file called Archive.zip. You can also create a new directory with these two files and then cd into the new directory and compress: zip -r Archive.zip . Please do not zip the new directory directly.

Make sure you have already created a project on Azkaban ( See Create Projects ). You can then upload Archive.zip to your project through Web UI ( See Upload Projects ).

Now you can click Execute Flow to test your first Flow 2.0 Azkaban project!

Job Dependencies¶

Jobs can have dependencies on each other. You can use dependsOn section to list all the parent jobs. In the below example, after jobA and jobB run successfully, jobC will start to run.

nodes:
  - name: jobC
    type: noop
    # jobC depends on jobA and jobB
    dependsOn:
      - jobA
      - jobB

  - name: jobA
    type: command
    config:
      command: echo "This is an echoed text."

  - name: jobB
    type: command
    config:
      command: pwd

You can zip the new basic.flow and flow20.project again and then upload it to Azkaban. Try to execute the flow and see the difference.

Job Config¶

Azkaban supports many job types. You just need to specify it in type, and other job-related info goes to config section in the format of key: value pairs. Here is an example of a Pig job:

nodes:
  - name: pigJob
    type: pig
    config:
      pig.script: sql/pig/script.pig

You need to write your own pig script and put it in your project zip and then specify the path for the pig.script in the config section.

Common Parameters¶

Besides the type and the dependencies parameters, there are several parameters that Azkaban reserves for all jobs. All of the parameters below are optional.

Parameter	Description
retries	The number of retries that will be automatically attempted for failed jobs
retry.backoff	The millisec time between each retry attempt
working.dir	Override the working directory for the execution. This is by default the directory that contains the job file that is being run
env.property	Set the environment variable with named property
failure.emails	Comma delimited list of emails to notify during a failure *
success.emails	Comma delimited list of emails to notify during a success *
notify.emails	Comma delimited list of emails to notify during either a success or failure *

Email properties¶

Note that for email properties, this property is retrieved from the last job in the flow and applied flow level. All other email properties of jobs in the flow are ignored.

Flow Config¶

Not only can you configure individual jobs, but you can also config the flow parameters for the entire flow. Simply add a config section at the beginning of the basic.flow file. For example:

---
config:
  user.to.proxy: foo
  failure.emails: noreply@foo.com

nodes:
  - name: jobA
    type: command
    config:
      command: echo "This is an echoed text."

When you execute the flow, the user.to.proxy and failure.emails flow parameters will apply to all jobs inside the flow.

Flow Level Retry¶

Flow Level Retry

Embedded Flows¶

Flows can have subflows inside the flow just like job nodes. To create embedded flows, specify the type of the node as flow. For example:

nodes:
  - name: embedded_flow
    type: flow
    config:
      prop: value
    nodes:
      - name: jobB
        type: noop
        dependsOn:
          - jobA

      - name: jobA
        type: command
        config:
          command: pwd

Download Examples¶

You can download the simple Flow 2.0 project zip examples to start playing with Azkaban: