Quickstart

Command line interface

Overview

Once installed, the azkaban executable provides several useful commands. These are divided into two kinds. The first will work out of the box with any existing Azkaban project:

• azkaban run [options] WORKFLOW [JOB ...]

  Launch a workflow (asynchronously). By default the entire workflow will be run, but you can specify specific jobs to only run those. This command will print the corresponding execution’s URL to standard out.

• azkaban upload [options] ZIP

  Upload an existing project zip archive to the Azkaban server.

• azkaban schedule [options] (-d DATE) (-t TIME) [-s SPAN]

  Schedule a workflow to be run on a particular day and time. An optional span argument can also be specified to enable recurring runs.

• azkaban log [options] EXECUTION [JOB]

  View execution logs for a workflow or single job. If the execution is still running, the command will return on completion.

The second require a project configuration file (cf. building projects):

• azkaban build [options]

  Generate a project’s job files and package them in a zip file along with any other project dependencies (e.g. jars, pig scripts). This archive can either be saved to disk or directly uploaded to Azkaban.

• azkaban info [options]

  View information about all the jobs inside a project, its static dependencies, or a specific job’s options. In the former case, each job will be prefixed by W if it has no children (i.e. it “commands” a workflow), or J otherwise (regular job).

Running azkaban --help will show the full list of commands and options available for each.

URLs and aliases

The previous commands all take a --url, option used to specify where to find the Azkaban server (and which user to connect as).

$ azkaban build -u http://url.to.foo.server:port

In order to avoid having to input the entire URL every time, it is possible to defines aliases in ~/.azkabanrc:

[azkaban]
default.alias = foo
[alias.foo]
url = http://url.to.foo.server:port
[alias.bar]
url = http://baruser@url.to.bar.server
# Optional keys (see corresponding `Session` argument for details):
verify = false
attempts = 5

We can now interact directly with each of these URLs using the --alias option followed by their corresponding alias. In particular, note that since we also specified a default alias, it is also possible to omit the option altogether. As a result, the commands below are now all equivalent:

$ azkaban build -u http://url.to.foo.server:port
$ azkaban build -a foo
$ azkaban build

Session IDs are conveniently cached after each successful login, so that we don’t have to authenticate every time.

Building projects

We provide here a framework to define projects, jobs, and workflows from a single python file.

Motivation

For medium to large sized projects, it quickly becomes tricky to manage the multitude of files required for each workflow. .properties files are helpful but still do not provide the flexibility to generate jobs programmatically (i.e. using for loops, etc.). This approach also requires us to manually bundle and upload our project to the gateway every time.

Additionally, this will enable the build and info commands.

Quickstart

We start by creating a file. Let’s call it jobs.py (the default file name the command line tool will look for), although any name would work. Below is a simple example of how we could define a project with a single job and static file:

from azkaban import Job, Project

project = Project('foo')
project.add_file('/path/to/bar.txt', 'bar.txt')
project.add_job('bar', Job({'type': 'command', 'command': 'cat bar.txt'}))

The Project class corresponds transparently to a project on the Azkaban server. The add_file() method then adds a file to the project archive (the second optional argument specifies the destination path inside the zip file). Similarly, the add_job() method will trigger the creation of a .job file. The first argument will be the file’s name, the second is a Job instance (cf. Job options).

Once we’ve saved our jobs file, running the azkaban executable in the same directory will pick it up automatically and activate all commands. Note that we could also specify a custom configuration file location with the -p --project option (e.g. if the jobs file was in a different location).

Job options

The Job class is a light wrapper which allows the creation of .job files using python dictionaries.

It also provides a convenient way to handle options shared across multiple jobs: the constructor can take in multiple options dictionaries and the last definition of an option (i.e. later in the arguments) will take precedence over earlier ones.

We can use this to efficiently share default options among jobs, for example:

defaults = {'user.to.proxy': 'foo', 'retries': 0}

jobs = [
  Job({'type': 'noop'}),
  Job(defaults, {'type': 'noop'}),
  Job(defaults, {'type': 'command', 'command': 'ls'}),
  Job(defaults, {'type': 'command', 'command': 'ls -l', 'retries': 1}),
]

All jobs except the first one will have their user.to.proxy property set. Note also that the last job overrides the retries property.

Alternatively, if we really don’t want to pass the defaults dictionary around, we can create a new Job subclass to do it for us:

class FooJob(Job):

  def __init__(self, *options):
    super(FooJob, self).__init__(defaults, *options)

Finally, since many Azkaban options are space/comma-separated strings (e.g. dependencies), the Job class provides two helpers to better handle their configuration: join_option() and join_prefix().

More

Project properties

Any options added to a Project’s properties attribute will be available to all jobs inside of the project (under the hood, these get written to a global .properties file):

project.properties = {
  'user.to.proxy': 'foo',
  'my.custom.key': 'bar',
}

Note that this is particularly useful when combined with the merge_into() method to avoid job duplication when running projects with the same jobs but different options (e.g. a test and a production project).

Nested options

Nested dictionaries can be used to group options concisely:

# e.g. this job
Job({
  'proxy.user': 'boo',
  'proxy.keytab.location': '/path',
  'param.input': 'foo',
  'param.output': 'bar',
})
# is equivalent to this one
Job({
  'proxy': {'user': 'boo', 'keytab.location': '/path'},
  'param': {'input': 'foo', 'output': 'bar'},
})

Merging projects

If you have multiple projects, you can merge them together to create a single project. The merge is done in place on the project the method is called on. The first project will retain its original name.

from azkaban import Job, Project

project1 = Project('foo')
project1.add_file('/path/to/bar.txt', 'bar.txt')
project1.add_job('bar', Job({'type': 'command', 'command': 'cat bar.txt'}))

project2 = Project('qux')
project2.add_file('/path/to/baz.txt', 'baz.txt')
project2.add_job('baz', Job({'type': 'command', 'command': 'cat baz.txt'}))

# project1 will now contain baz.txt and the baz job from project2
project2.merge_into(project1)

Next steps

Any valid python code can go inside a jobs configuration file. This includes using loops to add jobs, subclassing the base Job class to better suit a project’s needs (e.g. by implementing the on_add handler), etc.