# Scaling Out with Mesos (community contributed)¶

There are two ways you can run airflow as a mesos framework:

1. Running airflow tasks directly on mesos slaves, requiring each mesos slave to have airflow installed and configured.
2. Running airflow tasks inside a docker container that has airflow installed, which is run on a mesos slave.

## Tasks executed directly on mesos slaves¶

MesosExecutor allows you to schedule airflow tasks on a Mesos cluster. For this to work, you need a running mesos cluster and you must perform the following steps -

1. Install airflow on a mesos slave where web server and scheduler will run, let’s refer to this as the “Airflow server”.
2. On the Airflow server, install mesos python eggs from mesos downloads.
3. On the Airflow server, use a database (such as mysql) which can be accessed from all mesos slaves and add configuration in airflow.cfg.
4. Change your airflow.cfg to point executor parameter to MesosExecutor and provide related Mesos settings.
5. On all mesos slaves, install airflow. Copy the airflow.cfg from Airflow server (so that it uses same sql alchemy connection).
6. On all mesos slaves, run the following for serving logs:
airflow serve_logs

1. On Airflow server, to start processing/scheduling DAGs on mesos, run:
airflow scheduler -p


Note: We need -p parameter to pickle the DAGs.

You can now see the airflow framework and corresponding tasks in mesos UI. The logs for airflow tasks can be seen in airflow UI as usual.

1. Create a mesos configuration block within the airflow.cfg.
The configuration block remains the same as the default airflow configuration (default_airflow.cfg), but has the addition of an option docker_image_slave. This should be set to the name of the image you would like mesos to use when running airflow tasks. Make sure you have the proper configuration of the DNS record for your mesos master and any sort of authorization if any exists.
1. Change your airflow.cfg to point the executor parameter to MesosExecutor (executor = SequentialExecutor).
2. Make sure your mesos slave has access to the docker repository you are using for your docker_image_slave.