Mistral

Workflow Service for OpenStack cloud.

Prerequisites

It is necessary to install some specific system libs for installing Mistral. They can be installed on most popular operating system using their package manager (for Ubuntu - apt, for Fedora, CentOS - yum, for Mac OS - brew or macports). The list of needed packages is shown below:

1. python-dev
2. python-setuptools
3. python-pip
4. libffi-dev
5. libxslt1-dev (or libxslt-dev)
6. libxml2-dev
7. libyaml-dev
8. libssl-dev

In case of ubuntu, just run:

apt-get install python-dev python-setuptools libffi-dev libxslt1-dev libxml2-dev libyaml-dev libssl-dev

Mistral can be used without authentication at all or it can works with OpenStack. In case of OpenStack, it works only on Keystone v3, make sure Keystone v3 is installed.

Installation

First of all, clone the repo and go to the repo directory:

git clone https://github.com/openstack/mistral.git
cd mistral

Devstack installation

Information about how to install Mistral with devstack can be found here: https://github.com/openstack/mistral/tree/master/contrib/devstack

Virtualenv installation:

tox

This will install necessary virtual environments and run all the project tests. Installing virtual environments may take significant time (~10-15 mins).

Local installation:

pip install -e .

or:

python setup.py install

Configuring Mistral

Mistral configuration is needed for getting it work correctly either with real OpenStack environment or without OpenStack environment.

1. Copy mistral.conf:

   cp etc/mistral.conf.sample etc/mistral.conf

Note: mistral.conf.sample is the example configuration file.

2. Edit file etc/mistral.conf

3. If you are not using OpenStack, skip this item. Provide valid keystone auth properties:

   [keystone_authtoken]
   auth_uri = http://<Keystone-host>:5000/v3
   identity_uri = http://<Keystone-host:35357/
   auth_version = v3
   admin_user = <user>
   admin_password = <password>
   admin_tenant_name = <tenant>

4. If you don't use OpenStack, provide auth_enable = False in config file:

   [pecan]
   auth_enable = False

5. Also, configure rabbit properties: rabbit_userid, rabbit_password, rabbit_host in section default.

6. Configure database. SQLite can't be used in production. Use MySQL or PostreSQL instead. Here are the steps how to connect MySQL DB to Mistral:

   • Make sure you have installed mysql-server package on your Mistral machine.

   • Install MySQL driver for python:

     pip install mysql-python

     or, if you work in virtualenv, run:

     tox -evenv -- pip install mysql-python

   • Create the database and grant privileges:

     mysql -u root -p
     
     CREATE DATABASE mistral;
     USE mistral
     GRANT ALL ON mistral.* TO 'root'@'localhost';

   • Configure connection in Mistral config:

     [database]
     connection = mysql://root:<password>@localhost:3306/mistral

Before the first run

After local installation you will see mistral-server and mistral-db-manage commands in your environment.

mistral-db-manage command can be used for migrations. If Mistral is not installed in system then this script can be found at mistral/db/sqlalchemy/migration/cli.py, it can be executed using Python.

For updating the database to the latest revision type:

mistral-db-manage --config-file <path-to-mistral.conf> upgrade head

For more detailed information about mistral-db-manage script please see migration readme here.

NOTE: For users want a dry run with SQLite database backend(not used in production), mistral-db-manage is not recommended for database initialization because of SQLite limitations. Please use sync_db script described below instead for database initilization.

Before starting Mistral server, run sync_db script. It prepares the DB, creates in it with all standard actions and standard workflows which Mistral provides for all mistral users.

If you use virtualenv:

tools/sync_db.sh --config-file path_to_config*

Or run sync_db directly:

python tools/sync_db.py --config-file path_to_config*

Running Mistral API server

To run Mistral API server perform the following command in a shell:

tox -evenv -- python mistral/cmd/launch.py --server api --config-file path_to_config*

Running Mistral Engines

To run Mistral Engine perform the following command in a shell:

tox -evenv -- python mistral/cmd/launch.py --server engine --config-file path_to_config*

Running Mistral Task Executors

To run Mistral Task Executor instance perform the following command in a shell:

tox -evenv -- python mistral/cmd/launch.py --server executor --config-file path_to_config

Note that at least one Engine instance and one Executor instance should be running so that workflow tasks are processed by Mistral.

If it is needed to run some tasks on specific executor then task affinity feature can be used to send these tasks directly to specific executor. In configuration file edit section "executor" host property:

[executor]
host = my_favorite_executor

Then start (restart) executor. Use target task property to specify this executor:

... Workflow YAML ...
task1:
  ...
  target: my_favorite_executor
... Workflow YAML ...

Running Multiple Mistral Servers Under the Same Process

To run more than one server (API, Engine, or Task Executor) on the same process, perform the following command in a shell:

tox -evenv -- python mistral/cmd/launch.py --server api,engine --config-file path_to_config

The --server command line option can be a comma delimited list. The valid options are "all" (by default if not specified) or any combination of "api", "engine", and "executor". It's important to note that the "fake" transport for the rpc_backend defined in the config file should only be used if "all" the Mistral servers are launched on the same process. Otherwise, messages do not get delivered if the Mistral servers are launched on different processes because the "fake" transport is using an in process queue.

Mistral client

Python-mistralclient is available here.

Debugging

To debug using a local engine and executor without dependencies such as RabbitMQ, create etc/mistral.conf with the following settings:

[DEFAULT]
rpc_backend = fake

[pecan]
auth_enable = False

and run in pdb, PyDev or PyCharm:

mistral/cmd/launch.py --server all --config-file etc/mistral.conf --use-debugger

Running examples

To run the examples find them in mistral-extra repository (https://github.com/openstack/mistral-extra) and follow the instructions on each example.

Tests

There is an ability to run part of functional tests in non-openstack mode locally. To do this:

1. set auth_enable = False in the mistral.conf and restart Mistral

2. execute:

   ./run_functional_tests.sh

To run tests for only one version need to specify it: bash run_functional_tests.sh v1

More information about automated tests for Mistral can be found here: https://wiki.openstack.org/wiki/Mistral/Testing