Mistral Configuration Guide
===========================

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

**NOTE:** Most of the following operations should be performed in mistral
directory.

#. Generate *mistral.conf* (if it does not already exist)::

    $ oslo-config-generator \
      --config-file tools/config/config-generator.mistral.conf \
      --output-file /etc/mistral/mistral.conf

#. Edit file **/etc/mistral/mistral.conf**.

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

    [keystone_authtoken]
    www_authenticate_uri = http://keystone1.example.com:5000/v3
    identity_uri = http://<keystone-host:5000
    auth_version = v3
    admin_user = <user>
    admin_password = <password>
    admin_tenant_name = <tenant>

#. Mistral can be also configured to authenticate with Keycloak server
   via OpenID Connect protocol. In order to enable Keycloak authentication,
   the following section should be in the config file::

    auth_type = keycloak-oidc

    [keycloak_oidc]
    auth_url = https://<keycloak-server-host>:<keycloak-server-port>/auth

   Property ``auth_type`` is assigned to ``keystone`` by default.
   If SSL/TLS verification needs to be disabled then ``insecure = True``
   should also be added under ``[keycloak_oidc]`` group.

#. If you want to configure SSL for Mistral API server, provide following
   options in config file::

    [api]
    enable_ssl_api = True

    [ssl]
    ca_file = <path-to-ca file>
    cert_file = <path-to-certificate file>
    key_file = <path-to-key file>

#. **If you don't use OpenStack or you want to disable authentication for the
   Mistral service**, provide ``auth_enable = False`` in the config file::

    [pecan]
    auth_enable = False

#. **If you are not using OpenStack, skip this item**. Register Mistral service
   and Mistral endpoints on Keystone::

    $ MISTRAL_URL="http://[host]:[port]/v2"
    $ openstack service create workflowv2 --name mistral \
      --description 'OpenStack Workflow service'
    $ openstack endpoint create workflowv2 public $MISTRAL_URL
    $ openstack endpoint create workflowv2 internal $MISTRAL_URL
    $ openstack endpoint create workflowv2 admin $MISTRAL_URL

#. Configure transport properties in the ``[DEFAULT]`` section::

    [DEFAULT]
    transport_url = rabbit://<user_id>:<password>@<host>:5672/

#. Configure database. **SQLite can't be used in production; use MySQL or
   PostgreSQL instead.** Here are the steps how to connect *MySQL* DB to
   Mistral:

   Make sure you have installed ``mysql-server`` package on your database
   machine (it can be your Mistral machine as well).

   Install MySQL driver for python::

    $ pip install PyMySQL

   Create the database and grant privileges::

    # mysql

    CREATE DATABASE mistral;
    USE mistral
    GRANT ALL ON mistral.* TO 'root'@<database-host> IDENTIFIED BY <password>;

   Configure connection in Mistral config::

    [database]
    connection = mysql+pymysql://<user>:<password>@<database-host>:3306/mistral

   **NOTE**: If PostgreSQL is used, configure connection item as below::

    connection = postgresql://<user>:<password>@<database-host>:5432/mistral

#. **If you are not using OpenStack, skip this item.**
   Update ``mistral/actions/openstack/mapping.json`` file which contains all
   allowed OpenStack actions, according to the specific client versions
   of OpenStack projects in your deployment. Please find more detailed
   information in ``tools/get_action_list.py`` script.

#. Configure Task affinity feature if needed. It is needed for distinguishing
   either single task executor or one task executor from group of task
   executors::

    [executor]
    host = my_favorite_executor

   Then, this executor can be referred in Workflow Language by

   .. code-block:: yaml

    ...Workflow YAML...
    my_task:
      ...
      target: my_favorite_executor
    ...Workflow YAML...

#. Configure role based access policies for Mistral endpoints (policy.yaml)::

     [oslo_policy]
     policy_file = <path-of-policy.yaml file>

   Default policy.yaml file is in ``mistral/etc/``.
   For more details see `policy.yaml file
   <https://docs.openstack.org/oslo.policy/latest/admin/policy-yaml-file.html>`_.

#. Modify the action execution reporting configuration if needed.

   It is possible that actions stuck in *"RUNNING"* state, for example if the
   assigned executor dies or the message that signals the completion of the
   action is lost. This section describes a heartbeat based solution to close
   these forgotten action executions. The related configuration options are
   ``max_missed_heartbeats`` and ``check_interval``. Note that if either
   of these options are *"0"* then the feature won't be enabled.

   The default configuration is the following::

     [action_heartbeat]
     max_missed_heartbeats = 15
     check_interval = 20
     first_heartbeat_timeout = 3600

   *"check_interval = 20"*, so check action executions every
   20 seconds. When the checker runs it will transit all running action
   executions to error if the last heartbeat received is older than *"20 \*
   15"* seconds. Note that *"first_heartbeat_timeout = 3600"*, so the action
   execution won't be closed for 3600 seconds if no heartbeat was received for
   it.

   - **max_missed_heartbeats**

    Defines the maximum amount of missed heartbeats to be allowed. If the number
    of missed heartbeats exceeds this number, then the related action execution
    will be transited to *"ERROR"* state with cause *"Heartbeat wasn't received."*.

   - **check_interval**

    The interval between checks (in seconds).

   - **first_heartbeat_timeout**

    The grace period for the first heartbeat (in seconds).

#. Configure event publishers. Event publishers are plugins that are
   optionally installed in the same virtual environment as Mistral.
   Event notification can be configured for all workflow execution for one or
   more event publishers. The configuration is under the notify param at the
   notifier section. The notify param is a list of dictionaries, one for each
   publisher identifying the type or the registered plugin name and additional
   key value pairs to be passed as kwargs into the publisher::

    [notifier]
    notify = [ {"type": "webhook", "url": "http://example.com", "headers": {"X-Auth-Token": "XXXX"}}, {"type": "custom_publisher"} ]

#. Finally, try to run mistral engine and verify that it is running without
   any error::

     $ mistral-server --config-file <path-to-config> --server engine

