openstack/monasca-api
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monasca-api/doc/source/admin/index.rst
Bharat Kunwar 967b918bae Implement separate db per tenancy 
At present, all time series are accumulated in the same database in
InfluxDB. This makes queries slow for tenants that have less data. This
patch enables the option to use separate database per tenancy.

This changeset implements the changes on monasca-api which handles read
requests to InfluxDB database.

It also updates the relevant docs providing link to the migration tool
which enables users to migrate their existing data to a database per
tenant model.

Change-Id: I7de6e0faf069b889d3953583b29a876c3d82c62c
Story: 2006331
Task: 36073
2019-09-27 14:24:37 +00:00

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Administration guide

Schema Setup

For setting up the Monasca configuration database, we provide monasca_db, an Alembic based database migration tool. Historically, the schema for the configuration database was created by a SQL script. This SQL was changed a couple of times, so monasca_db comes with a mechanism to detect the SQL script revision being used to create it and stamp the database with the matching Alembic revision.

Setting up a new database

If you are deploying Monasca from scratch, database setup is quite straightforward:

  1. Create a database and configure access credentials with ALL PRIVILEGES permission level on it in the Monasca API configuration file's [database] section.
  2. Run schema migrations: monasca_db upgrade. It will run all migrations up to and including the most recent one (head) unless a revision to migrate to is explicitly specified.

Upgrading Existing Database from Legacy Schema

If you have been running an older version of Monasca, you can attempt to identify and stamp its database schema:

monasca_db stamp --from-fingerprint

This command will generate a unique fingerprint for the database schema in question and match that fingerprint with an in-code map of fingerprints to database schema revisions. This should work for all official (shipped as part of the monasca-api repository) schema scripts. If you used a custom third-party schema script to set up the database, it may not be listed and you'll get an error message similar to this one (the fingerprint hash will vary):

Schema fingerprint 3d45493070e3b8e6fc492d2369e51423ca4cc1ac does not match any known legacy revision.

If this happens to you, please create a Storyboard story against the openstack/monasca-api project. Provide the following alongside the story:

  1. A copy of or pointer to the schema SQL script being used to set up the database.
  2. The fingerprint shown in the error message.
  3. The output of monasca_db fingerprint --raw.

Time Series Databases Setup

Enabling InfluxDB Time Series Index in existing deployments

If enabling TSI on an existing InfluxDB install please follow the instructions for migrating existing data here: https://docs.influxdata.com/influxdb/v1.7/administration/upgrading/#upgrading-influxdb-1-3-1-4-no-tsi-preview-to-1-7-x-tsi-enabled

Database Per Tenant

It is envisaged that separate database per tenant will be the default behaviour in a future release of Monasca. Not only would it make queries faster for tenants, it would also allow administrators to define retention policy per tenancy. To enable this, set influxdb.db_per_tenant to True in monasca-{api,persister} config (it defaults to False at the moment if not set).

To migrate existing data to database per tenant, refer to README.rst under the following URL which also contains the Python script to facilitate migration: https://opendev.org/openstack/monasca-persister/src/branch/master/monasca_persister/tools/db-per-tenant/