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Scale applications based on MySQL query result.

Availability: v1.2+ Maintainer: Community


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Trigger Specification

This specification describes the mysql trigger that scales based on result of MySQL query.

The trigger always requires the following information:

  • query - A MySQL query that should return single numeric value.
  • queryValue - A threshold that is used as targetAverageValue in HPA.

Note that the query must return a single integer value. If the query has a possibility of returning null, a default value can be set using the COALESCE function. For example, SELECT COALESCE(column_name, 0) FROM table_name;. See MySQL documentation for more information on the COALESCE function.

To provide information about how to connect to MySQL you can provide:

  • connectionString - MySQL connection string that should point to environment variable with valid value.

Or provide more detailed information:

  • username - Used to access MySQL database.
  • password - Used for the given user, this should be blank (no password) or point to an environment variable with the password.
  • host - Host of the database.
  • port - Port of the database.
  • dbName - As name of the database.

Authentication Parameters

You can authenticate by using connection string or password authentication.

Connection String Authentication:

  • connection - Connection string for MySQL database.

Password Authentication:

  • connection - Password for configured user to login to MySQL database variables.


Here is an example of how to deploy a scaled object with the mysql scale trigger which uses TriggerAuthentication.

apiVersion: v1
kind: Secret
  name: mysql-secrets
  namespace: my-project
type: Opaque
  mysql_conn_str: dXNlckB0Y3AobXlzcWw6MzMwNikvc3RhdHNfZGI= # base64 encoded value of mysql connectionString of format user@tcp(mysql:3306)/stats_db
kind: TriggerAuthentication
  name: keda-trigger-auth-mysql-secret
  namespace: my-project
  - parameter: connectionString
    name: mysql-secrets
    key: mysql_conn_str
kind: ScaledObject
  name: mysql-scaledobject
  namespace: my-project
    deploymentName: worker
  - type: mysql
      queryValue: "4"
      query: "SELECT CEIL(COUNT(*) / 6) FROM task_instance WHERE state='running' OR state='queued'"
      name: keda-trigger-auth-mysql-secret