billingMode scope
billingMode is a custom policy check that ensures the billing mode for new tables is PROVISIONED.
Learn how to create and customize the billingMode Liquibase Custom Policy Check using a Python script.
This example utilizes DynamoDB. You can use this check as it is or customize it further to fit your needs in your NoSQL database.
For a conceptual overview of this feature, see Liquibase Pro Custom Policy Checks.
Before you begin
Scope | Database |
| DynamoDB |
Liquibase Prerequisites
Liquibase 4.29.0+
Configure a valid Liquibase Pro license key
Create a Check Settings file
Ensure the Liquibase Checks extension is installed. In Liquibase 4.31.0+, it is already installed in the
/liquibase/internal/lib
directory, so no action is needed.If the checks JAR is not installed, download
liquibase-checks-<version>.jar
and put it in theliquibase/lib
directory.Maven users only:
Add this dependency to your
pom.xml
file:
<dependency> <groupId>org.liquibase.ext</groupId> <artifactId>liquibase-checks</artifactId> <version>2.0.0</version> </dependency>
Java Development Kit 17+ (available for Open JDK and Oracle JDK)
Linux, macOS, or Windows operating system
Procedure
These steps describe how to create the Custom Policy Check. It does not exist by default in Liquibase Pro.
Add this code to your Checks Settings file:
billingMode Python Script
billingMode Python Script
# # #
# # # This script ensures the billing mode
for new tables is PROVISIONED.
# # #
# # # Notes:
# # #
# # # Helpers come from Liquibase
# # #
import sys
import liquibase_utilities
# # #
# # # Retrieve log handler
# # # Ex.liquibase_logger.info(message)
# # #
liquibase_logger = liquibase_utilities.get_logger()
# # #
# # # Retrieve status handler
# # #
liquibase_status = liquibase_utilities.get_status()
# # #
# # # Retrive billing mode from check definition
# # #
billing_mode = liquibase_utilities.get_arg("BILLING_MODE")
if len(billing_mode) == 0:
liquibase_logger.error(f "Missing billing mode from check definition.")
sys.exit(1)
# # #
# # # Retrieve all changes in changeset
# # #
changes = liquibase_utilities.get_changeset().getChanges()
# # #
# # # Loop through all changes
# # #
for change in changes:
change_type = change.getClass().getSimpleName()
if change_type.casefold() != "DynamoCreateTableChange".casefold():
liquibase_logger.info(f "{change_type} changetype skipped.")
continue
new_billing_mode = change.getBillingMode()
if new_billing_mode.casefold() != billing_mode.casefold():
liquibase_status.fired = True
liquibase_status.message = str(liquibase_utilities.get_script_message()).replace("__BILLING_MODE__", f "'{billing_mode}'")
sys.exit(1)
# # #
# # # Default
return code
# # #
False
Initiate the customization process
In the CLI, run this command:
liquibase checks customize --check-name=CustomCheckTemplate
The CLI prompts you to finish configuring your file. A message displays:
This check cannot be customized directly because one or more fields does not have a default value.
Liquibase will then create a copy of CustomCheckTemplate
and initiate the customization workflow.
Give your check a short name so you can easily identify what Python script it is associated with
You may use up to 64 alpha-numeric characters only.
In this example we will name the check:
billingMode
Set the Severity to return a code of 0-4 when triggered.
These severity codes allow you to determine if the job moves forward or stops when this check triggers.
Learn more here: Use Policy Checks in Automation: Severity and Exit Code
options: 'INFO'=0
, 'MINOR'=1
, 'MAJOR'=2
, 'CRITICAL'=3
, 'BLOCKER'=4
Set SCRIPT_DESCRIPTION
In this example, we will set the description to:
This script checks that the Buffer Pool specified in the tablespace matches the default Buffer Pool for the database.
Set the SCRIPT_SCOPE
In this example, we will set the scope to:
changelog
: for example, if your check looks for syntax patterns or attributes in your Liquibase Changelog (the changes you author in your repository). With this value, the check runs once per changeset.
Set the SCRIPT_MESSAGE.
This message will display when the check is triggered. In this example, we will use:
This script identified new tables that need a PROVISIONED billing mode. Specify __BILLING_MODE__ mode for all new tables.
Set the SCRIPT_PATH
This is the relative path where your script is stored in relation to the changelog specified in --changelog-file
, whether it is stored locally or in a repository.
In this example, we will set the path to:
scripts/billing-mode.py
Set the SCRIPT_ARGUMENT
This allows you to pass dynamic information into the custom policy check without modifying the Python code.
In this example, specify BILLING_MODE=PROVISIONED
to retrieve it in your code with a variable
billing_mode = liquibase_utilities.get_arg("BILLING_MODE")
If you customize your check later, you can specify a new value in the CLI. If you don't need dynamic arguments, leave this field blank.
Set the REQUIRES_SNAPSHOT
If your script scope is changelog
, set whether the check requires a database snapshot. Specify true
if your check needs to inspect database objects.
If your script scope is database
, Liquibase always takes a snapshot, so this prompt does not appear.
Note: The larger your database, the more performance impact a snapshot causes. If you cannot run a snapshot due to memory limitations, see Memory Limits of Inspecting Large Schemas.