What is a Flow file?

Organization

The Flow File contains one or more Stages and Actions. Below are their definitions and a visual aid.

Stages are bundles of related actions in the Flow File. You can add a single action or multiple actions per Stage.

Actions are individual Liquibase Commands or Shell Commands that execute within stages or endStage as part of the Flow File. Any Liquibase command arguments (abbreviated as cmdArgs in the Flow File) can be placed in any action section, with the exception of the global arguments shown in the Incompatible commands and global arguments section below.

Syntax

The Liquibase Flow File is written in YAML. To run Liquibase commands in actions, set the type argument for that action to liquibase. To run shell commands in actions, set the type argument for that action to shell.

Command arguments use the following format:

cmdArgs: {argument: value, snapshot-format: JSON}

This example Flow File is the simplest scenario in which only cmdArgs are specified in the actions:

## Note: Any command which fails in any stage below result in the command stopping, and endStage being run. ## A flow file can have one or more stages, each with multiple "actions", ## or your flow file can have multiple stages with fewer actions in each stage. stages: ## The first stage of actions. Default: actions: # Policy Checks for changelog - type: liquibase command: checks run cmdArgs: {checks-scope: changelog} continueOnError: true #Continue flow execution if this command fails. if: 'exitCode == 4' # Flow failed with an exit command, but continue-on-error is true # Exit code is 4 so checks run will execute # Run the update - type: liquibase command: update # Policy Checks for database - type: liquibase command: checks run cmdArgs: {checks-scope: database} ## The endStage ALWAYS RUNS. ## So put actions here which you desire to perform, whether previous stages' actions succeed or fail. ## If you do not want any actions to ALWAYS RUN, simply delete the endStage from your flow file. endStage: actions: - type: liquibase command: history

Note: For this example to run, a changelog file and a liquibase.properties file with url, username, and password must be available. The liquibase.properties file should be in the same directory as the flow file.

Validation

Once the Flow File is written, you can verify that it works by using the flow validate command. This ensures that the Liquibase commands have all of the parameters necessary to run successfully, and the YAML formatting is correct. See the Syntax section below for more information. In the CLI, run this command:

flow validate --flow-file=update-status-diff.flowfile.yaml

If the file fails the validation check, Liquibase will state what command argument(s) were not resolved. You can then review and correct your Flow File, and then run the flow validate command again to ensure it is working as expected.

Outside the CLI, you can use the LIQUIBASE_COMMAND_FLOW_FILE environment variable or the liquibase.command.flowFile property.

Incompatible commands and global arguments

You must use the following commands and global arguments in the CLI instead of the Flow File:

Incompatible commands

• init start-h2

  – This command locks the console

Incompatible global arguments

• ARGUMENT_CONVERTER

• CLASSPATH

• DEFAULTS_FILE

• INCLUDE_SYSTEM_CLASSPATH

• LOG_CHANNELS

• LOG_FILE

• LOG_LEVEL

• MONITOR_PERFORMANCE

• PROMPT_FOR_NON_LOCAL_DATABASE

• SEARCHPATH

• SHOULD_RUN

• SHOW_BANNER