How do placeholders work in Flyway?

Question

I'm evaluating Flyway for use in my project. Our current SQL scripts contain placeholders for things like URLs which will have a different domain names depending on the environment (dev, qa, prod).

Specifically, we might have INSERT statements like

INSERT INTO FEED VALUES ('app.${env.token}.company.org/feed1', 'My Feed');

${env.token} needs to be replaced with 'dev', 'qa', or 'prod'.

We have about 50 different properties that could potentially need replacement in SQL scripts. The properties all reside in one or two properties files.

Is there a way to run the Flyway Ant migration task so that it pulls the replacement tokens and values from a properties file? Something along the lines of the Ant filter task?

Answer 1

Currently when supplying placeholders as properties, the property name should be prefixed with flyway.placeholders.

For example the ${env.token} placeholder can be specified directly as this Ant property: flyway.placeholders.env.token

There is currently no support for passing a property file directly, without using prefixes for the property names. Feel free to raise an issue in the Issue Tracker. :-)

Answer 2

If the token was subdomain:

INSERT INTO FEED VALUES ('app.${subdomain}.company.org/feed1', 'My Feed');

The values in flyway.conf:

flyway.url=jdbc:mydb://db
flyway.user=root
flyway.schemas=schema1
flyway.placeholders.subdomain=example

Or command line:

flyway -url=jdbc:mydb://db -user=root -schemas=schema1 -placeholders.subdomain=example migrate

Would run the script as:

INSERT INTO FEED VALUES ('app.example.company.org/feed1', 'My Feed');

Answer 3

From my experience, it's much easier to use environment variables instead of CLI or config file (especialy when using docker and k8s).

You can use environment variables in the following format -

export FLYWAY_PLACEHOLDERS_USER=${USER}

Then in you sql statement, use this variable like this -

INSERT INTO tmptable (user)
VALUES ('${user}')

read more about environment variables here

Answer 4

Maven version:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
        <plugin>
            <groupId>org.flywaydb</groupId>
            <artifactId>flyway-maven-plugin</artifactId>
            <configuration>
                <url>jdbc:mysql://localhost/cloud</url>
                <user>root</user>
                <password>root</password>
                <placeholderReplacement>false</placeholderReplacement>
            </configuration>
            <dependencies>
                <dependency>
                    <groupId>mysql</groupId>
                    <artifactId>mysql-connector-java</artifactId>
                    <version>${mysql.version}</version>
                    <scope>runtime</scope>
                </dependency>
            </dependencies>
        </plugin>
    </plugins>
</build>