Usage

this program expects a property file in ${HOME}/Desktop/test.properties containing values like this:

spring.datasource.url=jdbc:postgresql://localhost:5430/a
spring.datasource.password=a
spring.datasource.username=a
# spring.datasource.url=jdbc:postgresql://localhost:5431/b
# spring.datasource.password=b
# spring.datasource.username=b

You'll need two databases to see the refresh work. Use docker compose up in the root directory to spin up two PostgreSQL instances.

Ensure that you have the same table, customer, in both. Insert different records to verify that things are working.

create table customer(
    id serial primary key, 
    name varchar(255) not null
);

You can connect to the a PostgreSQL instance using psql thusly:

PGPASSWORD=a psql -U a -h localhost -p 5430 a

You can connect to the b PostgreSQL instance using psql thusly:

PGPASSWORD=b psql -U b -h localhost -p 5431 b

In the a database, run:

insert into customer(name) values('afitz');

In the b database, run:

insert into customer(name) values('rwang');

Load the application and then hit the /customers endpoint to see values in the first database. Uncomment the configuration for the alternate database, b, and then comment out the configuration for the first database, a.

Trigger the refresh endpoint:

curl -d{} -H"content-type: application/json" http://localhost:8080/actuator/refresh

The app should now be pointing to the alternate DataSource. Verify as much by refreshing the http://localhost:8080/customers endpoint

Formatting

This demonstration uses the Spring Javaformat Maven plugin. It can format your Java code in a consistent way, allowing you to focus on the stuff that matters, not things like tabs vs spaces, etc.

Use it thusly to format the code:

mvn spring-javaformat:apply

It'll stop the build if it detects that the source code has not been formatted correctly.

joshlong-attic/refreshable-vault-config-2022-08-23

Usage

Formatting