[Enhancement]: JdbcDatabaseContainer - Improve ``waitUntilContainerStarted``

[AB-xdev]

Module

Core

Proposal

Currently https://github.com/testcontainers/testcontainers-java/blob/7d8301903a6b45591605fd376702d24fc878a61d/modules/jdbc/src/main/java/org/testcontainers/containers/JdbcDatabaseContainer.java#L176-L216 behaves very weird and this also impacts performance:

• It doesn't utilize WaitStrategy and completely ignores/overrides it
• It constantly tries to query if the container is running or builds database connections (these are very costly in terms of CPU usage)
  • These attempts use a hardcoded throttling value of 100ms and completely ignore the RateLimiter of WaitStrategy

I would propose that you use - as in all other containers - the WaitStrategy.

• Remove the override/method JdbcDatabaseContainer#waitUntilContainerStarted
• Create a custom WaitStrategy called JDBCWaitStrategy. It could look like this:

  class JDBCWaitStrategy extends AbstractWaitStrategy
  {
  	@Override
  	protected void waitUntilReady()
  	{
  		if(!(this.waitStrategyTarget instanceof final JdbcDatabaseContainer<?> container))
  		{
  			throw new IllegalArgumentException(
  				"Container must implement JdbcDatabaseContainer");
  		}
  
  		try
  		{
  			Unreliables.retryUntilTrue(
  				(int)this.startupTimeout.getSeconds(),
  				TimeUnit.SECONDS,
  				() -> this.getRateLimiter().getWhenReady(() -> {
  					try(final Connection connection = container.createConnection("");
  						final Statement statement = connection.createStatement())
  					{
  						return statement.execute(container.getTestQueryString());
  					}
  				})
  			);
  		}
  		catch(final TimeoutException e)
  		{
  			throw new ContainerLaunchException(
  				"JDBCContainer cannot be accessed by (JDBC URL: "
  					+ container.getJdbcUrl()
  					+ "), please check container logs");
  		}
  	}
  }
  

• Use the following default WaitStrategy for JDBCDatabaseContainer:

  new WaitAllStrategy()
  	.withStrategy(Wait.defaultWaitStrategy())
  	.withStrategy(new JDBCWaitStrategy())
  

Full example implementation:

• https://github.com/xdev-software/tci-base/blob/13ca7984f6a732981cbd1912d9535076969004fa/tci-advanced-demo/tci-db/src/main/java/software/xdev/tci/demo/tci/db/containers/WaitableJDBCContainer.java
• https://github.com/xdev-software/tci-base/blob/13ca7984f6a732981cbd1912d9535076969004fa/tci-advanced-demo/tci-db/src/main/java/software/xdev/tci/demo/tci/db/containers/DBContainer.java

[vlsi]

JDBC has a standard API: java.sql.Connection#isValid, so it would probably be a better choice by default.