Improve ToxiProxyContainer test and docs

[eddumelendez]

Current implementation exposed utilities to handle ToxiProxyClient
and proxies. However, there are some issues which demonstrate that
the container class is coupled to the client. Tests and docs have
been updated in order to promote the usage of its own ToxiProxyClient.
Also, a note about the number of ports reserved by Testcontainers
is added.

[kiview]

I think it's exactly the right thing to do, making the usage more idiomatic and also less confusing.

[kiview]

This is so opinionated 😅

[eddumelendez]

just documenting for existing support and avoiding breaking changes.

[kiview]

Should we add to the Javadoc the deprecation comment, to use the Toxiproxy client directly instead?

[perlun]

Note: the MR title/release notes are a bit misleading here. Since ToxyproxyContainer.getProxy() was now deprecated this might actually break the build for projects relying on -Werror (treat warnings as errors).

The workaround if your code to extract some of the code that previously has been available in ToxiproxyContainer into your own code (perhaps as static helper methods). Something like this:

// Previously handled by ToxiproxyContainer, but since
// ToxiproxyContainer#getProxy(GenericContainer<?>, int) is now deprecated, we need to take care
// of the port handling ourselves. See https://github.com/testcontainers/testcontainers-java/pull/6065
// for details on the deprecation.
public static final int FIRST_PROXY_PORT = 8666;

// proxyPort should be between FIRST_PROXY_PORT and FIRST_PROXY_PORT+30
public static Proxy createProxy( ToxiproxyContainer toxiproxyContainer, String upstream, int proxyPort ) throws IOException {
    ToxiproxyClient toxiproxyClient = new ToxiproxyClient( toxiproxyContainer.getHost(), toxiproxyContainer.getControlPort() );

    return toxiproxyClient.createProxy(
            upstream,
            "0.0.0.0:" + proxyPort,
            upstream
    );
}

And then in your calling code, do something like this in your test to add a toxic:

proxy.toxics().timeout( "infinite-upstream-timeout", ToxicDirection.UPSTREAM, 0 );

Remember to tear down the proxy after your test has executed:

@AfterEach
void tearDown() throws IOException {
    if ( proxy != null ) {
        proxy.delete();
    }
}

If your code relied on ToxyproxyContainer.setConnectionCut(), things are a bit complex but copy the following snippet to your helper class and you should be covered:

private static final Map<Proxy, Boolean> IS_CURRENTLY_CUT_MAP = new HashMap<>();

private static final String CUT_CONNECTION_DOWNSTREAM = "CUT_CONNECTION_DOWNSTREAM";
private static final String CUT_CONNECTION_UPSTREAM = "CUT_CONNECTION_UPSTREAM";

// Inspired by org.testcontainers.containers.ToxiproxyContainer.ContainerProxy#setConnectionCut,
// which is now deprecated.

/**
 * Cuts the connection by setting bandwidth in both directions to zero.
 *
 * @param shouldCutConnection true if the connection should be cut, or false if it should be re-enabled
 */
public static void setConnectionCut( Proxy proxy, boolean shouldCutConnection ) {
    try {
        if ( shouldCutConnection ) {
            proxy.toxics().bandwidth( CUT_CONNECTION_DOWNSTREAM, ToxicDirection.DOWNSTREAM, 0 );
            proxy.toxics().bandwidth( CUT_CONNECTION_UPSTREAM, ToxicDirection.UPSTREAM, 0 );
            IS_CURRENTLY_CUT_MAP.put( proxy, true );
        }
        else if ( IS_CURRENTLY_CUT_MAP.getOrDefault( proxy, false ) ) {
            proxy.toxics().get( CUT_CONNECTION_DOWNSTREAM ).remove();
            proxy.toxics().get( CUT_CONNECTION_UPSTREAM ).remove();
            IS_CURRENTLY_CUT_MAP.put( proxy, false );
        }
    }
    catch ( IOException e ) {
        throw new RuntimeException( "Could not control proxy", e );
    }
}

@eddumelendez Before the deprecated method(s) are dropped completely (in 2.0?), it would perhaps be worth adding more about this migration path somewhere, to help people moving away from the deprecated methods. 👍