ContainerGebSpec.download* methods fails with UnknownHostException

[matrei]

Caused by: java.net.UnknownHostException: host.testcontainers.internal
	at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:572)
	at java.base/java.net.Socket.connect(Socket.java:633)
	at java.base/java.net.Socket.connect(Socket.java:583)
	at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:183)
	at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:533)
	at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:638)
	at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:281)
	at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:386)
	at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:408)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1323)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1256)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1142)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1071)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1701)
	at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1625)
	at geb.download.DefaultDownloadSupport.downloadStream_closure1(DefaultDownloadSupport.groovy:73)
	at geb.download.DefaultDownloadSupport.wrapInDownloadException(DefaultDownloadSupport.groovy:221)
	... 3 more

[matrei]

The reason for this is that the connections from the download*() methods are not made from within the container. They are made from the host system.

You can override the base and uri directly when invoking the method, to make it work:

downloadBytes([base: "http://localhost:$serverPort", uri: '/json/index'])

However, this is not the best user experience.

I have not yet found a way to switch out the default DownloadSupport implementation DefaultDownloadSupport, to another implementation that resolves the URI:s correctly when using ContainerGebSpec.