feat(baseuri): add baseuri-range config property to control servers the Agent will register with

[andrewazores]

Fixes #242

ex. try patching the usual Cryostat smoketest script as follows:

diff --git a/smoketest.sh b/smoketest.sh
index 187c5a7e..409808e9 100755
--- a/smoketest.sh
+++ b/smoketest.sh
@@ -211,7 +211,8 @@ runDemoApps() {
         --env CRYOSTAT_AGENT_WEBSERVER_HOST="localhost" \
         --env CRYOSTAT_AGENT_WEBSERVER_PORT="9977" \
         --env CRYOSTAT_AGENT_CALLBACK="http://localhost:9977/" \
-        --env CRYOSTAT_AGENT_BASEURI="${protocol}://localhost:${webPort}/" \
+        --env CRYOSTAT_AGENT_BASEURI_RANGE="loopback" \
+        --env CRYOSTAT_AGENT_BASEURI="${protocol}://cryostat:${webPort}/" \
         --env CRYOSTAT_AGENT_TRUST_ALL="true" \
         --env CRYOSTAT_AGENT_AUTHORIZATION="Basic $(echo user:pass | base64)" \
         --env CRYOSTAT_AGENT_HARVESTER_PERIOD_MS=60000 \

then do podman logs -f quarkus-test-agent-1. This should produce log output like:

podman logs -f quarkus-test-agent-1 
Starting the Java application using /opt/jboss/container/java/run/run-java.sh ...
INFO exec  java -Dquarkus.http.host=0.0.0.0 -Djava.util.logging.manager=org.jboss.logmanager.LogManager -Dcom.sun.management.jmxremote.port=9097 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -javaagent:/deployments/app/cryostat-agent.jar -XX:+UseParallelGC -XX:MinHeapFreeRatio=10 -XX:MaxHeapFreeRatio=20 -XX:GCTimeRatio=4 -XX:AdaptiveSizePolicyWeight=90 -XX:+ExitOnOutOfMemoryError -cp "." -jar /deployments/quarkus-run.jar 
SLF4J: Class path contains multiple SLF4J providers.
SLF4J: Found provider [io.cryostat.agent.shaded.org.slf4j.simple.SimpleServiceProvider@26a1ab54]
SLF4J: Found provider [io.cryostat.agent.shaded.org.slf4j.jul.JULServiceProvider@3d646c37]
SLF4J: See https://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual provider is of type [io.cryostat.agent.shaded.org.slf4j.simple.SimpleServiceProvider@26a1ab54]
2023-11-06 17:28:51:662 +0000 [cryostat-agent-main] INFO io.cryostat.agent.Agent - Cryostat Agent starting...
2023-11-06 17:28:51:713 +0000 [cryostat-agent-main] ERROR io.cryostat.agent.Agent - Agent startup failure
java.lang.IllegalArgumentException: cryostat.agent.baseuri of "https://cryostat:8181/" is unacceptable with URI range "LOOPBACK"
	at io.cryostat.agent.Agent.main(Agent.java:56)
	at io.cryostat.agent.Agent.lambda$agentmain$2(Agent.java:143)
	at java.base/java.lang.Thread.run(Thread.java:833)
__  ____  __  _____   ___  __ ____  ______ 
 --/ __ \/ / / / _ | / _ \/ //_/ / / / __/ 
 -/ /_/ / /_/ / __ |/ , _/ ,< / /_/ /\ \   
--\___\_\____/_/ |_/_/|_/_/|_|\____/___/   
2023-11-06 17:28:52,195 INFO  [io.quarkus] (main) quarkus-test 1.0.0-SNAPSHOT on JVM (powered by Quarkus 2.7.2.Final) started in 0.456s. Listening on: http://0.0.0.0:10010
2023-11-06 17:28:52,195 INFO  [io.quarkus] (main) Profile prod activated. 
2023-11-06 17:28:52,196 INFO  [io.quarkus] (main) Installed features: [cdi, rest-client, rest-client-jackson, resteasy, smallrye-context-propagation, vertx]
2023-11-06 17:29:01,889 INFO  [io.quarkus] (Shutdown thread) quarkus-test stopped in 0.015s

indicating that the Agent instance has refused to start because the server base URI provided uses the hostname cryostat, which the Agent cannot guarantee resolves to an address in the specified LOOPBACK range.

If the smoketest script is not patched to override the baseuri-range then the Agent instances fall back to the default DNS_LOCAL range from this patch, which will accept the smoketest's normal localhost value, as well as values like $HOSTNAME.local or dummy.localhost.

[ebaron]

Looks good!