close http-connection on internal server error from broker

[rdhabalia]

Motivation

By default AsyncHttpClient has Keep-alive enabled and it get connected to the bad-broker then client repeatedly fails to perform lookup requests. In that case, connection should be closed and client should be able to connect with other broker to get the request served.

eg: sometimes broker is not able to create zk-session and it keeps failing to authenticate client-request so, client should be redirected to other broker by closing client-side connection on broker's InternalServerError

WARN  c.y.p.b.a.AuthorizationManager       - Client  with Role - my-role failed to get permissions for destination - persistent://property/cluster/ns/topic-1
org.apache.zookeeper.KeeperException$SessionExpiredException: KeeperErrorCode = Session expired for /admin/policies/property/cluster/ns
:
at com.yahoo.pulsar.broker.admin.PersistentTopics.getPartitionedMetadata(PersistentTopics.java:359) [pulsar-broker-1.15.7.jar:na]

Modifications

add KeepAliveStrategy in httpClient to disable keep-alive after internalServerError.

Result

AsyncHttpClient should close the connection on InternalServerError

[merlimat]

Could we also set the closing of the HTTP session on the server side? When Jetty catches the exception is maybe possible to force it to use Connection: close in the response itself.