SolrException: Error trying to proxy request for url

[#1]

When using search through Hue we see this error where the HOST is not a valid solr server.  Someone had installed Solr a while back and then removed it and re-installed again later so there maybe some left overs not cleand up but we don't know where to look:

null:org.apache.solr.common.SolrException: Error trying to proxy request for url: http://HOST:8983/solr/[collection XXX]/yyyy
at org.apache.solr.servlet.SolrDispatchFilter.remoteQuery(SolrDispatchFilter.java:707)
at org.apache.solr.servlet.SolrDispatchFilter.httpSolrCall(SolrDispatchFilter.java:395)
at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:260)
at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:254)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.solr.servlet.SolrHadoopAuthenticationFilter$2.doFilter(SolrHadoopAuthenticationFilter.java:408)
at org.apache.hadoop.security.authentication.server.AuthenticationFilter.doFilter(AuthenticationFilter.java:631)
at org.apache.hadoop.security.token.delegation.web.DelegationTokenAuthenticationFilter.doFilter(DelegationTokenAuthenticationFilter.java:301)
at org.apache.hadoop.security.authentication.server.AuthenticationFilter.doFilter(AuthenticationFilter.java:579)
at org.apache.solr.servlet.SolrHadoopAuthenticationFilter.doFilter(SolrHadoopAuthenticationFilter.java:413)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:610)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:503)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.http.conn.HttpHostConnectException: Connection to http://host:8983refused
at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:190)
at org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:294)
at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:643)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:479)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:906)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:805)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:784)
at org.apache.solr.servlet.SolrDispatchFilter.remoteQuery(SolrDispatchFilter.java:679)
... 22 more
Caused by: java.net.ConnectException: Connection refused (Connection refused)
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:127)
at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180)
... 29 more

[#2]

It is usually caused by a wrong solr url configured somewhere in HUE, you can try to correct it:

1) Check if any one has a safety value configured in HUE -> Configuration -> "Hue Service Advanced Configuration Snippet (Safety Valve) for hue_safety_valve.ini"

2) Make sure Solr is selected as a depency service in HUE -> Configuration -> Solr.

3) If above still does not resovle your issue, try to overide solr url with a correct (protocal, host, port) by following :

a) Verify the solr URL, Solr -> Instance -> any one of the Solr instance -> Solr Server -> Solr Server Web UI. Note the url, and we will use it in next step.

b) Use a safety value for solr url in HUE -> Configuration -> search for "Hue Service Advanced Configuration Snippet (Safety Valve) for hue_safety_valve.ini", add:

[search]
## URL of the Solr Server
solr_url=http://hostname:port/solr

 Restart your HUE server.

[#3]

We have validated the safety valve, as well as the solr URL.  It seems that someone had deployed some examples a long timago and never cleaned them up so we had old information stored in collections listed in zookeeper.  We deleted those and ran solrctrl init --force and that seemed to resolve the issue.  We still however see the old dashboard entries in the search menu in Hue and they remain even after deleting them from the Hue database.  We have an open case now for it.