[jboss-jira] [JBoss JIRA] (JGRP-2363) DNS Ping cannot lookup SRV record for service port

[Howard Gao (Jira)]

    [ https://issues.jboss.org/browse/JGRP-2363?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13761673#comment-13761673 ] 

Howard Gao commented on JGRP-2363:
----------------------------------

upstream ref:

https://github.com/jboss-openshift/openshift-ping/issues/45




> DNS Ping cannot lookup SRV record for service port
> --------------------------------------------------
>
>                 Key: JGRP-2363
>                 URL: https://issues.jboss.org/browse/JGRP-2363
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 4.0.20
>            Reporter: Howard Gao
>            Assignee: Bela Ban
>            Priority: Major
>
> I've got a problem regarding getting service port in DNS_PING DNS lookup.
> It seems in my openshift environment the JNDI DNS lookup cannot query the
> correct SRV record from the openshift DNS server. Ref:
> https://github.com/jboss-openshift/openshift-ping/blob/1.2.1.Final/dns/src/main/java/org/openshift/ping/dns/GetServicePort.java#L48
> For example, here is the ping service:
> apiVersion: v1
> kind: Service
> metadata:
> annotations:
> description: The JGroups ping port for clustering.
> service.alpha.kubernetes.io/tolerate-unready-endpoints: 'true'
> labels:
> application: application0
> template: amq-broker-73-persistence-clustered
> xpaas: 1.4.16
> name: application0-ping
> spec:
> clusterIP: None
> publishNotReadyAddresses: true
> ports:
>     port: 8888
>     protocol: TCP
>     name: jgroup-port
>     targetPort: 8888
>     selector:
>     deploymentConfig: application0-amq
> After it is deployed I deployed a application pod
> with JGroups DNS_PING protocol loaded. The relevant
> jgroups xml part looks like this:
> <config> ... <openshift.DNS_PING timeout="3000" serviceName="application0-ping" /> ... </config>
> After my application pod is in running state, I checked the log
> and there is a warning message from DNS_PING:
> 2019-07-22 04:16:59,600 INFO [org.openshift.ping.common.Utils] 3 attempt(s) with a 1000ms sleep to execute [GetServicePort] failed. Last failure was [java.lang.NullPointerException: null]
> 2019-07-22 04:16:59,601 WARNING [org.jgroups.protocols.openshift.DNS_PING] No DNS SRV record found for service [application0-ping]
> After some debugging it turns out that the DNS lookup for the record by this name
> "_tcp.application0-ping" returned null.
> However if I logged into the application pod and do nslookup it will give me correct record:
> sh-5.0# nslookup -type=srv _tcp.application0-ping
> Server: 10.74.177.77
> Address: 10.74.177.77#53
> _tcp.application0-ping.default.svc.cluster.local service = 10 100 8888 44c84e52.application0-ping.default.svc.cluster.local.
> And you can get the full name from the record, which is
> _tcp.application0-ping.default.svc.cluster.local
> If I then pass the full qualified name into the application and it can query the SRV
> record successfully.
> I have no idea why my application can't query the record using the short form name (i.e. _tcp.application0-ping). Could it be some configuration issue for the DNS ping?
> My openshift env details are:
> oc v3.11.117
> kubernetes v1.11.0+d4cacc0
> features: Basic-Auth GSSAPI Kerberos SPNEGO
> and the java version used in pod:
> sh-5.0# java -version
> openjdk version "1.8.0_212"
> OpenJDK Runtime Environment (build 1.8.0_212-b04)
> OpenJDK 64-Bit Server VM (build 25.212-b04, mixed mode)
> and the base OS is fedora 30.



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