Bug 1261736 - containers running on node can not resolve internal service name when setting up native master HA using haproxy as LB
containers running on node can not resolve internal service name when setting...
Product: OpenShift Container Platform
Classification: Red Hat
Component: Installer (Show other bugs)
Unspecified Unspecified
medium Severity medium
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Assigned To: Andrew Butcher
Ma xiaoqiang
Depends On:
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Reported: 2015-09-10 01:45 EDT by Johnny Liu
Modified: 2016-07-03 20:46 EDT (History)
7 users (show)

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Doc Type: Bug Fix
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Last Closed: 2015-11-20 10:42:31 EST
Type: Bug
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RHEL 7.3 requirements from Atomic Host:
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Description Johnny Liu 2015-09-10 01:45:13 EDT
Description of problem:
Use https://github.com/detiber/openshift-ansible -b next-ha to set up a mutli-masters HA env. 

In the env, a haproxy LB will take over master api role as frontend which is listening at 8443, the real masters will be backend of the LB. 

In some use cases, containers running on nodes need resolve internal service name, skydns (which is running together with master api) could resolve these internal service names, "dnsIP" setting in node yaml config file should be pointed to the skydns IP so that containers know where to resolve them. 

In current installation, the "dnsIP" is being pointed to the LB's IP, it is not real master, there is no skydns service is running, so containers running on nodes can not resolve service name.

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Comment 2 Brenton Leanhardt 2015-09-30 09:27:30 EDT
This is related to https://bugzilla.redhat.com/show_bug.cgi?id=1242961#c9 and the work Andrew is doing to have resolv.conf on the Nodes point to the kubernetes Service.
Comment 3 Andrew Butcher 2015-11-02 11:00:06 EST
Node configuration will use the master service address as the node dns ip.

Comment 4 Johnny Liu 2015-11-03 05:38:18 EST
Verified this bug with AtomicOpenShift/3.1/2015-11-02.1 puddle and https://github.com/abutcher/openshift-ansible -b native-ha, PASS.

# oc get svc kubernetes
NAME         CLUSTER_IP   EXTERNAL_IP   PORT(S)                 SELECTOR   AGE
kubernetes   <none>        443/TCP,53/UDP,53/TCP   <none>     4h

# grep dnsIP /etc/origin/node/node-config.yaml 

# docker exec -ti 09744e8e6f2b /bin/sh
sh-4.2$ cat /etc/resolv.conf 
search jialiu.svc.cluster.local svc.cluster.local cluster.local openstacklocal lab.eng.nay.redhat.com
options ndots:5
sh-4.2$ curl simple-openshift-sinatra:8080
Hello, Sinatra!

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