Bug 1418153

Summary:	[DOCS] Integrating external services
Product:	OpenShift Container Platform	Reporter:	Miheer Salunke <misalunk>
Component:	Documentation	Assignee:	brice <bfallonf>
Status:	CLOSED CURRENTRELEASE	QA Contact:	zhaozhanqi <zzhao>
Severity:	high	Docs Contact:	Vikram Goyal <vigoyal>
Priority:	high
Version:	3.2.1	CC:	aos-bugs, jokerman, misalunk, mmccomas
Target Milestone:	---
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Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	3.7-release-plan
Fixed In Version:		Doc Type:	If docs needed, set a value
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Last Closed:	2017-09-19 03:37:36 UTC	Type:	Bug
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Embargoed:

Description Miheer Salunke 2017-02-01 02:48:01 UTC

Document URL:

https://docs.openshift.com/container-platform/3.4/dev_guide/integrating_external_services.html

Section Number and Name:

Describe the issue:

The Kubernetes 1.4 API was updated to support specifying external names in a headless service specification, which allows the DNS service to automatically inject a CNAME mapping the service name directly to an outside DNS address, bypassing the need for endpoint records.

This is an awesome feature that removes a lot of pain involved with integrating to external services. Does OCP 3.4 have support for using this at all?

If it does can the documentation be updated to indicate this fact?

Looking at https://github.com/kubernetes/kubernetes/issues/13748
the functionality I described is used to create headless services that use a DNS name rather then am IP address. Kubernetes from version 1.4 supports this technique (at the API level, (some commandline/UI support was left off to 1.5+) . OCP 3.4 is supposed to be based off Kubernetes 1.4 . OCP 3.4 documentation has no documentation on using this technique at all. This is a very useful technique.

Suggestions for improvement:

Support for ExternalName was added here: https://github.com/openshift/origin/pull/11790 and https://github.com/openshift/origin/pull/11798. This will be in OCP 3.4.

We still use SkyDNS and do not currently use kube-dns.

Minor point - kubeDNS uses skydns as do we. We just don't implement it the way they do, instead distributing it throughout the cluster for resilience and latency.

Additional information:

Comment 1 Miheer Salunke 2017-02-01 02:50:06 UTC

Related BZ -> https://bugzilla.redhat.com/show_bug.cgi?id=1409240

Comment 2 brice 2017-09-01 04:02:56 UTC

PR created for this BZ:

https://github.com/openshift/openshift-docs/pull/5145

The feature was documented in the Integrating Services Topic, but needed a little more context.

Miheer, please let me know if what's there is not fulfilling this BZ.

Comment 3 openshift-github-bot 2017-09-15 00:27:12 UTC

Commit pushed to master at https://github.com/openshift/openshift-docs

https://github.com/openshift/openshift-docs/commit/21c0699790f29b77f3a2cce60e82ec450aa16e1b
Merge pull request #5145 from bfallonf/int_ext_ser_1418153

Bug 1418153 Added information about externalname to external services topic

Comment 4 Miheer Salunke 2017-09-19 03:13:59 UTC

looks good

Comment 5 brice 2017-09-19 03:37:36 UTC

Thanks.

Link to released docs:

https://access.redhat.com/documentation/en-us/openshift_container_platform/3.6/html-single/developer_guide/#defining-a-service-for-an-external-database