Smartsense view displays "Service Unavailable" "The SmartSense service is currently unavailable. Please make sure the SmartSense Server is up and running" after Ambari upgrade

[#1]

(I think) this occurred after upgrading from Ambari 2.4.2 to 2.5.0.3 (only looked for this when on Ambari 2.5.1.0)

Here are the messages in SmartSense View

Found these messages in /var/log/ambari-server/ambari-server.log when clicking on launch SmartSense View

14 Jul 2017 11:14:05,523 ERROR [ambari-client-thread-467377] ServerProxy:162 - Failed to execute GET /recommendations. Reason: Connection refused
14 Jul 2017 11:14:13,695 ERROR [ambari-client-thread-467507] ServerProxy:162 - Failed to execute GET /context. Reason: Connection refused
14 Jul 2017 11:14:14,900 ERROR [ambari-client-thread-467507] ServerProxy:162 - Failed to execute GET /checkconfig. Reason: Connection refused

Diff'ing current hst-server.ini versus a previous (think it was from Ambari 2.4.2) yields

# diff conf/hst-server.ini conf_13_04_17_04_17.save/
2,4d1
< enable.flex.subscription = false
< smartsense.id=X-00000000-X-00000000
< flex.subscription.id =
6a4
> smartsense.id=X-00000000-X-00000000
27,28d24
< url = http://:9000
< max.heap = 2048
30d25
< run.as.user =
33d27
< version = 1.4.0.2.5.0.3-7
52,57d45
< [recommendation]
< auto.download.interval = 300
< feedback.push.maxentries = 50
< feedback.push.interval = 1800
< expiry = 30
<

The issue was the missing HST server name in the [server] url property (ie server.url in Ambari if you can find it - this was the issue - and still is - this ghosted into and then out of view in Ambari SmartSense Config tab)

Managed to change the server.url property to http://<hst server name>:9000 in Ambari (when it reappeared)

Restarted SmartSense server

And retried the SmartSense view and it now works fine.

TBC - work out why server.url property is not always visible in the SmartSense Config tabs all the time.

[#2]

It all depends on the SS version. In latest versions (> 1.3.1), cluster property is used for the url. This property will be set properly only for manual url entry.