Karamel UI getting connected/disconnected multiple times automatically while installing HopsWorks

I am installing hopsworks on an Azure VM which is configured with private end points. I chose to do Single Machine cluster set up/installation. (By default Karamel UI runs on 9090 port).

I am able to connect to ipaddress:port where Karamel UI runs (from my local machine - through port forwarding rules). it opens the Karamel UI, but the issue with Karamel UI is that, the status button (Connected/Disconnected) on top right banner is fluctuating. sometime it is connected and after that it goes disconnected even though Karamel UI web service is running on the VM.

Any help is greatly appreciated. Thank you,

Hi @km805u,

Usually the Karamel UI gets marked as Disconnected if the Karamel UI can’t reach the backend or when the installation is done.

Did you manage to get to the “terminal” page with the list of running recipes? Also, do you see any error in the installation.log ?


I see stacktrace of HTTP requests from my IP.

like below.
“GET /karamel/thirdparties/css/angular-block-ui.css.map HTTP/1.1” 200 - “http://x.x.x.x:8088/index.html” “Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36” 2

But still Karamel UI is getting disconnected continuously.
When I do telnet x.x.x.x 8088 - Its getting connected successfully everytime.

I did get error with elastic::default installation- trying to connect to like below.

The server its referring to is hostname of the particular ip.

Oh, now I see what’s going on. There is a (quite stupid) bug in the Karamel frontend.
Use the port 9090 on your machine as well and the UI will work ( so -L 9090:localhost:9090 )

Hello Fabio,
Basically, I am working on an Azure VM where private endpoints are configured, so we have to use mapped ports. (target port)
8088 redirects to 9090.
which is why I am using 8088, and the ip I am using here “http://x.x.x.x:8088/index.html” is private end point.
and public & private ip of Azure VM are different from x.x.x.x.

I wanted to confirm whether the Forward/Reverse DNS are working properly with this Azure VM, so I did the following.

Ran this command - dig h1.internal.cloudapp.net
It resolved to {privateIP} address
after that, - dig -x {privateIP},
it resolved to two addresses h1.internal.cloudapp.net and h1.xxx.xxx.com, in the same order

While running hopsworks installation - I provided h1.internal.cloudapp.net as Reverse Proxy because suspected one is h1.xxx.xxx.com, and I provided http proxy as well.

So, Does this extra layer of security causing the issue? if so, what are the changes need to make in installer.yaml file?

or is there any other changes need to be done.

Update to the Question: Karamel is showing empty screen as attached file.
It’s not taking cluster configurations automatically.

@km805u - We fixed the UI bug and made a new release of Karamel so that you can have any port on your machine.

Can you run the purge command, make sure that the karamel-0.6 directory is gone as well, and try again?

Also you opened several threads with different issues and I’m not sure what is solved and what you still need help with. Could we stick to this thread only?


Hello Fabio,
Sorry for multiple threads, I closed/flagged other threads I have opened. I am still at Karamel UI issue.

When I do “telnet x.x.x.x 8088” from my local terminal (x.x.x.x - Azure private end point IP and 8088 is a port which maps to target port 9090)
I am getting this.
Trying x.x.x.x…
Connected to x.x.x.x.
Escape character is ‘^]’.
Connection closed by foreign host.

(The port is running with Karamel on VM, as I checked with netstat -lntp | grep 9090, and I can able to do ssh successfully to x.x.x.x on 22)

Currently I am facing the exact issue which is stated in the below link (I am running from terminal),
Error installing in Azure VM Single Host.