Jupyter ceased to work: jupyter could not be resolved (3: Host not found)

Technical Help
#1

Jupyter is not active anymore.
The error in the log is:

quantrocket_houston_1|2018/02/17 12:16:39 [error] 9#9: *69 jupyter could not be resolved (3: Host not found), client: 172.18.0.1, server: , request: "GET /jupyter HTTP/1.1", host: "localhost:1969"

The result of a ping to Houston is postive:

$ quantrocket houston ping
msg: hello from houston
#2

Sounds like the Jupyter container is not running, which you can confirm by running docker ps. You can bring it back up with:

docker-compose -p quantrocket up -d jupyter

As to why it disappeared in the first place...

#3

Thanks a lot, Brian.
That solved the problem!

No idea, why it disappeared in the first place…

#4

Jupyter stopped again to run and I needed the restart it with the command above.
Where should I look to understand why this happens?

#5

Part of the explanation is that the YAML file that was being produced by the website did not have restart: always for the jupyter service like it does for other services. This was an oversight (which has been corrected). As for why Docker would need to restart jupyter, it would need to if you rebooted the host for example. Or if jupyter crashed for some reason, in which case I would check if there's anything in the logs.

You can update your YAML file to the following to avoid the manual step:

  jupyter:
    image: 'quantrocket/jupyter:4.4.0.8'
    volumes_from:
      - codeload
    restart: always

Then redeploy jupyter with the above command.