Unrecoverable error in TUI install using all default choices

[ydirson]

When making an install with v10.10.8 and selecting all default choices in the TUI, during installation the user is presented with a 'NoneType' object is not iterable error and can only reboot.

The log shows it happens in rewriteNTPConf while attempting to iterate on ntp_servers.

Cannot guess the source while just looking at the NTP rework patch, and cannot bisect it either: that big commit doing several things demonstrates the value of splitting into individual commits (eg. "Replace time-config-method with ntp-config-method to prepare for DHCP support", "Separate NTP servers manual selection into a separate dialog", "Introduce option to get NTP servers from DHCP", and likely more that whose need would naturally arise as separate from those 3 main topics during careful review if the patches).

Likely linked with #64.

[alexbrett]

I believe this is fixed by a9a5901

[ydirson]

Right, I just stumbled on it, by diffing the source in the latest xs8 install ISO.

[ydirson]

Doesn't that makes #62 a good idea? ;)

[ydirson]

Still, I would have valued an explanation in the fix commit, explaining why this can be None (it does not even say it is protecting against None, BTW). Everywhere in the code answers['ntp-servers'] seems to be assigned an iterable value: this additional check seems to just be hiding the source of the problem rather than fixing it.

[GeraldEV]

Apologies, this was fixed/worked-around in a rush to meet a deadline, it was resolved in this PR https://github.com/xenserver/host-installer/pull/60/files
I've not yet had time to investigate the root cause - as observed the paths through the installer would seem to set it properly and yet the issue still occurred

[ydirson]

I've not yet had time to investigate the root cause - as observed the paths through the installer would seem to set it properly and yet the issue still occurred

Yes, as it is, it is not easy to test changes. We should really put our thoughts towards getting automated tests on this codebase.

Note I have a done some time ago a prototype that allows to manually test UI changes by running some of the code locally (told @bernhardkaindl about that). Certainly limited and not suited to running automatically - just ideas.