graceful handling of common issues - check ppa format before engaging LP

[Christian Ehrhardt ]

This works:

$ ppa wait ppa:paelzer/lp-1975764-dpdk-mre-sept-2022

But many other close syntaxes that are just wrong could be typed accidentially, for example:

$ ppa wait ppa/paelzer/lp-1975764-dpdk-mre-sept-2022
Traceback (most recent call last):
  File "/usr/local/bin/ppa", line 4, in <module>
    __import__('pkg_resources').run_script('ppa-dev-tools==0.1.0', 'ppa')
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 656, in run_script
    self.require(requires)[0].run_script(script_name, ns)
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 1453, in run_script
    exec(code, namespace, namespace)
  File "/usr/local/lib/python3.10/dist-packages/ppa_dev_tools-0.1.0-py3.10.egg/EGG-INFO/scripts/ppa", line 533, in <module>
    sys.exit(main(args))
  File "/usr/local/lib/python3.10/dist-packages/ppa_dev_tools-0.1.0-py3.10.egg/EGG-INFO/scripts/ppa", line 522, in main
    return func(lp, config)
  File "/usr/local/lib/python3.10/dist-packages/ppa_dev_tools-0.1.0-py3.10.egg/EGG-INFO/scripts/ppa", line 434, in command_wait
    ppa = get_ppa(lp, config)
  File "/usr/local/lib/python3.10/dist-packages/ppa_dev_tools-0.1.0-py3.10.egg/EGG-INFO/scripts/ppa", line 203, in get_ppa
    return Ppa(
  File "/usr/local/lib/python3.10/dist-packages/ppa_dev_tools-0.1.0-py3.10.egg/ppa/ppa.py", line 70, in __init__
    assert team_name
AssertionError

[✗=1]─[paelzer@Keschdeichel ~/work/dpdk/deb_dpdk]──[289970]──[10:43 Do Sep 08]──(lp-1975764-MRE-Sept-2022-KINETIC)
$ ppa wait ppa:paelzer/lp-1975764-dpdk-mre-sept-2022/kinetic
Traceback (most recent call last):
  File "/usr/local/bin/ppa", line 4, in <module>
    __import__('pkg_resources').run_script('ppa-dev-tools==0.1.0', 'ppa')
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 656, in run_script
    self.require(requires)[0].run_script(script_name, ns)
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 1453, in run_script
    exec(code, namespace, namespace)
  File "/usr/local/lib/python3.10/dist-packages/ppa_dev_tools-0.1.0-py3.10.egg/EGG-INFO/scripts/ppa", line 533, in <module>
    sys.exit(main(args))
  File "/usr/local/lib/python3.10/dist-packages/ppa_dev_tools-0.1.0-py3.10.egg/EGG-INFO/scripts/ppa", line 522, in main
    return func(lp, config)
  File "/usr/local/lib/python3.10/dist-packages/ppa_dev_tools-0.1.0-py3.10.egg/EGG-INFO/scripts/ppa", line 437, in command_wait
    if not ppa.has_packages():
  File "/usr/local/lib/python3.10/dist-packages/ppa_dev_tools-0.1.0-py3.10.egg/ppa/ppa.py", line 222, in has_packages
    return list(self.archive.getPublishedSources()) != []
  File "/usr/local/lib/python3.10/dist-packages/ppa_dev_tools-0.1.0-py3.10.egg/ppa/ppa.py", line 96, in archive
    return owner.getPPAByName(name=self.ppa_name)
  File "/usr/lib/python3/dist-packages/lazr/restfulclient/resource.py", line 592, in __call__
    response, content = self.root._browser._request(
  File "/usr/lib/python3/dist-packages/lazr/restfulclient/_browser.py", line 429, in _request
    raise error
lazr.restfulclient.errors.BadRequest: HTTP Error 400: Bad Request
Response headers:
---
-content-encoding: gzip
connection: close
content-length: 279
content-security-policy: frame-ancestors 'self';
content-type: text/plain;charset=utf-8
date: Thu, 08 Sep 2022 08:43:56 GMT
server: gunicorn/19.8.1
status: 400
strict-transport-security: max-age=15552000
vary: Accept,Accept-Encoding
x-content-type-options: nosniff
x-frame-options: SAMEORIGIN
x-launchpad-revision: b6507fd2ad40d5507636508b2c5a315f269f7007
x-lazr-notifications: []
x-powered-by: Zope (www.zope.org), Python (www.python.org)
x-request-id: 7814bcca-7f04-4e17-9dd1-e7f74cc8a581
x-vcs-revision: b6507fd2ad40d5507636508b2c5a315f269f7007
x-xss-protection: 1; mode=block
---
Response body:
---
b"name: \nInvalid name 'lp-1975764-dpdk-mre-sept-2022/kinetic'. Names must be at least two characters long\nand start with a letter or number. All letters must be lower-case.\nThe characters <samp>+</samp>, <samp>-</samp> and <samp>.</samp>\nare also allowed after the first character."
---

AFAICS there is a clear syntax we have to follow, should we consider throwing a regex on it before bothering LP, and gracefully tell the user "your argument seems to be wrong and does not match <format>"?
That seems more friendly and comfortable to me.

[Bryce Harrington (bryce)]

The regex pre-check is not a bad idea.

At a minimum from this and other bugs it looks clear that this code needs wrapped in a try block, and the error extracted (and de-html'd) from the exception's response for the user.

[Bryce Harrington (bryce)]

commit 639f536b31052f05769fb7dc271311b203133afd
Author: Bryce Harrington <email address hidden>
AuthorDate: Tue Sep 13 00:59:02 2022 -0700
Commit: Bryce Harrington <email address hidden>
CommitDate: Tue Sep 13 00:59:02 2022 -0700

    ppa: Improve handling of invalid ppa formats

    Instead of dumping a backtrace when incorrect ppa ID's are given, print
    out a distinct error message and then print usage information.

    Fixes: https://bugs.launchpad.net/ppa-dev-tools/+bug/1989084