Benoit Formet requested to merge web-error-page into master Mar 11, 2020

When

When there is an error in the yaml files preventing the config web app or the web portal to show, because static.get_config() raises an exception. For example because of a duplicated name in config.

What

The web page crash (error 500) with a bad error message "Internal Server Error" with no hint to what the problem is. And you have to dig in the logs to find the reason.

After this MR

Now the web page will display a useful error message telling the reason why the config could not be loaded, so that the user knows what to change.

example:

An error occurred (cannot get beamline configuration)

ValueError: Duplicate key name (dacm1) in config files (motors/wago.yml) and (motors/wago.yml)

Traceback (most recent call last):
  File "/home/formet/bliss/bliss/config/conductor/web/homepage/homepage_app.py", line 37, in index
    cfg = static.get_config()
  File "/home/formet/bliss/bliss/config/static.py", line 211, in get_config
    CONFIG = Config(base_path, timeout)
  File "/home/formet/bliss/bliss/config/static.py", line 519, in __init__
    self.reload(timeout=timeout)
  File "/home/formet/bliss/bliss/config/static.py", line 623, in reload
    self._parse(d, parents)
  File "/home/formet/bliss/bliss/config/static.py", line 897, in _parse
    parent[key] = self._parse_list(value, parent)
  File "/home/formet/bliss/bliss/config/static.py", line 876, in _parse_list
    self._parse(value, node)
  File "/home/formet/bliss/bliss/config/static.py", line 897, in _parse
    parent[key] = self._parse_list(value, parent)
  File "/home/formet/bliss/bliss/config/static.py", line 877, in _parse_list
    self._create_index(node)
  File "/home/formet/bliss/bliss/config/static.py", line 855, in _create_index
    "(%s) and (%s)" % (name, prev_node.filename, node.filename)
ValueError: Duplicate key name (dacm1) in config files (motors/wago.yml) and (motors/wago.yml)

Display useful error message on web page after get config error