Blow up startup if init auth providers or modules failed

[awarecan]

Description:

Blow up startup if init auth providers or modules failed, either import module error or config error

Related issue (if applicable): fixes #

Pull request in home-assistant.github.io with documentation (if applicable): home-assistant/home-assistant.github.io#<home-assistant.github.io PR number goes here>

Example entry for configuration.yaml (if applicable):

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.github.io

If the code communicates with devices, web services, or third-party tools:

• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc.

If the code does not interact with devices:

• Tests have been added to verify that the new code works.

[houndci-bot]

local variable 'provider' is assigned to but never used

[pvizeli]

I don't think we should do that. Because in unattended system it is ugly

[awarecan]

Failed load auth provider will leave system unprotected. Have discussion regarding this in #beta channel

[balloob]

An alternative is that when the config is invalid, we default to the default config and issue a warning? That way the system is still accessible?

[balloob]

Actually, we should not load a single config entry when auth is invalid, start in a "light" mode would be the best

[balloob]

Was talking with Pascal: if config validation passes, HASS should successfully startup. If not, it's ok to fail.

[awarecan]

Double confirm my understanding is right, in bootstrap.async_from_config_dict

try:
    await async_process_ha_core_config();
except vol.Invalid:
    return None                # startup will hang
except HomeAssistantError:     # such as import error
    _LOGGER.error()
    return None                # (Solution A) startup will hang
or
    return hass                # (Solution B) a minimal HASS
or
    pass                       # (Solution C) a HASS without auth protection

So which solution is our final decision?

[houndci-bot]

redefinition of unused 'test_disallowed_auth_provider_config' from line 889

[houndci-bot]

'homeassistant.exceptions.HomeAssistantError' imported but unused

[awarecan]

Have moved duplicate auth provider check to schema, so all config issue will raise vol.Invalid.

I implemented as Solution A right now, startup will hang if load auth provider/mfa module failed. But can easily change to Solution B or C.

[balloob]

I think this is perfect.

I wonder if we also need to validate CONF_TYPE exists, but that might be for another PR.