[jira] [Created] (AIRFLOW-3616) Connection parsed from URI - unacceptable underscore in schema part

["Kamil Bregula (JIRA)" <ji...@apache.org>]

Kamil Bregula created AIRFLOW-3616:
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             Summary: Connection parsed from URI  - unacceptable underscore in schema part
                 Key: AIRFLOW-3616
                 URL: https://issues.apache.org/jira/browse/AIRFLOW-3616
             Project: Apache Airflow
          Issue Type: Bug
            Reporter: Kamil Bregula


There is a problem with creating a new connection based on the state of the environment variable if the connection type contains the underscore character.

If we want to configure a connection based on an environment variable, we must create an environment variable. The name of the environment must be given according to the scheme:
 {{AIRFLOW_CONN_[CONN_ID]}}
 where {{[CONN_ID]}} is the connection identifier to be used, written in upper case.
 The content of the variable defines the connection and is saved in the form of URI.

Defining a URI is complex, but the key is that the connection type is given as the schema. There are many possible values to give. but the sample values are {{mysql}}, {{postgresql}} or {{google_cloud_platform}}. Unfortunately, the last case is not properly handled.

This is caused by using {{urllib.parse}} to process the value. Unfortunately, this module does not support the uppercase character in schema port of URI - see below snippets showing the behaviour.

Since urllib.parse is really there to parse URLs and it is not good for parsing non-URL URIs - we should likely use different parser which handles more generic URIs. 
 Especially that it also creates other problems:
 https://issues.apache.org/jira/browse/AIRFLOW-3615

Another solution is to create aliases for each connection type with a variant that does not contain an unacceptable character. For example {{google_cloud_platform => gcp}}. It is worth noting that one alias is currently defined - {{postgresql => postgres}}.

Snippet showing urrlib.parse behaviour:

{{Python 3.6.5 (default, Oct 3 2018, 10:03:09)}}
{{ Type 'copyright', 'credits' or 'license' for more information}}
{{ IPython 7.0.1 – An enhanced Interactive Python. Type '?' for help.}}

{{In [1]: from urllib.parse import urlparse}}

{{In [2]: urlparse("google_cloud_platform://user:pass@hostname/path?extra_param=extra_param_value")}}
{{ Out[2]: ParseResult(scheme='', netloc='', path='google_cloud_platform://user:pass@hostname/path', params='', query='extra_param=extra_param_value', fragment='')}}

{{In [3]: urlparse("gcp://user:pass@hostname/path?extra_param=extra_param_value")}}
{{ Out[3]: ParseResult(scheme='gcp', netloc='user:pass@hostname', path='/path', params='', query='extra_param=extra_param_value', fragment='')}}

Connection parsed from URI - unacceptable underscore in schema part



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