74 lines
2.6 KiB
ReStructuredText
74 lines
2.6 KiB
ReStructuredText
Environment Variables
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=======================
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Best practice holds that variables should be passed to graphs via environment variables.
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Doing this is important for keeping sensitive data out of the code - such as an
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API token or username and password used to access a database. Not only is this
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approach more secure, it also makes graphs more flexible by allowing adjustments
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for a variety of environments and contexts. Importantly, environment variables
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are also the means by-which arguments can be passed to graphs.
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Passing / Setting Environment Variables
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::::::::::::::::::::::::::::::::::::::::::::
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The recommended way to set environment variables for a given graph is simply to use
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the optional ``--env`` argument when running bonobo from the shell (bash, command prompt, etc).
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``--env`` (or ``-e`` for short) should then be followed by the variable name and value using the
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syntax `VAR_NAME=VAR_VALUE`. Multiple environment variables can be passed by using
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multiple ``--env`` / ``-e`` flags.
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Example:
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.. code-block:: bash
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# Using one environment variable via --env flag:
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bonobo run csvsanitizer --env SECRET_TOKEN=secret123
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# Using multiple environment variables via -e (env) flag:
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bonobo run csvsanitizer -e SRC_FILE=inventory.txt -e DST_FILE=inventory_processed.csv
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# Using one environment variable in bash (*bash only):
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SECRET_TOKEN=secret123 bonobo run csvsanitizer
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# Using multiple environment variables in bash (*bash only):
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SRC_FILE=inventory.txt DST_FILE=inventory_processed.csv bonobo run csvsanitizer
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Accessing Environment Variables from within the Graph Context
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:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
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Environment variables, whether global or only for the scope of the graph,
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can be can be accessed using any of the normal means. It is important to note
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that whether set globally for the system or just for the graph context,
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environment variables are accessed by bonobo in the same way. In the example
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below the database user and password are accessed via the ``os`` module's ``getenv``
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function and used to get data from the database.
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.. code-block:: python
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import os
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from bonobo import Graph, run
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def extract():
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database_user = os.getenv('DB_USER')
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database_password = os.getenv('DB_PASS')
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# ...
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# (connect to database using database_user and database_password)
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# (get data from database)
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# ...
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return database_data
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def load(database_data: dict):
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for k, v in database_data.items():
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print('{key} = {value}'.format(key=k, value=v))
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graph = Graph(extract, load)
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if __name__ == '__main__':
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run(graph)
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