75 lines
3.1 KiB
ReStructuredText
75 lines
3.1 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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Setting environment variables for your graphs to use can be done in a variety of ways and which one used can vary
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based-upon context. Perhaps the most immediate and simple way to set/override a variable for a given graph is
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simply to use 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 multiple ``--env`` / ``-e`` flags
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(i.e. ``bonobo run --env FIZZ=buzz ...`` and ``bonobo run --env FIZZ=buzz --env Foo=bar ...``). Additionally, in bash
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you can also set environment variables by listing those you wish to set before the `bonobo run` command with space
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separating the key-value pairs (i.e. ``FIZZ=buzz bonobo run ...`` or ``FIZZ=buzz FOO=bar bonobo run ...``).
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The Examples below demonstrate setting one or multiple variables using both of these methods:
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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 inline (bash only):
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SECRET_TOKEN=secret123 bonobo run csvsanitizer
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# Using multiple environment variables inline (bash only):
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SRC_FILE=inventory.txt DST_FILE=inventory_processed.csv bonobo run csvsanitizer
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*Though not-yet implemented, the bonobo roadmap includes implementing environment / .env files as well.*
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Accessing Environment Variables from within the Graph Context
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:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
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Environment variables, whether set globally 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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import bonobo
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from bonobo.config import use
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DB_USER = os.getenv('DB_USER')
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DB_PASS = os.getenv('DB_PASS')
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@use('database')
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def extract(database):
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with database.connect(DB_USER, DB_PASS) as conn:
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yield from conn.query_all()
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graph = bonobo.Graph(
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extract,
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bonobo.PrettyPrinter(),
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)
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