41 lines
1.3 KiB
ReStructuredText
41 lines
1.3 KiB
ReStructuredText
Environment Variables
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=====================
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CircuitPython 8.0.0 introduces support for environment variables. Environment
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variables are commonly used to store "secrets" such as Wi-Fi passwords and API
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keys. This method *does not* make them secure. It only separates them from the
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code.
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CircuitPython supports these by mimicking the `dotenv <https://github.com/theskumar/python-dotenv>`_
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CPython library. Other languages such as Javascript, PHP and Ruby also have
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dotenv libraries.
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These libraries store environment variables in a ``.env`` file. Here is a simple
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example:
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.. code-block:: bash
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KEY1='value1'
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# Comment
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KEY2='value2
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is multiple lines'
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CircuitPython uses the ``.env`` at the drive root (no folder) as the environment.
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User code can access the values from the file using `os.getenv()`. It is
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recommended to save any values used repeatedly in a variable because `os.getenv()`
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will parse the ``/.env`` on every access.
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CircuitPython behavior
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----------------------
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CircuitPython will also read the environment to configure its behavior. Other
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keys are ignored by CircuitPython. Here are the keys it uses:
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CIRCUITPY_WIFI_PASSWORD
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~~~~~~~~~~~~~~~~~~~~~~~
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Wi-Fi password used to auto connect to CIRCUITPY_WIFI_SSID
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CIRCUITPY_WIFI_SSID
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~~~~~~~~~~~~~~~~~~~
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Wi-Fi SSID to auto-connect to even if user code is not running.
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