Content: Environment variable interpolation?

[johndodev]

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Hello,

I couldn't find the answer to this question: is environment variable interpolation possible?

Whatever the answer, I think it deserves a place in the doc.

If this is possible, it would allow us to define env variables with some parts replaced by others (notably by env variables defined by addons).

For example:

REDIS_SESSION_DSN="redis://:${REDIS_PASSWORD}@${REDIS_HOST}:${REDIS_PORT}?timeout=0.5&read_timeout=0.5"
DATABASE_URL="${MYSQL_ADDON_URI}?serverVersion=${MYSQL_ADDON_VERSION}&charset=utf8mb4"

If it's not possible, could we add a short phrase mentioning that it isn't?

This content could be added at the end of the "#How do I use these variables?" section on this page: https://www.clever.cloud/developers/doc/develop/env-variables/

I can open a PR according to your response if necessary.

Thanks

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[davlgd]

Thanks for the issue, I'll check where we can put that (as we're reorganizing doc and especially env vars stuff). In the meantime, you can use a pre-run script for example, as we do in the oTree guide : https://www.clever.cloud/developers/guides/otree/#configure-the-application