Allow environment variables in parser and postoverflow config

[ToshY]

What would you like to be added?

/kind enhancement

Why is this needed?

I've already mentioned this in a Discord thread, and after some reconsidering, I thought I would still like to have an enhancement where environment variables could be used in other config files as well.

---

Currently, the section regarding Notification plugins show that you can use environment variables in the config files (https://docs.crowdsec.net/docs/notification_plugins/intro#environment-variables).

It would be nice to have this for other configs as well, like for parsers/postoverflows. An example would be using a parser to whilelist certain user IPs.

/etc/crowdsec/parsers/s02-enrich/user-whitelist.yaml

name: crowdsecurity/user-whitelist
description: "Whitelist events from my ipv4 addresses"
filter: "1 == 1"
whitelist:
  reason: "My ipv4 ranges"
  ip: [${USER_IPV4_WHITELIST}]
  cidr:
    - "10.0.0.0/8"
    - "172.16.0.0/12"
    - "192.168.0.0/16"

And where ${USER_IPV4_WHITELIST} contains the following:

.env

USER_IPV4_WHITELIST="'12.34.56.78','10.11.12.13'"

[github-actions]

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In the meantime, you can:

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[github-actions]

@ToshY: There are no 'kind' label on this issue. You need a 'kind' label to start the triage process.

• /kind feature
• /kind enhancement
• /kind refactoring
• /kind bug
• /kind packaging

Details

I am a bot created to help the crowdsecurity developers manage community feedback and contributions. You can check out my manifest file to understand my behavior and what I can do. If you want to use this for your project, you can check out the BirthdayResearch/oss-governance-bot repository.