Set OpenDAL secrects via environment variables

[HaleTom]

There are several B2 variables listed in this OpenDAL .env example:

OPENDAL_B2_ROOT=/path/to/dir
OPENDAL_B2_BUCKET=<bucket>
OPENDAL_B2_BUCKET_ID=<bucket_id>
OPENDAL_B2_APPLICATION_KEY_ID=<key_id>
OPENDAL_B2_APPLICATION_KEY=<application_key>

OpenDAL asserts that they are working correctly.

But with these set, I get:

08:23:27 [DEBUG] (1) opendal::services::b2::backend: backend build started: B2Builder { config: B2Config { root: Some("/"), application_key_id: None, bucket_id: "", bucket: "", .. }, .. }

Do these need to be accessed and/or passed on to OpenDAL?

---

Prior art:

opendal: Do OPENDAL_B2_* environment variables work? #4199
apache/opendal#4199

[Xuanwo]

Hi, the OPENDAL_ prefix is used internally within the opendal project and isn't part of its public API. This means applications like rustic cannot initialize storage using this method unless they decided to implement the same env loading logic.

[HaleTom]

To not force secrets being stored in config files, it would be great to support reading secrets from environment variables, (like is available in restic).