feat: sync the served environment set from the proxy config

[gagantrivedi]

Thanks for submitting a PR! Please check the boxes below:

• I have read the Contributing Guide.
• I have added information to docs/ if required so people know about the feature.
• I have filled in the "Changes" section below.
• I have filled in the "How did you test this code" section below.

Changes

Contributes to Flagsmith/edge-proxy#128

Re-lands #18, already reviewed and approved there: it merged into the #17 branch 36 seconds after #17 had merged into main, so its code never reached main. This is the same squash commit cherry-picked onto main, applied cleanly with no changes.

With a proxy_key configured, the proxy keeps its served environments in sync with the proxy config endpoint (GET /api/v1/proxy/config/, X-Proxy-Key header): a newly created environment is served within one poll interval, rotations and removals propagate automatically, and per-environment configuration is no longer needed.

• New proxy_key setting (a single key — organisation-level grants make one key multi-org).
• models/proxy_config.rs: serde DTOs declaring only the fields acted on; everything else the endpoint sends is ignored.
• EnvironmentIndex::sync_to(desired): inserts new/changed environments, removes absent ones — statically configured environments (the index remembers their keys) are never overridden, removed, or key-hijacked by the config.
• Sync runs at the top of each poll pass, so new environments get their documents in the same tick. An environment is removed only when a successful fetch no longer lists it — an outage or a rejected proxy key never removes anything.
• Environments with no usable server key (e.g. freshly created, keys not minted yet) are skipped rather than failing the poll, and a deactivated or expired server key stops authenticating on the next request.

How did you test this code?

cargo test: 70 green on top of main — reconcile unit tests plus tests/test_proxy_config_discovery.rs, wiremock against the frozen contract shape: environment added / dropped / key-rotated, static-never-removed, and fetch-failure-removes-nothing. Clippy and fmt clean.

[coderabbitai]

Important

• 🔍 Trigger review

This repository does not receive automatic reviews because it has fewer than 10 stars.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Advanced

Run ID: 16e00afe-ef2f-4546-a0ef-25c4d54f22d9

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}