niemne commented on issue #13179:
URL: https://github.com/apache/apisix/issues/13179#issuecomment-4245575413
refer: (#12977, #12967, #13000, #13004)
1. Schema Changes:
- `rate` and `burst` will accept both numbers and strings (for variable
expressions like `$http_a`).
- Introduce an optional `rules` array for multi-level limiting. Each rule
contains its own `rate`, `burst`, `key`, `key_type`, and optional
`header_prefix`.
- Use `oneOf` validation to require either the legacy fields (`rate` +
`burst`) or the `rules` array, ensuring strict backward compatibility.
2. Implementation Approach:
- Add a runtime helper to resolve `rate`/`burst` string variables to numbers
via `core.utils.resolve_var`.
- In the `access` phase, normalize the configuration into a unified rule
list: legacy mode wraps single fields into one rule; multi-rule mode iterates
the `rules` array, resolves variables, and filters invalid entries.
- Dynamically create the `resty.limit.req` object per request. The
`lrucache.plugin_ctx` will be removed to avoid stale/colliding state when rates
change dynamically, fully aligning with the recent `limit-count` and
`limit-conn` PRs.
- Execute the leaky bucket algorithm (`lim:incoming`) for each normalized
rule, apply delay/reject logic, and support per-rule `header_prefix` for
differentiated response headers.
3. Backward Compatibility:
- Existing configurations without the `rules` field will continue to work
exactly as before.
- Removing the LRU cache guarantees accurate dynamic rate limiting without
side effects.
4. Example Configurations:
- Variable rate (legacy mode):
```json
{"rate": "$http_a", "burst": 10, "key": "remote_addr", "policy": "local"}
```
- Multi-level rules:
```json
{"rules": [{"rate": 100, "burst": 20, "key": "remote_addr"}, {"rate":
"$http_a", "burst": 50, "key": "http_x_user_id", "header_prefix": "user"}],
"policy": "redis", "rejected_code": 429}
```
@Baoyuantop Please review this proposal. Welcome any feedback or
suggestions.
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