## Summary
This adds configurable overload protection to the AI Bridge daemon to
prevent the server from being overwhelmed during periods of high load.
Partially addresses coder/internal#1153 (rate limits and concurrency
control; circuit breakers are deferred to a follow-up).
## New Configuration Options
| Option | Environment Variable | Description | Default |
|--------|---------------------|-------------|---------|
| `--aibridge-max-concurrency` | `CODER_AIBRIDGE_MAX_CONCURRENCY` |
Maximum number of concurrent AI Bridge requests. Set to 0 to disable
(unlimited). | `0` |
| `--aibridge-rate-limit` | `CODER_AIBRIDGE_RATE_LIMIT` | Maximum number
of AI Bridge requests per second. Set to 0 to disable rate limiting. |
`0` |
## Behavior
When limits are exceeded:
- **Concurrency limit**: Returns HTTP `503 Service Unavailable` with
message "AI Bridge is currently at capacity. Please try again later."
- **Rate limit**: Returns HTTP `429 Too Many Requests` with
`Retry-After` header.
Both protections are optional and disabled by default (0 values).
## Implementation
The overload protection is implemented as reusable middleware in
`coderd/httpmw/ratelimit.go`:
1. **`RateLimitByAuthToken`**: Per-user rate limiting that uses
`APITokenFromRequest` to extract the authentication token, with fallback
to `X-Api-Key` header for AI provider compatibility (e.g., Anthropic).
Falls back to IP-based rate limiting if no token is present. Includes
`Retry-After` header for backpressure signaling.
2. **`ConcurrencyLimit`**: Uses an atomic counter to track in-flight
requests and reject when at capacity.
The middleware is applied in `enterprise/coderd/aibridge.go` via
`r.Group` in the following order:
1. Concurrency check (faster rejection for load shedding)
2. Rate limit check
**Note**: Rate limiting currently applies to all AI Bridge requests,
including pass-through requests. Ideally only actual interceptions
should count, but this would require changes in the aibridge library.
## Testing
Added comprehensive tests for:
- Rate limiting by auth token (Bearer token, X-Api-Key, no token
fallback to IP)
- Different tokens not rate limited against each other
- Disabled when limit is zero
- Retry-After header is set on 429 responses
- Concurrency limiting (allows within limit, rejects over limit,
disabled when zero)
* chore: create type for unique role names
Using `string` was confusing when something should be combined with
org context, and when not to. Naming this new name, "RoleIdentifier"
* chore: add /v2 to import module path
go mod requires semantic versioning with versions greater than 1.x
This was a mechanical update by running:
```
go install github.com/marwan-at-work/mod/cmd/mod@latest
mod upgrade
```
Migrate generated files to import /v2
* Fix gen
* chore: rename `AgentConn` to `WorkspaceAgentConn`
The codersdk was becoming bloated with consts for the workspace
agent that made no sense to a reader. `Tailnet*` is an example
of these consts.
* chore: remove `Get` prefix from *Client functions
* chore: remove `BypassRatelimits` option in `codersdk.Client`
It feels wrong to have this as a direct option because it's so infrequently
needed by API callers. It's better to directly modify headers in the two
places that we actually use it.
* Merge `appearance.go` and `buildinfo.go` into `deployment.go`
* Merge `experiments.go` and `features.go` into `deployment.go`
* Fix `make gen` referencing old type names
* Merge `error.go` into `client.go`
`codersdk.Response` lived in `error.go`, which is wrong.
* chore: refactor workspace agent functions into agentsdk
It was odd conflating the codersdk that clients should use
with functions that only the agent should use. This separates
them into two SDKs that are closely coupled, but separate.
* Merge `insights.go` into `deployment.go`
* Merge `organizationmember.go` into `organizations.go`
* Merge `quota.go` into `workspaces.go`
* Rename `sse.go` to `serversentevents.go`
* Rename `codersdk.WorkspaceAppHostResponse` to `codersdk.AppHostResponse`
* Format `.vscode/settings.json`
* Fix outdated naming in `api.ts`
* Fix app host response
* Fix unsupported type
* Fix imported type
Kacper Sawicki