Remote Configuration¶

Recourse supports dynamic policy configuration, allowing you to update retry policies, circuit breakers, and hedging settings at runtime without redeploying your application.

RemoteProvider¶

The controlplane.RemoteProvider fetches policies from an external source (e.g., HTTP endpoint, database, or file) and caches them locally.

Setup¶

import (
    "github.com/aponysus/recourse/controlplane"
    "github.com/aponysus/recourse/retry"
)

// Define a source
type MyHTTPSource struct { ... }
func (s *MyHTTPSource) GetPolicy(ctx context.Context, key policy.PolicyKey) (policy.EffectivePolicy, error) {
    // Fetch from URL, JSON unmarshal...
}

// Create the provider
provider := controlplane.NewRemoteProvider(
    &MyHTTPSource{},
    controlplane.WithCacheTTL(1 * time.Minute),
    controlplane.WithNegativeCacheTTL(10 * time.Second),
)

// Register with Executor
exec := retry.NewExecutor(
    retry.WithProvider(provider),
    // Fallback behavior if remote is unavailable/missing
    retry.WithMissingPolicyMode(retry.FailureFallback), 
)

Caching¶

To prevent hammering the control plane, RemoteProvider implements robust caching:

TTL Cache: Successfully fetched policies are cached for CacheTTL (default 1 min).
Negative Caching: If a policy is not found (404), this result is cached for NegativeCacheTTL (default 10s) to prevent hot-spotting on missing keys.

Resolution Logic¶

When exec.Do(ctx, "key", op) is called: 1. Cache Lookup: The provider checks its local cache. 2. Fetch: If missing/expired, it calls result Source.GetPolicy. 3. Fallback: If the source errors (network down), the executor falls back based on MissingPolicyMode (e.g., using a static default or failing closed).