feat: ensure RediSearch index exists on startup

On startup, omni-pitcher now checks if the RediSearch index exists via
FT.INFO and creates it with FT.CREATE ON JSON if missing. This prevents
"no such index" errors on fresh deployments or Redis restarts.

Skips index creation when REDIS_SEARCH_INDEX is not configured.

Closes #95

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: patrick-hermann-sva

internal/pitcher/index.go

@@ -0,0 +1,58 @@
+package pitcher
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"strings"
+
+	"github.com/redis/go-redis/v9"
+)
+
+// EnsureIndex checks whether the RediSearch index exists and creates it if missing.
+// This should be called once at startup before any messages are pitched.
+func (p *RedisPitcher) EnsureIndex(ctx context.Context) error {
+	if p.Config.Index == "" {
+		slog.Debug("redisearch index not configured, skipping ensure")
+		return nil
+	}
+
+	client := redis.NewClient(&redis.Options{
+		Addr:     p.Config.Addr + ":" + p.Config.Port,
+		Password: p.Config.Password,
+	})
+	defer func() { _ = client.Close() }()
+
+	// Check if index already exists
+	_, err := client.Do(ctx, "FT.INFO", p.Config.Index).Result()
+	if err == nil {
+		slog.Info("redisearch index already exists", "index", p.Config.Index)
+		return nil
+	}
+
+	if !strings.Contains(err.Error(), "no such index") {
+		return fmt.Errorf("failed to check redisearch index: %w", err)
+	}
+
+	slog.Info("redisearch index not found, creating", "index", p.Config.Index)
+
+	args := []any{
+		"FT.CREATE", p.Config.Index,
+		"ON", "JSON",
+		"SCHEMA",
+		"$.severity", "AS", "severity", "TAG",
+		"$.system", "AS", "system", "TAG",
+		"$.timestamp", "AS", "timestamp", "TEXT",
+		"$.title", "AS", "title", "TEXT",
+		"$.message", "AS", "message", "TEXT",
+		"$.author", "AS", "author", "TAG",
+		"$.tags", "AS", "tags", "TAG",
+	}
+
+	if err := client.Do(ctx, args...).Err(); err != nil {
+		return fmt.Errorf("failed to create redisearch index: %w", err)
+	}
+
+	slog.Info("redisearch index created", "index", p.Config.Index)
+	return nil
+}

internal/pitcher/index_test.go

@@ -0,0 +1,22 @@
+package pitcher
+
+import (
+	"context"
+	"testing"
+
+	homerun "github.com/stuttgart-things/homerun-library/v2"
+)
+
+func TestEnsureIndexSkipsWhenEmpty(t *testing.T) {
+	rp := &RedisPitcher{
+		Config: homerun.RedisConfig{
+			Index: "",
+		},
+	}
+
+	// Should return nil immediately when index is not configured
+	err := rp.EnsureIndex(context.Background())
+	if err != nil {
+		t.Errorf("EnsureIndex() with empty index should return nil, got: %v", err)
+	}
+}

main.go

@@ -52,6 +52,11 @@ func main() {
 		}
 		cancel()
 
+		// Ensure RediSearch index exists before accepting requests
+		if err := rp.EnsureIndex(context.Background()); err != nil {
+			slog.Warn("failed to ensure redisearch index", "index", redisConfig.Index, "error", err)
+		}
+
 		p = rp
 		slog.Info("pitcher mode: redis", "addr", redisConfig.Addr, "port", redisConfig.Port, "stream", redisConfig.Stream, "searchIndex", redisConfig.Index)
 	}