fix: race on cluster init by waiting for corrosion service to become ready with schema applied

internal/machine/corroservice/service.go

@@ -1,6 +1,16 @@
 package corroservice
 
-import "context"
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/BurntSushi/toml"
+	"github.com/cenkalti/backoff/v4"
+	"github.com/psviderski/uncloud/internal/corrosion"
+)
 
 type Service interface {
 	Start(ctx context.Context) error
@@ -8,3 +18,45 @@ type Service interface {
 	Restart(ctx context.Context) error
 	Running() bool
 }
+
+// WaitReady waits for the Corrosion service to be ready with the uncloud schema applied.
+func WaitReady(ctx context.Context, dataDir string) error {
+	// Read the config file to get the API address.
+	configPath := filepath.Join(dataDir, "config.toml")
+	configData, err := os.ReadFile(configPath)
+	if err != nil {
+		return fmt.Errorf("read config file: %w", err)
+	}
+
+	var config Config
+	if err = toml.Unmarshal(configData, &config); err != nil {
+		return fmt.Errorf("unmarshal config: %w", err)
+	}
+
+	corro, err := corrosion.NewAPIClient(config.API.Addr)
+	if err != nil {
+		return fmt.Errorf("create corrosion API client: %w", err)
+	}
+
+	// Corrosion starts serving the API before applying the schema. Query the cluster table with exponential backoff
+	// to check if the uncloud schema has been applied.
+	checkReady := func() error {
+		rows, err := corro.QueryContext(ctx, "SELECT 1 FROM cluster LIMIT 1")
+		if err != nil {
+			return fmt.Errorf("query cluster table: %w", err)
+		}
+		defer rows.Close()
+
+		return nil
+	}
+
+	b := backoff.NewExponentialBackOff(
+		backoff.WithInitialInterval(50*time.Millisecond),
+		backoff.WithMaxInterval(1*time.Second),
+		backoff.WithMaxElapsedTime(15*time.Second),
+	)
+	if err = backoff.Retry(checkReady, backoff.WithContext(b, ctx)); err != nil {
+		return fmt.Errorf("corrosion service did not become ready: %w", err)
+	}
+	return nil
+}