[feature] Add healthcheck endpoints `/livez` and `/readyz` (#2783)

* [feature] Add healthcheck endpoints `/livez` and `/readyz`

* use select that returns no data

2 files changed, 10 insertions, 4 deletions

diff --git a/internal/db/basic.go b/internal/db/basic.go
index 3a8e2af8d..4c27b7ea6 100644
--- a/internal/db/basic.go
+++ b/internal/db/basic.go
@@ -33,8 +33,8 @@ type Basic interface {
 	// If the database implementation doesn't need to be stopped, this can just return nil.
 	Close() error
 
-	// IsHealthy should return nil if the database connection is healthy, or an error if not.
-	IsHealthy(ctx context.Context) error
+	// Ready returns nil if the database connection is ready, or an error if not.
+	Ready(ctx context.Context) error
 
 	// GetByID gets one entry by its id. In a database like postgres, this might be the 'id' field of the entry,
 	// for other implementations (for example, in-memory) it might just be the key of a map.
diff --git a/internal/db/bundb/basic.go b/internal/db/bundb/basic.go
index 7b523f309..82212fc42 100644
--- a/internal/db/bundb/basic.go
+++ b/internal/db/bundb/basic.go
@@ -124,8 +124,14 @@ func (b *basicDB) DropTable(ctx context.Context, i interface{}) error {
 	return err
 }
 
-func (b *basicDB) IsHealthy(ctx context.Context) error {
-	return b.db.PingContext(ctx)
+func (b *basicDB) Ready(ctx context.Context) error {
+	if _, err := b.db.
+		NewRaw("SELECT NULL FROM ? LIMIT 0", bun.Ident("instances")).
+		Exec(ctx); err != nil {
+		return err
+	}
+
+	return nil
 }
 
 func (b *basicDB) Close() error {