improved s3 hydration (#997)

- Improvement: Hub shares a single S3 client and IMDS credential provider across all modules, reducing IMDS load and surviving transient IMDS blips during bulk provisioning
- Improvement: Hub validates hydration config at startup; bad `--hub-hydration-target-spec` or `--hub-hydration-target-config` now fails `zen hub` at boot instead of per-module at first hydrate
- Improvement: S3 hydration multipart chunk size configurable via `settings.chunk-size` (default 32 MiB)
- Improvement: S3 client extracts `<Error><Code>` and `<Message>` from XML error bodies (previously logged as `<unhandled content format>`)
- Improvement: S3 client fails fast with a "no credentials available" error when AWS credentials are missing, instead of sending an unsigned request that S3 rejects with a generic 400
- Improvement: IMDS credential provider retries transient connection failures (up to 3 attempts with backoff)
- Improvement: HTTP clients with `RetryCount > 0` also retry on `CURLE_COULDNT_CONNECT`

1 files changed, 10 insertions, 10 deletions

diff --git a/src/zenserver/hub/storageserverinstance.cpp b/src/zenserver/hub/storageserverinstance.cpp
index af2c19113..97edc5223 100644
--- a/src/zenserver/hub/storageserverinstance.cpp
+++ b/src/zenserver/hub/storageserverinstance.cpp
@@ -11,8 +11,12 @@
 
 namespace zen {
 
-StorageServerInstance::StorageServerInstance(ZenServerEnvironment& RunEnvironment, const Configuration& Config, std::string_view ModuleId)
-: m_Config(Config)
+StorageServerInstance::StorageServerInstance(ZenServerEnvironment& RunEnvironment,
+											 HydrationBase&		   Hydration,
+											 const Configuration&  Config,
+											 std::string_view	   ModuleId)
+: m_Hydration(Hydration)
+, m_Config(Config)
 , m_ModuleId(ModuleId)
 , m_ServerInstance(RunEnvironment, ZenServerInstance::ServerMode::kStorageServer)
 {
@@ -156,7 +160,7 @@ StorageServerInstance::ObliterateLocked()
 	std::atomic<bool>					   AbortFlag{false};
 	std::atomic<bool>					   PauseFlag{false};
 	HydrationConfig						   Config	= MakeHydrationConfig(AbortFlag, PauseFlag);
-	std::unique_ptr<HydrationStrategyBase> Hydrator = CreateHydrator(Config);
+	std::unique_ptr<HydrationStrategyBase> Hydrator = m_Hydration.CreateHydrator(Config);
 	Hydrator->Obliterate();
 }
 
@@ -204,7 +208,7 @@ StorageServerInstance::Hydrate()
 	std::atomic<bool>					   AbortFlag{false};
 	std::atomic<bool>					   PauseFlag{false};
 	HydrationConfig						   Config	= MakeHydrationConfig(AbortFlag, PauseFlag);
-	std::unique_ptr<HydrationStrategyBase> Hydrator = CreateHydrator(Config);
+	std::unique_ptr<HydrationStrategyBase> Hydrator = m_Hydration.CreateHydrator(Config);
 	m_HydrationState								= Hydrator->Hydrate();
 }
 
@@ -214,18 +218,14 @@ StorageServerInstance::Dehydrate()
 	std::atomic<bool>					   AbortFlag{false};
 	std::atomic<bool>					   PauseFlag{false};
 	HydrationConfig						   Config	= MakeHydrationConfig(AbortFlag, PauseFlag);
-	std::unique_ptr<HydrationStrategyBase> Hydrator = CreateHydrator(Config);
+	std::unique_ptr<HydrationStrategyBase> Hydrator = m_Hydration.CreateHydrator(Config);
 	Hydrator->Dehydrate(m_HydrationState);
 }
 
 HydrationConfig
 StorageServerInstance::MakeHydrationConfig(std::atomic<bool>& AbortFlag, std::atomic<bool>& PauseFlag)
 {
-	HydrationConfig Config{.ServerStateDir		= m_Config.StateDir,
-						   .TempDir				= m_Config.TempDir,
-						   .ModuleId			= m_ModuleId,
-						   .TargetSpecification = m_Config.HydrationTargetSpecification,
-						   .Options				= m_Config.HydrationOptions};
+	HydrationConfig Config{.ServerStateDir = m_Config.StateDir, .TempDir = m_Config.TempDir, .ModuleId = m_ModuleId};
 	if (m_Config.OptionalWorkerPool)
 	{
 		Config.Threading.emplace(