feat: Prepare raft storage promotion (#659)

Formalize the storage service to become usable for the backend drivers.

- add ADR for the storage specification
- normalize interface - the storage exposes the command interface
- prepare for data encryption:
  - transfer data as msgpack binary (to be encrypted next)
  - store data is serialized using msgpack and set/get commands use
    Serialize/Deserialize for the data for automatic serialization. The
    data in the store will be encrypted next)

Author: gtema

Cargo.lock

@@ -58,6 +58,7 @@ clap = { version = "4.6" }
 color-eyre = { version = "0.6" }
 config = { version = "0.15" }
 criterion = { version = "0.8" }
+dashmap = "6.1"
 derive_builder = { version = "0.20" }
 dyn-clone = { version = "1.0" }
 eyre = { version = "0.6" }

Cargo.toml

@@ -16,19 +16,25 @@ workspace = true
 [dependencies]
 async-trait.workspace = true
 byteorder.workspace = true
+dashmap.workspace = true
 eyre.workspace = true
 fjall = { version = "3.1" }
 futures.workspace = true
+http.workspace = true
 openraft = { workspace = true, features = ["serde", "type-alias"] }
 openstack-keystone-config = { version = "0.1", path = "../config/" }
 prost.workspace = true
 rand.workspace = true
+rmp.workspace = true
+rmp-serde = "1.3"
 serde = { workspace = true, features = ["derive"] }
+serde_bytes.workspace = true
 serde_json.workspace = true
-tracing.workspace = true
 thiserror.workspace = true
 tonic = { workspace = true, features = ["router", "_tls-any"] }
 tonic-prost.workspace = true
+tracing.workspace = true
+tokio.workspace = true
 
 [dev-dependencies]
 rcgen = "0.14.7"

crates/storage/Cargo.toml

@@ -1,8 +1,8 @@
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let proto_files = [
         "proto/raft.proto",
-        "proto/identity_types.proto",
-        "proto/identity.proto",
+        "proto/storage_types.proto",
+        "proto/storage.proto",
     ];
 
     tonic_prost_build::configure()
@@ -23,11 +23,24 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             "#[derive(Deserialize, Serialize)]",
         )
         .type_attribute("keystone.raft.Vote", "#[derive(Deserialize, Serialize)]")
+        .type_attribute("keystone.api.Response", "#[derive(Deserialize, Serialize)]")
         .type_attribute(
-            "keystone.api.SetRequest",
+            "keystone.api.CommandRequest",
             "#[derive(Deserialize, Serialize)]",
         )
-        .type_attribute("keystone.api.Response", "#[derive(Deserialize, Serialize)]")
+        //        .type_attribute(
+        //            "keystone.api.DeleteRequest",
+        //            "#[derive(Deserialize, Serialize)]",
+        //        )
+        //        .type_attribute(
+        //            "keystone.api.StoreRequest",
+        //            "#[derive(Deserialize, Serialize)]",
+        //        )
+        //        .type_attribute(
+        //            "keystone.api.StoreRequest.request",
+        //            "#[derive(serde::Deserialize, serde::Serialize)]",
+        //        )
+        //.type_attribute("keystone.api.Response", "#[derive(Deserialize, Serialize)]")
         .compile_protos(&proto_files, &["proto"])?;
     Ok(())
 }

crates/storage/build.rs

@@ -3,7 +3,7 @@ syntax = "proto3";
 package keystone.raft;
 
 import "google/protobuf/empty.proto";
-import "identity_types.proto";
+import "storage_types.proto";
 
 
 // Node represents a single node in the Raft cluster.
@@ -30,11 +30,11 @@ message Entry {
   uint64 term = 1;
   uint64 index = 2;
 
-  // Optional Application data.
-  keystone.api.SetRequest app_data = 12;
-
   // Optional Membership config.
-  Membership membership = 13;
+  Membership membership = 3;
+
+  // Optional Store request.
+  optional bytes app_data = 4;
 }
 
 // NodeIds is a set of NodeIds.
@@ -190,11 +190,11 @@ message AdminResponse {
   // The log id of the committed log entry.
   keystone.raft.LogId log_id = 1;
 
-  // If the committed log entry is a normal one.
-  keystone.api.Response data = 2;
-
   // If the committed log entry is a change-membership entry.
-  keystone.raft.Membership membership = 3;
+  keystone.raft.Membership membership = 2;
+
+  // If the committed log entry is a normal one.
+  keystone.api.Response data = 3;
 }
 
 message MetricsResponse {
@@ -224,3 +224,4 @@ service ClusterAdminService {
   // Metrics retrieves cluster metrics and status information.
   rpc Metrics(google.protobuf.Empty) returns (MetricsResponse) {}
 }
+

crates/storage/proto/identity.proto

@@ -0,0 +1,13 @@
+syntax = "proto3";
+
+package keystone.api;
+
+import "google/protobuf/empty.proto";
+import "google/protobuf/wrappers.proto";
+import "storage_types.proto";
+
+// StorageService provides the key-value store API operations.
+service StorageService {
+  // Write the command
+  rpc Command(keystone.api.CommandRequest) returns (keystone.api.Response) {}
+}

crates/storage/proto/identity_types.proto

@@ -0,0 +1,14 @@
+syntax = "proto3";
+
+package keystone.api;
+
+message CommandRequest {
+  // Store request.
+  bytes payload = 1;
+}
+
+// GetResponse contains the value associated with the requested key.
+message Response {
+  // Retrieved value.
+  optional bytes value = 1;
+}