feat: promql service (#26)

* feat: promql service

* feat: promql service

* feat: prometheus service, and common.proto, prom.proto

* feat: add header in prom request/response

* docs: include new proto files in readme

proto/greptime/v1/common.proto

@@ -0,0 +1,44 @@
+syntax = "proto3";
+
+package greptime.v1;
+
+option java_package = "io.greptime.v1";
+option java_outer_classname = "Common";
+option go_package = "github.com/GreptimeTeam/greptime-proto/go/greptime/v1";
+
+message ResponseHeader {}
+
+message RequestHeader {
+  // The `catalog` that is selected to be used in this request.
+  string catalog = 1;
+  // The `schema` that is selected to be used in this request.
+  string schema = 2;
+  // The `authorization` header, much like http's authorization header.
+  AuthHeader authorization = 3;
+  // The `dbname` for the request
+  string dbname = 4;
+}
+
+message AuthHeader {
+  oneof auth_scheme {
+    Basic basic = 1;
+    Token token = 2;
+  }
+}
+
+message Basic {
+  string username = 1;
+  string password = 2;
+}
+
+message Token {
+  string token = 1;
+}
+
+message AffectedRows {
+  uint32 value = 1;
+}
+
+message FlightMetadata {
+  AffectedRows affected_rows = 1;
+}

proto/greptime/v1/database.proto

@@ -8,6 +8,8 @@ option go_package = "github.com/GreptimeTeam/greptime-proto/go/greptime/v1";
 
 import "greptime/v1/ddl.proto";
 import "greptime/v1/column.proto";
+import "greptime/v1/prom.proto";
+import "greptime/v1/common.proto";
 
 service GreptimeDatabase {
   rpc Handle(GreptimeRequest) returns (GreptimeResponse);
@@ -15,33 +17,6 @@ service GreptimeDatabase {
   rpc HandleRequests(stream GreptimeRequest) returns (GreptimeResponse);
 }
 
-message RequestHeader {
-  // The `catalog` that is selected to be used in this request.
-  string catalog = 1;
-  // The `schema` that is selected to be used in this request.
-  string schema = 2;
-  // The `authorization` header, much like http's authorization header.
-  AuthHeader authorization = 3;
-  // The `dbname` for the request
-  string dbname = 4;
-}
-
-message AuthHeader {
-  oneof auth_scheme {
-    Basic basic = 1;
-    Token token = 2;
-  }
-}
-
-message Basic {
-  string username = 1;
-  string password = 2;
-}
-
-message Token {
-  string token = 1;
-}
-
 message GreptimeRequest {
   RequestHeader header = 1;
   oneof request {
@@ -51,8 +26,6 @@ message GreptimeRequest {
   }
 }
 
-message ResponseHeader {}
-
 message GreptimeResponse {
   ResponseHeader header = 1;
   oneof response {
@@ -68,13 +41,6 @@ message QueryRequest {
   }
 }
 
-message PromRangeQuery {
-  string query = 1;
-  string start = 2;
-  string end = 3;
-  string step = 4;
-}
-
 message InsertRequest {
   string table_name = 1;
 
@@ -89,11 +55,3 @@ message InsertRequest {
   // The region number of current insert request.
   uint32 region_number = 5;
 }
-
-message AffectedRows {
-  uint32 value = 1;
-}
-
-message FlightMetadata {
-  AffectedRows affected_rows = 1;
-}

proto/greptime/v1/prom.proto

@@ -0,0 +1,34 @@
+syntax = "proto3";
+
+package greptime.v1;
+
+option java_package = "io.greptime.v1";
+option java_outer_classname = "Prometheus";
+option go_package = "github.com/GreptimeTeam/greptime-proto/go/greptime/v1";
+
+import "greptime/v1/common.proto";
+
+// PrometheusGateway behaves absolutely the same as Prometheus HTTP API
+service PrometheusGateway {
+  rpc Handle(PromqlRequest) returns (PromqlResponse);
+}
+
+message PromqlRequest {
+  RequestHeader header = 1;
+  oneof promql {
+    string query = 2;
+    PromRangeQuery range_query = 3;
+  }
+}
+
+message PromqlResponse {
+  ResponseHeader header = 1;
+  bytes body = 2; // absolutely same format as Prometheus in JSON
+}
+
+message PromRangeQuery {
+  string query = 1;
+  string start = 2;
+  string end = 3;
+  string step = 4;
+}