Introduce a new /assignIds HTTP endpoint in Zero, so users can allocate UIDs to nodes externally to Dgraph.

Author: manishrjain

dgraph/cmd/zero/http.go

@@ -17,6 +17,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/dgraph-io/dgraph/protos/intern"
 	"github.com/dgraph-io/dgraph/x"
 	"github.com/gogo/protobuf/jsonpb"
 )
@@ -40,6 +41,37 @@ func intFromQueryParam(w http.ResponseWriter, r *http.Request, name string) (uin
 	return val, true
 }
 
+func (st *state) assignUids(w http.ResponseWriter, r *http.Request) {
+	x.AddCorsHeaders(w)
+	w.Header().Set("Content-Type", "application/json")
+	if r.Method == "OPTIONS" {
+		return
+	}
+	if r.Method != http.MethodGet {
+		w.WriteHeader(http.StatusBadRequest)
+		x.SetStatus(w, x.ErrorInvalidMethod, "Invalid method")
+		return
+	}
+	val, ok := intFromQueryParam(w, r, "num")
+	if !ok {
+		return
+	}
+	num := &intern.Num{Val: uint64(val)}
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+	ids, err := st.zero.AssignUids(ctx, num)
+	if err != nil {
+		x.SetStatus(w, x.Error, err.Error())
+		return
+	}
+
+	m := jsonpb.Marshaler{}
+	if err := m.Marshal(w, ids); err != nil {
+		x.SetStatus(w, x.ErrorNoData, err.Error())
+		return
+	}
+}
+
 // removeNode can be used to remove a node from the cluster. It takes in the RAFT id of the node
 // and the group it belongs to. It can be used to remove Dgraph server and Zero nodes(group=0).
 func (st *state) removeNode(w http.ResponseWriter, r *http.Request) {

dgraph/cmd/zero/run.go

@@ -191,6 +191,7 @@ func run() {
 	http.HandleFunc("/state", st.getState)
 	http.HandleFunc("/removeNode", st.removeNode)
 	http.HandleFunc("/moveTablet", st.moveTablet)
+	http.HandleFunc("/assignIds", st.assignUids)
 
 	// This must be here. It does not work if placed before Grpc init.
 	x.Check(st.node.initAndStartNode())

dgraph/docker-compose.yml

@@ -20,24 +20,33 @@ services:
       # - type: bind
       #   source: "${DATA}"
       #   target: /data
-  # zero2:
-  #   image: debian:latest
-  #   container_name: bank-dg0.2
-  #   command: /gobin/dgraph zero --my=zero2:5080 --replicas 3 --peer=zero1:5080 --idx 2
-  #   volumes:
-  #     - type: bind
-  #       source: $GOPATH/bin
-  #       target: /gobin
-  #       read_only: true
-  # zero3:
-  #   image: debian:latest
-  #   container_name: bank-dg0.3
-  #   command: /gobin/dgraph zero --my=zero3:5080 --replicas 3 --peer=zero1:5080 --idx 3
-  #   volumes:
-  #     - type: bind
-  #       source: $GOPATH/bin
-  #       target: /gobin
-  #       read_only: true
+
+  zero2:
+    image: debian:latest
+    container_name: bank-dg0.2
+    command: /gobin/dgraph zero -o 2 --my=zero2:5082 --replicas 3 --peer=zero1:5080 --idx 2
+    ports:
+      - 5082:5082
+      - 6082:6082
+    volumes:
+      - type: bind
+        source: $GOPATH/bin
+        target: /gobin
+        read_only: true
+
+  zero3:
+    image: debian:latest
+    container_name: bank-dg0.3
+    command: /gobin/dgraph zero -o 3 --my=zero3:5083 --replicas 3 --peer=zero1:5080 --idx 3
+    ports:
+      - 5083:5083
+      - 6083:6083
+    volumes:
+      - type: bind
+        source: $GOPATH/bin
+        target: /gobin
+        read_only: true
+
   # zero4:
   #   image: debian:latest
   #   container_name: bank-dg0.4
@@ -47,6 +56,7 @@ services:
   #       source: $GOPATH/bin
   #       target: /gobin
   #       read_only: true
+
   # zero5:
   #   image: debian:latest
   #   container_name: bank-dg0.5
@@ -108,7 +118,6 @@ services:
       - 9183:9183
     command: /gobin/dgraph server --my=dg3:7183 --lru_mb=1024 --zero=zero1:5080 -o 103 --expose_trace   --trace 1.0 --profile_mode block --block_rate 10
 
-
   # dg4:
   #   image: debian:latest
   #   container_name: bank-dg4

wiki/content/deploy/index.md

@@ -1068,6 +1068,9 @@ to see useful information, like the following:
 
 * `/state` Information about the nodes that are part of the cluster. Also contains information about
   size of predicates and groups they belong to.
+* `/assignIds?num=100` This would allocate `num` ids and return a JSON map
+containing `startId` and `endId`, both inclusive. This id range can be safely assigned
+externally to new nodes, during data ingestion.
 * `/removeNode?id=3&group=2` If a replica goes down and can't be recovered, you can remove it and add a new node to the quorum.
 This endpoint can be used to remove a dead Zero or Dgraph server node. To remove dead Zero nodes, just pass `group=0` and the
 id of the Zero node.