Starter code for raft-otel project

projects/raft-otel/raft/Dockerfile

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+FROM golang:1.22.3
+
+WORKDIR /
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY *.go ./
+COPY main/*.go ./main/
+COPY raft_proto/*.go ./raft_proto/
+
+
+EXPOSE 7600
+
+# Bit lazy not to build properly but that's not the main point of this exercise
+CMD ["go", "run", "main/main.go"]

projects/raft-otel/raft/Dockerfile.client

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+FROM golang:1.22.3
+
+WORKDIR /
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY *.go ./
+COPY client/*.go ./client/
+COPY raft_proto/*.go ./raft_proto/
+
+
+EXPOSE 7600
+
+# Bit lazy not to build properly but that's not the main point of this exercise
+CMD ["go", "run", "client/client.go"]

projects/raft-otel/raft/README.md

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+# Sample Raft implementation
+
+This is based on Eli Bendersky's [https://eli.thegreenplace.net] RAFT demo code.
+
+I've modified it in a few ways:
+ * Adds a main.go so you can run the RAFT code as docker containers (or Kube) - peers are found via DNS lookup
+ * Changed from integer based peer IDs to use of IP addresses, so that the instances can come up without coordination with each other
+ * Changed from standard RPC to gRPC (as we've been using throughout this course)
+ * Adds Dockerfile and docker-compose.yml
+ * Added structure to Command (to simplify gRPCing)
+ * Removed one test (TestCrashAfterSubmit) as could not make the timing work to reliably crash leader before it had a chance to commit a change (would be easier to do this if code were restructured to inject time)
+ * Added endpoint for doing some sets/gets of data, and a simple client that calls this - to demo what's usually done with RAFT, also added a client that exercises it
+
+ ## Building and running this project
+
+ If you change the raft.proto protocol buffer definitions, you must regenerate the bindings by:
+
+ ```
+protoc --proto_path=. --go_out=. --go-grpc_out=. raft.proto
+ ```
+
+ To run this under docker-compose, use `docker-compose up --build -d` or your preferred variant. 
+ Docker must be installed and running.

projects/raft-otel/raft/client/client.go

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+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"net"
+	"os"
+	"raft/raft_proto"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+const port = 7600
+
+func main() {
+	addr := flag.String("dns", "raft", "dns address for raft cluster")
+
+	if addr == nil || *addr == "" {
+		fmt.Printf("Must supply dns address of cluster\n")
+		os.Exit(1)
+	}
+
+	time.Sleep(time.Second * 5) // wait for raft servers to come up
+
+	ips, err := net.LookupIP(*addr)
+	if err != nil {
+		fmt.Printf("Could not get IPs: %v\n", err)
+		os.Exit(1)
+	}
+
+	clients := make([]raft_proto.RaftKVServiceClient, 0)
+
+	for _, ip := range ips {
+		fmt.Printf("Connecting to %s\n", ip.String())
+		conn, err := grpc.Dial(fmt.Sprintf("%s:%d", ip.String(), port), grpc.WithTransportCredentials(insecure.NewCredentials()))
+		if err != nil {
+			log.Fatalf("%v", err)
+		}
+		client := raft_proto.NewRaftKVServiceClient(conn)
+		clients = append(clients, client)
+	}
+
+	for {
+		for _, c := range clients {
+			n := time.Now().Second()
+			res, err := c.Set(context.TODO(), &raft_proto.SetRequest{Keyname: "cursec", Value: fmt.Sprintf("%d", n)})
+			fmt.Printf("Called set cursec %d, got %v, %v\n", n, res, err)
+
+			time.Sleep(1 * time.Second) // allow consensus to happen
+
+			getres, err := c.Get(context.TODO(), &raft_proto.GetRequest{Keyname: "cursec"})
+			fmt.Printf("Called get cursec, got %v, %v\n", getres, err)
+		}
+		time.Sleep(5 * time.Second)
+	}
+}

projects/raft-otel/raft/docker-compose.yaml

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+services:
+  raft:
+    build: .
+    deploy:
+      mode: replicated
+      replicas: 3
+  client:
+    build:
+      dockerfile: ./Dockerfile.client
+    deploy:
+      mode: replicated
+      replicas: 1

projects/raft-otel/raft/go.mod

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+module raft
+
+go 1.19
+
+require (
+	github.com/fortytw2/leaktest v1.3.0
+	google.golang.org/grpc v1.64.0
+	google.golang.org/protobuf v1.34.1
+)
+
+require (
+	golang.org/x/net v0.22.0 // indirect
+	golang.org/x/sys v0.18.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240318140521-94a12d6c2237 // indirect
+)

projects/raft-otel/raft/go.sum

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+github.com/fortytw2/leaktest v1.3.0 h1:u8491cBMTQ8ft8aeV+adlcytMZylmA5nnwwkRZjI8vw=
+github.com/fortytw2/leaktest v1.3.0/go.mod h1:jDsjWgpAGjm2CA7WthBh/CdZYEPF31XHquHwclZch5g=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+golang.org/x/net v0.22.0 h1:9sGLhx7iRIHEiX0oAJ3MRZMUCElJgy7Br1nO+AMN3Tc=
+golang.org/x/net v0.22.0/go.mod h1:JKghWKKOSdJwpW2GEx0Ja7fmaKnMsbu+MWVZTokSYmg=
+golang.org/x/sys v0.18.0 h1:DBdB3niSjOA/O0blCZBqDefyWNYveAYMNF1Wum0DYQ4=
+golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
+golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20240318140521-94a12d6c2237 h1:NnYq6UN9ReLM9/Y01KWNOWyI5xQ9kbIms5GGJVwS/Yc=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20240318140521-94a12d6c2237/go.mod h1:WtryC6hu0hhx87FDGxWCDptyssuo68sk10vYjF+T9fY=
+google.golang.org/grpc v1.64.0 h1:KH3VH9y/MgNQg1dE7b3XfVK0GsPSIzJwdF617gUSbvY=
+google.golang.org/grpc v1.64.0/go.mod h1:oxjF8E3FBnjp+/gVFYdWacaLDx9na1aqy9oovLpxQYg=
+google.golang.org/protobuf v1.34.1 h1:9ddQBjfCyZPOHPUiPxpYESBLc+T8P3E+Vo4IbKZgFWg=
+google.golang.org/protobuf v1.34.1/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=

projects/raft-otel/raft/main/main.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"net"
+	"os"
+	"os/signal"
+	"raft"
+	"strings"
+	"syscall"
+	"time"
+)
+
+const port = 7600
+
+func main() {
+	addr := flag.String("dns", "raft", "dns address for raft cluster")
+	if_addr := flag.String("if", "eth0", "use IPV4 address of this interface") // eth0 works on docker, may vary for other platforms
+
+	if addr == nil || *addr == "" {
+		fmt.Printf("Must supply dns address of cluster\n")
+		os.Exit(1)
+	}
+
+	id := getOwnAddr(*if_addr)
+	fmt.Printf("My address/node ID is %s\n", id)
+
+	ready := make(chan interface{})
+	storage := raft.NewMapStorage()
+	commitChan := make(chan raft.CommitEntry)
+	server := raft.NewServer(id, id, storage, ready, commitChan, port)
+	server.Serve(raft.NewKV())
+
+	ips, err := net.LookupIP(*addr)
+	if err != nil {
+		fmt.Printf("Could not get IPs: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Connect to all peers with appropriate waits
+	// TODO: we only do this once, on startup - we really should periodically check to see if the DNS listing for peers has changed
+	for _, ip := range ips {
+		// if not own IP
+		if !ownAddr(ip, id) {
+			peerAddr := fmt.Sprintf("%s:%d", ip.String(), port)
+
+			connected := false
+			for rt := 0; rt <= 3 && !connected; rt++ {
+				fmt.Printf("Connecting to peer %s\n", peerAddr)
+				err = server.ConnectToPeer(peerAddr, peerAddr)
+				if err == nil {
+					connected = true
+				} else { // probably just not started up yet, retry
+					fmt.Printf("Error connecting to peer: %+v", err)
+					time.Sleep(time.Duration(rt+1) * time.Second)
+				}
+			}
+			if err != nil {
+				fmt.Printf("Exhausted retries connecting to peer %s", peerAddr)
+				os.Exit(1)
+			}
+		}
+	}
+
+	close(ready) // start raft server, peers are connected
+
+	gracefulShutdown := make(chan os.Signal, 1)
+	signal.Notify(gracefulShutdown, syscall.SIGINT, syscall.SIGTERM)
+	<-gracefulShutdown
+	server.DisconnectAll()
+	server.Shutdown()
+}
+
+func getOwnAddr(intf string) string {
+	ifs, err := net.Interfaces()
+	if err != nil {
+		fmt.Printf("Could not get intf: %v\n", err)
+		os.Exit(1)
+	}
+
+	for _, cif := range ifs {
+		if cif.Name == intf {
+			ads, _ := cif.Addrs()
+			for _, addr := range ads {
+				if isIPV4(addr.String()) {
+					ip := getIP(addr.String())
+					return ip.String()
+				}
+
+			}
+		}
+	}
+
+	fmt.Printf("Could not find intf: %s\n", intf)
+	os.Exit(1)
+	return ""
+}
+
+func isIPV4(addr string) bool {
+	parts := strings.Split(addr, "::")
+	return len(parts) == 1
+}
+
+func getIP(addr string) net.IP {
+	parts := strings.Split(addr, "/")
+	return net.ParseIP(parts[0])
+}
+
+func ownAddr(ip net.IP, myAddr string) bool {
+	res := ip.String() == myAddr
+	return res
+}