config: support passing multiple server RPC addrs for registration (#14)

internal/config/config.go

@@ -27,9 +27,9 @@ type Config struct {
 	// generating the simulated client name and ID.
 	NodeNamePrefix string `hcl:"node_name_prefix,optional"`
 
-	// ServerAddr is the RPC address of a Nomad server which will be used to
-	// set up the clients initial registration contact.
-	ServerAddr string `hcl:"server_addr,optional"`
+	// ServerAddr is a slice of server RPC addresses which will be used for the
+	// clients initial registration.
+	ServerAddr arrayFlagVar `hcl:"server_addr,optional"`
 
 	// NodeNum is the number of Nomad clients/nodes that will be started within
 	// this single nodesim process. Some basic testing indicates you will need
@@ -66,7 +66,7 @@ func Default() *Config {
 	return &Config{
 		WorkDir:        fmt.Sprintf("nomad-nodesim-%d", os.Getpid()),
 		NodeNamePrefix: fmt.Sprintf("node-%s", uuid.Short()),
-		ServerAddr:     "127.0.0.1:4647",
+		ServerAddr:     []string{"127.0.0.1:4647"},
 		NodeNum:        1,
 		Log: &Log{
 			Level:           "debug",
@@ -96,7 +96,7 @@ func (c *Config) Merge(z *Config) *Config {
 	if z.NodeNamePrefix != "" {
 		result.NodeNamePrefix = z.NodeNamePrefix
 	}
-	if z.ServerAddr != "" {
+	if len(z.ServerAddr) > 0 {
 		result.ServerAddr = z.ServerAddr
 	}
 	if z.NodeNum > 0 {

internal/config/flag.go

@@ -0,0 +1,13 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package config
+
+type arrayFlagVar []string
+
+func (i *arrayFlagVar) String() string { return "" }
+
+func (i *arrayFlagVar) Set(value string) error {
+	*i = append(*i, value)
+	return nil
+}

main.go

@@ -41,7 +41,7 @@ func main() {
 	}
 
 	flag.StringVar(&flagConfig.WorkDir, "work-dir", "", "working directory")
-	flag.StringVar(&flagConfig.ServerAddr, "server-addr", "", "address of server's rpc port")
+	flag.Var(&flagConfig.ServerAddr, "server-addr", "address of server's rpc port; can be specified multiple times")
 	flag.StringVar(&flagConfig.NodeNamePrefix, "node-name-prefix", "", "nodes will be named [prefix]-[i]")
 	flag.IntVar(&flagConfig.NodeNum, "node-num", 0, "number of client nodes")
 
@@ -184,12 +184,7 @@ func startClient(logger hclog.Logger, buildInfo *internalSimnode.BuildInfo, cfg
 
 	clientCfg.MaxKillTimeout = time.Minute
 
-	//FIXME inject servers?
-	if cfg.ServerAddr != "" {
-		clientCfg.Servers = []string{cfg.ServerAddr}
-	} else {
-		clientCfg.Servers = []string{}
-	}
+	clientCfg.Servers = cfg.ServerAddr
 
 	tlsConfig := tlsConfigFromEnv()
 	tlsEnabled := true