tendermint testnet: Allow for better hostname control (#3661)

* Allow testnet hostnames to be overridden

This allows one to specify the `--hostname` flag multiple times, each
time providing an additional custom hostname for a respective peer
(validator or non-validator). This overrides any of the
`--hostname-prefix` or `--starting-ip-address` flags.

The string array approach is taken instead of the string slice approach
(see the pflag docs:
https://godoc.org/github.com/spf13/pflag#StringArray) because the string
slice approach (a comma-separated string) doesn't allow for cleaner
multi-line BASH scripts - where this feature is intended to be used.

* Reorder conditional for clarity with simpler earlier return

* Allow for specifying peer hostname suffix

* Quote values in help strings for greater clarity

* Fix command switch

* Add CHANGELOG_PENDING entry for PR

* Allow for unique monikers

The current approach to generating monikers for testnet nodes assigns
the local hostname of the machine on which the testnet config was
generated to all nodes. This results in the same moniker for each and
every node.

This commit makes use of the supplied `--hostname-prefix` and
`--hostname-suffix`, or `--hostname` parameters to generate unique
monikers for each node. Alternatively, another parameter
(`--random-monikers`) allows one to forcibly override all of the other
options with random hexadecimal strings.

* Update CHANGELOG_PENDING entry for new command line switch

CHANGELOG_PENDING.md

@@ -35,8 +35,11 @@
 - [p2p] [\#3463](https://github.com/tendermint/tendermint/pull/3463) Do not log "Can't add peer's address to addrbook" error for a private peer
 - [p2p] [\#3552](https://github.com/tendermint/tendermint/pull/3552) Add PeerBehaviour Interface (@brapse)
 - [rpc] [\#3534](https://github.com/tendermint/tendermint/pull/3534) Add support for batched requests/responses in JSON RPC
+- [cli] [\#3661](https://github.com/tendermint/tendermint/pull/3661) Add
+  `--hostname-suffix`, `--hostname` and `--random-monikers` options to `testnet`
+  cmd for greater peer address/identity generation flexibility.
 - [cli] \#3585 Add option to not clear address book with unsafe reset (@climber73)
-- [cli] [\#3160](https://github.com/tendermint/tendermint/issues/3160) Add `-config=<path-to-config>` option to `testnet` cmd (@gregdhill)
+- [cli] [\#3160](https://github.com/tendermint/tendermint/issues/3160) Add `--config=<path-to-config>` option to `testnet` cmd (@gregdhill)
 - [cs/replay] \#3460 check appHash for each block
 - [rpc] \#3362 `/dial_seeds` & `/dial_peers` return errors if addresses are incorrect (except when IP lookup fails)
 - [node] \#3362 returns an error if `persistent_peers` list is invalid (except when IP lookup fails)

cmd/tendermint/commands/testnet.go

@@ -27,8 +27,11 @@ var (
 
 	populatePersistentPeers bool
 	hostnamePrefix          string
+	hostnameSuffix          string
 	startingIPAddress       string
+	hostnames               []string
 	p2pPort                 int
+	randomMonikers          bool
 )
 
 const (
@@ -50,11 +53,17 @@ func init() {
 	TestnetFilesCmd.Flags().BoolVar(&populatePersistentPeers, "populate-persistent-peers", true,
 		"Update config of each node with the list of persistent peers build using either hostname-prefix or starting-ip-address")
 	TestnetFilesCmd.Flags().StringVar(&hostnamePrefix, "hostname-prefix", "node",
-		"Hostname prefix (node results in persistent peers list ID0@node0:26656, ID1@node1:26656, ...)")
+		"Hostname prefix (\"node\" results in persistent peers list ID0@node0:26656, ID1@node1:26656, ...)")
+	TestnetFilesCmd.Flags().StringVar(&hostnameSuffix, "hostname-suffix", "",
+		"Hostname suffix (\".xyz.com\" results in persistent peers list ID0@node0.xyz.com:26656, ID1@node1.xyz.com:26656, ...)")
 	TestnetFilesCmd.Flags().StringVar(&startingIPAddress, "starting-ip-address", "",
-		"Starting IP address (192.168.0.1 results in persistent peers list ID0@192.168.0.1:26656, ID1@192.168.0.2:26656, ...)")
+		"Starting IP address (\"192.168.0.1\" results in persistent peers list ID0@192.168.0.1:26656, ID1@192.168.0.2:26656, ...)")
+	TestnetFilesCmd.Flags().StringArrayVar(&hostnames, "hostname", []string{},
+		"Manually override all hostnames of validators and non-validators (use --hostname multiple times for multiple hosts)")
 	TestnetFilesCmd.Flags().IntVar(&p2pPort, "p2p-port", 26656,
 		"P2P Port")
+	TestnetFilesCmd.Flags().BoolVar(&randomMonikers, "random-monikers", false,
+		"Randomize the moniker for each generated node")
 }
 
 // TestnetFilesCmd allows initialisation of files for a Tendermint testnet.
@@ -76,6 +85,13 @@ Example:
 }
 
 func testnetFiles(cmd *cobra.Command, args []string) error {
+	if len(hostnames) > 0 && len(hostnames) != (nValidators+nNonValidators) {
+		return fmt.Errorf(
+			"testnet needs precisely %d hostnames (number of validators plus non-validators) if --hostname parameter is used",
+			nValidators+nNonValidators,
+		)
+	}
+
 	config := cfg.DefaultConfig()
 
 	// overwrite default config if set and valid
@@ -181,6 +197,7 @@ func testnetFiles(cmd *cobra.Command, args []string) error {
 		if populatePersistentPeers {
 			config.P2P.PersistentPeers = persistentPeers
 		}
+		config.Moniker = moniker(i)
 
 		cfg.WriteConfigFile(filepath.Join(nodeDir, "config", "config.toml"), config)
 	}
@@ -190,21 +207,23 @@ func testnetFiles(cmd *cobra.Command, args []string) error {
 }
 
 func hostnameOrIP(i int) string {
-	if startingIPAddress != "" {
-		ip := net.ParseIP(startingIPAddress)
-		ip = ip.To4()
-		if ip == nil {
-			fmt.Printf("%v: non ipv4 address\n", startingIPAddress)
-			os.Exit(1)
-		}
-
-		for j := 0; j < i; j++ {
-			ip[3]++
-		}
-		return ip.String()
+	if len(hostnames) > 0 && i < len(hostnames) {
+		return hostnames[i]
+	}
+	if startingIPAddress == "" {
+		return fmt.Sprintf("%s%d%s", hostnamePrefix, i, hostnameSuffix)
+	}
+	ip := net.ParseIP(startingIPAddress)
+	ip = ip.To4()
+	if ip == nil {
+		fmt.Printf("%v: non ipv4 address\n", startingIPAddress)
+		os.Exit(1)
 	}
 
-	return fmt.Sprintf("%s%d", hostnamePrefix, i)
+	for j := 0; j < i; j++ {
+		ip[3]++
+	}
+	return ip.String()
 }
 
 func persistentPeersString(config *cfg.Config) (string, error) {
@@ -220,3 +239,20 @@ func persistentPeersString(config *cfg.Config) (string, error) {
 	}
 	return strings.Join(persistentPeers, ","), nil
 }
+
+func moniker(i int) string {
+	if randomMonikers {
+		return randomMoniker()
+	}
+	if len(hostnames) > 0 && i < len(hostnames) {
+		return hostnames[i]
+	}
+	if startingIPAddress == "" {
+		return fmt.Sprintf("%s%d%s", hostnamePrefix, i, hostnameSuffix)
+	}
+	return randomMoniker()
+}
+
+func randomMoniker() string {
+	return cmn.HexBytes(cmn.RandBytes(8)).String()
+}