[#25] Show default environments

- Add possibility to display default environments
- Add Prefix constant
- Update README

closes #25

Signed-off-by: Evgeniy Kulikov <kim@nspcc.ru>

README.md

@@ -1,11 +1,59 @@
 # NeoFS S3 Gate
 
-... 
+## Example of configuration
+
+```
+# Flags
+      --pprof                           enable pprof
+      --metrics                         enable prometheus metrics
+  -h, --help                            show help
+  -v, --version                         show version
+      --neofs-key string                set value to hex string, WIF string, or path to NeoFS private key file (use "generated" to generate key) (default "generated")
+      --auth-key string                 set path to file with auth (curve25519) private key to use in auth scheme
+      --verbose                         set debug mode of gRPC connections
+      --request_timeout duration        set gRPC request timeout (default 15s)
+      --connect_timeout duration        set gRPC connect timeout (default 30s)
+      --rebalance_timer duration        set gRPC connection rebalance timer (default 15s)
+      --max_clients_count int           set max-clients count (default 100)
+      --max_clients_deadline duration   set max-clients deadline (default 30s)
+  -t, --con_ttl duration                set gRPC connection time to live (default 5m0s)
+      --listen_address string           set address to listen (default "0.0.0.0:8080")
+  -p, --peers stringArray               set NeoFS nodes
+
+# Environments
+
+S3_AUTH-KEY = 
+S3_CON_TTL = 5m0s
+S3_CONNECT_TIMEOUT = 30s
+S3_KEEPALIVE_PERMIT_WITHOUT_STREAM = true
+S3_KEEPALIVE_TIME = 10s
+S3_KEEPALIVE_TIMEOUT = 10s
+S3_LISTEN_ADDRESS = 0.0.0.0:8080
+S3_LOGGER_FORMAT = console
+S3_LOGGER_LEVEL = debug
+S3_LOGGER_NO_DISCLAIMER = true
+S3_LOGGER_SAMPLING_INITIAL = 1000
+S3_LOGGER_SAMPLING_THEREAFTER = 1000
+S3_LOGGER_TRACE_LEVEL = panic
+S3_MAX_CLIENTS_COUNT = 100
+S3_MAX_CLIENTS_DEADLINE = 30s
+S3_METRICS = false
+S3_NEOFS-KEY = generated
+S3_PPROF = false
+S3_REBALANCE_TIMER = 15s
+S3_REQUEST_TIMEOUT = 15s
+S3_VERBOSE = false
+
+# Peers preset
+
+S3_PEERS_[N]_ADDRESS = string
+S3_PEERS_[N]_WEIGHT = 0..1 (float)
+``` 
 
 ---
 <footer>
 
-# MinIO Fork
+#### MinIO Fork
 
 Forked from https://github.com/minio/minio (https://github.com/minio/minio/releases/tag/RELEASE.2020-07-02T00-15-09Z)
 

cmd/gate/app-settings.go

@@ -9,6 +9,7 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -84,14 +85,32 @@ const ( // settings
 	cfgEnableProfiler = "pprof"
 	cfgListenAddress  = "listen_address"
 
+	// Peers
+	cfgPeers = "peers"
+
 	// Application
 	cfgApplicationName      = "app.name"
 	cfgApplicationVersion   = "app.version"
 	cfgApplicationBuildTime = "app.build_time"
+
+	// command line args
+	cmdHelp    = "help"
+	cmdVersion = "version"
 )
 
 type empty int
 
+var ignore = map[string]struct{}{
+	cfgApplicationName:      {},
+	cfgApplicationVersion:   {},
+	cfgApplicationBuildTime: {},
+
+	cfgPeers: {},
+
+	cmdHelp:    {},
+	cmdVersion: {},
+}
+
 func (empty) Read([]byte) (int, error) { return 0, io.EOF }
 
 func fetchGateAuthKeys(v *viper.Viper) (*hcs.X25519Keys, error) {
@@ -142,7 +161,7 @@ func fetchPeers(l *zap.Logger, v *viper.Viper) []pool.Peer {
 
 	for i := 0; ; i++ {
 
-		key := "peers." + strconv.Itoa(i) + "."
+		key := cfgPeers + "." + strconv.Itoa(i) + "."
 		address := v.GetString(key + "address")
 		weight := v.GetFloat64(key + "weight")
 
@@ -164,7 +183,7 @@ func newSettings() *viper.Viper {
 	v := viper.New()
 
 	v.AutomaticEnv()
-	v.SetEnvPrefix("S3")
+	v.SetEnvPrefix(misc.Prefix)
 	v.SetConfigType("yaml")
 	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
 
@@ -175,8 +194,8 @@ func newSettings() *viper.Viper {
 	flags.Bool(cfgEnableProfiler, false, "enable pprof")
 	flags.Bool(cfgEnableMetrics, false, "enable prometheus metrics")
 
-	help := flags.BoolP("help", "h", false, "show help")
+	help := flags.BoolP(cmdHelp, "h", false, "show help")
-	version := flags.BoolP("version", "v", false, "show version")
+	version := flags.BoolP(cmdVersion, "v", false, "show version")
 
 	flags.String(cfgNeoFSPrivateKey, generated, fmt.Sprintf(`set value to hex string, WIF string, or path to NeoFS private key file (use "%s" to generate key)`, generated))
 	flags.String(cfgGateAuthPrivateKey, "", "set path to file with auth (curve25519) private key to use in auth scheme")
@@ -192,7 +211,7 @@ func newSettings() *viper.Viper {
 	ttl := flags.DurationP(cfgConnectionTTL, "t", defaultTTL, "set gRPC connection time to live")
 
 	flags.String(cfgListenAddress, "0.0.0.0:8080", "set address to listen")
-	peers := flags.StringArrayP("peers", "p", nil, "set NeoFS nodes")
+	peers := flags.StringArrayP(cfgPeers, "p", nil, "set NeoFS nodes")
 
 	// set prefers:
 	v.Set(cfgApplicationName, misc.ApplicationName)
@@ -227,10 +246,40 @@ func newSettings() *viper.Viper {
 		panic(err)
 	}
 
+	if peers != nil && len(*peers) > 0 {
+		for i := range *peers {
+			v.SetDefault(cfgPeers+"."+strconv.Itoa(i)+".address", (*peers)[i])
+			v.SetDefault(cfgPeers+"."+strconv.Itoa(i)+".weight", 1)
+		}
+	}
+
 	switch {
 	case help != nil && *help:
 		fmt.Printf("NeoFS S3 Gateway %s (%s)\n", misc.Version, misc.Build)
 		flags.PrintDefaults()
+
+		fmt.Println()
+		fmt.Println("Default environments:")
+		fmt.Println()
+		keys := v.AllKeys()
+		sort.Strings(keys)
+
+		for i := range keys {
+			if _, ok := ignore[keys[i]]; ok {
+				continue
+			}
+
+			k := strings.Replace(keys[i], ".", "_", -1)
+			fmt.Printf("%s_%s = %v\n", misc.Prefix, strings.ToUpper(k), v.Get(keys[i]))
+		}
+
+		fmt.Println()
+		fmt.Println("Peers preset:")
+		fmt.Println()
+
+		fmt.Printf("%s_%s_[N]_ADDRESS = string\n", misc.Prefix, strings.ToUpper(cfgPeers))
+		fmt.Printf("%s_%s_[N]_WEIGHT = 0..1 (float)\n", misc.Prefix, strings.ToUpper(cfgPeers))
+
 		os.Exit(0)
 	case version != nil && *version:
 		fmt.Printf("NeoFS S3 Gateway %s (%s)\n", misc.Version, misc.Build)
@@ -239,12 +288,5 @@ func newSettings() *viper.Viper {
 		fmt.Printf("connection ttl should not be less than %s", defaultTTL)
 	}
 
-	if peers != nil && len(*peers) > 0 {
-		for i := range *peers {
-			v.SetDefault("peers."+strconv.Itoa(i)+".address", (*peers)[i])
-			v.SetDefault("peers."+strconv.Itoa(i)+".weight", 1)
-		}
-	}
-
 	return v
 }

misc/build.go

@@ -1,6 +1,10 @@
 package misc
 
-const ApplicationName = "neofs-s3-gate"
+const (
+	Prefix = "S3"
+
+	ApplicationName = "neofs-s3-gate"
+)
 
 var (
 	Build   = "now"