Specify runtime parameters in TOML format config file

In addition to specifying parameters in the command line and environment variables, you can now omit all parameters and provide a config file.

Example:

./documize myconfig.conf

Note: there is no switch setting, just provide the filename as an argument.

Fixes #243

core/env/flags.go

@@ -12,24 +12,15 @@
 // Package env provides runtime, server level setup and configuration
 package env
 
-import (
-	"flag"
-	"fmt"
-	"os"
-	"sort"
-	"strings"
-	"sync"
-)
-
 // Flags provides access to environment and command line switches for this program.
 type Flags struct {
+	DBType            string // database type
 	DBConn            string // database connection string
 	Salt              string // the salt string used to encode JWT tokens
-	DBType            string // database type
-	SSLCertFile       string // (optional) name of SSL certificate PEM file
-	SSLKeyFile        string // (optional) name of SSL key PEM file
 	HTTPPort          string // (optional) HTTP or HTTPS port
 	ForceHTTPPort2SSL string // (optional) HTTP that should be redirected to HTTPS
+	SSLCertFile       string // (optional) name of SSL certificate PEM file
+	SSLKeyFile        string // (optional) name of SSL key PEM file
 	SiteMode          string // (optional) if 1 then serve offline web page
 	Location          string // reserved
 }
@@ -39,125 +30,26 @@ func (f *Flags) SSLEnabled() bool {
 	return f.SSLCertFile != "" && f.SSLKeyFile != ""
 }
 
-type flagItem struct {
-	target              *string
-	name, setter, value string
-	required            bool
+// ConfigToml represents configuration file that contains all flags as per above.
+type ConfigToml struct {
+	HTTP     httpConfig     `toml:"http"`
+	Database databaseConfig `toml:"database"`
+	Install  installConfig  `toml:"install"`
 }
 
-type progFlags struct {
-	items []flagItem
+type httpConfig struct {
+	Port         int
+	ForceSSLPort int
+	Cert         string
+	Key          string
 }
 
-// Len is part of sort.Interface.
-func (v *progFlags) Len() int {
-	return len(v.items)
+type databaseConfig struct {
+	Type       string
+	Connection string
+	Salt       string
 }
 
-// Swap is part of sort.Interface.
-func (v *progFlags) Swap(i, j int) {
-	v.items[i], v.items[j] = v.items[j], v.items[i]
-}
-
-// Less is part of sort.Interface.
-func (v *progFlags) Less(i, j int) bool {
-	return v.items[i].name < v.items[j].name
-}
-
-// prefix provides the prefix for all environment variables
-const prefix = "DOCUMIZE"
-const goInit = "(default)"
-
-var flagList progFlags
-var loadMutex sync.Mutex
-
-// ParseFlags loads command line and OS environment variables required by the program to function.
-func ParseFlags() (f Flags, ok bool) {
-	ok = true
-	var dbConn, dbType, jwtKey, siteMode, port, certFile, keyFile, forcePort2SSL, location string
-
-	register(&jwtKey, "salt", false, "the salt string used to encode JWT tokens, if not set a random value will be generated")
-	register(&certFile, "cert", false, "the cert.pem file used for https")
-	register(&keyFile, "key", false, "the key.pem file used for https")
-	register(&port, "port", false, "http/https port number")
-	register(&forcePort2SSL, "forcesslport", false, "redirect given http port number to TLS")
-	register(&siteMode, "offline", false, "set to '1' for OFFLINE mode")
-	register(&dbType, "dbtype", true, "specify the database provider: mysql|percona|mariadb|postgresql|sqlserver")
-	register(&dbConn, "db", true, `'database specific connection string for example "user:password@tcp(localhost:3306)/dbname"`)
-	register(&location, "location", false, `reserved`)
-
-	if !parse("db") {
-		ok = false
-	}
-
-	f.DBType = strings.ToLower(dbType)
-	f.DBConn = dbConn
-	f.ForceHTTPPort2SSL = forcePort2SSL
-	f.HTTPPort = port
-	f.Salt = jwtKey
-	f.SiteMode = siteMode
-	f.SSLCertFile = certFile
-	f.SSLKeyFile = keyFile
-
-	// reserved
-	if len(location) == 0 {
-		location = "selfhost"
-	}
-	f.Location = strings.ToLower(location)
-
-	return f, ok
-}
-
-// register prepares flag for subsequent parsing
-func register(target *string, name string, required bool, usage string) {
-	loadMutex.Lock()
-	defer loadMutex.Unlock()
-
-	name = strings.ToLower(strings.TrimSpace(name))
-	setter := prefix + strings.ToUpper(name)
-
-	value := os.Getenv(setter)
-	if value == "" {
-		value = *target // use the Go initialized value
-		setter = goInit
-	}
-
-	flag.StringVar(target, name, value, usage)
-	flagList.items = append(flagList.items, flagItem{target: target, name: name, required: required, value: value, setter: setter})
-}
-
-// parse loads flags from OS environment and command line switches
-func parse(doFirst string) (ok bool) {
-	loadMutex.Lock()
-	defer loadMutex.Unlock()
-
-	flag.Parse()
-	sort.Sort(&flagList)
-
-	for pass := 1; pass <= 2; pass++ {
-		for vi, v := range flagList.items {
-			if (pass == 1 && v.name == doFirst) || (pass == 2 && v.name != doFirst) {
-				if v.value != *(v.target) || (v.value != "" && *(v.target) == "") {
-					flagList.items[vi].setter = "-" + v.name // v is a local copy, not the underlying data
-				}
-				if v.required {
-					if *(v.target) == "" {
-						fmt.Fprintln(os.Stderr)
-						fmt.Fprintln(os.Stderr, "In order to run", os.Args[0], "the following must be provided:")
-						for _, vv := range flagList.items {
-							if vv.required {
-								fmt.Fprintf(os.Stderr, "* setting from environment variable '%s' or flag '-%s' or an application setting '%s', current value: '%s' set by '%s'\n",
-									prefix+strings.ToUpper(vv.name), vv.name, vv.name, *(vv.target), vv.setter)
-							}
-						}
-						fmt.Fprintln(os.Stderr)
-						flag.Usage()
-						return false
-					}
-				}
-			}
-		}
-	}
-
-	return true
+type installConfig struct {
+	Location string
 }