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/command_line.go

@@ -0,0 +1,108 @@
+// Copyright 2016 Documize Inc. <legal@documize.com>. All rights reserved.
+//
+// This software (Documize Community Edition) is licensed under
+// GNU AGPL v3 http://www.gnu.org/licenses/agpl-3.0.en.html
+//
+// You can operate outside the AGPL restrictions by purchasing
+// Documize Enterprise Edition and obtaining a commercial license
+// by contacting <sales@documize.com>.
+//
+// https://documize.com
+
+// Package env provides runtime, server level setup and configuration
+package env
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+	"sync"
+)
+
+// prefix provides the prefix for all environment variables
+const prefix = "DOCUMIZE"
+const goInit = "(default)"
+
+var flagList progFlags
+var cliMutex sync.Mutex
+
+type flagItem struct {
+	target              *string
+	name, setter, value string
+	required            bool
+}
+
+type progFlags struct {
+	items []flagItem
+}
+
+// Len is part of sort.Interface.
+func (v *progFlags) Len() int {
+	return len(v.items)
+}
+
+// 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
+}
+
+// register prepares flag for subsequent parsing
+func register(target *string, name string, required bool, usage string) {
+	cliMutex.Lock()
+	defer cliMutex.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) {
+	cliMutex.Lock()
+	defer cliMutex.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
+}