154 lines
3.5 KiB
Go
154 lines
3.5 KiB
Go
// Package config implements a simple global configuration system that
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// supports a file with key=value pairs and environment variables. Note
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// that the config system is global.
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//
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// This package is intended to be used for small daemons: some configuration
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// file is optionally populated at program start, then this is used to
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// transparently look up configuration values from either that file or the
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// environment.
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package config
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import (
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"bufio"
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"fmt"
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"log"
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"os"
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"sort"
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"strings"
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"git.wntrmute.dev/kyle/goutils/config/iniconf"
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)
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// NB: Rather than define a singleton type, everything is defined at
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// the top-level
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var (
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vars = map[string]string{}
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prefix = ""
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)
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// SetEnvPrefix sets the prefix for all environment variables; it's
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// assumed to not be needed for files.
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func SetEnvPrefix(pfx string) {
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prefix = pfx
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}
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func addLine(line string) {
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if strings.HasPrefix(line, "#") || line == "" {
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return
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}
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lineParts := strings.SplitN(line, "=", 2)
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if len(lineParts) != 2 {
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log.Print("skipping line: ", line)
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return // silently ignore empty keys
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}
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lineParts[0] = strings.TrimSpace(lineParts[0])
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lineParts[1] = strings.TrimSpace(lineParts[1])
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vars[lineParts[0]] = lineParts[1]
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}
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// LoadFile scans the file at path for key=value pairs and adds them
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// to the configuration.
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func LoadFile(path string) error {
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file, err := os.Open(path)
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if err != nil {
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return err
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}
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defer file.Close()
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scanner := bufio.NewScanner(file)
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for scanner.Scan() {
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line := strings.TrimSpace(scanner.Text())
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addLine(line)
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}
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if err = scanner.Err(); err != nil {
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return err
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}
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return nil
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}
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// LoadFileFor scans the ini file at path, loading the default section
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// and overriding any keys found under section. If strict is true, the
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// named section must exist (i.e. to catch typos in the section name).
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func LoadFileFor(path, section string, strict bool) error {
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cmap, err := iniconf.ParseFile(path)
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if err != nil {
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return err
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}
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for key, value := range cmap[iniconf.DefaultSection] {
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vars[key] = value
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}
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smap, ok := cmap[section]
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if !ok {
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if strict {
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return fmt.Errorf("config: section '%s' wasn't found in the config file", section)
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}
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return nil
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}
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for key, value := range smap {
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vars[key] = value
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}
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return nil
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}
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// Get retrieves a value from either a configuration file or the
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// environment. Note that values from a file will override environment
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// variables.
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func Get(key string) string {
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if v, ok := vars[key]; ok {
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return v
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}
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return os.Getenv(prefix + key)
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}
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// GetDefault retrieves a value from either a configuration file or
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// the environment. Note that value from a file will override
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// environment variables. If a value isn't found (e.g. Get returns an
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// empty string), the default value will be used.
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func GetDefault(key, def string) string {
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if v := Get(key); v != "" {
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return v
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}
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return def
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}
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// Require retrieves a value from either a configuration file or the
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// environment. If the key isn't present, it will call log.Fatal, printing
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// the missing key.
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func Require(key string) string {
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if v, ok := vars[key]; ok {
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return v
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}
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v, ok := os.LookupEnv(prefix + key)
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if !ok {
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var envMessage string
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if prefix != "" {
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envMessage = " (note: looked for the key " + prefix + key
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envMessage += " in the local env)"
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}
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log.Fatalf("missing required configuration value %s%s", key, envMessage)
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}
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return v
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}
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// ListKeys returns a slice of the currently known keys.
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func ListKeys() []string {
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keyList := []string{}
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for k := range vars {
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keyList = append(keyList, k)
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}
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sort.Strings(keyList)
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return keyList
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}
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