Watch and reload on config changes
This commit is contained in:
Vikram Rangnekar
@ -7,17 +7,18 @@ import (
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)
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type config struct {
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AppName string `mapstructure:"app_name"`
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Env string
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HostPort string `mapstructure:"host_port"`
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Host string
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Port string
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WebUI bool `mapstructure:"web_ui"`
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LogLevel string `mapstructure:"log_level"`
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EnableTracing bool `mapstructure:"enable_tracing"`
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UseAllowList bool `mapstructure:"use_allow_list"`
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AuthFailBlock string `mapstructure:"auth_fail_block"`
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Inflections map[string]string
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AppName string `mapstructure:"app_name"`
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Env string
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HostPort string `mapstructure:"host_port"`
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Host string
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Port string
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WebUI bool `mapstructure:"web_ui"`
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LogLevel string `mapstructure:"log_level"`
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EnableTracing bool `mapstructure:"enable_tracing"`
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UseAllowList bool `mapstructure:"use_allow_list"`
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WatchAndReload bool `mapstructure:"reload_on_config_change"`
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AuthFailBlock string `mapstructure:"auth_fail_block"`
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Inflections map[string]string
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Auth struct {
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Type string
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195
serv/reload.go
Normal file
195
serv/reload.go
Normal file
@ -0,0 +1,195 @@
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// Package reload offers lightweight automatic reloading of running processes.
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//
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// After initialisation with reload.Do() any changes to the binary will
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// restart the process.
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//
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// Example:
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//
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// go func() {
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// err := reload.Do(log.Printf)
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// if err != nil {
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// panic(err)
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// }
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// }()
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//
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// A list of additional directories to watch can be added:
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//
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// go func() {
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// err := reload.Do(log.Printf, reload.Dir("tpl", reloadTpl)
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// if err != nil {
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// panic(err)
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// }
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// }()
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//
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// Note that this package won't prevent race conditions (e.g. when assigning to
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// a global templates variable). You'll need to use sync.RWMutex yourself.
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package serv // import "github.com/teamwork/reload"
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import (
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"fmt"
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"os"
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"path/filepath"
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"runtime"
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"strings"
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"syscall"
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"time"
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"github.com/fsnotify/fsnotify"
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"github.com/pkg/errors"
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)
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var binSelf string
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type dir struct {
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path string
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cb func()
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}
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// Dir is an additional directory to watch for changes. Directories are watched
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// non-recursively.
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//
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// The second argument is the callback that to run when the directory changes.
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// Use reload.ReExec() to restart the process.
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func Dir(path string, cb func()) dir { return dir{path, cb} } // nolint: golint
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// Do reload the current process when its binary changes.
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//
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// The log function is used to display an informational startup message and
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// errors. It works well with e.g. the standard log package or Logrus.
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//
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// The error return will only return initialisation errors. Once initialized it
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// will use the log function to print errors, rather than return.
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func Do(log func(string, ...interface{}), additional ...dir) error {
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watcher, err := fsnotify.NewWatcher()
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if err != nil {
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return errors.Wrap(err, "cannot setup watcher")
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}
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defer watcher.Close() // nolint: errcheck
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binSelf, err = self()
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if err != nil {
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return err
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}
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// Watch the directory, because a recompile renames the existing
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// file (rather than rewriting it), so we won't get events for that.
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dirs := make([]string, len(additional)+1)
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dirs[0] = filepath.Dir(binSelf)
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for i := range additional {
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path, err := filepath.Abs(additional[i].path)
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if err != nil {
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return errors.Wrapf(err, "cannot get absolute path to %q: %v",
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additional[i].path, err)
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}
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s, err := os.Stat(path)
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if err != nil {
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return errors.Wrap(err, "os.Stat")
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}
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if !s.IsDir() {
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return errors.Errorf("not a directory: %q; can only watch directories",
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additional[i].path)
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}
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additional[i].path = path
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dirs[i+1] = path
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}
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done := make(chan bool)
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go func() {
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for {
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select {
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case err := <-watcher.Errors:
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// Standard logger doesn't have anything other than Print,
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// Panic, and Fatal :-/ Printf() is probably best.
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log("reload error: %v", err)
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case event := <-watcher.Events:
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// Ensure that we use the correct events, as they are not uniform accross
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// platforms. See https://github.com/fsnotify/fsnotify/issues/74
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var trigger bool
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switch runtime.GOOS {
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case "darwin", "freebsd", "openbsd", "netbsd", "dragonfly":
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trigger = event.Op&fsnotify.Create == fsnotify.Create
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case "linux":
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trigger = event.Op&fsnotify.Write == fsnotify.Write
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default:
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trigger = event.Op&fsnotify.Create == fsnotify.Create
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log("reload: untested GOOS %q; this package may not work correctly", runtime.GOOS)
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}
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if !trigger {
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continue
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}
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if event.Name == binSelf {
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// Wait for writes to finish.
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time.Sleep(100 * time.Millisecond)
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ReExec()
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}
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for _, a := range additional {
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if strings.HasPrefix(event.Name, a.path) {
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time.Sleep(100 * time.Millisecond)
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a.cb()
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}
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}
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}
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}
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}()
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for _, d := range dirs {
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if err := watcher.Add(d); err != nil {
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return errors.Wrapf(err, "cannot add %q to watcher", d)
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}
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}
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add := ""
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if len(additional) > 0 {
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reldirs := make([]string, len(dirs)-1)
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for i := range dirs[1:] {
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reldirs[i] = relpath(dirs[i+1])
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}
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add = fmt.Sprintf(" (additional dirs: %s)", strings.Join(reldirs, ", "))
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}
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log("restarting %q when it changes%s", relpath(binSelf), add)
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<-done
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return nil
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}
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// Exec replaces the current process with a new copy of itself.
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func ReExec() {
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err := syscall.Exec(binSelf, append([]string{binSelf}, os.Args[1:]...), os.Environ())
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if err != nil {
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panic(fmt.Sprintf("cannot restart: %v", err))
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}
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}
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// Get location to executable.
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func self() (string, error) {
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bin := os.Args[0]
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if !filepath.IsAbs(bin) {
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var err error
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bin, err = os.Executable()
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if err != nil {
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return "", errors.Wrapf(err,
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"cannot get path to binary %q (launch with absolute path): %v",
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os.Args[0], err)
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}
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}
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return bin, nil
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}
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// Get path relative to cwd
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func relpath(p string) string {
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cwd, err := os.Getwd()
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if err != nil {
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return p
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}
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if strings.HasPrefix(p, cwd) {
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return "./" + strings.TrimLeft(p[len(cwd):], "/")
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}
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return p
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}
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21
serv/serv.go
21
serv/serv.go
@ -171,6 +171,26 @@ func initCompilers(c *config) (*qcode.Compiler, *psql.Compiler, error) {
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return qc, pc, nil
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}
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func initWatcher(path string) {
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if conf.WatchAndReload == false {
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return
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}
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var d dir
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if len(path) == 0 || path == "./" {
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d = Dir("./config", ReExec)
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} else {
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d = Dir(path, ReExec)
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}
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go func() {
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err := Do(logger.Printf, d)
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if err != nil {
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panic(err)
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}
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}()
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}
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func Init() {
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var err error
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@ -206,6 +226,7 @@ func Init() {
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initAllowList(*path)
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initPreparedList()
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initWatcher(*path)
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startHTTP()
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}
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