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file.go
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file.go
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package secrets
import (
"bytes"
"errors"
"os"
"path/filepath"
"sync"
"sync/atomic"
"syscall"
"time"
log "github.com/sirupsen/logrus"
)
const (
defaultCredentialsUpdateInterval = 10 * time.Minute
)
var (
ErrWrongFileType = errors.New("file type not supported")
ErrFailedToReadFile = errors.New("failed to read file")
)
// SecretsProvider is a SecretsReader and can add secret sources that
// contain a secret. It will automatically update secrets if the source
// changed.
type SecretsProvider interface {
SecretsReader
// Add adds the given source that contains a secret to the
// automatically updated secrets store
Add(string) error
}
type secretMap map[string][]byte
type SecretPaths struct {
// See https://pkg.go.dev/sync/atomic#example-Value-ReadMostly
secrets atomic.Value // secretMap
closed sync.Once
quit chan struct{}
mu sync.Mutex
paths map[string]struct{}
}
// NewSecretPaths creates a SecretPaths, that implements a
// SecretsProvider. It runs every d interval background refresher as a
// side effect. On tear down make sure to Close() it.
func NewSecretPaths(d time.Duration) *SecretPaths {
if d <= 0 {
d = defaultCredentialsUpdateInterval
}
sp := &SecretPaths{
quit: make(chan struct{}),
paths: make(map[string]struct{}),
}
sp.secrets.Store(make(secretMap))
go sp.runRefresher(d)
return sp
}
// GetSecret returns secret and if found or not for a given name.
func (sp *SecretPaths) GetSecret(s string) ([]byte, bool) {
m := sp.secrets.Load().(secretMap)
data, ok := m[s]
return data, ok
}
// Add registers path to a file or directory to find secrets.
// Background refresher discovers files added or removed later to the directory path.
// The path of the file will be the key to get the secret.
func (sp *SecretPaths) Add(path string) error {
fi, err := os.Lstat(path)
if err != nil {
return err
}
switch mode := fi.Mode(); {
// Kubernetes uses symlink to file
case mode.IsRegular() || mode&os.ModeSymlink != 0:
if _, err := os.ReadFile(path); err != nil {
return err
}
case mode.IsDir():
// handled by refresh
default:
return ErrWrongFileType
}
sp.mu.Lock()
sp.paths[path] = struct{}{}
sp.refreshLocked()
sp.mu.Unlock()
return nil
}
// runRefresher periodically refreshes all registered paths
func (sp *SecretPaths) runRefresher(d time.Duration) {
ticker := time.NewTicker(d)
defer ticker.Stop()
for {
select {
case <-ticker.C:
sp.mu.Lock()
sp.refreshLocked()
sp.mu.Unlock()
case <-sp.quit:
log.Infoln("Stop secrets background refresher")
return
}
}
}
// refreshLocked reads secrets from all registered paths and updates secrets map.
// sp.mu must be held
func (sp *SecretPaths) refreshLocked() {
sizeHint := len(sp.secrets.Load().(secretMap))
actual := make(secretMap, sizeHint)
for path := range sp.paths {
addPath(actual, path)
}
old := sp.secrets.Swap(actual).(secretMap)
for path, data := range actual {
oldData, existed := old[path]
if !existed {
log.Infof("Added secret file: %s", path)
} else if !bytes.Equal(data, oldData) {
log.Infof("Updated secret file: %s", path)
}
}
for path := range old {
if _, exists := actual[path]; !exists {
log.Infof("Removed secret file: %s", path)
}
}
}
func addPath(secrets secretMap, path string) {
fi, err := os.Lstat(path)
if err != nil {
log.Errorf("Failed to stat path %s: %v", path, err)
return
}
switch mode := fi.Mode(); {
// Kubernetes uses symlink to file
case mode.IsRegular() || mode&os.ModeSymlink != 0:
data, err := readSecretFile(path)
if err != nil {
log.Errorf("Failed to read file %s: %v", path, err)
return
}
secrets[path] = data
case mode.IsDir():
matches, err := filepath.Glob(path + "/*")
if err != nil {
log.Errorf("Failed to read directory %s: %v", path, err)
return
}
for _, match := range matches {
data, err := readSecretFile(match)
if err == nil {
secrets[match] = data
} else if !errors.Is(err, syscall.EISDIR) {
log.Errorf("Failed to read path %s: %v", match, err)
}
}
}
}
func readSecretFile(path string) ([]byte, error) {
data, err := os.ReadFile(path)
if err != nil {
return nil, err
}
if len(data) > 0 && data[len(data)-1] == 0xa {
data = data[:len(data)-1]
}
return data, nil
}
func (sp *SecretPaths) Close() {
sp.closed.Do(func() {
close(sp.quit)
})
}