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|
// Package reload periodically checks if the Corefile has changed, and reloads if so.
package reload
import (
"bytes"
"crypto/md5"
"encoding/hex"
"encoding/json"
"sync"
"time"
"github.com/coredns/caddy"
"github.com/coredns/caddy/caddyfile"
"github.com/prometheus/client_golang/prometheus"
)
const (
unused = 0
maybeUsed = 1
used = 2
)
type reload struct {
dur time.Duration
u int
mtx sync.RWMutex
quit chan bool
}
func (r *reload) setUsage(u int) {
r.mtx.Lock()
defer r.mtx.Unlock()
r.u = u
}
func (r *reload) usage() int {
r.mtx.RLock()
defer r.mtx.RUnlock()
return r.u
}
func (r *reload) setInterval(i time.Duration) {
r.mtx.Lock()
defer r.mtx.Unlock()
r.dur = i
}
func (r *reload) interval() time.Duration {
r.mtx.RLock()
defer r.mtx.RUnlock()
return r.dur
}
func parse(corefile caddy.Input) ([]byte, error) {
serverBlocks, err := caddyfile.Parse(corefile.Path(), bytes.NewReader(corefile.Body()), nil)
if err != nil {
return nil, err
}
return json.Marshal(serverBlocks)
}
func hook(event caddy.EventName, info interface{}) error {
if event != caddy.InstanceStartupEvent {
return nil
}
// if reload is removed from the Corefile, then the hook
// is still registered but setup is never called again
// so we need a flag to tell us not to reload
if r.usage() == unused {
return nil
}
// this should be an instance. ok to panic if not
instance := info.(*caddy.Instance)
parsedCorefile, err := parse(instance.Caddyfile())
if err != nil {
return err
}
md5sum := md5.Sum(parsedCorefile)
log.Infof("Running configuration MD5 = %x\n", md5sum)
go func() {
tick := time.NewTicker(r.interval())
for {
select {
case <-tick.C:
corefile, err := caddy.LoadCaddyfile(instance.Caddyfile().ServerType())
if err != nil {
continue
}
parsedCorefile, err := parse(corefile)
if err != nil {
log.Warningf("Corefile parse failed: %s", err)
continue
}
s := md5.Sum(parsedCorefile)
if s != md5sum {
reloadInfo.Delete(prometheus.Labels{"hash": "md5", "value": hex.EncodeToString(md5sum[:])})
// Let not try to restart with the same file, even though it is wrong.
md5sum = s
// now lets consider that plugin will not be reload, unless appear in next config file
// change status of usage will be reset in setup if the plugin appears in config file
r.setUsage(maybeUsed)
_, err := instance.Restart(corefile)
reloadInfo.WithLabelValues("md5", hex.EncodeToString(md5sum[:])).Set(1)
if err != nil {
log.Errorf("Corefile changed but reload failed: %s", err)
failedCount.Add(1)
continue
}
// we are done, if the plugin was not set used, then it is not.
if r.usage() == maybeUsed {
r.setUsage(unused)
}
return
}
case <-r.quit:
return
}
}
}()
return nil
}
|
