TrueCloudLab/coredns
16
0
Fork 2
Code Issues Pull requests 4 Projects Releases Packages Wiki Activity Actions

plugin/file: make non-existent file non-fatal (#2955)

Browse source 
* plugin/file: make non-existent file non-fatal

If the zone file being loaded doesn't exist *and* reload is enabled,
just wait the file to pop up in the normal Reload routine.

If reload is set to 0s; we keep this a fatal error on startup. Aslo fix
the ticker in z.Reload(): remove the per second ticks and just use the
reload interval for the ticker.

Brush up the documentation a bit as well.

Fixes: #2951

Signed-off-by: Miek Gieben <miek@miek.nl>

* Stickler and test compile

Signed-off-by: Miek Gieben <miek@miek.nl>

* Remove there too

Signed-off-by: Miek Gieben <miek@miek.nl>

* Cant README test these because zone files dont exist

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben 2019-07-04 06:56:37 +01:00 • committed by Yong Tang
parent f9fb9db171
commit 18304ce9b7
7 changed files with 37 additions and 34 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

16
plugin/file/README.md
View file

@ -6,7 +6,7 @@
## Description
The file plugin is used for an "old-style" DNS server. It serves from a preloaded file that exists
The *file* plugin is used for an "old-style" DNS server. It serves from a preloaded file that exists
on disk. If the zone file contains signatures (i.e., is signed using DNSSEC), correct DNSSEC answers
are returned. Only NSEC is supported! If you use this setup *you* are responsible for re-signing the
zonefile.
@ -44,7 +44,7 @@ file DBFILE [ZONES... ] {
Load the `example.org` zone from `example.org.signed` and allow transfers to the internet, but send
notifies to 10.240.1.1
~~~ corefile
~~~ txt
example.org {
file example.org.signed {
transfer to *
@ -55,7 +55,7 @@ example.org {
Or use a single zone file for multiple zones:
~~~
~~~ txt
. {
file example.org.signed example.org example.net {
transfer to *
@ -67,7 +67,7 @@ Or use a single zone file for multiple zones:
Note that if you have a configuration like the following you may run into a problem of the origin
not being correctly recognized:
~~~
~~~ txt
. {
file db.example.org
}
@ -78,7 +78,7 @@ which, in this case, is the root zone. Any contents of `db.example.org` will the
origin set; this may or may not do what you want.
It's better to be explicit here and specify the correct origin. This can be done in two ways:
~~~
~~~ txt
. {
file db.example.org example.org
}
@ -86,8 +86,12 @@ It's better to be explicit here and specify the correct origin. This can be done
Or
~~~
~~~ txt
example.org {
file db.example.org
}
~~~
## Also See
See the *loadbalance* plugin if you need simple record shuffling.

9
plugin/file/file.go
View file

@ -129,12 +129,15 @@ func Parse(f io.Reader, origin, fileName string, serial int64) (*Zone, error) {
return nil, err
}
if !seenSOA && serial >= 0 {
if !seenSOA {
if s, ok := rr.(*dns.SOA); ok {
if s.Serial == uint32(serial) { // same serial
seenSOA = true
// -1 is valid serial is we failed to load the file on startup.
if serial >= 0 && s.Serial == uint32(serial) { // same serial
return nil, &serialErr{err: "no change in SOA serial", origin: origin, zone: fileName, serial: serial}
}
seenSOA = true
}
}

12
plugin/file/reload.go
View file

@ -5,15 +5,12 @@ import (
"time"
)
// TickTime is clock resolution. By default ticks every second. Handler checks if reloadInterval has been reached on every tick.
var TickTime = 1 * time.Second
// Reload reloads a zone when it is changed on disk. If z.NoReload is true, no reloading will be done.
func (z *Zone) Reload() error {
if z.ReloadInterval == 0 {
return nil
}
tick := time.NewTicker(TickTime)
tick := time.NewTicker(z.ReloadInterval)
go func() {
@ -21,13 +18,6 @@ func (z *Zone) Reload() error {
select {
case <-tick.C:
if z.LastReloaded.Add(z.ReloadInterval).After(time.Now()) {
//reload interval not reached yet
continue
}
//saving timestamp of last attempted reload
z.LastReloaded = time.Now()
zFile := z.File()
reader, err := os.Open(zFile)
if err != nil {

1
plugin/file/reload_test.go
View file

@ -29,7 +29,6 @@ func TestZoneReload(t *testing.T) {
t.Fatalf("Failed to parse zone: %s", err)
}
TickTime = 500 * time.Millisecond
z.ReloadInterval = 500 * time.Millisecond
z.Reload()
time.Sleep(time.Second)

28
plugin/file/setup.go
View file

@ -57,6 +57,9 @@ func fileParse(c *caddy.Controller) (Zones, error) {
config := dnsserver.GetConfig(c)
var openErr error
reload := 1 * time.Minute
for c.Next() {
// file db.file [zones...]
if !c.NextArg() {
@ -77,22 +80,23 @@ func fileParse(c *caddy.Controller) (Zones, error) {
reader, err := os.Open(fileName)
if err != nil {
// bail out
return Zones{}, err
openErr = err
}
for i := range origins {
origins[i] = plugin.Host(origins[i]).Normalize()
zone, err := Parse(reader, origins[i], fileName, 0)
if err == nil {
z[origins[i]] = zone
} else {
return Zones{}, err
z[origins[i]] = NewZone(origins[i], fileName)
if openErr == nil {
zone, err := Parse(reader, origins[i], fileName, 0)
if err == nil {
z[origins[i]] = zone
} else {
return Zones{}, err
}
}
names = append(names, origins[i])
}
reload := 1 * time.Minute
upstr := upstream.New()
t := []string{}
var e error
@ -129,5 +133,13 @@ func fileParse(c *caddy.Controller) (Zones, error) {
}
}
}
if openErr != nil {
if reload == 0 {
// reload hasn't been set make this a fatal error
return Zones{}, plugin.Error("file", openErr)
}
log.Warningf("Failed to open %q: trying again in %s", openErr, reload)
}
return Zones{Z: z, Names: names}, nil
}

2
plugin/file/zone.go
View file

@ -30,7 +30,6 @@ type Zone struct {
Expired *bool
ReloadInterval time.Duration
LastReloaded time.Time
reloadMu sync.RWMutex
reloadShutdown chan bool
Upstream *upstream.Upstream // Upstream for looking up external names during the resolution process.
@ -53,7 +52,6 @@ func NewZone(name, file string) *Zone {
Tree: &tree.Tree{},
Expired: new(bool),
reloadShutdown: make(chan bool),
LastReloaded: time.Now(),
}
*z.Expired = false
return z

3
test/file_reload_test.go
View file

@ -5,15 +5,12 @@ import (
"testing"
"time"
"github.com/coredns/coredns/plugin/file"
"github.com/coredns/coredns/plugin/test"
"github.com/miekg/dns"
)
func TestZoneReload(t *testing.T) {
file.TickTime = 1 * time.Second
name, rm, err := test.TempFile(".", exampleOrg)
if err != nil {
t.Fatalf("Failed to create zone: %s", err)