TrueCloudLab/coredns
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middleware/{log,errors}: output everything to stdout (#684)

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Limit the options in both errors and log middleware, just output to
stdout and let someone else (journald,docker) care about where to route
the logs. This removes syslog and logging to a file.

Fixes #573 #602
This commit is contained in:
Miek Gieben 2017-05-31 20:28:53 +01:00 • committed by GitHub
parent 6c774782e0
commit e261ac1a6e
9 changed files with 49 additions and 186 deletions
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26
middleware/errors/README.md
View file

@ -6,35 +6,21 @@ TODO: what are errors.
## Syntax
~~~
errors [LOGFILE]
errors [FILE]
~~~
* **LOGFILE** is the path to the error log file to create (or append to), relative to the current
working directory. It can also be `stdout` or `stderr` to write to the console, syslog to write to the
system log (except on Windows), or visible to write the error (including full stack trace, if
applicable) to the response. Writing errors to the response is NOT advised except in local debug
situations. The default is stderr. The above syntax will simply enable error reporting on the
server. To specify custom error pages, open a block:
~~~
errors {
what where
}
~~~
* `what` can only be `log`.
* `where` is the path to the log file (as described above) and you can enable rotation to manage the log files.
* **FILE** is the log file to create (or append to). The *only* valid name for **FILE** is *stdout*
## Examples
Log errors into a file in the parent directory:
Log errors to *stdout*.
~~~
errors ../error.log
errors
~~~
Make errors visible to the client (for debugging only):
Log errors to *stdout*.
~~~
errors visible
errors stdout
~~~

23
middleware/errors/errors.go
View file

@ -20,7 +20,6 @@ type errorHandler struct {
Next middleware.Handler
LogFile string
Log *log.Logger
Debug bool // if true, errors are written out to client rather than to a log
}
// ServeDNS implements the middleware.Handler interface.
@ -33,15 +32,6 @@ func (h errorHandler) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns
state := request.Request{W: w, Req: r}
errMsg := fmt.Sprintf("%s [ERROR %d %s %s] %v", time.Now().Format(timeFormat), rcode, state.Name(), state.Type(), err)
if h.Debug {
// Write error to response as a txt message instead of to log
answer := debugMsg(rcode, r)
txt, _ := dns.NewRR(". IN 0 TXT " + errMsg)
answer.Answer = append(answer.Answer, txt)
state.SizeAndDo(answer)
w.WriteMsg(answer)
return 0, err
}
h.Log.Println(errMsg)
}
@ -56,7 +46,6 @@ func (h errorHandler) recovery(ctx context.Context, w dns.ResponseWriter, r *dns
return
}
state := request.Request{W: w, Req: r}
// Obtain source of panic
// From: https://gist.github.com/swdunlop/9629168
var name, file string // function name, file name
@ -83,21 +72,9 @@ func (h errorHandler) recovery(ctx context.Context, w dns.ResponseWriter, r *dns
}
panicMsg := fmt.Sprintf("%s [PANIC %s %s] %s:%d - %v", time.Now().Format(timeFormat), r.Question[0].Name, dns.Type(r.Question[0].Qtype), file, line, rec)
if h.Debug {
// Write error and stack trace to the response rather than to a log
var stackBuf [4096]byte
stack := stackBuf[:runtime.Stack(stackBuf[:], false)]
answer := debugMsg(dns.RcodeServerFailure, r)
// add stack buf in TXT, limited to 255 chars for now.
txt, _ := dns.NewRR(". IN 0 TXT " + string(stack[:255]))
answer.Answer = append(answer.Answer, txt)
state.SizeAndDo(answer)
w.WriteMsg(answer)
} else {
// Currently we don't use the function name, since file:line is more conventional
h.Log.Printf(panicMsg)
}
}
// debugMsg creates a debug message that gets send back to the client.
func debugMsg(rcode int, r *dns.Msg) *dns.Msg {

24
middleware/errors/errors_test.go
View file

@ -66,30 +66,6 @@ func TestErrors(t *testing.T) {
}
}
func TestVisibleErrorWithPanic(t *testing.T) {
const panicMsg = "I'm a panic"
eh := errorHandler{
Debug: true,
Next: middleware.HandlerFunc(func(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
panic(panicMsg)
}),
}
ctx := context.TODO()
req := new(dns.Msg)
req.SetQuestion("example.org.", dns.TypeA)
rec := dnsrecorder.New(&test.ResponseWriter{})
code, err := eh.ServeDNS(ctx, rec, req)
if code != 0 {
t.Errorf("Expected error handler to return 0 (it should write to response), got status %d", code)
}
if err != nil {
t.Errorf("Expected error handler to return nil error (it should panic!), but got '%v'", err)
}
}
func genErrorHandler(rcode int, err error) middleware.Handler {
return middleware.HandlerFunc(func(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
return rcode, err

80
middleware/errors/setup.go
View file

@ -1,14 +1,13 @@
package errors
import (
"io"
"fmt"
"log"
"os"
"github.com/coredns/coredns/core/dnsserver"
"github.com/coredns/coredns/middleware"
"github.com/hashicorp/go-syslog"
"github.com/mholt/caddy"
)
@ -25,34 +24,7 @@ func setup(c *caddy.Controller) error {
return middleware.Error("errors", err)
}
var writer io.Writer
switch handler.LogFile {
case "visible":
handler.Debug = true
case "stdout":
writer = os.Stdout
case "stderr":
writer = os.Stderr
case "syslog":
writer, err = gsyslog.NewLogger(gsyslog.LOG_ERR, "LOCAL0", "coredns")
if err != nil {
return middleware.Error("errors", err)
}
default:
if handler.LogFile == "" {
writer = os.Stderr // default
break
}
var file *os.File
file, err = os.OpenFile(handler.LogFile, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0644)
if err != nil {
return middleware.Error("errors", err)
}
writer = file
}
handler.Log = log.New(writer, "", 0)
handler.Log = log.New(os.Stdout, "", 0)
dnsserver.GetConfig(c).AddMiddleware(func(next middleware.Handler) middleware.Handler {
handler.Next = next
@ -65,47 +37,19 @@ func setup(c *caddy.Controller) error {
func errorsParse(c *caddy.Controller) (errorHandler, error) {
handler := errorHandler{}
optionalBlock := func() (bool, error) {
var hadBlock bool
for c.NextBlock() {
hadBlock = true
what := c.Val()
if !c.NextArg() {
return hadBlock, c.ArgErr()
}
where := c.Val()
if what == "log" {
if where == "visible" {
handler.Debug = true
} else {
handler.LogFile = where
}
}
}
return hadBlock, nil
}
for c.Next() {
// Configuration may be in a block
hadBlock, err := optionalBlock()
if err != nil {
return handler, err
args := c.RemainingArgs()
switch len(args) {
case 0:
handler.LogFile = "stdout"
case 1:
if args[0] != "stdout" {
return handler, fmt.Errorf("invalid log file: %s", args[0])
}
// Otherwise, the only argument would be an error log file name or 'visible'
if !hadBlock {
if c.NextArg() {
if c.Val() == "visible" {
handler.Debug = true
} else {
handler.LogFile = c.Val()
handler.LogFile = args[0]
default:
return handler, c.ArgErr()
}
}
}
}
return handler, nil
}

21
middleware/errors/setup_test.go
View file

@ -13,18 +13,19 @@ func TestErrorsParse(t *testing.T) {
expectedErrorHandler errorHandler
}{
{`errors`, false, errorHandler{
LogFile: "stdout",
}},
{`errors stdout`, false, errorHandler{
LogFile: "stdout",
}},
{`errors errors.txt`, true, errorHandler{
LogFile: "",
}},
{`errors errors.txt`, false, errorHandler{
LogFile: "errors.txt",
}},
{`errors visible`, false, errorHandler{
{`errors visible`, true, errorHandler{
LogFile: "",
Debug: true,
}},
{`errors { log visible }`, false, errorHandler{
LogFile: "",
Debug: true,
{`errors { log visible }`, true, errorHandler{
LogFile: "stdout",
}},
}
for i, test := range tests {
@ -40,9 +41,5 @@ func TestErrorsParse(t *testing.T) {
t.Errorf("Test %d expected LogFile to be %s, but got %s",
i, test.expectedErrorHandler.LogFile, actualErrorsRule.LogFile)
}
if actualErrorsRule.Debug != test.expectedErrorHandler.Debug {
t.Errorf("Test %d expected Debug to be %v, but got %v",
i, test.expectedErrorHandler.Debug, actualErrorsRule.Debug)
}
}
}

23
middleware/log/README.md
View file

@ -1,6 +1,6 @@
# log
*log* enables query logging.
*log* enables query logging to standard output.
## Syntax
@ -8,20 +8,20 @@
log
~~~
* With no arguments, a query log entry is written to query.log in the common log format for all requests
* With no arguments, a query log entry is written to *stdout* in the common log format for all requests
~~~ txt
log FILE
~~~
* **FILE** is the log file to create (or append to).
* **FILE** is the log file to create (or append to). The *only* valid name for **FILE** is *stdout*.
~~~ txt
log [NAME] FILE [FORMAT]
~~~
* `NAME` is the name to match in order to be logged
* `FILE` is the log file to create (or append to)
* `FILE` is the log file (again only *stdout* is allowed here).
* `FORMAT` is the log format to use (default is Common Log Format)
You can further specify the class of responses that get logged:
@ -45,9 +45,8 @@ If no class is specified, it defaults to *all*.
## Log File
The log file can be any filename. It could also be *stdout* or *stderr* to write the log to the console,
or *syslog* to write to the system log (except on Windows). If the log file does not exist beforehand,
CoreDNS will create it before appending to it.
The "log file" can only be *stdout*. CoreDNS expects another service to pick up this output and deal
with it, i.e. journald when using systemd or Docker's logging capabilities.
## Log Format
@ -80,22 +79,22 @@ The default Common Log Format is:
## Examples
Log all requests to a file:
Log all requests to stdout
~~~
log /var/log/query.log
log stdout
~~~
Custom log format:
Custom log format, for all zones (`.`)
~~~
log . ../query.log "{proto} Request: {name} {type} {>id}"
log . stdout "{proto} Request: {name} {type} {>id}"
~~~
Only log denials for example.org (and below to a file)
~~~
log example.org example-query-log {
log example.org stdout {
class denial
}
~~~

4
middleware/log/log.go
View file

@ -78,8 +78,8 @@ type Rule struct {
}
const (
// DefaultLogFilename is the default log filename.
DefaultLogFilename = "query.log"
// DefaultLogFilename is the default output name.
DefaultLogFilename = "stdout"
// CommonLogFormat is the common log format.
CommonLogFormat = `{remote} ` + CommonLogEmptyValue + ` [{when}] "{type} {class} {name} {proto} {size} {>do} {>bufsize}" {rcode} {rsize} {duration}`
// CommonLogEmptyValue is the common empty log value.

28
middleware/log/setup.go
View file

@ -1,7 +1,7 @@
package log
import (
"io"
"fmt"
"log"
"os"
@ -9,7 +9,6 @@ import (
"github.com/coredns/coredns/middleware"
"github.com/coredns/coredns/middleware/pkg/response"
"github.com/hashicorp/go-syslog"
"github.com/mholt/caddy"
"github.com/miekg/dns"
)
@ -30,25 +29,10 @@ func setup(c *caddy.Controller) error {
// Open the log files for writing when the server starts
c.OnStartup(func() error {
for i := 0; i < len(rules); i++ {
var err error
var writer io.Writer
if rules[i].OutputFile == "stdout" {
writer = os.Stdout
} else if rules[i].OutputFile == "stderr" {
writer = os.Stderr
} else if rules[i].OutputFile == "syslog" {
writer, err = gsyslog.NewLogger(gsyslog.LOG_INFO, "LOCAL0", "coredns")
if err != nil {
return middleware.Error("log", err)
}
} else {
var file *os.File
file, err = os.OpenFile(rules[i].OutputFile, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0644)
if err != nil {
return middleware.Error("log", err)
}
writer = file
// We only support stdout
writer := os.Stdout
if rules[i].OutputFile != "stdout" {
return middleware.Error("log", fmt.Errorf("invalid log file: %s", rules[i].OutputFile))
}
rules[i].Log = log.New(writer, "", 0)
@ -78,7 +62,7 @@ func logParse(c *caddy.Controller) ([]Rule, error) {
Format: DefaultLogFormat,
})
} else if len(args) == 1 {
// Only an output file specified
// Only an output file specified.
rules = append(rules, Rule{
NameScope: ".",
OutputFile: args[0],