Merge pull request #9 from eyakubovich/errors

report errors via JSON

pkg/plugin/ipam.go

@@ -125,9 +125,18 @@ func ConfigureIface(ifName string, res *Result) error {
 	return nil
 }
 
-// PrintResult writes out prettified Result to stdout
+// PrintResult writes out prettified Result JSON to stdout
 func PrintResult(res *Result) error {
-	data, err := json.MarshalIndent(res, "", "    ")
+	return prettyPrint(res)
+}
+
+// PrintError writes out prettified Error JSON to stdout
+func PrintError(err *Error) error {
+	return prettyPrint(err)
+}
+
+func prettyPrint(obj interface{}) error {
+	data, err := json.MarshalIndent(obj, "", "    ")
 	if err != nil {
 		return err
 	}

pkg/plugin/types.go

@@ -48,6 +48,12 @@ type Route struct {
 	GW  net.IP
 }
 
+type Error struct {
+	Code    uint   `json:"code"`
+	Msg     string `json:"msg"`
+	Details string `json:"details,omitempty"`
+}
+
 // net.IPNet is not JSON (un)marshallable so this duality is needed
 // for our custom ip.IPNet type
 

pkg/skel/skel.go

@@ -17,9 +17,12 @@
 package skel
 
 import (
+	"fmt"
 	"io/ioutil"
 	"log"
 	"os"
+
+	"github.com/appc/cni/pkg/plugin"
 )
 
 // CmdArgs captures all the arguments passed in to the plugin
@@ -61,13 +64,12 @@ func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error) {
 	}
 
 	if argsMissing {
-		os.Exit(1)
+		die("required env variables missing")
 	}
 
 	stdinData, err := ioutil.ReadAll(os.Stdin)
 	if err != nil {
-		log.Printf("Error reading from stdin: %v", err)
+		die("error reading from stdin: %v", err)
-		os.Exit(1)
 	}
 
 	cmdArgs := &CmdArgs{
@@ -87,12 +89,18 @@ func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error) {
 		err = cmdDel(cmdArgs)
 
 	default:
-		log.Printf("Unknown CNI_COMMAND: %v", cmd)
+		die("unknown CNI_COMMAND: %v", cmd)
-		os.Exit(1)
 	}
 
 	if err != nil {
-		log.Printf("%v: %v", cmd, err)
+		die(err.Error())
-		os.Exit(1)
 	}
 }
+
+func die(f string, args ...interface{}) {
+	plugin.PrintError(&plugin.Error{
+		Code: 100,
+		Msg:  fmt.Sprintf(f, args...),
+	})
+	os.Exit(1)
+}