report errors via JSON

This reflects the latest SPEC draft.

diff --git a/plugin/ipam.go b/plugin/ipam.go
index 8b59cab..4124d0f 100644 (file)
--- a/plugin/ipam.go
+++ b/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
        }

diff --git a/plugin/types.go b/plugin/types.go
index 6eb6ac2..9db0f10 100644 (file)
--- a/plugin/types.go
+++ b/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
 

diff --git a/skel/skel.go b/skel/skel.go
index 9f03335..4f159ad 100644 (file)
--- a/skel/skel.go
+++ b/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)
-               os.Exit(1)
+               die("error reading from stdin: %v", err)
        }
 
        cmdArgs := &CmdArgs{
@@ -87,12 +89,18 @@ func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error) {
                err = cmdDel(cmdArgs)
 
        default:
-               log.Printf("Unknown CNI_COMMAND: %v", cmd)
-               os.Exit(1)
+               die("unknown CNI_COMMAND: %v", cmd)
        }
 
        if err != nil {
-               log.Printf("%v: %v", cmd, err)
-               os.Exit(1)
+               die(err.Error())
        }
 }
+
+func die(f string, args ...interface{}) {
+       plugin.PrintError(&plugin.Error{
+               Code: 100,
+               Msg:  fmt.Sprintf(f, args...),
+       })
+       os.Exit(1)
+}