skel: adds PluginMainWithError which returns a *types.Error

Enables plugins to do their own error-handling and cleanup logic

diff --git a/pkg/skel/skel.go b/pkg/skel/skel.go
index 8fc9636..8644c25 100644 (file)
--- a/pkg/skel/skel.go
+++ b/pkg/skel/skel.go
@@ -189,25 +189,40 @@ func (t *dispatcher) pluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error, versionIn
        return nil
 }
 
-// PluginMain is the "main" for a plugin. It accepts
-// two callback functions for add and del commands.
-func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error, versionInfo version.PluginInfo) {
-       caller := dispatcher{
+// PluginMainWithError is the core "main" for a plugin. It accepts
+// callback functions for add and del CNI commands and returns an error.
+//
+// The caller must also specify what CNI spec versions the plugin supports.
+//
+// It is the responsibility of the caller to check for non-nil error return.
+//
+// For a plugin to comply with the CNI spec, it must print any error to stdout
+// as JSON and then exit with nonzero status code.
+//
+// To let this package automatically handle errors and call os.Exit(1) for you,
+// use PluginMain() instead.
+func PluginMainWithError(cmdAdd, cmdDel func(_ *CmdArgs) error, versionInfo version.PluginInfo) *types.Error {
+       return (&dispatcher{
                Getenv: os.Getenv,
                Stdin:  os.Stdin,
                Stdout: os.Stdout,
                Stderr: os.Stderr,
-       }
-
-       err := caller.pluginMain(cmdAdd, cmdDel, versionInfo)
-       if err != nil {
-               dieErr(err)
-       }
+       }).pluginMain(cmdAdd, cmdDel, versionInfo)
 }
 
-func dieErr(e *types.Error) {
-       if err := e.Print(); err != nil {
-               log.Print("Error writing error JSON to stdout: ", err)
+// PluginMain is the core "main" for a plugin which includes automatic error handling.
+//
+// The caller must also specify what CNI spec versions the plugin supports.
+//
+// When an error occurs in either cmdAdd or cmdDel, PluginMain will print the error
+// as JSON to stdout and call os.Exit(1).
+//
+// To have more control over error handling, use PluginMainWithError() instead.
+func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error, versionInfo version.PluginInfo) {
+       if e := PluginMainWithError(cmdAdd, cmdDel, versionInfo); e != nil {
+               if err := e.Print(); err != nil {
+                       log.Print("Error writing error JSON to stdout: ", err)
+               }
+               os.Exit(1)
        }
-       os.Exit(1)
 }