Fix containerd config dump.

Signed-off-by: Lantao Liu <lantaol@google.com>

cmd/containerd/command/config.go

@@ -65,10 +65,14 @@ func outputConfig(cfg *srvconfig.Config) error {
 		}
 	}
 
+	if config.Timeouts == nil {
+		config.Timeouts = make(map[string]string)
+	}
 	timeouts := timeout.All()
-	config.Timeouts = make(map[string]string)
 	for k, v := range timeouts {
-		config.Timeouts[k] = v.String()
+		if config.Timeouts[k] == "" {
+			config.Timeouts[k] = v.String()
+		}
 	}
 
 	// for the time being, keep the defaultConfig's version set at 1 so that

docs/man/containerd-config.toml.5.md

@@ -39,6 +39,8 @@ separately (for example vendors may keep a custom runtime configuration in a
 separate file without modifying the main `config.toml`).
 Imported files will overwrite simple fields like `int` or
 `string` (if not empty) and will append `array` and `map` fields.
+Imported files are also versioned, and the version can't be higher than
+the main config.
 
 **[grpc]**
 : Section for gRPC socket listener settings. Contains three properties:

services/server/config/config.go

@@ -28,6 +28,8 @@ import (
 	"github.com/containerd/containerd/plugin"
 )
 
+// NOTE: Any new map fields added also need to be handled in mergeConfig.
+
 // Config provides containerd configuration data for the server
 type Config struct {
 	// Version of the config file
@@ -321,6 +323,10 @@ func mergeConfig(to, from *Config) error {
 		to.ProxyPlugins[k] = v
 	}
 
+	for k, v := range from.Timeouts {
+		to.Timeouts[k] = v
+	}
+
 	return nil
 }