Remove reaper from containerd daemon

This allows other packages and plugins to easily exec things without
racing with the reaper.

The reaper is mostly needed in the shim but can be removed in containerd
in favor of the `exec.Cmd` apis

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

server/config.go

@@ -23,8 +23,6 @@ type Config struct {
 	Metrics MetricsConfig `toml:"metrics"`
 	// Plugins provides plugin specific configuration for the initialization of a plugin
 	Plugins map[string]toml.Primitive `toml:"plugins"`
-	// NoSubreaper disables containerd as a subreaper
-	NoSubreaper bool `toml:"no_subreaper"`
 	// OOMScore adjust the containerd's oom score
 	OOMScore int `toml:"oom_score"`
 	// Cgroup specifies cgroup information for the containerd daemon process

server/server_linux.go

@@ -12,12 +12,6 @@ import (
 
 // apply sets config settings on the server process
 func apply(ctx context.Context, config *Config) error {
-	if !config.NoSubreaper {
-		log.G(ctx).Info("setting subreaper...")
-		if err := sys.SetSubreaper(1); err != nil {
-			return err
-		}
-	}
 	if config.OOMScore != 0 {
 		log.G(ctx).Debugf("changing OOM score to %d", config.OOMScore)
 		if err := sys.SetOOMScore(os.Getpid(), config.OOMScore); err != nil {