Implement bootcmd

cmd/cloudinitexecute/cloudinitexecute.go

@@ -94,18 +94,7 @@ func ApplyConsole(cfg *rancherConfig.CloudConfig) {
 		}
 	}
 
-	for _, runcmd := range cfg.Runcmd {
-		if len(runcmd) == 0 {
-			continue
-		}
-
-		cmd := exec.Command(runcmd[0], runcmd[1:]...)
-		cmd.Stdout = os.Stdout
-		cmd.Stderr = os.Stderr
-		if err := cmd.Run(); err != nil {
-			log.Errorf("Failed to run %s: %v", runcmd, err)
-		}
-	}
+	util.RunCommandSequence(cfg.Runcmd)
 }
 
 func WriteFiles(cfg *rancherConfig.CloudConfig, container string) {

cmd/control/bootstrap.go

@@ -34,6 +34,8 @@ func bootstrapAction(c *cli.Context) error {
 		}
 	}
 
+	util.RunCommandSequence(cfg.Bootcmd)
+
 	if cfg.Rancher.State.Dev != "" && cfg.Rancher.State.Wait {
 		waitForRoot(cfg)
 	}

config/types.go

@@ -89,6 +89,7 @@ type CloudConfig struct {
 	Mounts            [][]string    `yaml:"mounts,omitempty"`
 	Rancher           RancherConfig `yaml:"rancher,omitempty"`
 	Runcmd            [][]string    `yaml:"runcmd,omitempty"`
+	Bootcmd           [][]string    `yaml:"bootcmd,omitempty"`
 }
 
 type File struct {

docs/os/configuration/running-commands/index.md

@@ -21,7 +21,7 @@ Commands specified using `runcmd` will be executed within the context of the `co
 
 When using `runcmd`, RancherOS will wait for all commands to complete before starting Docker. As a result, any `docker run` command should not be placed under `runcmd`. Instead, the `/etc/rc.local` script can be used. RancherOS will not wait for commands in this script to complete, so you can use the `wait-for-docker` command to ensure that the Docker daemon is running before performing any `docker run` commands.
 
-```
+```yaml
 #cloud-config
 rancher:
 write_files:
@@ -35,3 +35,16 @@ write_files:
 ```
 
 Running Docker commands in this manner is useful when pieces of the `docker run` command are dynamically generated. For services whose configuration is static, [adding a system service]({{site.baseurl}}/os/system-services/adding-system-services/) is recommended.
+
+## Running Commands Early in the Boot Process
+---
+
+The `bootcmd` parameter can be used to run commands earlier in the boot process. In particular, `bootcmd` will be executed while RancherOS is still running from memory and before System Docker and any system services are started.
+
+The syntax for bootcmd is the same as `runcmd`.
+
+```yaml
+#cloud-config
+bootcmd:
+- [ mdadm, --assemble, --scan ]
+```

init/bootstrap.go

@@ -11,7 +11,7 @@ import (
 )
 
 func bootstrapServices(cfg *config.CloudConfig) (*config.CloudConfig, error) {
-	if len(cfg.Rancher.State.Autoformat) == 0 || util.ResolveDevice(cfg.Rancher.State.Dev) != "" {
+	if (len(cfg.Rancher.State.Autoformat) == 0 || util.ResolveDevice(cfg.Rancher.State.Dev) != "") && len(cfg.Bootcmd) == 0 {
 		return cfg, nil
 	}
 	log.Info("Running Bootstrap")

util/util.go

@@ -268,3 +268,18 @@ func RunScript(path string) error {
 
 	return cmd.Run()
 }
+
+func RunCommandSequence(commandSequence [][]string) {
+	for _, command := range commandSequence {
+		if len(command) == 0 {
+			continue
+		}
+
+		cmd := exec.Command(command[0], command[1:]...)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		if err := cmd.Run(); err != nil {
+			log.Errorf("Failed to run %s: %v", command, err)
+		}
+	}
+}