Split linuxkit run -data options into string and file

Signed-off-by: Avi Deitcher <avi@deitcher.net>

blueprints/README.md

@@ -33,7 +33,7 @@ $ linuxkit build -name docker-for-mac base.yml docker-ce.yml
 To run the VM with a 4G disk:
 
 ```
-linuxkit run hyperkit -networking=vpnkit -vsock-ports=2376 -disk size=4096M -data ./metadata.json docker-for-mac
+linuxkit run hyperkit -networking=vpnkit -vsock-ports=2376 -disk size=4096M -data-file ./metadata.json docker-for-mac
 ```
 
 In another terminal you should now be able to access docker via the socket `guest.00000947` in the state directory (`docker-for-mac-state/` by default):

docs/metadata.md

@@ -55,19 +55,22 @@ The JSON file consists of a map from `name` to an entry object. Each entry objec
 - `entries`: if present then the entry is a directory. The value is a map from `name` to entry objects.
 - `perm`: the permissions to create the file with.
 
-The `content` and `entries` fields are mutually exclusive, it is an error to include both, 
-one or the other _must_ be present. 
+The `content` and `entries` fields are mutually exclusive, it is an error to include both,
+one or the other _must_ be present.
 The file or directory's name in each case is the same as the key which referred to that entry.
- 
+
 This hierarchy can then be used by individual containers, who can bind
 mount the config sub-directory into their namespace where it is
 needed.
 
 # Metadata image creation
 
-Run `linuxkit run` backends accept a `-data=STRING` option which will
-cause the given string to be passed to the VM in a platform specific
-manner to be picked up by the `pkg/metadata` component.
+`linuxkit run` backends accept two options to pass metadata to the VM in a platform specific
+manner to be picked up by the `pkg/metadata` component:
+
+* `-data=STRING` will cause the given `STRING` to be passed to the VM
+* `-data-file=PATH` will cause the contents of the file at `PATH` to be passed to the VM
+
 
 Alternatively `linuxkit metadata create meta.iso STRING` will produce
 a correctly formatted ISO image which can be passed to a VM as a CDROM

docs/platform-hyperkit.md

@@ -166,7 +166,7 @@ there are a number of packages, such as `vsudd`, which enable
 tighter integration of the VM with the host (see below).
 
 The HyperKit backend also allows passing custom userdata into the
-[metadata package](./metadata.md) using the `-data` command-line
+[metadata package](./metadata.md) using either the `-data` or `-data-file` command-line
 option. This attaches a CD device with the data on.
 
 

src/cmd/linuxkit/run_hyperkit.go

@@ -42,7 +42,13 @@ func runHyperKit(args []string) {
 	mem := flags.Int("mem", 1024, "Amount of memory in MB")
 	var disks Disks
 	flags.Var(&disks, "disk", "Disk config. [file=]path[,size=1G]")
-	data := flags.String("data", "", "Metadata to pass to VM (either a path to a file or a string)")
+	data := flags.String("data", "", "String of metadata to pass to VM; error to specify both -data and -data-file")
+	dataPath := flags.String("data-file", "", "Path to file containing metadata to pass to VM; error to specify both -data and -data-file")
+
+	if *data != "" && *dataPath != "" {
+		log.Fatal("Cannot specify both -data and -data-file")
+	}
+
 	ipStr := flags.String("ip", "", "Preferred IPv4 address for the VM.")
 	state := flags.String("state", "", "Path to directory to keep VM state in")
 	vsockports := flags.String("vsock-ports", "", "List of vsock ports to forward from the guest on startup (comma separated). A unix domain socket for each port will be created in the state directory")
@@ -142,7 +148,7 @@ func runHyperKit(args []string) {
 		log.Fatalf("Could not create state directory: %v", err)
 	}
 
-	metadataPaths, err := CreateMetadataISO(*state, *data)
+	metadataPaths, err := CreateMetadataISO(*state, *data, *dataPath)
 	if err != nil {
 		log.Fatalf("%v", err)
 	}

src/cmd/linuxkit/run_qemu.go

@@ -148,7 +148,12 @@ func runQemu(args []string) {
 	// Paths and settings for disks
 	var disks Disks
 	flags.Var(&disks, "disk", "Disk config, may be repeated. [file=]path[,size=1G][,format=qcow2]")
-	data := flags.String("data", "", "Metadata to pass to VM (either a path to a file or a string)")
+	data := flags.String("data", "", "String of metadata to pass to VM; error to specify both -data and -data-file")
+	dataPath := flags.String("data-file", "", "Path to file containing metadata to pass to VM; error to specify both -data and -data-file")
+
+	if *data != "" && *dataPath != "" {
+		log.Fatal("Cannot specify both -data and -data-file")
+	}
 
 	// Paths and settings for UEFI firware
 	// Note, we do not use defaultFWPath here as we have a special case for containerised execution
@@ -223,7 +228,7 @@ func runQemu(args []string) {
 		isoPaths = append(isoPaths, path)
 	}
 
-	metadataPaths, err := CreateMetadataISO(*state, *data)
+	metadataPaths, err := CreateMetadataISO(*state, *data, *dataPath)
 	if err != nil {
 		log.Fatalf("%v", err)
 	}

src/cmd/linuxkit/util.go

@@ -256,22 +256,25 @@ func NewPublishedPort(publish string) (PublishedPort, error) {
 }
 
 // CreateMetadataISO writes the provided meta data to an iso file in the given state directory
-func CreateMetadataISO(state, data string) ([]string, error) {
-	if data == "" {
-		return []string{}, nil
-	}
-
+func CreateMetadataISO(state, data string, dataPath string) ([]string, error) {
 	var d []byte
-	if st, err := os.Stat(data); os.IsNotExist(err) {
-		d = []byte(data)
-	} else if st.Size() == 0 {
+
+	// if we have neither data nor dataPath, nothing to return
+	switch {
+	case data != "" && dataPath != "":
+		return nil, fmt.Errorf("Cannot specify options for both data and dataPath")
+	case data == "" && dataPath == "":
 		return []string{}, nil
-	} else {
-		d, err = ioutil.ReadFile(data)
+	case data != "":
+		d = []byte(data)
+	case dataPath != "":
+		var err error
+		d, err = ioutil.ReadFile(dataPath)
 		if err != nil {
-			return nil, fmt.Errorf("Cannot read user data: %v", err)
+			return nil, fmt.Errorf("Cannot read user data from path %s: %v", dataPath, err)
 		}
 	}
+
 	isoPath := filepath.Join(state, "data.iso")
 	if err := WriteMetadataISO(isoPath, d); err != nil {
 		return nil, fmt.Errorf("Cannot write user data ISO: %v", err)