Load mount-layout from .env-files

cmd/config/config.go

@@ -270,6 +270,11 @@ func ReadMountSpec(r *v1.RunConfig, flags *pflag.FlagSet) (*v1.MountSpec, error)
 		return mount, err
 	}
 
+	if err := applyMountEnvVars(r, mount); err != nil {
+		r.Logger.Errorf("Error reading mount env-vars: %s", err.Error())
+		return mount, err
+	}
+
 	if err := applyKernelCmdline(r, mount); err != nil {
 		r.Logger.Errorf("Error reading kernel cmdline: %s", err.Error())
 		return mount, err
@@ -312,6 +317,11 @@ func applyKernelCmdline(r *v1.RunConfig, mount *v1.MountSpec) error {
 				r.Logger.Errorf("Error parsing cmdline %s", cmd)
 				return errors.New("Unknown image path")
 			}
+		case "elemental.overlay", "rd.cos.overlay":
+			err := applyMountOverlay(mount, val)
+			if err != nil {
+				return err
+			}
 		case "elemental.oemlabel", "rd.cos.oemlabel":
 			mount.Partitions.OEM.FilesystemLabel = val
 		}
@@ -320,6 +330,70 @@ func applyKernelCmdline(r *v1.RunConfig, mount *v1.MountSpec) error {
 	return nil
 }
 
+func applyMountEnvVars(r *v1.RunConfig, mount *v1.MountSpec) error {
+	r.Logger.Debugf("Applying mount env-vars")
+
+	overlay := os.Getenv("OVERLAY")
+	if overlay != "" {
+		r.Logger.Debugf("Setting ephemeral settings based on OVERLAY")
+
+		err := applyMountOverlay(mount, overlay)
+		if err != nil {
+			return err
+		}
+	}
+
+	rwPaths := os.Getenv("RW_PATHS")
+	if rwPaths != "" {
+		r.Logger.Debugf("Setting ephemeral paths based on RW_PATHS")
+		mount.Ephemeral.Paths = strings.Split(rwPaths, " ")
+	}
+
+	persistentPaths := os.Getenv("PERSISTENT_STATE_PATHS")
+	if persistentPaths != "" {
+		r.Logger.Debugf("Setting persistent paths based on PERSISTENT_STATE_PATHS")
+		mount.Persistent.Paths = strings.Split(persistentPaths, " ")
+	}
+
+	persistentBind := os.Getenv("PERSISTENT_STATE_BIND")
+	if persistentBind != "" {
+		r.Logger.Debugf("Setting persistent bind based on PERSISTENT_STATE_BIND")
+		mount.Persistent.Mode = constants.BindMode
+	}
+
+	return nil
+}
+
+func applyMountOverlay(mount *v1.MountSpec, overlay string) error {
+	split := strings.Split(overlay, ":")
+
+	if len(split) == 2 && split[0] == constants.Tmpfs {
+		mount.Ephemeral.Device = ""
+		mount.Ephemeral.Type = split[0]
+		mount.Ephemeral.Size = split[1]
+		return nil
+	}
+
+	mount.Ephemeral.Type = constants.Block
+	mount.Ephemeral.Size = ""
+
+	blockSplit := strings.Split(overlay, "=")
+	if len(blockSplit) != 2 {
+		return fmt.Errorf("Unknown block overlay '%s'", overlay)
+	}
+
+	switch blockSplit[0] {
+	case "LABEL":
+		mount.Ephemeral.Device = fmt.Sprintf("/dev/disk/by-label/%s", blockSplit[1])
+	case "UUID":
+		mount.Ephemeral.Device = fmt.Sprintf("/dev/disk/by-uuid/%s", blockSplit[1])
+	default:
+		return fmt.Errorf("Unknown block overlay '%s'", overlay)
+	}
+
+	return nil
+}
+
 func ReadResetSpec(r *v1.RunConfig, flags *pflag.FlagSet) (*v1.ResetSpec, error) {
 	reset, err := config.NewResetSpec(r.Config)
 	if err != nil {

cmd/config/config_test.go

@@ -271,6 +271,11 @@ var _ = Describe("Config", Label("config"), func() {
 			fs, cleanup, err = vfst.NewTestFS(map[string]interface{}{})
 			Expect(err).Should(BeNil())
 
+			err = fs.Mkdir("/proc", constants.DirPerm)
+			Expect(err).Should(BeNil())
+			err = fs.WriteFile("/proc/cmdline", []byte("root=LABEL=COS_STATE elemental.image=active elemental.overlay=tmpfs:30%"), 0444)
+			Expect(err).Should(BeNil())
+
 			cfg, err = ReadConfigRun("fixtures/config/", nil, mounter)
 			Expect(err).Should(BeNil())
 
@@ -449,6 +454,28 @@ var _ = Describe("Config", Label("config"), func() {
 				Expect(spec.RecoveryUpgrade).To(BeTrue())
 			})
 		})
-
+		Describe("Read MountSpec", Label("mount"), func() {
+			It("inits a mount spec according to given configs", func() {
+				err := os.Setenv("ELEMENTAL_MOUNT_SYSROOT", "/newroot")
+				spec, err := ReadMountSpec(cfg, nil)
+				Expect(err).ShouldNot(HaveOccurred())
+				Expect(spec.Mode).To(Equal("active"))
+				Expect(spec.Sysroot).To(Equal("/newroot"))
+			})
+			It("picks kernel cmdline first then env-vars", func() {
+				err := os.Setenv("ELEMENTAL_MOUNT_IMAGE", "passive")
+				spec, err := ReadMountSpec(cfg, nil)
+				Expect(err).ShouldNot(HaveOccurred())
+				// Set by kernel cmdline
+				Expect(spec.Mode).To(Equal("active"))
+			})
+			It("picks kernel cmdline first then env-vars", func() {
+				err := os.Setenv("OVERLAY", "UUID=1234")
+				spec, err := ReadMountSpec(cfg, nil)
+				Expect(err).ShouldNot(HaveOccurred())
+				Expect(spec.Ephemeral.Type).To(Equal("tmpfs"))
+				Expect(spec.Ephemeral.Size).To(Equal("30%"))
+			})
+		})
 	})
 })

pkg/constants/constants.go

@@ -263,10 +263,8 @@ func GetInitKeyEnvMap() map[string]string {
 // GetMountKeyEnvMap returns environment variable bindings to MountSpec data
 func GetMountKeyEnvMap() map[string]string {
 	return map[string]string{
-		"write-fstab":         "WRITE_FSTAB",
-		"write-sentinel":      "WRITE_SENTINEL",
-		"sysroot":             "SYSROOT",
-		"read-kernel-cmdline": "READ_KERNEL_CMDLINE",
+		"write-fstab": "WRITE_FSTAB",
+		"sysroot":     "SYSROOT",
 	}
 }
 

pkg/features/embedded/cloud-config-essentials/system/oem/00_rootfs.yaml

@@ -13,7 +13,7 @@ stages:
         providers: ["aws", "gcp", "openstack", "cdrom"]
         path: "/oem"
   rootfs:
-    - if: '[ ! -f "/run/cos/recovery_mode" ]'
+    - if: '[ ! -f "/run/elemental/recovery_mode" ]'
       name: "Layout configuration"
       environment_file: /run/cos/cos-layout.env
       environment:

pkg/features/embedded/elemental-rootfs/usr/lib/systemd/system/elemental-rootfs.service

@@ -9,6 +9,8 @@ Conflicts=initrd-switch-root.target
 [Service]
 Type=oneshot
 RemainAfterExit=yes
+EnvironmentFile=-/run/cos/cos-layout.env
+EnvironmentFile=-/run/elemental/mount-layout.env
 ExecStart=/usr/bin/elemental mount --debug
 
 [Install]

pkg/features/embedded/elemental-setup/usr/lib/systemd/system/elemental-setup-rootfs.service

@@ -5,7 +5,7 @@ After=sysroot.mount
 Requires=sysroot.mount
 After=oem.mount
 Wants=oem.mount
-Before=initrd-fs.target
+Before=initrd-root-fs.target
 Conflicts=initrd-switch-root.target
 
 [Service]