making config option a slice instead of string + adding as conifg val…

…ue to make it easier for users to switch back to overlayfs from soci

Signed-off-by: Channing Gaddy <[email protected]>

README.md

@@ -99,15 +99,16 @@ An example `finch.yaml` looks like this:
 cpus: 4
 # memory: the amount of memory to dedicate to the virtual machine. (required)
 memory: 4GiB
-# snapshotter: the snapshotter a user want to use as their default snapshotter
+# snapshotters: the snapshotters a user wants to use (the first snapshotter will be set as the default snapshotter)
 # Supported Snapshotters List:
 # - soci https://github.com/awslabs/soci-snapshotter/tree/main
-# Once the option has been set the snapshotter will be installed on either finch vm init or finch vm start.
-# The snapshotter binary will be downloaded on the virtual machine and will be configured and ready for use.
-# To change your default snpahotter back to overlayfs, simply remove the snapshotter value from finch.yaml
-# To completely remove the snapshotter binary, shell into your VM and remove /usr/local/bin/{snapshotter binary}
+# Once the option has been set the snapshotters will be installed on either finch vm init or finch vm start.
+# The snapshotters binary will be downloaded on the virtual machine and will be configured and ready for use.
+# To change your default snpahotter back to overlayfs, simply remove the snapshotters value from finch.yaml or set snapshotters to `overlayfs`
+# To completely remove the snapshotters' binaries, shell into your VM and remove /usr/local/bin/{snapshotter binary}
 # and remove the snapshotter configuration in the containerd config file found at /etc/containerd/config.toml
-snapshotter: soci
+snapshotters: 
+    - soci
 # creds_helpers: a list of credential helpers that will be installed and configured automatically. 
 # Supported Credential Helpers List: 
 # - ecr-login https://github.com/awslabs/amazon-ecr-credential-helper

e2e/vm/soci_test.go

@@ -38,8 +38,8 @@ var testSoci = func(o *option.Option, installed bool) {
 		ginkgo.It("finch pull should have same mounts as nerdctl pull with SOCI", func() {
 			resetVM(o, installed)
 			resetDisks(o, installed)
-			writeFile(finchConfigFilePath, []byte("cpus: 6\nmemory: 4GiB\nsnapshotter: soci\n"+
-				"vmType: qemu\nrosetta: false"))
+			writeFile(finchConfigFilePath, []byte("cpus: 6\nmemory: 4GiB\nsnapshotters:\n    "+
+				"- soci\nvmType: qemu\nrosetta: false"))
 			command.New(o, virtualMachineRootCmd, "init").WithTimeoutInSeconds(600).Run()
 			command.New(o, "pull", ffmpegSociImage).WithTimeoutInSeconds(30).Run()
 			finchPullMounts := countMounts(limactlO)
@@ -54,8 +54,8 @@ var testSoci = func(o *option.Option, installed bool) {
 		ginkgo.It("finch run should have same mounts as nerdctl run with SOCI", func() {
 			resetVM(o, installed)
 			resetDisks(o, installed)
-			writeFile(finchConfigFilePath, []byte("cpus: 6\nmemory: 4GiB\nsnapshotter: soci\n"+
-				"vmType: qemu\nrosetta: false"))
+			writeFile(finchConfigFilePath, []byte("cpus: 6\nmemory: 4GiB\nsnapshotters:\n    "+
+				"- soci\nvmType: qemu\nrosetta: false"))
 			command.New(o, virtualMachineRootCmd, "init").WithTimeoutInSeconds(600).Run()
 			command.New(o, "run", ffmpegSociImage).WithTimeoutInSeconds(30).Run()
 			finchPullMounts := countMounts(limactlO)

go.mod

@@ -20,6 +20,7 @@ require (
 	github.com/stretchr/testify v1.8.4
 	github.com/xorcare/pointer v1.2.2
 	golang.org/x/crypto v0.11.0
+	golang.org/x/exp v0.0.0-20230810033253-352e893a4cad
 	golang.org/x/tools v0.11.1
 	gopkg.in/yaml.v3 v3.0.1
 	k8s.io/apimachinery v0.27.4

go.sum

@@ -400,6 +400,8 @@ golang.org/x/exp v0.0.0-20191227195350-da58074b4299/go.mod h1:2RIsYlXP63K8oxa1u0
 golang.org/x/exp v0.0.0-20200119233911-0405dc783f0a/go.mod h1:2RIsYlXP63K8oxa1u096TMicItID8zy7Y6sNkU49FU4=
 golang.org/x/exp v0.0.0-20200207192155-f17229e696bd/go.mod h1:J/WKrq2StrnmMY6+EHIKF9dgMWnmCNThgcyBT1FY9mM=
 golang.org/x/exp v0.0.0-20200224162631-6cc2880d07d6/go.mod h1:3jZMyOhIsHpP37uCMkUooju7aAi5cS1Q23tOzKc+0MU=
+golang.org/x/exp v0.0.0-20230810033253-352e893a4cad h1:g0bG7Z4uG+OgH2QDODnjp6ggkk1bJDsINcuWmJN1iJU=
+golang.org/x/exp v0.0.0-20230810033253-352e893a4cad/go.mod h1:FXUEEKJgO7OQYeo8N01OfiKP8RXMtf6e8aTskBGqWdc=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
 golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=

pkg/config/config.go

@@ -36,8 +36,8 @@ type Finch struct {
 	CPUs   *int    `yaml:"cpus"`
 	Memory *string `yaml:"memory"`
 	// Snapshotter: the snapshotter that will be installed and configured automatically on vm init or on vm start
-	// Values: `soci` for SOCI snapshotter or empty for default overlay snapshotter.
-	Snapshotter *string `yaml:"snapshotter,omitempty"`
+	// Values: `soci` for SOCI snapshotter; `overlayfs` for default overlay snapshotter.
+	Snapshotters []string `yaml:"snapshotters,omitempty"`
 	// CredsHelper: the list of credential helpers that will be installed and configured automatically on vm init or on vm start
 	CredsHelpers []string `yaml:"creds_helpers,omitempty"`
 	// AdditionalDirectories are the work directories that are not supported by default. In macOS, only home directory is supported by default.

pkg/config/lima_config_applier.go

@@ -10,6 +10,7 @@ import (
 	"github.com/lima-vm/lima/pkg/limayaml"
 	"github.com/spf13/afero"
 	"github.com/xorcare/pointer"
+	"golang.org/x/exp/slices"
 	"gopkg.in/yaml.v3"
 
 	"github.com/runfinch/finch/pkg/command"
@@ -122,14 +123,25 @@ func (lca *limaConfigApplier) Apply(isInit bool) error {
 		limaCfg = *cfgAfterInit
 	}
 
-	var sociEnabled bool
-	if lca.cfg.Snapshotter == nil {
-		sociEnabled = false
-	} else {
-		sociEnabled = (*lca.cfg.Snapshotter == "soci")
+	supportedSnapshotters := []string{"overlayfs", "soci"}
+	enabledSnapshotters := initializeEnabledSnapshotterSlice(len(supportedSnapshotters))
+
+	for i, snapshotter := range lca.cfg.Snapshotters {
+		supportedIdx := slices.Index(supportedSnapshotters, snapshotter)
+		if supportedIdx < 0 {
+			return fmt.Errorf("invalid snapshotter config value: %s", snapshotter)
+		}
+
+		isDefaultSnapshotter := false
+		if i == 0 {
+			isDefaultSnapshotter = true
+		}
+
+		isEnabled := true
+		enabledSnapshotters[supportedIdx] = [2]bool{isEnabled, isDefaultSnapshotter}
 	}
 
-	toggleSoci(&limaCfg, sociEnabled, sociVersion)
+	toggleSnaphotters(&limaCfg, supportedSnapshotters, enabledSnapshotters)
 
 	limaCfgBytes, err := yaml.Marshal(limaCfg)
 	if err != nil {
@@ -224,23 +236,60 @@ func hasUserModeEmulationInstallationScript(limaCfg *limayaml.LimaYAML) (int, bo
 	return scriptIdx, hasCrossArchToolInstallationScript
 }
 
-func toggleSoci(limaCfg *limayaml.LimaYAML, enabled bool, sociVersion string) {
+// initializes the bool slice for what snapshotter the user has enabled to all false
+// this will be changed later depending on the user's snapshotters config values.
+func initializeEnabledSnapshotterSlice(numSupportedSnapshotters int) [2][2]bool {
+	var enabledSnapshotters [2][2]bool
+
+	for i := 0; i < numSupportedSnapshotters; i++ {
+		enabledSnapshotters[i] = [2]bool{false, false}
+	}
+
+	return enabledSnapshotters
+}
+
+// toggles enabled snapshotters and sets default snapshotter.
+func toggleSnaphotters(limaCfg *limayaml.LimaYAML, supportedSnapshotters []string, enabledSnapshotters [2][2]bool) {
+	for i := len(enabledSnapshotters) - 1; i > 0; i-- {
+		enabledSlice := enabledSnapshotters[i]
+		if enabledSlice[0] {
+			if supportedSnapshotters[i] == "overlayfs" {
+				toggleOverlayFs(limaCfg, enabledSlice[1])
+			} else if supportedSnapshotters[i] == "soci" {
+				toggleSoci(limaCfg, enabledSlice[0], enabledSlice[1], sociVersion)
+			}
+		}
+	}
+}
+
+// sets overlayfs as the default snapshotter.
+func toggleOverlayFs(limaCfg *limayaml.LimaYAML, isDefault bool) {
+	if isDefault {
+		limaCfg.Env = map[string]string{"CONTAINERD_SNAPSHOTTER": ""}
+	}
+}
+
+func toggleSoci(limaCfg *limayaml.LimaYAML, enabled bool, isDefault bool, sociVersion string) {
 	idx, hasScript := findSociInstallationScript(limaCfg)
 	sociFileName := fmt.Sprintf(sociFileNameFormat, sociVersion, system.NewStdLib().Arch())
 	sociDownloadURL := fmt.Sprintf(sociDownloadURLFormat, sociVersion, sociFileName)
 	sociInstallationScript := fmt.Sprintf(sociInstallationScriptFormat, sociInstallationProvisioningScriptHeader, sociDownloadURL, sociFileName)
 	if !hasScript && enabled {
-		limaCfg.Env = map[string]string{"CONTAINERD_SNAPSHOTTER": "soci"}
 		limaCfg.Provision = append(limaCfg.Provision, limayaml.Provision{
 			Mode:   "system",
 			Script: sociInstallationScript,
 		})
 	} else if hasScript && !enabled {
-		limaCfg.Env = map[string]string{"CONTAINERD_SNAPSHOTTER": ""}
 		if len(limaCfg.Provision) > 0 {
 			limaCfg.Provision = append(limaCfg.Provision[:idx], limaCfg.Provision[idx+1:]...)
 		}
 	}
+
+	if isDefault {
+		limaCfg.Env = map[string]string{"CONTAINERD_SNAPSHOTTER": "soci"}
+	} else {
+		limaCfg.Env = map[string]string{"CONTAINERD_SNAPSHOTTER": ""}
+	}
 }
 
 func findSociInstallationScript(limaCfg *limayaml.LimaYAML) (int, bool) {