libpod: allow multiple oci runtimes

This deprecates the libpod.conf variable of `runtime_path=`, and now has
`runtimes=`, like a map for naming the runtime, preparing for a
`--runtime` flag to `podman run` (i.e. runc, kata, etc.)

Reference: https://github.com/containers/libpod/issues/1750

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

1 files changed, 39 insertions, 25 deletions

diff --git a/libpod/runtime.go b/libpod/runtime.go
index c9471247c..81d4cf3e3 100644
--- a/libpod/runtime.go
+++ b/libpod/runtime.go
@@ -86,7 +86,7 @@ type Runtime struct {
 	imageContext    *types.SystemContext
 	ociRuntime      *OCIRuntime
 	netPlugin       ocicni.CNIPlugin
-	ociRuntimePath  string
+	ociRuntimePath  OCIRuntimePath
 	conmonPath      string
 	valid           bool
 	lock            sync.RWMutex
@@ -96,6 +96,14 @@ type Runtime struct {
 	configuredFrom  *runtimeConfiguredFrom
 }
 
+// OCIRuntimePath contains information about an OCI runtime.
+type OCIRuntimePath struct {
+	// Name of the runtime to refer to by the --runtime flag
+	Name string
+	// Paths to check for this executable
+	Paths []string
+}
+
 // RuntimeConfig contains configuration options used to set up the runtime
 type RuntimeConfig struct {
 	// StorageConfig is the configuration used by containers/storage
@@ -118,10 +126,8 @@ type RuntimeConfig struct {
 	// cause conflicts in containers/storage
 	// As such this is not exposed via the config file
 	StateType RuntimeStateStore `toml:"-"`
-	// RuntimePath is the path to OCI runtime binary for launching
-	// containers
-	// The first path pointing to a valid file will be used
-	RuntimePath []string `toml:"runtime_path"`
+	// OCIRuntimes are the set of configured OCI runtimes (default is runc)
+	OCIRuntimes []OCIRuntimePath `toml:"runtimes"`
 	// ConmonPath is the path to the Conmon binary used for managing
 	// containers
 	// The first path pointing to a valid file will be used
@@ -213,14 +219,19 @@ var (
 		StorageConfig:         storage.StoreOptions{},
 		ImageDefaultTransport: DefaultTransport,
 		StateType:             BoltDBStateStore,
-		RuntimePath: []string{
-			"/usr/bin/runc",
-			"/usr/sbin/runc",
-			"/usr/local/bin/runc",
-			"/usr/local/sbin/runc",
-			"/sbin/runc",
-			"/bin/runc",
-			"/usr/lib/cri-o-runc/sbin/runc",
+		OCIRuntimes: []OCIRuntimePath{
+			{
+				Name: "runc",
+				Paths: []string{
+					"/usr/bin/runc",
+					"/usr/sbin/runc",
+					"/usr/local/bin/runc",
+					"/usr/local/sbin/runc",
+					"/sbin/runc",
+					"/bin/runc",
+					"/usr/lib/cri-o-runc/sbin/runc",
+				},
+			},
 		},
 		ConmonPath: []string{
 			"/usr/libexec/podman/conmon",
@@ -453,22 +464,25 @@ func NewRuntimeFromConfig(configPath string, options ...RuntimeOption) (runtime
 func makeRuntime(runtime *Runtime) (err error) {
 	// Find a working OCI runtime binary
 	foundRuntime := false
-	for _, path := range runtime.config.RuntimePath {
-		stat, err := os.Stat(path)
-		if err != nil {
-			continue
-		}
-		if stat.IsDir() {
-			continue
+outer:
+	for _, oruntime := range runtime.config.OCIRuntimes {
+		for _, path := range oruntime.Paths {
+			stat, err := os.Stat(path)
+			if err != nil {
+				continue
+			}
+			if stat.IsDir() {
+				continue
+			}
+			foundRuntime = true
+			runtime.ociRuntimePath = OCIRuntimePath{Name: oruntime.Name, Paths: []string{path}}
+			break outer
 		}
-		foundRuntime = true
-		runtime.ociRuntimePath = path
-		break
 	}
 	if !foundRuntime {
 		return errors.Wrapf(ErrInvalidArg,
 			"could not find a working binary (configured options: %v)",
-			runtime.config.RuntimePath)
+			runtime.config.OCIRuntimes)
 	}
 
 	// Find a working conmon binary
@@ -619,7 +633,7 @@ func makeRuntime(runtime *Runtime) (err error) {
 	}
 
 	// Make an OCI runtime to perform container operations
-	ociRuntime, err := newOCIRuntime("runc", runtime.ociRuntimePath,
+	ociRuntime, err := newOCIRuntime(runtime.ociRuntimePath,
 		runtime.conmonPath, runtime.config.ConmonEnvVars,
 		runtime.config.CgroupManager, runtime.config.TmpDir,
 		runtime.config.MaxLogSize, runtime.config.NoPivotRoot,