Search for local runtime per values in containers.conf

After determining the type of runtime to use,
either "runc" or "crun" dependent upon the system, search
the list of that type of runtime in the containers.conf
file.  It includes the location of those runtimes in a
number of different architectures.  Once found, set the
runtime to use to that value.

Fixes: containers#2113

Signed-off-by: TomSweeneyRedHat <[email protected]>

cmd/buildah/run.go

@@ -10,7 +10,6 @@ import (
 	"github.com/containers/buildah"
 	buildahcli "github.com/containers/buildah/pkg/cli"
 	"github.com/containers/buildah/pkg/parse"
-	"github.com/containers/buildah/util"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
@@ -62,7 +61,8 @@ func init() {
 	flags.StringSliceVar(&opts.capDrop, "cap-drop", []string{}, "drop the specified capability (default [])")
 	flags.StringVar(&opts.hostname, "hostname", "", "set the hostname inside of the container")
 	flags.StringVar(&opts.isolation, "isolation", buildahcli.DefaultIsolation(), "`type` of process isolation to use. Use BUILDAH_ISOLATION environment variable to override.")
-	flags.StringVar(&opts.runtime, "runtime", util.Runtime(), "`path` to an alternate OCI runtime")
+	// Do not set a default runtime here, we'll do that later in the processing.
+	flags.StringVar(&opts.runtime, "runtime", "", "`path` to an alternate OCI runtime")
 	flags.StringSliceVar(&opts.runtimeFlag, "runtime-flag", []string{}, "add global flags for the container runtime")
 	flags.BoolVar(&opts.noPivot, "no-pivot", false, "do not use pivot root to jail process inside rootfs")
 	flags.StringArrayVar(&opts.securityOption, "security-opt", []string{}, "security options (default [])")

run_linux.go

@@ -678,6 +678,11 @@ func runUsingRuntime(isolation Isolation, options RunOptions, configureNetwork b
 	runtime := options.Runtime
 	if runtime == "" {
 		runtime = util.Runtime()
+
+		localRuntime := util.FindLocalRuntime(runtime)
+		if localRuntime != "" {
+			runtime = localRuntime
+		}
 	}
 
 	// Default to just passing down our stdio.

util/util.go

@@ -10,6 +10,7 @@ import (
 	"sync"
 	"syscall"
 
+	"github.com/containers/common/pkg/config"
 	"github.com/containers/image/v5/docker/reference"
 	"github.com/containers/image/v5/pkg/sysregistriesv2"
 	"github.com/containers/image/v5/signature"
@@ -432,3 +433,33 @@ var (
 	isUnified     bool
 	isUnifiedErr  error
 )
+
+// fileExistsAndNotADir - Check to see if a file exists
+// and that it is not a directory.
+func fileExistsAndNotADir(path string) bool {
+	file, err := os.Stat(path)
+
+	if file == nil || err != nil || os.IsNotExist(err) == true {
+		return false
+	}
+	return !file.IsDir()
+}
+
+// FindLocalRuntime find the local runtime of the
+// system searching through the config file for
+// possible locations.
+func FindLocalRuntime(runtime string) string {
+	var localRuntime string
+	conf, err := config.Default()
+	if err != nil {
+		logrus.Debugf("Error loading container config when searching for local runtime.")
+		return localRuntime
+	}
+	for _, val := range conf.Libpod.OCIRuntimes[runtime] {
+		if fileExistsAndNotADir(val) {
+			localRuntime = val
+			break
+		}
+	}
+	return localRuntime
+}