Add support for --runtime.

Signed-off-by: Shishir Mahajan <[email protected]>

README.md

@@ -77,17 +77,25 @@ will launch the job.<br/>
 
 More detailed instructions are in the [`example README.md`](https://github.com/Roblox/nomad-driver-containerd/tree/master/example)
 
-## Supported options
+## Supported Options
 
 **Driver Config**
 
 | Option | Type | Required | Default | Description |
 | :---: | :---: | :---: | :---: | :--- |
 | **enabled** | bool | no | true | Enable/Disable task driver. |
-| **containerd_runtime** | string | yes | N/A | Runtime for containerd e.g. `io.containerd.runc.v1` or `io.containerd.runc.v2`. |
+| **containerd_runtime** | string | no | `io.containerd.runc.v2` | Runtime for containerd. |
 | **stats_interval** | string | no | 1s | Interval for collecting `TaskStats`. |
 | **allow_privileged** | bool | no | true | If set to `false`, driver will deny running privileged jobs. |
 
+## Supported Runtimes
+
+Valid options for `containerd_runtime` (**Driver Config**).
+
+- `io.containerd.runc.v1`: `runc` runtime that supports a single container.
+- `io.containerd.runc.v2` (Default): `runc` runtime that supports multiple containers per shim.
+- `io.containerd.runsc.v1`: `gVisor` is an OCI compliant container runtime which provides better security than `runc`. They achieve this by implementing a user space kernel written in go, which implements a substantial portion of the Linux system call interface. For more details, please check their [`official documentation`](https://gvisor.dev/docs/)
+
 **Task Config**
 
 | Option | Type | Required | Description |
@@ -104,6 +112,7 @@ More detailed instructions are in the [`example README.md`](https://github.com/R
 | **seccomp_profile** | string | no | Path to custom seccomp profile. `seccomp` must be set to `true` in order to use `seccomp_profile`. The default `docker` seccomp profile found [`here`](https://github.com/moby/moby/blob/master/profiles/seccomp/default.json) can be used as a reference, and modified to create a custom seccomp profile. |
 | **sysctl** | map[string]string | no | A key-value map of sysctl configurations to set to the containers on start. |
 | **readonly_rootfs** | bool | no | Container root filesystem will be read-only. |
+| **runtime** | string | no | A string representing a configured runtime to pass to containerd. This is equivalent to the `--runtime` argument in the docker CLI. |
 | **host_network** | bool | no | Enable host network. This is equivalent to `--net=host` in docker. |
 | **extra_hosts** | []string | no | A list of hosts, given as host:IP, to be added to /etc/hosts. |
 | **cap_add** | []string | no | Add individual capabilities. |

containerd/containerd.go

@@ -262,7 +262,7 @@ func (d *Driver) createContainer(containerConfig *ContainerConfig, config *TaskC
 	return d.client.NewContainer(
 		ctxWithTimeout,
 		containerConfig.ContainerName,
-		containerd.WithRuntime(d.config.ContainerdRuntime, nil),
+		buildRuntime(d.config.ContainerdRuntime, config.Runtime),
 		containerd.WithNewSnapshot(containerConfig.ContainerSnapshotName, containerConfig.Image),
 		containerd.WithNewSpec(opts...),
 	)

containerd/driver.go

@@ -78,7 +78,7 @@ var (
 			hclspec.NewAttr("enabled", "bool", false),
 			hclspec.NewLiteral("true"),
 		),
-		"containerd_runtime": hclspec.NewAttr("containerd_runtime", "string", true),
+		"containerd_runtime": hclspec.NewAttr("containerd_runtime", "string", false),
 		"stats_interval":     hclspec.NewAttr("stats_interval", "string", false),
 		"allow_privileged": hclspec.NewDefault(
 			hclspec.NewAttr("allow_privileged", "bool", false),
@@ -110,6 +110,7 @@ var (
 		"seccomp_profile": hclspec.NewAttr("seccomp_profile", "string", false),
 		"sysctl":          hclspec.NewAttr("sysctl", "list(map(string))", false),
 		"readonly_rootfs": hclspec.NewAttr("readonly_rootfs", "bool", false),
+		"runtime":         hclspec.NewAttr("runtime", "string", false),
 		"host_network":    hclspec.NewAttr("host_network", "bool", false),
 		"mounts": hclspec.NewBlockList("mounts", hclspec.NewObject(map[string]*hclspec.Spec{
 			"type": hclspec.NewDefault(
@@ -168,6 +169,7 @@ type TaskConfig struct {
 	HostDNS        bool               `codec:"host_dns"`
 	ExtraHosts     []string           `codec:"extra_hosts"`
 	Entrypoint     []string           `codec:"entrypoint"`
+	Runtime        string             `codec:"runtime"`
 	ReadOnlyRootfs bool               `codec:"readonly_rootfs"`
 	HostNetwork    bool               `codec:"host_network"`
 	Mounts         []Mount            `codec:"mounts"`

containerd/utils.go

@@ -20,10 +20,14 @@ package containerd
 import (
 	"context"
 	"os"
+	"strings"
 	"syscall"
 
+	"github.com/containerd/containerd"
 	"github.com/containerd/containerd/containers"
 	"github.com/containerd/containerd/oci"
+	"github.com/containerd/containerd/plugin"
+	runcoptions "github.com/containerd/containerd/runtime/v2/runc/options"
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
@@ -60,3 +64,30 @@ func WithSysctls(sysctls map[string]string) oci.SpecOpts {
 		return nil
 	}
 }
+
+// buildRuntime sets the container runtime e.g. runc or runsc (gVisor).
+func buildRuntime(pluginRuntime, jobRuntime string) containerd.NewContainerOpts {
+	var (
+		runcOpts    runcoptions.Options
+		runtimeOpts interface{} = &runcOpts
+	)
+
+	// plugin.RuntimeRuncV2 = io.containerd.runc.v2
+	runtime := plugin.RuntimeRuncV2
+
+	if jobRuntime != "" {
+		if strings.HasPrefix(jobRuntime, "io.containerd.runc.") {
+			runtime = jobRuntime
+		} else {
+			runcOpts.BinaryName = jobRuntime
+		}
+	} else if pluginRuntime != "" {
+		if strings.HasPrefix(pluginRuntime, "io.containerd.runc.") {
+			runtime = pluginRuntime
+		} else {
+			runcOpts.BinaryName = pluginRuntime
+		}
+	}
+
+	return containerd.WithRuntime(runtime, runtimeOpts)
+}

example/agent.hcl

@@ -3,7 +3,6 @@ log_level = "INFO"
 plugin "containerd-driver" {
   config {
     enabled = true
-    containerd_runtime = "io.containerd.runc.v2"
     stats_interval = "5s"
   }
 }

tests/009-test-allow-privileged.sh

@@ -9,7 +9,7 @@ test_allow_privileged() {
 
     cp agent.hcl agent.hcl.bkp
 
-    sed -i '8 i \    allow_privileged = false' agent.hcl
+    sed -i '7 i \    allow_privileged = false' agent.hcl
     sudo systemctl restart nomad
     is_systemd_service_active "nomad.service" true