Merge pull request #78 from Roblox/entrypoint

Add support for entrypoint.

Author: shishir-a412ed

README.md

@@ -95,6 +95,7 @@ More detailed instructions are in the [`example README.md`](https://github.com/R
 | **image** | string | yes | OCI image (docker is also OCI compatible) for your container. |
 | **command** | string | no | Command to override command defined in the image. |
 | **args** | []string | no | Arguments to the command. |
+| **entrypoint** | []string | no | A string list overriding the image's entrypoint. |
 | **cwd** | string | no | Specify the current working directory for your container process. If the directory does not exist, one will be created for you. |
 | **privileged** | bool | no | Run container in privileged mode. Your container will have all linux capabilities when running in privileged mode. |
 | **host_dns** | bool | no | Default (`true`). By default, a container launched using `containerd-driver` will use host `/etc/resolv.conf`. This is similar to [`docker behavior`](https://docs.docker.com/config/containers/container-networking/#dns-services). However, if you don't want to use host DNS, you can turn off this flag by setting `host_dns=false`. |

containerd/containerd.go

@@ -76,14 +76,16 @@ func (d *Driver) pullImage(imageName string) (containerd.Image, error) {
 }
 
 func (d *Driver) createContainer(containerConfig *ContainerConfig, config *TaskConfig) (containerd.Container, error) {
-	if config.Command == "" && len(config.Args) > 0 {
-		return nil, fmt.Errorf("Command is empty. Cannot set --args without --command.")
+	if config.Command != "" && config.Entrypoint != nil {
+		return nil, fmt.Errorf("Both command and entrypoint are set. Only one of them needs to be set.")
 	}
 
-	// Command set by the user, to override entrypoint or cmd defined in the image.
+	// Entrypoint or Command set by the user, to override entrypoint or cmd defined in the image.
 	var args []string
 	if config.Command != "" {
 		args = append(args, config.Command)
+	} else if config.Entrypoint != nil && config.Entrypoint[0] != "" {
+		args = append(args, config.Entrypoint...)
 	}
 
 	// Arguments to the command set by the user.
@@ -93,7 +95,14 @@ func (d *Driver) createContainer(containerConfig *ContainerConfig, config *TaskC
 
 	var opts []oci.SpecOpts
 
-	opts = append(opts, oci.WithImageConfigArgs(containerConfig.Image, args))
+	if config.Entrypoint != nil {
+		// WithProcessArgs replaces the args on the generated spec.
+		opts = append(opts, oci.WithProcessArgs(args...))
+	} else {
+		// WithImageConfigArgs configures the spec to from the configuration of an Image
+		// with additional args that replaces the CMD of the image.
+		opts = append(opts, oci.WithImageConfigArgs(containerConfig.Image, args))
+	}
 
 	if !d.config.AllowPrivileged && config.Privileged {
 		return nil, fmt.Errorf("Running privileged jobs are not allowed. Set allow_privileged to true in plugin config to allow running privileged jobs.")

containerd/driver.go

@@ -103,6 +103,7 @@ var (
 			hclspec.NewLiteral("true"),
 		),
 		"extra_hosts":     hclspec.NewAttr("extra_hosts", "list(string)", false),
+		"entrypoint":      hclspec.NewAttr("entrypoint", "list(string)", false),
 		"seccomp":         hclspec.NewAttr("seccomp", "bool", false),
 		"seccomp_profile": hclspec.NewAttr("seccomp_profile", "string", false),
 		"readonly_rootfs": hclspec.NewAttr("readonly_rootfs", "bool", false),
@@ -161,6 +162,7 @@ type TaskConfig struct {
 	Privileged     bool     `codec:"privileged"`
 	HostDNS        bool     `codec:"host_dns"`
 	ExtraHosts     []string `codec:"extra_hosts"`
+	Entrypoint     []string `codec:"entrypoint"`
 	ReadOnlyRootfs bool     `codec:"readonly_rootfs"`
 	HostNetwork    bool     `codec:"host_network"`
 	Mounts         []Mount  `codec:"mounts"`

example/entrypoint.nomad

@@ -0,0 +1,20 @@
+job "entrypoint" {
+  datacenters = ["dc1"]
+
+  group "entrypoint-group" {
+    task "entrypoint-task" {
+      driver = "containerd-driver"
+
+      config {
+        image      = "ubuntu:16.04"
+        entrypoint = ["/bin/echo"]
+        args       = ["container1", "container2"]
+      }
+
+      resources {
+        cpu    = 500
+        memory = 256
+      }
+    }
+  }
+}

tests/008-test-entrypoint.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+
+source $SRCDIR/utils.sh
+
+job_name=entrypoint
+
+test_entrypoint_nomad_job() {
+    pushd ~/go/src/github.com/Roblox/nomad-driver-containerd/example
+
+    echo "INFO: Starting nomad $job_name job using nomad-driver-containerd."
+    nomad job run $job_name.nomad
+
+    # Even though $(nomad job status) reports job status as "running"
+    # The actual container process might not be running yet.
+    # We need to wait for actual container to start running before executing $(nomad alloc logs).
+    echo "INFO: Wait for ${job_name} container to get into RUNNING state."
+    is_container_active ${job_name} true
+
+    echo "INFO: Checking status of $job_name job."
+    job_status=$(nomad job status -short $job_name|grep Status|awk '{split($0,a,"="); print a[2]}'|tr -d ' ')
+    if [ "$job_status" != "running" ];then
+        echo "ERROR: Error in getting ${job_name} job status."
+        return 1
+    fi
+
+    output=$(nomad logs -job ${job_name})
+    for result in "container1" "container2" ; do
+        echo -e "$output" |grep "$result" &>/dev/null
+        if [ $? -ne 0 ];then
+           echo "ERROR: $result not found in the output."
+           return 1
+        fi
+    done
+
+    echo "INFO: purge nomad ${job_name} job."
+    nomad job stop -purge ${job_name}
+    popd
+}
+
+test_entrypoint_nomad_job