Merge pull request #97 from hashicorp/f-qemu-driver-docs

Basic Qemu docs

client/driver/qemu_test.go

@@ -53,11 +53,10 @@ func TestQemuDriver_Start(t *testing.T) {
 	task := &structs.Task{
 		Config: map[string]string{
 			"image_source": "https://dl.dropboxusercontent.com/u/47675/jar_thing/linux-0.2.img",
+			"checksum":     "a5e836985934c3392cbbd9b26db55a7d35a8d7ae1deb7ca559dd9c0159572544",
 			"accelerator":  "tcg",
 			"host_port":    "8080",
 			"guest_port":   "8081",
-			"checksum":     "a5e836985934c3392cbbd9b26db55a7d35a8d7ae1deb7ca559dd9c0159572544",
-			// ssh u/p would be here
 		},
 	}
 

website/source/docs/drivers/qemu.html.md

@@ -10,5 +10,54 @@ description: |-
 
 Name: `qemu`
 
-TODO
+The `Qemu` driver provides a generic virtual machine runner. Qemu can utilize
+the KVM kernel module to utilize hardware virtualization features and provide
+great performance. Currently the `Qemu` driver can map a set of ports from the
+host machine to the guest virtual machine, and provides configuration for
+resource allocation. 
+
+The `Qemu` driver can execute any regular `qemu` image (e.g. `qcow`, `img`,
+`iso`), and is currently invoked with `qemu-system-x86_64`. 
+
+## Task Configuration
+
+The `Qemu` driver supports the following configuration in the job spec:
+
+* `image_source` - **(Required)** The hosted location of the source Qemu image. Must be accessible
+from the Nomad client, via HTTP. 
+* `checksum` - **(Required)** The MD5 checksum of the `qemu` image. If the
+checksums do not match, the `Qemu` diver will fail to start the image
+* `accelerator` - (Optional) The type of accelerator to use in the invocation.
+ If the host machine has `Qemu` installed with KVM support, users can specify `kvm` for the `accelerator`. Default is `tcg`
+* `host_port` - **(Required)** Port on the host machine to forward to the guest
+VM
+* `guest_port` - **(Required)** Port on the guest machine that is listening for
+traffic from the host
+
+## Client Requirements
+
+The `Qemu` driver requires Qemu to be installed and in your systems `$PATH`.
+The `image_source` must be accessible by the node running Nomad. This can be an 
+internal source, private to your cluster, but it must be reachable by the client 
+over HTTP. 
+
+## Client Attributes
+
+The `Qemu` driver will set the following client attributes:
+
+* `driver.qemu` - Set to `1` if Qemu is found on the host node. Nomad determines
+this by executing `qemu-system-x86_64 -version` on the host and parsing the output
+* `driver.qemu.version` - Version of `qemu-system-x86_64, ex: `2.4.0`
+
+## Resource Isolation
+
+The resource isolation provided varies by the operating system of
+the client and the configuration.
+
+On Linux, Nomad will attempt to use cgroups, namespaces, and chroot
+to isolate the resources of a process. If the Nomad agent is not
+running as root many of these mechanisms cannot be used.
+
+As a baseline, the Qemu images will be ran inside a virtual machine operated by
+Qemu, providing a minimum amount of isolation.