github.com/dkerwin/nomad@v0.3.3-0.20160525181927-74554135514b/website/source/docs/drivers/qemu.html.md (about) 1 --- 2 layout: "docs" 3 page_title: "Drivers: Qemu" 4 sidebar_current: "docs-drivers-qemu" 5 description: |- 6 The Qemu task driver is used to run virtual machines using Qemu/KVM. 7 --- 8 9 # Qemu Driver 10 11 Name: `qemu` 12 13 The `Qemu` driver provides a generic virtual machine runner. Qemu can utilize 14 the KVM kernel module to utilize hardware virtualization features and provide 15 great performance. Currently the `Qemu` driver can map a set of ports from the 16 host machine to the guest virtual machine, and provides configuration for 17 resource allocation. 18 19 The `Qemu` driver can execute any regular `qemu` image (e.g. `qcow`, `img`, 20 `iso`), and is currently invoked with `qemu-system-x86_64`. 21 22 The driver requires the image to be accessible from the Nomad client via the 23 [`artifact` downloader](/docs/jobspec/index.html#artifact_doc). 24 25 ## Task Configuration 26 27 The `Qemu` driver supports the following configuration in the job spec: 28 29 * `image_path` - The path to the downloaded image. In most cases this will just be 30 the name of the image. However, if the supplied artifact is an archive that 31 contains the image in a subfolder, the path will need to be the relative path 32 (`subdir/from_archive/my.img`). 33 34 * `accelerator` - (Optional) The type of accelerator to use in the invocation. 35 If the host machine has `Qemu` installed with KVM support, users can specify 36 `kvm` for the `accelerator`. Default is `tcg` 37 38 * `port_map` - (Optional) A `map[string]int` that maps port labels to ports 39 on the guest. This forwards the host port to the guest vm. For example, 40 `port_map { db = 6539 }` would forward the host port with label `db` to the 41 guest vm's port 6539. 42 43 ## Examples 44 45 A simple config block to run a `Qemu` image: 46 47 ``` 48 task "virtual" { 49 driver = "qemu" 50 51 config { 52 image_path = "local/linux.img" 53 accelerator = "kvm" 54 } 55 56 # Specifying an artifact is required with the "qemu" 57 # driver. This is the # mechanism to ship the image to be run. 58 artifact { 59 source = "https://dl.dropboxusercontent.com/u/1234/linux.img" 60 61 options { 62 checksum = "md5:123445555555555" 63 } 64 } 65 ``` 66 67 ## Client Requirements 68 69 The `Qemu` driver requires Qemu to be installed and in your system's `$PATH`. 70 The task must also specify at least one artifact to download as this is the only 71 way to retrieve the image being run. 72 73 ## Client Attributes 74 75 The `Qemu` driver will set the following client attributes: 76 77 * `driver.qemu` - Set to `1` if Qemu is found on the host node. Nomad determines 78 this by executing `qemu-system-x86_64 -version` on the host and parsing the output 79 * `driver.qemu.version` - Version of `qemu-system-x86_64`, ex: `2.4.0` 80 81 ## Resource Isolation 82 83 Nomad uses Qemu to provide full software virtualization for virtual machine 84 workloads. Nomad can use Qemu KVM's hardware-assisted virtualization to deliver 85 better performance. 86 87 Virtualization provides the highest level of isolation for workloads that 88 require additional security, and resource use is constrained by the Qemu 89 hypervisor rather than the host kernel. VM network traffic still flows through 90 the host's interface(s).