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---
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layout: "docs"
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page_title: "Drivers: Qemu"
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sidebar_current: "docs-drivers-qemu"
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description: |-
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The Qemu task driver is used to run virtual machines using Qemu/KVM.
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---
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# Qemu Driver
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Name: `qemu`
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The `Qemu` driver provides a generic virtual machine runner. Qemu can utilize
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the KVM kernel module to utilize hardware virtualization features and provide
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great performance. Currently the `Qemu` driver can map a set of ports from the
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host machine to the guest virtual machine, and provides configuration for
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resource allocation.
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The `Qemu` driver can execute any regular `qemu` image (e.g. `qcow`, `img`,
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`iso`), and is currently invoked with `qemu-system-x86_64`.
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## Task Configuration
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The `Qemu` driver supports the following configuration in the job spec:
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* `image_source` - **(Required)** The hosted location of the source Qemu image. Must be accessible
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from the Nomad client, via HTTP.
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* `checksum` - **(Required)** The MD5 checksum of the `qemu` image. If the
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checksums do not match, the `Qemu` diver will fail to start the image
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* `accelerator` - (Optional) The type of accelerator to use in the invocation.
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If the host machine has `Qemu` installed with KVM support, users can specify `kvm` for the `accelerator`. Default is `tcg`
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* `host_port` - **(Required)** Port on the host machine to forward to the guest
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VM
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* `guest_ports` - **(Optional)** Ports on the guest machine that are listening for
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traffic from the host. These ports match up with any `ReservedPorts` requested
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in the `Task` specification
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## Client Requirements
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The `Qemu` driver requires Qemu to be installed and in your systems `$PATH`.
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The `image_source` must be accessible by the node running Nomad. This can be an
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internal source, private to your cluster, but it must be reachable by the client
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over HTTP.
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## Client Attributes
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The `Qemu` driver will set the following client attributes:
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* `driver.qemu` - Set to `1` if Qemu is found on the host node. Nomad determines
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this by executing `qemu-system-x86_64 -version` on the host and parsing the output
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* `driver.qemu.version` - Version of `qemu-system-x86_64, ex: `2.4.0`
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## Resource Isolation
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Nomad uses Qemu to provide full software virtualization for virtual machine
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workloads. Nomad can use Qemu KVM's hardware-assisted virtualization to deliver
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better performance.
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Virtualization provides the highest level of isolation for workloads that
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require additional security, and resources use is constrained by the Qemu
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hypervisor rather than the host kernel. VM network traffic still flows through
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the host's interface(s).
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