102 lines
3.5 KiB
Plaintext
102 lines
3.5 KiB
Plaintext
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---
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description: |
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The azure-chroot Packer builder is able to create Azure Managed Images leveraging
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a VM in Azure.
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layout: docs
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page_title: 'Azure chroot - Builders'
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sidebar_current: 'docs-builders-azure-chroot'
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---
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# Azure Builder (chroot)
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Type: `azure-chroot`
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The `azure-chroot` builder is able to build Azure managed disk (MD) images. For
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more information on managed disks, see [Azure Managed Disks Overview](https://docs.microsoft.com/en-us/azure/virtual-machines/windows/managed-disks-overview).
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The difference between this builder and the `azure-arm` builder is that this
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builder is able to build a managed disk image without launching an Azure VM
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instance. This can dramatically speed up image builds. It also allows for more
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deterministic image content and enables some capabilities that are not possible
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with the `azure-arm` builder.
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> **This is an advanced builder** If you're just getting started with Packer,
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it is recommend to start with the [azure-arm builder](/docs/builders/azure-arm.html),
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which is much easier to use.
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## How Does it Work?
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This builder works by creating a new MD from either an existing source or from
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scratch and attaching it to the (already existing) Azure VM where Packer is
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running. Once attached, a [chroot](https://en.wikipedia.org/wiki/Chroot) is set
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up and made available to the provisioners. After provisioning, the MD is
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detached, snapshotted and a MD image is created.
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Using this process, minutes can be shaved off the image creation process
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because Packer does not need to launch a VM instance.
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There are some restrictions however:
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* The host system must be a similar system (generally the same OS version,
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kernel versions, etc.) as the image being built.
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* If the source is a user image or managed disk, it must be made available in
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the same region as the host system. ([name=Paul Meyer]: we could work around
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this restriction by doing a cross-region copy, but that takes away the main
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speed advantage.)
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* The host system SKU has to allow for all of the specified disks to be
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attached.
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## Configuration Reference
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There are many configuration options available for the builder. We'll start
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withauthentication parameters, then go over the builder specific options.
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### Authentication options
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The Azure builders [share this configuration](/docs/builders/azure.html).
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<%= partial "partials/builder/azure/common/client/_Config-not-required.html" %>
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### Builder specific options
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#### Required:
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<%= partial "partials/builder/azure/chroot/_Config-required.html" %>
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#### Optional:
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<%= partial "partials/builder/azure/chroot/_Config-not-required.html" %>
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## Chroot Mounts
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The `chroot_mounts` configuration can be used to mount specific devices within
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the chroot. By default, the following additional mounts are added into the
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chroot by Packer:
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- `/proc` (proc)
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- `/sys` (sysfs)
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- `/dev` (bind to real `/dev`)
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- `/dev/pts` (devpts)
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- `/proc/sys/fs/binfmt_misc` (binfmt\_misc)
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These default mounts are usually good enough for anyone and are sane defaults.
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However, if you want to change or add the mount points, you may using the
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`chroot_mounts` configuration. Here is an example configuration which only
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mounts `/prod` and `/dev`:
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``` json
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{
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"chroot_mounts": [
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["proc", "proc", "/proc"],
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["bind", "/dev", "/dev"]
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]
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}
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```
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`chroot_mounts` is a list of a 3-tuples of strings. The three components of the
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3-tuple, in order, are:
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- The filesystem type. If this is "bind", then Packer will properly bind the
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filesystem to another mount point.
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- The source device.
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- The mount directory.
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