195 lines
6.6 KiB
Plaintext
195 lines
6.6 KiB
Plaintext
---
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layout: docs
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page_title: 'Drivers: LXC'
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description: The LXC task driver is used to run application containers using LXC.
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---
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# LXC Driver
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Name: `lxc`
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The `lxc` driver provides an interface for using LXC for running application
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containers. You can download the external LXC driver [here][lxc-driver]. For more detailed instructions on how to set up and use this driver, please refer to the [LXC guide][lxc-guide].
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~> **Note:** The LXC client set up has changed in Nomad 0.9. You must use the new [plugin syntax][plugin] and install the external LXC driver in the [plugin_dir][plugin_dir] prior to upgrading. See [plugin options][plugin-options] below for an example. Note the job specification remains the same.
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## Task Configuration
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```hcl
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task "busybox" {
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driver = "lxc"
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config {
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log_level = "trace"
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verbosity = "verbose"
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template = "/usr/share/lxc/templates/lxc-busybox"
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template_args = []
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# these optional values can be set in the template
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distro = ""
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release = ""
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arch = ""
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image_variant = "default"
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image_server = "images.linuxcontainers.org"
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gpg_key_id = ""
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gpg_key_server = ""
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disable_gpg = false
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flush_cache = false
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force_cache = false
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}
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}
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```
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The `lxc` driver supports the following configuration in the job spec:
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- `template` - The LXC template to run.
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```hcl
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config {
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template = "/usr/share/lxc/templates/lxc-alpine"
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}
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```
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- `template_args` - A list of argument strings to pass into the template.
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- `log_level` - (Optional) LXC library's logging level. Defaults to `error`.
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Must be one of `trace`, `debug`, `info`, `warn`, or `error`.
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```hcl
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config {
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log_level = "debug"
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}
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```
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- `verbosity` - (Optional) Enables extra verbosity in the LXC library's
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logging. Defaults to `quiet`. Must be one of `quiet` or `verbose`.
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```hcl
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config {
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verbosity = "quiet"
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}
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```
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- `volumes` - (Optional) A list of `host_path:container_path` strings to
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bind-mount host paths to container paths. Mounting host paths outside of the
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[allocation working directory] is allowed by default. You can prevent
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mounting host paths outside of the [allocation working directory] on
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individual clients by setting the [`volumes_enabled`](#volumes_enabled)
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option to `false` in the client's configuration
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~> **Note:** Unlike the similar option for the docker driver, this
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option must not have an absolute path as the `container_path`
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component. This will cause an error when submitting a job.
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Setting this does not affect the standard bind-mounts of `alloc`,
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`local`, and `secrets`, which are always created.
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```hcl
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config {
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volumes = [
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# Use absolute paths to mount arbitrary paths on the host
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"/path/on/host:path/in/container",
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# Use relative paths to rebind paths already in the allocation dir
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"relative/to/task:also/in/container"
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]
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}
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```
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- `release` - (Optional) The name/version of the distribution. By default this is set by the template.
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- `arch` - (Optional) The architecture of the container. By default this is set by the template.
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- `image_server` - (Optional) The hostname of the image server. Defaults to `images.linuxcontainers.org`.
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- `image_variant` - (Optional) The variant of the image. Defaults to `default` or as set by the template.
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- `disable_gpg` - (Optional) Disable GPG validation of images. Defaults to `false`, and enabling this flag is not recommended.
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- `flush_cache` - (Optional) Flush the local copy of the image (if present) and force it to be fetched from the image server. Defaults to `false`.
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- `force_cache` - (Optional) Force the use of the local copy even if expired. Defaults to `false`.
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- `gpg_key_server`: GPG key server used for checking image signatures. Default is set by the underlying LXC library.
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- `gpg_key_id`: GPG key ID used for checking image signatures. Default is set by the underlying LXC library.
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## Networking
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Currently the `lxc` driver only supports host networking. See the `none`
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networking type in the `lxc.container.conf` [manual][lxc_man] for more
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information.
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## Client Requirements
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The `lxc` driver requires the following:
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- 64-bit Linux host
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- The `linux_amd64` Nomad binary
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- The LXC driver binary placed in the [plugin_dir][plugin_dir] directory.
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- `liblxc` to be installed
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- `lxc-templates` to be installed
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## Plugin Options
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- `enabled` - The `lxc` driver may be disabled on hosts by setting this option to `false` (defaults to `true`).
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- `volumes_enabled`<a id="volumes_enabled"></a> - Specifies whether host can bind-mount host paths to container paths (defaults to `true`).
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- `lxc_path` - The location in which all containers are stored (commonly defaults to `/var/lib/lxc`). See [`lxc-create`][lxc-create] for more details.
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- `gc` stanza:
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- `container` - Defaults to `true`. This option can be used to disable Nomad
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from removing a container when the task exits. Under a name conflict,
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Nomad may still remove the dead container.
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An example of using these plugin options with the new [plugin
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syntax][plugin] is shown below:
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```hcl
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plugin "nomad-driver-lxc" {
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config {
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enabled = true
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volumes_enabled = true
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lxc_path = "/var/lib/lxc"
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gc {
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container = false
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}
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}
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}
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```
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Please note the plugin name should match whatever name you have specified for the external driver in the [plugin_dir][plugin_dir] directory.
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## Client Configuration
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-> Only use this section for pre-0.9 releases of Nomad. If you are using Nomad
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0.9 or above, please see [plugin options][plugin-options]
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The `lxc` driver has the following [client-level options][client_options]:
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- `lxc.enable` - The `lxc` driver may be disabled on hosts by setting this
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option to `false` (defaults to `true`).
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## Client Attributes
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The `lxc` driver will set the following client attributes:
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- `driver.lxc` - Set to `1` if LXC is found and enabled on the host node.
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- `driver.lxc.version` - Version of `lxc` e.g.: `1.1.0`.
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## Resource Isolation
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This driver supports CPU and memory isolation via the `lxc` library. Network
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isolation is not supported as of now.
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[lxc-create]: https://linuxcontainers.org/lxc/manpages/man1/lxc-create.1.html
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[lxc-driver]: https://releases.hashicorp.com/nomad-driver-lxc
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[lxc-guide]: https://learn.hashicorp.com/tutorials/nomad/plugin-lxc
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[lxc_man]: https://linuxcontainers.org/lxc/manpages/man5/lxc.container.conf.5.html#lbAM
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[plugin]: /docs/configuration/plugin
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[plugin_dir]: /docs/configuration#plugin_dir
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[plugin-options]: #plugin-options
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[client_options]: /docs/configuration/client#options
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[allocation working directory]: /docs/runtime/environment#task-directories 'Task Directories'
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