148 lines
4.3 KiB
Markdown
148 lines
4.3 KiB
Markdown
---
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layout: "docs"
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page_title: "Drivers: Raw Exec"
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sidebar_current: "docs-drivers-raw-exec"
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description: |-
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The Raw Exec task driver simply fork/execs and provides no isolation.
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---
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# Raw Fork/Exec Driver
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Name: `raw_exec`
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The `raw_exec` driver is used to execute a command for a task without any
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isolation. Further, the task is started as the same user as the Nomad process.
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As such, it should be used with extreme care and is disabled by default.
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## Task Configuration
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```hcl
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task "webservice" {
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driver = "raw_exec"
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config {
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command = "my-binary"
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args = ["-flag", "1"]
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}
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}
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```
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The `raw_exec` driver supports the following configuration in the job spec:
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* `command` - The command to execute. Must be provided. If executing a binary
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that exists on the host, the path must be absolute. If executing a binary that
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is downloaded from an [`artifact`](/docs/job-specification/artifact.html), the
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path can be relative from the allocation's root directory.
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* `args` - (Optional) A list of arguments to the `command`. References
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to environment variables or any [interpretable Nomad
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variables](/docs/runtime/interpolation.html) will be interpreted before
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launching the task.
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## Examples
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To run a binary present on the Node:
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```
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task "example" {
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driver = "raw_exec"
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config {
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# When running a binary that exists on the host, the path must be absolute/
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command = "/bin/sleep"
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args = ["1"]
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}
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}
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```
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To execute a binary downloaded from an [`artifact`](/docs/job-specification/artifact.html):
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```
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task "example" {
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driver = "raw_exec"
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config {
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command = "name-of-my-binary"
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}
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artifact {
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source = "https://internal.file.server/name-of-my-binary"
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options {
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checksum = "sha256:abd123445ds4555555555"
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}
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}
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}
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```
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## Client Requirements
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The `raw_exec` driver can run on all supported operating systems. For security
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reasons, it is disabled by default. To enable raw exec, the Nomad client
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configuration must explicitly enable the `raw_exec` driver in the plugin's options:
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```
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plugin "raw_exec" {
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config {
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enabled = true
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}
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}
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```
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Nomad versions before v0.9 use the following client configuration. This configuration is
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also supported in Nomad v0.9.0, but is deprecated in favor of the plugin stanza:
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```
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client {
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options = {
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"driver.raw_exec.enable" = "1"
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}
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}
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```
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## Plugin Options
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* `enabled` - Specifies whether the driver should be enabled or disabled.
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Defaults to `false`.
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* `no_cgroups` - Specifies whether the driver should not use
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cgroups to manage the process group launched by the driver. By default,
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cgroups are used to manage the process tree to ensure full cleanup of all
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processes started by the task. The driver uses cgroups by default on
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Linux and when `/sys/fs/cgroup/freezer/nomad` is writable for the
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Nomad process. Using a cgroup significantly reduces Nomad's CPU
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usage when collecting process metrics.
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## Client Options
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~> Note: client configuration options will soon be deprecated. Please use
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[plugin options][plugin-options] instead. See the [plugin stanza][plugin-stanza] documentation for more information.
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* `driver.raw_exec.enable` - Specifies whether the driver should be enabled or
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disabled. Defaults to `false`.
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* `driver.raw_exec.no_cgroups` - Specifies whether the driver should not use
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cgroups to manage the process group launched by the driver. By default,
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cgroups are used to manage the process tree to ensure full cleanup of all
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processes started by the task. The driver only uses cgroups when Nomad is
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launched as root, on Linux and when cgroups are detected.
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## Client Attributes
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The `raw_exec` driver will set the following client attributes:
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* `driver.raw_exec` - This will be set to "1", indicating the driver is available.
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## Resource Isolation
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The `raw_exec` driver provides no isolation.
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If the launched process creates a new process group, it is possible that Nomad
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will leak processes on shutdown unless the application forwards signals
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properly. Nomad will not leak any processes if cgroups are being used to manage
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the process tree. Cgroups are used on Linux when Nomad is being run with
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appropriate privileges, the cgroup system is mounted and the operator hasn't
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disabled cgroups for the driver.
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[plugin-options]: #plugin-options
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[plugin-stanza]: /docs/configuration/plugin.html
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