Clint Shryock 343daeb1ea drivers: Add/Use go-getter to fetch remote binaries

Updates Qemu, Java drivers to use go-getter to fetch binaries
Adds remote artifact support for Exec, Raw Exec drivers

2015-10-26 09:40:06 -05:00

2.3 KiB

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layout	page_title	sidebar_current	description
docs	Drivers: Exec	docs-drivers-exec	The Exec task driver is used to run binaries using OS isolation primitives.

Isolated Fork/Exec Driver

Name: exec

The exec driver is used to simply execute a particular command for a task. However unlike raw_exec it uses the underlying isolation primitives of the operating system to limit the tasks access to resources. While simple, since the exec driver can invoke any command, it can be used to call scripts or other wrappers which provide higher level features.

Task Configuration

The exec driver supports the following configuration in the job spec:

command - (Required) The command to execute. Must be provided.
artifact_source – (Optional) Source location of an executable artifact. Must be accessible from the Nomad client. If you specify an artifact_source to be executed, you must reference it in the command as show in the examples below
args - The argument list to the command, space seperated. Optional.

Client Requirements

The exec driver can run on all supported operating systems but to provide proper isolation the client must be run as root on non-Windows operating systems. Further, to support cgroups, /sys/fs/cgroups/ must be mounted.

You must specify a command to be executed. Optionally you can specify an artifact_source to be downloaded as well. Any command is assumed to be present on the running client, or a downloaded artifact.

Examples

To run a binary present on the Node:

  config {
    command = "/bin/sleep"
    args = 1
  }

To execute a binary specified by artifact_source:

  config {
    artifact_source = "https://dl.dropboxusercontent.com/u/1234/binary.bin"
    command = "$NOMAD_TASK_DIR/binary.bin"
  }

Client Attributes

The exec driver will set the following client attributes:

driver.exec - This will be set to "1", indicating the driver is available.

Resource Isolation

The resource isolation provided varies by the operating system of the client and the configuration.

On Linux, Nomad will use cgroups, namespaces, and chroot to isolate the resources of a process and as such the Nomad agent must be run as root.

On Windows, the task driver will just execute the command with no additional resource isolation.

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