Singularity task driver plugin

Name: Singularity

The Singularity driver provides an interface for using Singularity for running application containers. Download the external Singularity driver from its releases page.

Task Configuration

task "lolcow" {
  driver = "Singularity"

  config {
     # this example run an image from sylabs container library with the
     # canonical example of lolcow
     image = "library://sylabsed/examples/lolcow:latest"
     # command can be run, exec or test
     command = "run"
  }
}

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

image - The Singularity image to run. It can be a local path or a supported URI.
```
config {
  image = "library://sylabsed/examples/lolcow:latest"
}
```
verbose - (Optional) Enables extra verbosity in the Singularity runtime logging. Defaults to false.
```
config {
  verbose = "false"
}
```
debug - (Optional) Enables extra debug output in the Singularity runtime logging. Defaults to false.
```
config {
  debug = "false"
}
```
command - Singularity command action; can be run, exec or test.
```
config {
  command = "run"
}
```
args - (Optional) Singularity command action arguments, when trying to pass arguments to run, exec or test. Multiple args can be given by a comma separated list.
```
config {
  args = [ "echo", "hello Cloud" ]
}
```
binds - (Optional) A user-bind path specification. This spec has the format src[:dest[:opts]], where src and dest are outside and inside paths. If dest is not given, it is set equal to src. Mount options ('opts') may be specified as 'ro' (read-only) or 'rw' (read/write, which is the default). Multiple bind paths can be given by a comma separated list.
```
config {
  bind = [ "host/path:/container/path" ]
}
```
overlay - (Optional) Singularity command action flag, to enable an overlayFS image for persistent data storage or as read-only layer of container. Multiple overlay paths can be given by a comma separated list.
```
config {
  overlay = [ "host/path/to/overlay" ]
}
```
security - (Optional) Allows the root user to leverage security modules such as SELinux, AppArmor, and seccomp within your Singularity container. You can also change the UID and GID of the user within the container at runtime.
```
config {
  security = [ "uid:1000 " ]
}
```
contain - (Optional) Use minimal /dev and empty other directories (e.g. /tmp and $HOME) instead of sharing filesystems from your host.
```
config {
  contain = "false"
}
```
workdir - (Optional) Working directory to be used for /tmp, /var/tmp and $HOME (if -c/--contain was also used).
```
config {
  workdir = "/path/to/folder"
}
```
pwd - (Optional) Initial working directory for payload process inside the container.
```
config {
  pwd = "/path/to/folder"
}
```

Networking

Currently the Singularity driver only supports host networking. For more detailed instructions on how to set up networking options, please refer to the Singularity user guides singularity-network

Client Requirements

The Singularity driver requires the following:

64-bit Linux host
The linux_amd64 Nomad binary
The Singularity driver binary placed in the plugin_dir directory.
Singularity v3.1.1+ to be installed

Plugin Options

enabled - The Singularity driver may be disabled on hosts by setting this option to false (defaults to true).
singularity_cache - The location in which all containers are stored (commonly defaults to /var/lib/singularity). See Singularity-cache for more details.

An example of using these plugin options with the new plugin syntax is shown below:

plugin "nomad-driver-Singularity" {
  config {
    enabled = true
    singularity_path = "/var/lib/singularity"
  }
}

Please note the plugin name should match whatever name you have specified for the external driver in the plugin_dir directory.

Client Attributes

The Singularity driver will set the following client attributes:

driver.singularity - Set to 1 if Singularity is found and enabled on the host node.
driver.singularity.version - Version of Singularity e.g.: 3.1.0.

Resource Isolation

This driver supports CPU and memory isolation via the Singularity cgroups feature. Network isolation is supported via --net and --network feature (Singularity v3.1.1+ required).