# Singularity
Singularity is container software written at Lawrence Berkeley Labs.

If you need a specialized computing environment, you can use a Singularity container on Bridges. Your Singularity container will execute on Bridges-2 compute nodes and can use other Bridges-2 resources, including filesystems. Within your container you can use a different Unix operating system and any software you need. You can set up your Singularity container without any intervention from PSC staff.

If you have questions about using Singularity containers on Bridges-2 send email to `[e-mail]`.

## Documentation
Singularity [documentation and examples](https://sylabs.io/docs/) at Sylabs.io.

## Usage
You can use the Singularity containers that are installed on Bridges-2 or you can bring your own. Execute the container on Bridges-2 compute nodes; containers cannot be executed on the front end nodes.

### Singularity images on Bridges-2
We have installed many of the NVIDIA GPU Cloud (NGC) containers as Singularity images on Bridges-2. These containers have been optimized for Volta architectures by NVIDIA, including rigorous quality assurance.

These containers can all be found on Bridges-2 under the directory /ocean/containers/ e.g., /ocean/containers/ngc/caffe.

NVIDIA requests that you create an account at http://ngc.nvidia.com if you will use any of these containers.

See also:

PSC documentation on Singularity for more details on Singularity use on Bridges-2
Additional information about the NVIDIA NGC Registry is at http://ngc.nvidia.com
Much more detail on the NGC containers at https://docs.nvidia.com/deeplearning/dgx/support-matrix/index.html

### Common Singularity commands
Some common commands are listed here, this document does not attempt to reinvent the wheel. For more information about Singularity, see the Singularity [documentation and examples](https://sylabs.io/docs/) at Sylabs.io.

#### `singularity shell`

shell
Start a shell within your container using the operating system you have set up your container to use.

#### `singularity exec`
exec
Run a single command within your container.

#### `singularity run`
Run a recipe script you have set up within your container. Using a recipe script forces users of your container to use a pre-established workflow.

##### `singularity pull`

##### `singularity help`

singularity --help

Linux container platform optimized for High Performance Computing (HPC) and
Enterprise Performance Computing (EPC)

Usage:
  singularity [global options...]

Description:
  Singularity containers provide an application virtualization layer enabling
  mobility of compute via both application and environment portability. With
  Singularity one is capable of building a root file system that runs on any 
  other Linux system where Singularity is installed.

Options:
  -c, --config string   specify a configuration file (for root or
                        unprivileged installation only) (default
                        "/usr/local/etc/singularity/singularity.conf")
  -d, --debug           print debugging information (highest verbosity)
  -h, --help            help for singularity
      --nocolor         print without color output (default False)
  -q, --quiet           suppress normal output
  -s, --silent          only print errors
  -v, --verbose         print additional information
      --version         version for singularity

Available Commands:
  build       Build a Singularity image
  cache       Manage the local cache
  capability  Manage Linux capabilities for users and groups
  completion  generate the autocompletion script for the specified shell
  config      Manage various singularity configuration (root user only)
  delete      Deletes requested image from the library
  exec        Run a command within a container
  help        Help about any command
  inspect     Show metadata for an image
  instance    Manage containers running as services
  key         Manage OpenPGP keys
  oci         Manage OCI containers
  overlay     Manage an EXT3 writable overlay image
  plugin      Manage Singularity plugins
  pull        Pull an image from a URI
  push        Upload image to the provided URI
  remote      Manage singularity remote endpoints, keyservers and OCI/Docker registry credentials
  run         Run the user-defined default command within a container
  run-help    Show the user-defined help for an image
  search      Search a Container Library for images
  shell       Run a shell within a container
  sif         Manipulate Singularity Image Format (SIF) images
  sign        Attach digital signature(s) to an image
  test        Run the user-defined tests within a container
  verify      Verify cryptographic signatures attached to an image
  version     Show the version for Singularity

Examples:
  $ singularity help <command> [<subcommand>]
  $ singularity help build
  $ singularity help instance start


For additional help or support, please visit https://www.sylabs.io/docs/