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Installing {Singularity}

This section will guide you through the process of installing {Singularity} {InstallationVersion} via several different methods. (For instructions on installing earlier versions of {Singularity} please see earlier versions of the docs.)

Installation on Linux

{Singularity} can be installed on any modern Linux distribution, on bare-metal or inside a Virtual Machine. Nested installations inside containers are not recommended, and require the outer container to be run with full privilege.

System Requirements

{Singularity} requires ~180MiB disk space once compiled and installed.

There are no specific CPU or memory requirements at runtime, though 2GB of RAM is recommended when building from source.

Full functionality of {Singularity} requires that the kernel supports:

  • OverlayFS mounts - (minimum kernel >=3.18) Required for full flexibility in bind mounts to containers, and to support persistent overlays for writable containers.
  • Unprivileged user namespaces - (minimum kernel >=3.8, >=3.18 recommended) Required to run containers without root or setuid privilege. Required to build containers unprivileged in --fakeroot mode. Required to run containers in OCI-mode (-oci).
  • FUSE in unprivileged user namespaces - (minimum kernel >=4.18) Required to run containers in OCI-Mode (-oci).
  • Unprivileged overlay - (minimum kernel >=5.11, >=5.13 recommended) Required to use --overlay, to mount a persistent overlay directory onto the container, when running without root or setuid in native mode. OCI-mode will fall-back to the fuse-overlayfs userspace implementation.

Note that the indicated kernel versions correspond to the mainline Linux kernel. Some Linux distributions may back-port features to older kernels.

External Binaries

Singularity depends on a number of external binaries for full functionality. The methods that are used to find these binaries have been standardized as below.

Bundled Utilities

In a standard {Singularity} installation, the following are bundled and installed into {Singularity}'s libexec/bin directory. However, at compilation time mconfig options can be used to disable building these tools, in which case they will be searched for on $PATH at runtime.

  • squashfuse or squashfuse_ll are used to mount squashfs filesystems from OCI-SIF images in OCI-mode. They may be used to mount squashfs filesystems from SIF images and bare squashfs containers in non-OCI mode.
  • conmon is used to manage monitoring and attaching to non-interactive containers started with the singularity oci start command.
Configurable Paths

The following binaries are found on $PATH during build time when ./mconfig is run, and their location is added to the singularity.conf configuration file. At runtime this configured location is used. To specify an alternate executable, change the relevant path entry in singularity.conf.

  • cryptsetup version 2 with kernel LUKS2 support is required for building or executing encrypted containers.
  • ldconfig is used to resolve library locations / symlinks when using the -nv or --rocm GPU support.
  • nvidia-container-cli is used to configure a container for Nvidia GPU / CUDA support when running with the experimental --nvccli option.

For the following additional binaries, if the singularity.conf entry is left blank, then $PATH will be searched at runtime.

  • go is required to compile plugins, and must be an identical version as that used to build {Singularity}.
  • mksquashfs from squashfs-tools 4.3+ is used to create the squashfs container filesystem that is embedded into SIF container images. The mksquashfs procs and mksquashfs mem directives in singularity.conf can be used to control its resource usage.
  • unsquashfs from squashfs-tools 4.3+ is used to extract the squashfs container filesystem from a SIF file when necessary.
Searching $PATH

The following utilities are always found by searching $PATH at runtime:

  • true
  • mkfs.ext3 is used to create overlay images.
  • cp
  • dd
  • newuidmap and newgidmap are distribution provided setuid binaries used to configure subuid/gid mappings for --fakeroot in non-setuid installs, and in OCI-mode.
  • crun or runc are OCI runtimes used for the singularity oci commands and OCI-mode for run / shell / exec. crun is preferred over runc if it is available. runc is provided by a package in all common Linux distributions. crun is packaged in more recent releases of common Linux distributions.
  • proot is an optional dependency that can be used to permit limited unprivileged builds without user namespace / subuid support. It is packaged in the community repositories for common Linux distributions, and is available as a static binary from proot-me.github.io.
  • sqfstar or tar2sqfs are used in the creation of OCI-SIF images from OCI sources, in OCI-mode (--oci).
  • fuse2fs is used to mount extfs images in unprivileged flows, or when kernel extfs mount is disabled by configuration. Version 1.46.6 or above is required to use OCI-SIF embedded overlays in OCI-mode.
  • fuse-overlayfs is used to setup overlay filesystems when the kernel does not support unprivileged overlay or the required overlay configuration.
  • fusermount3 or fusermount is used to unmount FUSE filesystems safely, in OCI-mode and other flows.
Bootstrap Utilities

The following utilities are required to bootstrap containerized distributions using their native tooling:

  • mount, umount, pacstrap for Arch Linux.
  • mount, umount, mknod, debootstrap for Debian based distributions.
  • dnf, rpm, curl for EL derived RPM based distributions.
  • uname, zypper, SUSEConnect for SLES derived RPM based distributions.
Installing sqfstar / tar2sqfs for OCI-mode

If you intend to use the --oci execution mode of SingularityCE, your system must provide either:

  • squashfs-tools / squashfs >= 4.5, which provides the sqfstar utility. Older versions packaged by many distributions do not include sqfstar.
  • squashfs-tools-ng, which provides the tar2sqfs utility. This is not packaged by all distributions.
Debian / Ubuntu

On Debian/Ubuntu squashfs-tools-ng is available in the distribution repositories. It has been included in the "Install system dependencies" step above. No further action is necessary.

RHEL / Alma Linux / Rocky Linux

On RHEL and derivatives, the squashfs-tools-ng package is now available in the EPEL repositories.

Follow the EPEL Quickstart for you distribution to enable the EPEL repository. Install squashfs-tools-ng with dnf.

sudo dnf install squashfs-tools-ng
SLES / openSUSE Leap

On SLES/openSUSE, follow the instructions at the filesystems project to obtain an more recent squashfs package that provides sqfstar.

Non-standard ldconfig / Nix & Guix Environments

If {Singularity} is installed under a package manager such as Nix or Guix, but on top of a standard Linux distribution (e.g. RHEL or Debian), it may be unable to correctly find the libraries for --nv and --rocm GPU support. This issue occurs as the package manager supplies an alternative ldconfig, which does not identify GPU libraries installed from host packages.

To allow {Singularity} to locate the host (i.e. RHEL / Debian) GPU libraries correctly, set ldconfig path in singularity.conf to point to the host ldconfig. I.E. it should be set to /sbin/ldconfig or /sbin/ldconfig.real rather than a Nix or Guix related path.

Filesystem support / limitations

{Singularity} supports most filesystems, but there are some limitations when installing {Singularity} on, or running containers from, common parallel / network filesystems. In general:

  • We strongly recommend installing {Singularity} on local disk on each compute node.
  • If {Singularity} is installed to a network location, a --localstatedir should be provided on each node, and Singularity configured to use it.
  • The --localstatedir filesystem should support overlay mounts.
  • TMPDIR / SINGULARITY_TMPDIR should be on a local filesystem wherever possible.

Note

Set the --localstatedir location by by providing --localstatedir my/dir as an option when you configure your {Singularity} build with ./mconfig.

Disk usage at the --localstatedir location is negligible (<1MiB). The directory is used as a location to mount the container root filesystem, overlays, bind mounts etc. that construct the runtime view of a container. You will not see these mounts from a host shell, as they are made in a separate mount namespace.

Overlay support

Various features of {Singularity}, such as the --writable-tmpfs and --overlay options, use overlay mounts to construct a container root filesystem that combines files from different locations. Overlay mounts may use the Linux kernel overlay filesystem driver or the fuse-overlayfs userspace implementation, depending on the workflow and support from the host kernel.

Overlays are mounted with the Linux kernel driver when:

  • The native runtime is used in setuid mode.
  • The native runtime is used in unprivileged / non-setuid mode, and the kernel supports unprivileged overlay mounts.
  • OCI-mode is used without an extfs overlay image, and the kernel supports unprivileged overlay mounts.

Overlays are mounted with the fuse-overlayfs userspace implementation when:

  • OCI-mode is used, and the kernel does not support unprivileged overlay mounts.
  • OCI-mode is used, with an extfs overlay image.

Not all filesystems can be used with the overlay driver, so when containers are run from these filesystems some {Singularity} features may not be available.

Overlay support has two aspects:

  • lowerdir support for a filesystem allows a directory on that filesystem to act as the 'base' of a container. A filesystem must support overlay lowerdir for you be able to run a Singularity sandbox container on it, while using functionality such as --writable-tmpfs / --overlay.
  • upperdir support for a filesystem allows a directory on that filesystem to be merged on top of a lowerdir to construct a container. If you use the --overlay option to overlay a directory onto a container, then the filesystem holding the overlay directory must support upperdir.

Note that any overlay limitations mainly apply to sandbox (directory) containers only. A SIF container is mounted into the --localstatedir location, which should generally be on a local filesystem that supports overlay.

Fakeroot & OCI-Mode subuid/gid mapping

When {Singularity} is run using the :ref:`fakeroot <fakeroot>` option, or in OCI-Mode, it creates a user namespace for the container, and UIDs / GIDs in that user namespace are mapped to different host UID / GIDs.

Most local filesystems (ext4/xfs etc.) support this uid/gid mapping in a user namespace.

Most network filesystems (NFS/Lustre/GPFS etc.) do not support this uid/gid mapping in a user namespace. Because the fileserver is not aware of the mappings it will deny many operations, with 'permission denied' errors. This is currently a generic problem for rootless container runtimes.

{Singularity} cache / atomic rename

{Singularity} will cache SIF container images generated from remote sources, and any OCI/docker layers used to create them. The cache is created at $HOME/.singularity/cache by default. The location of the cache can be changed by setting the SINGULARITY_CACHEDIR environment variable.

The directory used for SINGULARITY_CACHEDIR should be:

  • A unique location for each user. Permissions are set on the cache so that private images cached for one user are not exposed to another. This means that SINGULARITY_CACHEDIR cannot be shared.
  • Located on a filesystem with sufficient space for the number and size of container images anticipated.
  • Located on a filesystem that supports atomic rename, if possible.

In {Singularity} version 3.6 and above the cache is concurrency safe. Parallel runs of {Singularity} that would create overlapping cache entries will not conflict, as long as the filesystem used by SINGULARITY_CACHEDIR supports atomic rename operations.

Support for atomic rename operations is expected on local POSIX filesystems, but varies for network / parallel filesystems and may be affected by topology and configuration. For example, Lustre supports atomic rename of files only on a single MDT. Rename on NFS is only atomic to a single client, not across systems accessing the same NFS share.

If you are not certain that your $HOME or SINGULARITY_CACHEDIR filesystems support atomic rename, do not run singularity in parallel using remote container URLs. Instead use singularity pull to create a local SIF image, and then run this SIF image in a parallel step. An alternative is to use the --disable-cache option, but this will result in each {Singularity} instance independently fetching the container from the remote source, into a temporary location.

NFS

NFS filesystems support overlay mounts as a lowerdir only, and do not support user-namespace (sub)uid/gid mapping.

  • Containers run from SIF files located on an NFS filesystem do not have restrictions.
  • You cannot use --overlay mynfsdir/ to overlay a directory onto a container when the overlay (upperdir) directory is on an NFS filesystem.
  • When using --fakeroot to build or run a container, your TMPDIR / SINGULARITY_TMPDIR should not be set to an NFS location.
  • You should not run a sandbox container with --fakeroot from an NFS location.
Lustre / GPFS / PanFS

Lustre, GPFS, and PanFS do not have sufficient upperdir or lowerdir overlay support for certain {Singularity} features, and do not support user-namespace (sub)uid/gid mapping.

  • You cannot use --overlay or --writable-tmpfs with a sandbox container that is located on a Lustre, GPFS, or PanFS filesystem. SIF containers on Lustre, GPFS, and PanFS will work correctly with these options.
  • You cannot use --overlay to overlay a directory onto a container, when the overlay (upperdir) directory is on a Lustre, GPFS, or PanFS filesystem.
  • When using --fakeroot to build or run a container, your TMPDIR/SINGULARITY_TMPDIR should not be a Lustre, GPFS, or PanFS location.
  • You should not run a sandbox container with --fakeroot from a Lustre, GPFS, or PanFS location.

OCI-mode Limitations

Because {Singularity} 4's OCI-mode is unprivileged, and never uses a setuid starter executable for container configuration, it has requirements that may not be satisified by older Linux distributions.

OCI-mode, including Dockerfile builds to OCI-SIF, will generally operate correctly on Linux distributions that use kernel 4.18 or later and v2 cgroups. Some distributions that use earlier kernels may have backported functionality that allows OCI-Mode to be used, but certain features may be limited as below. Distributions using v1 cgroups also have limitations, discussed below.

RHEL / Alma Linux / Rocky Linux

On RHEL 9, all features of OCI-mode are supported. crun is the recommended low-level runtime, and is listed as a requirement by {Singularity} RPM packages.

On RHEL 8, container resource limits cannot be applied as v1 cgroups are used by default. crun is the recommended low-level runtime, and is listed as a requirement by {Singularity} RPM packages.

SLES / openSUSE Leap

On SLES 15, container resource limits cannot be applied as v1 cgroups are used by default. runc is the recommended low-level runtime, and is listed as a requirement by {Singularity} RPM packages. The --no-setgroups option, to preserve host supplementary group membership, is not supported by runc.

OCI-mode, including building Dockerfiles with singularity build --oci, is not supported on SLES12. The kernel does not support FUSE in unprivileged user namespaces nor does it support unprivileged kernel overlays.

Ubuntu

On Ubuntu 22.04 LTS, runc is the recommended low-level runtime, and is listed as a requirement by {Singularity} Deb packages. The --no-setgroups option, to preserve host supplementary group membership, is not supported by runc.

On Ubuntu 20.04 LTS, container resource limits cannot be applied as v1 cgroups are used by default. runc is the recommended low-level runtime, and is listed as a requirement by {Singularity} Deb packages. The --no-setgroups option, to preserve host supplementary group membership, is not supported by runc.

Install from Provided RPM / Deb Packages

Sylabs provides .rpm packages of {Singularity}, for mainstream-supported versions of RHEL and derivatives (e.g. Alma Linux / Rocky Linux). We also provide .deb packages for current Ubuntu LTS releases.

These packages can be downloaded from the GitHub release page and installed using your distribution's package manager.

The packages are provided as a convenience for users of the open source project, and are built in our public CircleCI workflow. They are not signed, but SHA256 sums are provided on the release page.

Install from Source

To use the latest version of {Singularity} from GitHub you will need to build and install it from source. This may sound daunting, but the process is straightforward, and detailed below.

If you have an earlier version of {Singularity} installed, you should :ref:`remove it <remove-an-old-version>` before executing the installation commands. You will also need to install some dependencies and install Go.

Install Dependencies

On Debian-based systems, including Ubuntu:

# Ensure repositories are up-to-date
sudo apt-get update
# Install debian packages for dependencies
sudo apt-get install -y \
   autoconf \
   automake \
   cryptsetup \
   fuse \
   fuse2fs \
   git \
   libfuse-dev \
   libglib2.0-dev \
   libseccomp-dev \
   libtool \
   pkg-config \
   runc \
   squashfs-tools \
   squashfs-tools-ng \
   uidmap \
   wget \
   zlib1g-dev

On versions 8 or later of RHEL / Alma Linux / Rocky Linux, as well as on Fedora:

# Install basic tools for compiling
sudo dnf groupinstall -y 'Development Tools'
# Install RPM packages for dependencies
sudo dnf install -y \
   autoconf \
   automake \
   crun \
   cryptsetup \
   fuse \
   fuse3 \
   fuse3-devel \
   git \
   glib2-devel \
   libseccomp-devel \
   libtool \
   squashfs-tools \
   wget \
   zlib-devel

On SLES / openSUSE Leap:

# Install RPM packages for dependencies
sudo zypper in \
   autoconf \
   automake \
   cryptsetup \
   fuse2fs \
   fuse3 \
   fuse3-devel \
   gcc \
   gcc-c++ \
   git \
   glib2-devel \
   libseccomp-devel \
   libtool \
   make \
   pkg-config \
   runc \
   squashfs \
   wget \
   zlib-devel

Note

You can build {Singularity} without cryptsetup available, but you will not be able to use encrypted containers without it installed on your system.

If you will not use the singularity oci commands, or OCI-mode, crun / runc is not required.

Install Go

{Singularity} is written in Go, and aims to maintain support for the two most recent stable versions of Go. This corresponds to the Go Release Maintenance Policy and Security Policy, ensuring critical bug fixes and security patches are available for all supported language versions.

Building {Singularity} may require a newer version of Go than is available in the repositories of your distribution. We recommend installing the latest version of Go from the [official binaries](https://golang.org/dl/).

This is one of several ways to install and configure Go.

Note

If you have previously installed Go from a download, rather than an operating system package, you should remove your go directory, e.g. rm -r /usr/local/go before installing a newer version. Extracting a new version of Go over an existing installation can lead to errors when building Go programs, as it may leave old files, which have been removed or replaced in newer versions.

Visit the Go download page and pick a package archive to download. Copy the link address and download with wget. Then extract the archive to /usr/local (or use other instructions on go installation page).

$ export VERSION={GoVersion} OS=linux ARCH=amd64 && \
    wget https://dl.google.com/go/go$VERSION.$OS-$ARCH.tar.gz && \
    sudo tar -C /usr/local -xzvf go$VERSION.$OS-$ARCH.tar.gz && \
    rm go$VERSION.$OS-$ARCH.tar.gz

Then, set up your environment for Go.

$ echo 'export GOPATH=${HOME}/go' >> ~/.bashrc && \
    echo 'export PATH=/usr/local/go/bin:${PATH}:${GOPATH}/bin' >> ~/.bashrc && \
    source ~/.bashrc

Download {Singularity} from a release

You can download {Singularity} from one of the releases. To see a full list, visit the GitHub release page. After deciding on a release to install, you can run the following commands to proceed with the installation.

$ export VERSION={InstallationVersion} && # adjust this as necessary \
    wget https://github.com/sylabs/singularity/releases/download/v${VERSION}/singularity-ce-${VERSION}.tar.gz && \
    tar -xzf singularity-ce-${VERSION}.tar.gz && \
    cd singularity-ce-${VERSION}

Checkout Code from Git

The following commands will install {Singularity} from the GitHub repo to /usr/local. This method will work for >=v{InstallationVersion}. To install an older tagged release see older versions of the docs.

When installing from source, you can decide to install from either a tag, a release branch, or from the main branch.

  • tag: GitHub tags form the basis for releases, so installing from a tag is the same as downloading and installing a specific release. Tags are expected to be relatively stable and well-tested.
  • release branch: A release branch represents the latest version of a minor release with all the newest bug fixes and enhancements (even those that have not yet made it into a point release). For instance, to install v3.10 with the latest bug fixes and enhancements checkout release-3.10. Release branches may be less stable than code in a tagged point release.
  • main branch: The main branch contains the latest, bleeding edge version of {Singularity}. This is the default branch when you clone the source code, so you don't have to check out any new branches to install it. The main branch changes quickly and may be unstable.

To ensure that the {Singularity} source code is downloaded to the appropriate directory use these commands.

$ git clone --recurse-submodules https://github.com/sylabs/singularity.git && \
    cd singularity && \
    git checkout --recurse-submodules v{InstallationVersion}

Compile Singularity

{Singularity} uses a custom build system called makeit. mconfig is called to generate a Makefile and then make is used to compile and install.

To support the SIF image format, automated networking setup etc., and older Linux distributions without user namespace support, Singularity must be make install``ed as root or with ``sudo, so it can install the libexec/singularity/bin/starter-setuid binary with root ownership and setuid permissions for privileged operations. If you need to install as a normal user, or do not want to use setuid functionality :ref:`see below <install-nonsetuid>`.

$ ./mconfig && \
    make -C ./builddir && \
    sudo make -C ./builddir install

By default {Singularity} will be installed in the /usr/local directory hierarchy. You can specify a custom directory with the --prefix option, to mconfig like so:

$ ./mconfig --prefix=/opt/singularity

This option can be useful if you want to install multiple versions of {Singularity}, install a personal version of {Singularity} on a shared system, or if you want to remove {Singularity} easily after installing it.

For a full list of mconfig options, run mconfig --help. Here are some of the most common options that you may need to use when building {Singularity} from source.

  • --sysconfdir: Install read-only config files in sysconfdir. This option is important if you need the singularity.conf file or other configuration files in a custom location.
  • --localstatedir: Set the state directory where containers are mounted. This is a particularly important option for administrators installing {Singularity} on a shared file system. The --localstatedir should be set to a directory that is present on each individual node.
  • -b: Build {Singularity} in a given directory. By default this is ./builddir.
  • --without-conmon: Do not build the conmon OCI container monitor. Use this option if you are certain you will not use the singularity oci commands, or wish to use conmon >=2.0.24 provided by your distribution, and available on $PATH.
  • --reproducible: Enable support for reproducible builds. Ensures
    that the compiled binaries do not include any temporary paths, the source directory path, etc. This disables support for building plugins.

Unprivileged (non-setuid) Installation

If you need to install {Singularity} as a non-root user, or do not wish to allow the use of a setuid root binary, you can configure {Singularity} with the --without-suid option to mconfig:

$ ./mconfig --without-suid --prefix=/home/dave/singularity-ce && \
    make -C ./builddir && \
    make -C ./builddir install

If you have already installed {Singularity} you can disable the setuid flow by setting the option allow setuid = no in etc/singularity/singularity.conf within your installation directory.

When {Singularity} does not use setuid all container execution will use a user namespace. This requires support from your operating system kernel, and imposes some limitations on functionality. You should review the :ref:`requirements <userns-requirements>` and :ref:`limitations <userns-limitations>` in the :ref:`user namespace <userns>` section of this guide.

Relocatable Installation

Since {Singularity} 3.8, an unprivileged (non-setuid) installation is relocatable. As long as the structure inside the installation directory (--prefix) is maintained, it can be moved to a different location and {Singularity} will continue to run normally.

Relocation of a default setuid installation is not supported, as restricted location / ownership of configuration files is important to security.

Source bash completion file

To enjoy bash shell completion with {Singularity} commands and options, source the bash completion file:

$ . /usr/local/etc/bash_completion.d/singularity

Add this command to your ~/.bashrc file so that bash completion continues to work in new shells. (Adjust the path if you installed {Singularity} to a different location.)

Build and install an RPM

If you use RHEL, RHEL derivatives, or SUSE, building and installing a Singularity RPM allows your {Singularity} installation to be more easily managed, upgraded and removed. You can build an RPM directly from the release tarball.

Note

Be sure to download the correct asset from the GitHub releases page. It should be named singularity-ce-<version>.tar.gz.

After installing the :ref:`dependencies <install-dependencies>` and installing :ref:`Go <install-go>` as detailed above, you are ready to download the tarball and build and install the RPM.

$ export VERSION={InstallationVersion} && # adjust this as necessary \
    wget https://github.com/sylabs/singularity/releases/download/v${VERSION}/singularity-ce-${VERSION}.tar.gz && \
    rpmbuild -tb singularity-ce-${VERSION}.tar.gz && \
    sudo rpm -ivh ~/rpmbuild/RPMS/x86_64/singularity-ce-$VERSION-1.el9.x86_64.rpm && \
    rm -rf ~/rpmbuild singularity-ce-$VERSION*.tar.gz

If you encounter a failed dependency error for golang but installed it from source, build with this command:

rpmbuild -tb --nodeps singularity-ce-${VERSION}.tar.gz

Options to mconfig can be passed using the familiar syntax to rpmbuild. For example, if you want to force the local state directory to /mnt (instead of the default /var) you can do the following:

rpmbuild -tb --define='_localstatedir /mnt' singularity-ce-$VERSION.tar.gz

Note

It is very important to set the local state directory to a directory that physically exists on nodes within a cluster when installing {Singularity} in an HPC environment with a shared file system.

Build an RPM from Git source

Alternatively, to build an RPM from a branch of the Git repository you can clone the repository, directly make an rpm, and use it to install Singularity:

$ ./mconfig && \
make -C builddir rpm && \
sudo rpm -ivh ~/rpmbuild/RPMS/x86_64/singularity-ce-{InstallationVersion}.el9.x86_64.rpm # or whatever version you built

To build an rpm with an alternative install prefix set RPMPREFIX on the make step, for example:

$ make -C builddir rpm RPMPREFIX=/usr/local

For finer control of the rpmbuild process you may wish to use make dist to create a tarball that you can then build into an rpm with rpmbuild -tb as above.

Remove an old version

In a standard installation of {Singularity} (when building from source), the command sudo make -C builddir install lists all the files as they are installed. You must remove all of these files and directories to completely remove {Singularity}.

$ sudo rm -rf \
    /usr/local/libexec/singularity \
    /usr/local/var/singularity \
    /usr/local/etc/singularity \
    /usr/local/bin/singularity \
    /usr/local/bin/run-singularity \
    /usr/local/etc/bash_completion.d/singularity

If you anticipate needing to remove {Singularity}, it might be easier to install it in a custom directory using the --prefix option to mconfig. In that case {Singularity} can be uninstalled simply by deleting the parent directory. Or it may be useful to install {Singularity} :ref:`using a package manager <install-rpm>` so that it can be updated and/or uninstalled with ease in the future.

Testing & Checking the Build Configuration

After installation you can perform a basic test of Singularity functionality by executing a simple container from the Sylabs Cloud library:

$ singularity exec library://alpine cat /etc/alpine-release
3.10.0

See the user guide for more information about how to use {Singularity}.

singularity buildcfg

Running singularity buildcfg will show the build configuration of an installed version of {Singularity}, and lists the paths used by {Singularity}. Use singularity buildcfg to confirm paths are set correctly for your installation, and troubleshoot any 'not-found' errors at runtime.

$ singularity buildcfg
PACKAGE_NAME=singularity-ce
PACKAGE_VERSION={InstallationVersion}
BUILDDIR=/home/myuser/singularity/builddir
PREFIX=/usr/local
EXECPREFIX=/usr/local
BINDIR=/usr/local/bin
SBINDIR=/usr/local/sbin
LIBEXECDIR=/usr/local/libexec
DATAROOTDIR=/usr/local/share
DATADIR=/usr/local/share
SYSCONFDIR=/usr/local/etc
SHAREDSTATEDIR=/usr/local/com
LOCALSTATEDIR=/usr/local/var
RUNSTATEDIR=/usr/local/var/run
INCLUDEDIR=/usr/local/include
DOCDIR=/usr/local/share/doc/singularity-ce
INFODIR=/usr/local/share/info
LIBDIR=/usr/local/lib
LOCALEDIR=/usr/local/share/locale
MANDIR=/usr/local/share/man
SINGULARITY_CONFDIR=/usr/local/etc/singularity
SESSIONDIR=/usr/local/var/singularity/mnt/session
PLUGIN_ROOTDIR=/usr/local/libexec/singularity/plugin
SINGULARITY_CONF_FILE=/usr/local/etc/singularity/singularity.conf
SINGULARITY_SUID_INSTALL=1

Note that the LOCALSTATEDIR and SESSIONDIR should be on local, non-shared storage.

The list of files installed by a successful setuid installation of {Singularity} can be found in the :ref:`appendix, installed files section <installed-files>`.

Test Suite

The {Singularity} codebase includes a test suite that is run during development using CI services.

If you would like to run the test suite locally you can run the test targets from the builddir directory in the source tree:

  • make check runs source code linting and dependency checks
  • make test runs basic unit and integration tests
  • make e2e-test runs end-to-end tests, which exercise a large number of operations by calling the {Singularity} CLI with different execution profiles.

Note

Running the full test suite requires a docker installation, and nc in order to test docker and instance/networking functionality.

{Singularity} must be installed in order to run the full test suite, as it must run the CLI with setuid privilege for the starter-suid binary.

Warning

sudo privilege is required to run the full tests, and you should not run the tests on a production system. We recommend running the tests in an isolated development or build environment.

Installation on Windows or Mac

Linux container runtimes like {Singularity} cannot run natively on Windows or Mac because of basic incompatibilities with the host kernel. (Contrary to a popular misconception, macOS does not run on a Linux kernel. It runs on a kernel called Darwin originally forked from BSD.)

To run {Singularity} on a Windows or macOS computer, a Linux virtual machine (VM) is required. There are various ways to configure a VM on both Windows and macOS. On WIndows, we recommend the Windows Subsystem for Linux (WSL2), and macOS, we recommend Lima.

Windows

Recent builds of Windows 10, and all builds of Windows 11, include version 2 of the Windows Subsystem for Linux. WSL2 provides a Linux virtual machine that is tightly integrated with the Windows environment. The default Linux distribution used by WSL2 is Ubuntu. It is straightforward to install {Singularity} inside WSL2 Ubuntu, and use all of its features.

Follow the WSL2 installation instructions to enable WSL2 with the default Ubuntu 22.04 environment. On Windows 11 and the most recent builds of Windows 10 this is as easy as opening an administrator command prompt or Powershell window and entering:

wsl --install

Follow the prompts. A restart is required, and when you open the 'Ubuntu' app for the first time you'll be asked to set a username and password for the Linux environment.

You can install SingularityCE from source, or from the Ubuntu packages at the GitHub releases page. To quickly install the 4.0.0 package use the following commands inside the WSL2 Ubuntu window:

$ wget https://github.com/sylabs/singularity/releases/download/v4.0.0/singularity-ce_4.0.0-jammy_amd64.deb
$ sudo apt install ./singularity-ce_4.0.0-jammy_amd64.deb

The singularity command will now be available in your WSL2 environment:

$ singularity exec library://ubuntu echo "Hello World!"
INFO:    Downloading library image
28.4MiB / 28.4MiB [=================================================================================] 100 % 5.6 MiB/s 0s
Hello World!

GPU Support

WSL2 supports using an NVIDIA GPU from the Linux environment. To use a GPU from {Singularity} in WSL2, you must first install libnvidia-container-tools, following the instructions in the libnvidia-container documentation:

curl -fsSL https://nvidia.github.io/libnvidia-container/gpgkey | sudo gpg --dearmor -o /usr/share/keyrings/nvidia-container-toolkit-keyring.gpg \
curl -s -L https://nvidia.github.io/libnvidia-container/stable/deb/nvidia-container-toolkit.list | \
  sed 's#deb https://#deb [signed-by=/usr/share/keyrings/nvidia-container-toolkit-keyring.gpg] https://#g' | \
  sudo tee /etc/apt/sources.list.d/nvidia-container-toolkit.list \
sudo apt-get update
sudo apt-get install -y nvidia-container-toolkit

Once this process has been completed, GPU containers can be run under WSL2 using the --nv and --nvccli flags together:

$ singularity pull docker://tensorflow/tensorflow:latest-gpu

$  singularity run --nv --nvccli tensorflow_latest-gpu.sif
INFO:    Setting 'NVIDIA_VISIBLE_DEVICES=all' to emulate legacy GPU binding.
INFO:    Setting --writable-tmpfs (required by nvidia-container-cli)
________                               _______________
___  __/__________________________________  ____/__  /________      __
__  /  _  _ \_  __ \_  ___/  __ \_  ___/_  /_   __  /_  __ \_ | /| / /
_  /   /  __/  / / /(__  )/ /_/ /  /   _  __/   _  / / /_/ /_ |/ |/ /
/_/    \___//_/ /_//____/ \____//_/    /_/      /_/  \____/____/|__/
You are running this container as user with ID 1000 and group 1000,
which should map to the ID and group for your user on the Docker host. Great!
Singularity> python
Python 3.8.10 (default, Nov 26 2021, 20:14:08)
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import tensorflow as tf
>>> tf.config.list_physical_devices('GPU')
2022-03-25 11:42:25.672088: I tensorflow/stream_executor/cuda/cuda_gpu_executor.cc:922] could not open file to read NUMA node: /sys/bus/pci/devices/0000:01:00.0/numa_node
Your kernel may have been built without NUMA support.
2022-03-25 11:42:25.713295: I tensorflow/stream_executor/cuda/cuda_gpu_executor.cc:922] could not open file to read NUMA node: /sys/bus/pci/devices/0000:01:00.0/numa_node
Your kernel may have been built without NUMA support.
2022-03-25 11:42:25.713892: I tensorflow/stream_executor/cuda/cuda_gpu_executor.cc:922] could not open file to read NUMA node: /sys/bus/pci/devices/0000:01:00.0/numa_node
Your kernel may have been built without NUMA support.
[PhysicalDevice(name='/physical_device:GPU:0', device_type='GPU')]

Note that the --nvccli flag is required to enable container setup using the nvidia-container-cli utility. {Singularity}'s simpler library binding approach (--nv only) is not sufficient for GPU support under WSL2.

Mac

To install {Singularity} on macOS, we recommend using the lima VM platform, available on Homebrew.

If you don't already have Homebrew installed, you can install it as follows:

$ /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Follow the instructions at the end of the installation process. In particular, make sure to add the relevant lines to your shell configuration:

$ (echo; echo 'eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"') >> $HOME/.profile
$ eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"

Once Homebrew is installed, install lima:

$ brew install lima

As part of the {Singularity} distribution (starting with version 4), we have provided an example template for using {Singularity} with lima. The example is available under the examples/lima directory in the {Singularity} source bundle, and can also be downloaded directly from the code repository.

The template is named singularity-ce.yml, and:

  • Is based on AlmaLinux 9.
  • Supports both Intel and Apple Silicon (ARM64) Macs.
  • Installs the latest stable release of SingularityCE that has been published to the Fedora EPEL repositories.

Once you have obtained the template file, use it to start a lima VM:

$ limactl start ./singularity-ce.yml

You will be presented with an interactive menu:

$ limactl start ./singularity-ce.yml
? Creating an instance "singularity-ce"  [Use arrows to move, type to filter]
> Proceed with the current configuration
  Open an editor to review or modify the current configuration
  Choose another template (docker, podman, archlinux, fedora, ...)
  Exit

Choose the Proceed with the current configuration option, and lima will proceed to configure the VM according to the specifications in the template file. This can take a couple of minutes.

Once lima is done with the configuration step, you can enter the VM interactively and run {Singularity} commands:

$ limactl shell singularity-ce
[myuser@lima-singularity-ce myuser]$ singularity run library://alpine
INFO:    Downloading library image
2.8MiB / 2.8MiB [==========================================================================================] 100 % 0.0 b/s 0s
Singularity> cat /etc/os-release
NAME="Alpine Linux"
ID=alpine
VERSION_ID=3.15.5
PRETTY_NAME="Alpine Linux v3.15"
HOME_URL="https://alpinelinux.org/"
BUG_REPORT_URL="https://bugs.alpinelinux.org/"
Singularity>

Your home directory is shared into the lima VM by default. However, since macOS places home directories under /Users (rather than /home), {Singularity} will not mount your home directory in the container unless you explicitly specify your macOS homedir, as shown here:

$ limactl shell singularity-ce
[myuser@lima-singularity-ce myuser]$ singularity run -H /Users/myuser library://alpine
INFO:    Using cached image
Singularity> ls
Applications Documents    Library      Music        Public
Desktop      Downloads    Movies       Pictures

You can also run {Singularity} using lima directly from the macOS command-line:

$ limactl shell singularity-ce singularity run library://alpine
INFO:    Using cached image
Singularity>

Or, with homedir mounting:

$ limactl shell singularity-ce singularity run -H /Users/myuser library://alpine
INFO:    Using cached image
Singularity>

To stop the lima VM:

$ limactl stop singularity-ce

To delete the lima VM:

$ limactl delete singularity-ce

{Singularity} Docker Image

It is also possible to run {Singularity} inside Docker, or another compatible OCI container runtime. This may be convenient if you have Docker Desktop, or a similar solution, already installed on your PC or Mac.

Docker containers for {Singularity} are maintained at https://quay.io/repository/singularity/singularity.

Note

These containers are maintained by a third party. They are not part of the {Singularity} project, nor are they reviewed by Sylabs.

An example of a suitable compose.yaml file to start up {Singularity} in a Docker container is given below. Note that privileged operation is needed to successfully run {Singularity} nested inside of Docker. Change the version number on the image: line to your preferred release.

services:
  singularity:
    image: quay.io/singularity/singularity:v3.11.4-slim
    stdin_open: true
    tty: true
    privileged: true
    volumes:
      - .:/root
    entrypoint: ["/bin/sh"]

Singularity in Docker can have various disadvantages, but basic container operations will work. Currently, the intended use case is continuous integration, meaning that you should be able to build a Singularity container using this Docker Compose file. For more information see issue#5 and the image's source repo