Cloud Library


The Sylabs Cloud Library is the place to push your containers to the cloud so other users can pull, verify, and use them.

The Sylabs Cloud also provides a Remote Builder, allowing you to build containers on a secure remote service. This is convenient so that you can build containers on systems where you do not have root privileges.

Make an Account

Making an account is easy, and straightforward:

  1. Go to:

  2. Click “Sign in to Sylabs” (top right corner).

  3. Select your method to sign in, with Google, GitHub, GitLab, or Microsoft.

  4. Type your passwords, and that’s it!

Creating a Access token

Access tokens for pushing a container, and remote builder.

To generate a access token, do the following steps:

  1. Go to:

  2. Click “Sign In” and follow the sign in steps.

  3. Click on your login id (same and updated button as the Sign in one).

  4. Select “Access Tokens” from the drop down menu.

  5. Enter a name for your new access token, such as “test token”

  6. Click the “Create a New Access Token” button.

  7. Click “Copy token to Clipboard” from the “New API Token” page.

  8. Run singularity remote login and paste the access token at the prompt.

Now that you have your token, you are ready to push your container!

Pushing a Container

The singularity push command will push a container to the container library with the given URL. Here’s an example of a typical push command:

$ singularity push my-container.sif library://your-name/project-dir/my-container:latest

The :latest is the container tag. Tags are used to have different version of the same container.


When pushing your container, there’s no need to add a .sif (Singularity Image Format) to the end of the container name, (like on your local machine), because all containers on the library are SIF containers.

Let’s assume you have your container (v1.0.1), and you want to push that container without deleting your :latest container, then you can add a version tag to that container, like so:

$ singularity push my-container.sif library://your-name/project-dir/my-container:1.0.1

You can download the container with that tag by replacing the :latest, with the tagged container you want to download.

To set a description against the container image as you push it, use the -D flag introduced in SingularityCE 3.7. This provides an alternative to setting the description via the web interface:

$ singularity push -D "My alpine 3.11 container" alpine_3.11.sif library://myuser/examples/alpine:3.11
2.7MiB / 2.7MiB [=========================================================================] 100 % 1.1 MiB/s 0s

Library storage: using 13.24 MiB out of 11.00 GiB quota (0.1% used)
Container URL:

Note that when you push to a library that supports it, SingularityCE 3.7 and above will report your quota usage and the direct URL to view the container in your web browser.

Pulling a container

The singularity pull command will download a container from the Library (library://), Docker Hub (docker://), and also Shub (shub://).


When pulling from Docker, the container will automatically be converted to a SIF (Singularity Image Format) container.

Here’s a typical pull command:

$ singularity pull file-out.sif library://alpine:latest

# or pull from docker:

$ singularity pull file-out.sif docker://alpine:latest


If there’s no tag after the container name, SingularityCE automatically will pull the container with the :latest tag.

To pull a container with a specific tag, just add the tag to the library URL:

$ singularity pull file-out.sif library://alpine:3.8

Of course, you can pull your own containers. Here’s what that will look like:

Pulling your own container

Pulling your own container is just like pulling from Github, Docker, etc…

$ singularity pull out-file.sif library://your-name/project-dir/my-container:latest

# or use a different tag:

$ singularity pull out-file.sif library://your-name/project-dir/my-container:1.0.1


You don’t have to specify a output file, one will be created automatically, but it’s good practice to always specify your output file.

Verify/Sign your Container

Verify containers that you pull from the library, ensuring they are bit-for-bit reproductions of the original image.

Check out this page on how to: verify a container, making PGP key, and sign your own containers.

Searching the Library for Containers

To find interesting or useful containers in the library, you can open in your browser and search from there through the web GUI.

Alternatively, from the CLI you can use singularity search <query>. This will search the library for container images matching <query>.

Remote Builder

The remote builder service can build your container in the cloud removing the requirement for root access.

Here’s a typical remote build command:

$ singularity build --remote file-out.sif docker://ubuntu:18.04

Building from a definition file:

This is our definition file. Let’s call it ubuntu.def:

bootstrap: library
from: ubuntu:18.04

    echo "hello world from ubuntu container!"

Now, to build the container, use the --remote flag, and without sudo:

$ singularity build --remote ubuntu.sif ubuntu.def


Make sure you have a access token, otherwise the build will fail.

After building, you can test your container like so:

$ ./ubuntu.sif
hello world from ubuntu container!

You can also use the web GUI to build containers remotely. First, go to (make sure you are signed in). Then you can copy and paste, upload, or type your definition file. When you are finished, click build. Then you can download the container with the URL.