apptainer(1)

NAME
apptainer-build - Build an Apptainer image

SYNOPSIS
apptainer build [local options...]

DESCRIPTION
IMAGE PATH:

When Apptainer builds the container, output can be one of a few formats:
      default:    The compressed Apptainer read only image format (default)
      sandbox:    This is a read-write container within a directory structure

note: It is a common workflow to use the "sandbox" mode for development of the
  container, and then build it as a default Apptainer image for production
  use. The default format is immutable.

BUILD SPEC:

The build spec target is a definition (def) file, local image, or URI that can
  be used to create an Apptainer container. Several different local target
  formats exist:
      def file  : This is a recipe for building a container (examples below)
      buildkit:   A build context directory, containing a Dockerfile to build
      directory:  A directory structure containing a (ch)root file system
      image:      A local image on your machine (will convert to sif if
                  it is legacy format)

Targets can also be remote and defined by a URI of the following formats:
      library://  an image library (no default)
      docker://   a Docker/OCI registry (default Docker Hub)
      shub://     an Apptainer registry (default Singularity Hub)
      oras://     an OCI registry that holds SIF files using ORAS
      ipfs://     an IPFS cluster, using a HTTP gateway

Temporary files:

The location used for temporary directories defaults to '/tmp' but
  can be overridden by the TMPDIR environment variable, and that can be
  overridden by the APPTAINER_TMPDIR environment variable. The
  temporary directory used during a build must be on a filesystem that
  has enough space to hold the entire container image, uncompressed,
  including any temporary files that are created and later removed
  during the build. You may need to set APPTAINER_TMPDIR or TMPDIR when
  building a large container on a system that has a small /tmp filesystem.

OPTIONS
--arch="amd64"
    architecture to build for

--arch-variant=""
    architecture variant to build for

--authfile=""
    Docker-style authentication file to use for writing/reading OCI registry credentials

-B, --bind=[]
    a user-bind path specification. 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.

--build-arg=[]
    defines variable=value to replace {{ variable }} entries in build definition file

--build-arg-file=""
    specifies a file containing variable=value lines to replace '{{ variable }}' with value in build definition files

--buildkit-host=""
    specify a custom BuildKit daemon host

--data[=false]
    build image with data partition instead of system partition

--disable-cache[=false]
    do not use cache or create cache

--docker-host=""
    specify a custom Docker daemon host

--docker-login[=false]
    login to a Docker Repository interactively

-e, --encrypt[=false]
    build an image with an encrypted file system

-f, --fakeroot[=false]
    build with the appearance of running as root (default when building from a definition file unprivileged)

--fix-perms[=false]
    ensure owner has rwX permissions on all container content for oci/docker sources

-F, --force[=false]
    overwrite an image file if it exists

-h, --help[=false]
    help for build

--json[=false]
    interpret build definition as JSON

--library=""
    container Library URL

--mksquashfs-args=""
    extra arguments to pass to mksquashfs when creating SIF files

--mount=[]
    a mount specification e.g. 'type=bind,source=/opt,destination=/hostopt'.

--no-cleanup[=false]
    do NOT clean up bundle after failed build, can be helpful for debugging

--no-https[=false]
    use http instead of https for docker:// oras:// and library:///... URIs

-T, --notest[=false]
    build without running tests in %test section

--nv[=false]
    inject host Nvidia libraries during build for post and test sections

--nvccli[=false]
    use nvidia-container-cli for GPU setup (experimental)

--passphrase[=false]
    prompt for an encryption passphrase

--pem-path=""
    enter an path to a PEM formatted RSA key for an encrypted container

--reproducible[=false]
    creates a reproducible build by using the creation date of the source image

--rocm[=false]
    inject host Rocm libraries during build for post and test sections

-s, --sandbox[=false]
    build image as sandbox format (chroot directory structure)

--section=[all]
    only run specific section(s) of deffile (setup, post, files, environment, test, labels, none)

-u, --update[=false]
    run definition over existing container (skips header)

--userns[=false]
    build without using setuid even if available

--warn-unused-build-args[=false]
    shows warning instead of fatal message when build args are not exact matched

--writable-tmpfs[=false]
    during the %test section, makes the file system accessible as read-write with non persistent data (with overlay support only)

EXAMPLE
      DEF FILE BASE OS:
          Library:
              Bootstrap: library
              From: debian:9
          Docker:
              Bootstrap: docker
              From: tensorflow/tensorflow:latest
              IncludeCmd: yes # Use the CMD as runscript instead of ENTRYPOINT
          Singularity Hub:
              Bootstrap: shub
              From: singularityhub/centos
          YUM/RHEL:
              Bootstrap: yum
              OSVersion: 7
              MirrorURL: http://mirror.centos.org/centos-%{OSVERSION}/%{OSVERSION}/os/x86_64/
              Include: yum
          SUSE:
              Bootstrap: zypper # on SLE system registration of build host is used
              Include: zypper

          openSUSE:
              Bootstrap: zypper
              MirrorURL: http://download.opensuse.org/distribution/openSUSE-stable/repo/oss
              Include: zypper
          Debian/Ubuntu:
              Bootstrap: debootstrap
              OSVersion: trusty
              MirrorURL: http://us.archive.ubuntu.com/ubuntu/
          Local Image:
              Bootstrap: localimage
              From: /home/dave/starter.img
          Scratch:
              Bootstrap: scratch # Populate the container with a minimal rootfs in %setup
      DEFFILE SECTIONS:
      The following sections are presented in the order of processing, with the exception
      that labels and environment can also be manipulated in %post.
          %pre
              echo "This is a scriptlet that will be executed on the host, as root before"
              echo "the container has been bootstrapped. This section is not commonly used."
          %setup
              echo "This is a scriptlet that will be executed on the host, as root, after"
              echo "the container has been bootstrapped. To install things into the container"
              echo "reference the file system location with $APPTAINER_ROOTFS."
          %files
              /path/on/host/file.txt /path/on/container/file.txt
              relative_file.txt /path/on/container/relative_file.txt
          %post
              echo "This scriptlet section will be executed from within the container after"
              echo "the bootstrap/base has been created and setup."
          %environment
              LUKE=goodguy
              VADER=badguy
              HAN=someguy
              export HAN VADER LUKE
          %test
              echo "Define any test commands that should be executed after container has been"
              echo "built. This scriptlet will be executed from within the running container"
              echo "as the root user. Pay attention to the exit/return value of this scriptlet"
              echo "as any non-zero exit code will be assumed as failure."
              exit 0
          %runscript
              echo "Define actions for the container to be executed with the run command or"
              echo "when container is executed."
          %startscript
              echo "Define actions for container to perform when started as an instance."
          %labels
              HELLO MOTO
              KEY VALUE
          %help
              This is a text file to be displayed with the run-help command.
      COMMANDS:
          Build a sif file from an Apptainer recipe file:
              $ apptainer build /tmp/debian0.sif /path/to/debian.def
          Build a sif image from the Library:
              $ apptainer build /tmp/debian1.sif library://debian:latest
          Build a base sandbox from DockerHub, make changes to it, then build sif
              $ apptainer build --sandbox /tmp/debian docker://debian:latest
              $ apptainer exec --writable /tmp/debian apt-get install python
              $ apptainer build /tmp/debian2.sif /tmp/debian

SEE ALSO
apptainer(1)

HISTORY
7-May-2026 Auto generated by spf13/cobra