Build a new Clear Linux OS-based container image

This guide describes how to build a new Clear Linux* OS-based container image. The official base Clear Linux* OS container image is published on Docker* Hub and is updated on a regular basis.

Prerequisites

  • You must perform these steps on a Clear Linux OS system because the swupd is used to manage bundles in the container.

  • You must install the containers-basic bundle on the Clear Linux OS system or Docker will not work.

  • You have a basic understanding of Docker.

Build the base container image

  1. Log in and get root privileges.

    sudo -s

  2. Verify Docker is installed and running.

    docker info

    If Docker is installed and running, the output is similar to this example:

    Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 4
Server Version: 17.05.0-ce
Storage Driver: overlay
 Backing Filesystem: extfs
 Supports d_type: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version:  (expected: 9048e5e50717ea4497b757314bad98ea3763c145)
runc version: N/A (expected: 9c2d8d184e5da67c95d601382adf14862e4f2228)
init version: N/A (expected: )
Kernel Version: 4.12.7-377.native
Operating System: Clear Linux OS for Intel Architecture
OSType: linux
Architecture: x86_64
CPUs: 4
Total Memory: 15.62GiB
Name: clr-os
ID: XQHJ:DYEM:3Q4D:DKLM:JOA4:RUSF:GAFR:DLPA:HOJP:W5FF:ULEE:7HZ3
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false

    If Docker is not installed, enter the commands:

    swupd bundle-add containers-basic
systemctl start docker

  3. Use os-install to download and install the bundles.

    swupd os-install --url https://cdn.download.clearlinux.org/update --statedir "$PWD"/swupd-state --no-boot-update -B os-core-update,editors,network-basic base

    The swupd example uses the following flags:

    • os-install tells swupd to download and install.

    • --url specifies the URL of the bundles repository.

    • --statedir specifies the state directory where downloaded bundles and any state information are stored.

    • --no-boot-update tells swupd to skip updating boot files because boot files are not required for a container.

    For more information on swupd flags, enter the swupd os-install -h command.

    Example output:

    swupd-client software verify 3.12.2
Copyright (C) 2012-2017 Intel Corporation

Verifying version 17870
Attempting to download version string to memory
Downloading packs...

Extracting python-basic pack for version 17820
  ...14%
Extracting perl-basic pack for version 17790
  ...28%
Extracting openssh-server pack for version 17660
  ...42%
Extracting editors pack for version 17850
  ...57%
Extracting network-basic pack for version 17650
  ...71%
Extracting os-core pack for version 17870
  ...85%
Extracting os-core-update pack for version 17870
  ...100%
Adding any missing files
  ...88%
Inspected 33982 files
  33974 files were missing
    33974 of 33974 missing files were replaced
    0 of 33974 missing files were not replaced
Calling post-update helper scripts.
WARNING: boot files update skipped due to --no-boot-update argument
Fix successful

    Note

    The WARNING message is expected and can be ignored.

  4. Create a tarball and compress it.

    tar -C base -cf base.tar .
xz -v -T0 base.tar

  5. Create the Dockerfile to build the image.

    cat > Dockerfile << EOF
FROM scratch
MAINTAINER First Last <first.last@example.com>
ADD base.tar.xz /
CMD ["/bin/bash"]
EOF

  6. Build the Clear Linux OS container image.

    docker build -t my-custom-clear-linux-container .

    Example output:

    Sending build context to Docker daemon  806.5MB
Step 1/4 : FROM scratch
  --->
Step 2/4 : MAINTAINER First Last <first.last@example.com>
  ---> Running in 7238f35abcd0
  ---> ec5064287c60
Removing intermediate container 7238f35abcd0
Step 3/4 : ADD base.tar.xz /
  ---> 2723b7d20716
Removing intermediate container 16e3ed0df8da
Step 4/4 : CMD /bin/bash
  ---> Running in efa893350647
  ---> 5414c3a12993
Removing intermediate container efa893350647
Successfully built 5414c3a12993
Successfully tagged my-custom-clear-linux-container:latest

  7. List the newly created Clear Linux OS container image.

    docker images

    Example output:

    REPOSITORY                        TAG                 IMAGE ID            CREATED              SIZE
my-custom-clear-linux-container   latest              5414c3a12993        About a minute ago   616MB

  8. Launch the built Clear Linux OS container.

    docker run -it my-custom-clear-linux-container

Manage bundles in a container

You can add and remove bundles from a Clear Linux OS container using the RUN swupd command in the Dockerfile.

Add a bundle

This example Dockerfile adds the pxe-server bundle to an existing Clear Linux OS Docker image:

cat > Dockerfile << EOF
FROM my-customer-clear-linux-container
MAINTAINER First Last <first.last@example.com>
RUN swupd bundle-add pxe-server
CMD ["/bin/bash/bash"]
EOF

Example output:

docker build -t my-clearlinux-with-pxe-server-bundle .

Sending build context to Docker daemon  806.5MB
Step 1/4 : FROM my-custom-clear-linux-container
 ---> 5414c3a12993
Step 2/4 : MAINTAINER First Last <first.last@example.com>
 ---> Running in 19b4411cf4bd
 ---> 08d400baffde
Removing intermediate container 19b4411cf4bd
Step 3/4 : RUN swupd bundle-add pxe-server
 ---> Running in 3e634d6e0792
swupd-client bundle adder 3.12.2
   Copyright (C) 2012-2017 Intel Corporation

Attempting to download version string to memory
Downloading packs...

Extracting pxe-server pack for version 17820
.
Installing bundle(s) files...
..............................................................................
..............................................................................
..............................................................................
..............................................................................
..............................................................................
..............................................................................
Calling post-update helper scripts.
WARNING: systemctl not operable, unable to run systemd update triggers
Bundle(s) installation done.
 ---> 8ead5f2c0c33
Removing intermediate container 3e634d6e0792
Step 4/4 : CMD /bin/bash
 ---> Running in 0ceae320279b
 ---> dcd9adb40611
Removing intermediate container 0ceae320279b
Successfully built dcd9adb40611
Successfully tagged my-clearlinux-with-pxe-server-bundle:latest

Note

The WARNING message can be ignored because systemd does not run inside a container.

Remove a bundle

This example Dockerfile removes the pxe-server bundle from an existing Clear Linux OS Docker image:

cat > Dockerfile << EOF
FROM my-clearlinux-with-pxe-server-bundle
MAINTAINER First Last <first.last@example.com>
RUN swupd bundle-remove pxe-server
CMD ["/bin/bash/bash"]
EOF

Example output:

docker build -t my-clearlinux-remove-pxe-server-bundle .

Sending build context to Docker daemon  806.5MB
Step 1/4 : FROM my-clearlinux-with-pxe-server-bundle
 ---> dcd9adb40611
Step 2/4 : MAINTAINER First Last <first.last@example.com>
 ---> Running in 71b60f15003e
 ---> 742192751c1a
Removing intermediate container 71b60f15003e
Step 3/4 : RUN swupd bundle-remove pxe-server
 ---> Running in ad28a3390ecc
swupd-client bundle remover 3.12.2
   Copyright (C) 2012-2017 Intel Corporation

Removing bundle: pxe-server
Deleting bundle files...
Total deleted files: 92
Untracking bundle from system...
Success: Bundle removed
1 bundle(s) were removed successfully
 ---> d6ee7903e14d
Removing intermediate container ad28a3390ecc
Step 4/4 : CMD /bin/bash
 ---> Running in 7694989e97de
 ---> ec23189ef954
Removing intermediate container 7694989e97de
Successfully built ec23189ef954
Successfully tagged my-clearlinux-remove-pxe-server-bundle:latest