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This adds a systemd system container image which allows for the creation of 1 systemd system container image using local.conf variable(s), without the need to touch any recipe files. As described in the included README the use of an .inc file will allow users to create additional systemd system container images with only a few lines in a new image recipe file. Signed-off-by: Mark Asselstine <mark.asselstine@windriver.com>
86 lines
3.1 KiB
Plaintext
86 lines
3.1 KiB
Plaintext
c3-app-container
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The meta-cube layer comes with a single 'flexible' systemd system
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image called 'c3-systemd-container'. This image allows you to build a
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single systemd system container where you select the application(s)
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which the image will contain. Application selection(s) is made via
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local.conf, by setting 'C3_SYSTEMD_CONTAINER_APPS' to the name of the
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application.
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Configuration
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-------------------------
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How c3-systemd-container is configured is controlled by 3 variables
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which are intended to be defined in local.conf:
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* C3_SYSTEMD_CONTAINER_APPS - required - a space separated list of
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application(s) to included in the image. Usually this is one
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application such as 'apached2'.
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* C3_SYSTEMD_CONTAINER_ENABLE_SERVICES - optional - a space separated
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list of systemd services to enable. This is performed during
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do_rootfs(). This may not always be needed but some recipes default
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disabled (via 'SYSTEMD_AUTO_ENABLE_${PN} = "disable"') such as
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apache2. You can use other methods to overwrite this default, this
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variable just makes it easy.
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* C3_SYSTEMD_CONTAINER_DISABLE_SERVICES - optional - additional
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systemd services to disable, c3-systemd-container.inc defines a
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minimal set of services that shouldn't be run in a container. Like
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C3_SYSTEMD_CONTAINER_ENABLE_SERVICES this is performed during
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do_rootfs(). If you want to overwrite the minimal list you can
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assign 'SERVICES_TO_DISABLE_pn-c3-systemd-container' in local.conf.
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So for example you might define the following in your local.conf to
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build a systemd system container for apache2:
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C3_SYSTEMD_CONTAINER_APPS = "apache2"
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C3_SYSTEMD_CONTAINER_ENABLE_SERVICES = "apache2.service"
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Building
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-------------------------
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The image is built using the normal bitbake commands:
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%> bitbake c3-systemd-container
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The output will be found in the tmp/deploy/images/* directory
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alongside the other images.
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Usage
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-------------------------
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You can use the c3-systemd-container as an artifact to the cubeit
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installer but more likely you will install the image on a running
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system. This would be done by copying the image tarball to the target
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running OverC and then running the following commands on dom0 or in a
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container with bindings to dom0:
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# c3 add -n systemd-container c3-systemd-container-genericx86-64.tar.bz2
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# c3 start [options] systemd-container
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Image size
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-------------------------
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The image size will depend on your selected application. As with any
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image, bitbake will include any dependencies in the image (including
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those of systemd itself) and as such the size can easily grow. A small
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application with no/few dependencies will result in a image of about
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15 MB.
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Creating more than one app container
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-------------------------
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The use of the 'c3-systemd-container' and 'C3_SYSTEMD_CONTAINER_*' is
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restricted to one image/configuration. However, you may use the
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c3-systemd-container.inc in your own image recipe in a similar same
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way as c3-systemd-container_*.bb does. This will allow you to write
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your own systemd system container images in only a few lines, and, any
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improvements made to the c3-systemd-container.inc will immediately be
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available in your image.
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