The prompt and variable name for the OCI "entrypoint arguments" are
somewhat incorrect. Indeed, they are in fact used to set the image
"command". Yet, using "command" would be confusing too, because the
interplay between entrypoint and command is tricky [0].
TL-DR; when both entrrypoint and command are set, command acts as
arguments passed to the entrypoint.
Additionally, we currently can only pass a single item as either
entrypoint or command. This precludes passing actual arguments to the
entrypoint, or passing multiple arguments as command.
For example:
BR2_TARGET_ROOTFS_OCI_ENTRYPOINT="/bin/tini -g -p SIGTERM --"
BR2_TARGET_ROOTFS_OCI_ENTRYPOINT_ARGS="/usr/bin/env sh"
generates an images with (only relevant fields are included below):
{
"config": {
"Entrypoint": [ "/bin/tini -g -p SIGTERM --" ],
"Cmd": [ "/usr/bin/env sh" ]
}
}
This is obviously incorrect, and not what one would expect:
{
"config": {
"Entrypoint": [ "/bin/tini", "-g", "-p", "SIGTERM", "--" ],
"Cmd": [ "/usr/bin/env", "sh" ]
}
}
However, some people do want to be able to pass an actual shell
scriptlet as a command, such as:
{
"config": {
"Entrypoint": [ "/bin/sh", "-c" ],
"Cmd": [ "my shell logic goes here" ]
}
}
Handling both is obviously conflicting: we can't both split-on-spaces
and not-split-on-spaces at the same time...
So, we fix that in two ways:
- make the current _OCI_ENTRYPOINT_ARGS a legacy option, and introduce
the new _OCI_CMD option with different semantics (see below) and an
appropriate prompt;
- we interpret both _OCI_ENTRYPOINT and _OCI_CMD as shell strings,
which we subject to the usual shell quoting [1] and token
recognition [2];
Since _OCI_ENTRYPOINT_ARGS used to be interpreted as a single string, we
can't easily change its meaning to be a space-separated list, as that
would break existing setups, which is the reason we make it legacy and
introduce a new option.
Ideally, we would like to default the new option _OCI_CMD to be the
quoted value of the previous _OCI_ENTRYPOINT_ARGS, but this is not
possible in Kconfig. Still, users that had a _OCI_ENTRYPOINT_ARGS set
will now get an early build error, and can still detect they need to do
something about it.
As for _OCI_ENTRYPOINT, it does not make much sense to support both cases.
Indeed, without splitting on spaces, we'd end up with an entrypoint that
would have a single item:
{
"config": {
"entrypoint: [ "some string with some spaces" ]
}
}
which in this case would try to execute the program which name is
actually "some string with some spaces", so we do not expect that
existing entrypoints are set with any space in them, and so the new
behaviour, unlike for _OCI_ENTRYPOINT_ARGS vs. _OCI_CMD, is compatible
with existing configurations, and so we do not need to make it a legacy
option and introduce a new one.
[0] https://docs.docker.com/engine/reference/builder/#understand-how-cmd-and-entrypoint-interact
[1] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_02
[2] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_03
Signed-off-by: Yann E. MORIN <yann.morin@orange.com>
Cc: Sergio Prado <sergio.prado@e-labworks.com>
Cc: Matthew Weber <matthew.weber@collins.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Add a dependency on BR2_PACKAGE_HOST_GO_TARGET_ARCH_SUPPORTS to avoid
the following build failure when GO_GOARCH is empty (e.g. on mips32)
which leads to an empty --arch argument in the sloci-image call, raised
since the addition of the package in commmit
ccda2f4bdc:
printf ' rm -rf /home/autobuild/autobuild/instance-6/output-1/images/rootfs-oci\n /home/autobuild/autobuild/instance-6/output-1/host/bin/sloci-image --arch --entrypoint "sh" --author "Buildroot" --user "0" /home/autobuild/autobuild/instance-6/output-1/build/buildroot-fs/oci/target /home/autobuild/autobuild/instance-6/output-1/images/rootfs-oci:latest\n' >> /home/autobuild/autobuild/instance-6/output-1/build/buildroot-fs/oci/fakeroot
chmod a+x /home/autobuild/autobuild/instance-6/output-1/build/buildroot-fs/oci/fakeroot
PATH="/home/autobuild/autobuild/instance-6/output-1/host/bin:/home/autobuild/autobuild/instance-6/output-1/host/sbin:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl" FAKEROOTDONTTRYCHOWN=1 /home/autobuild/autobuild/instance-6/output-1/host/bin/fakeroot -- /home/autobuild/autobuild/instance-6/output-1/build/buildroot-fs/oci/fakeroot
rootdir=/home/autobuild/autobuild/instance-6/output-1/build/buildroot-fs/oci/target
table='/home/autobuild/autobuild/instance-6/output-1/build/buildroot-fs/full_devices_table.txt'
Usage:
sloci-image [options] ROOTFS NAME[:TAG]
sloci-image [-h | -V]
Create a single-layer OCI image with the given rootfs.
Arguments:
ROOTFS Directory or tar.gz archive with rootfs to pack into the image.
Important: Archive will be *moved* to the image, so make a copy if you
need it. Directory will be preserved.
NAME Name of the image.
TAG Tag for the image. Defaults to "latest".
Options:
-m --arch ARCH CPU architecture which the binaries in this image are built to run on.
Defaults to $(uname -m).
--arch-variant Variant of the CPU. This is typically used only for arm (v6, v7, v8).
-a --author NAME Name and/or email address of the person which created the image.
-c --cmd CMD Default arguments to the entrypoint of the container.
--debug Print debug messages (it can be also enabled with env. variable DEBUG).
-C --entrypoint EP Arguments to use as the command to execute when the container starts.
-e --env VAR=VAL Default environment variables for container.
-l --label KEY=VALUE Metadata for the container compliant with OCI annotation rules.
If KEY starts with a dot, it will be prefixed with
"org.opencontainers.image" (e.g. .url -> org.opencontainers.image.url).
--os OS Name of the OS which the image is built to run on. Defaults to "linux".
-p --port PORT[/PROT] Default set of ports to expose from a container running this image in
format: <port>/tcp, <port>/udp, or <port> (same as <port>/tcp).
Aliases: --expose.
-t --tar Pack image in a TAR archive.
-u --user USER The username or UID of user the process run as.
-v --volume PATH Default set of directories describing where the process is likely write
data specific to a container instance.
-w --working-dir DIR Sets the current working directory of the entrypoint process in the
container.
-V --version Print version and exit.
-h --help Print this message and exit.
Please report bugs at <https://github.com/jirutka/sloci-image/issues>.
make: *** [fs/oci/oci.mk:99: /home/autobuild/autobuild/instance-6/output-1/images/rootfs.oci] Error 1
Fixes:
- http://autobuild.buildroot.org/results/44da17a393421dfcb8bbdd63074cb82b436dfa94
Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Add support to generate OCI (Open Container Initiative) images.
An OCI image consists of a manifest, an image index (optional), a set of
filesystem layers, and a configuration. The complete specification is
available in the link below:
https://github.com/opencontainers/image-spec/blob/master/spec.md
The image is generated with the host tool sloci-image, and config
options can be used to configure image parameters.
By default, the image is generated in a directory called rootfs-oci:
$ cd output/images
$ ls rootfs-oci/
blobs index.json oci-layout
Optionally, the image can be packed into a tar archive.
The image can be pushed to a registry using containers tools like
skopeo:
$ skopeo copy --dest-creds <user>:<pass> oci:rootfs-oci:<tag> \
docker://<user>/<image>[:tag]
And then we can pull/run the container image with tools like docker:
$ docker run -it <user>/<image>[:tag]
Signed-off-by: Sergio Prado <sergio.prado@e-labworks.com>
Signed-off-by: Matthew Weber <matthew.weber@collins.com>
[Arnout:
- mention in help text that options are space separated;
- use GO_GOARCH and GO_GOARM for architecture;
- quote all arguments;
- don't cd to BINARIES_DIR;
- remove ROOTFS_OCI_IMAGE_NAME variable;
- remove wildcard from rm.
]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Yann E. MORIN
Fabrice Fontaine
Sergio Prado