diff mbox series

[v3,2/3] fs: new OCI filesystem type

Message ID 20210827205430.39745-3-matthew.weber@collins.com
State Accepted
Headers show
Series Add support for OCI rootfs images | expand

Commit Message

Matthew Weber Aug. 27, 2021, 8:54 p.m. UTC 
From: Sergio Prado <sergio.prado@e-labworks.com>

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>
---
 fs/Config.in     |  1 +
 fs/oci/Config.in | 88 ++++++++++++++++++++++++++++++++++++++++++
 fs/oci/oci.mk    | 99 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 188 insertions(+)
 create mode 100644 fs/oci/Config.in
 create mode 100644 fs/oci/oci.mk

Comments

Arnout Vandecappelle Sept. 10, 2021, 7:08 p.m. UTC | #1 
On 27/08/2021 22:54, Matthew Weber via buildroot wrote:
> From: Sergio Prado <sergio.prado@e-labworks.com>
> 
> 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>

[snip]
> +
> +config BR2_TARGET_ROOTFS_OCI_ENTRYPOINT
> +	string "entrypoint"
> +	default "sh"
> +	help
> +	  Command to execute when the container starts.
> +
> +config BR2_TARGET_ROOTFS_OCI_ENTRYPOINT_ARGS
> +	string "entrypoint arguments"
> +	help
> +	  Default arguments to the entrypoint of the container.
> +
> +config BR2_TARGET_ROOTFS_OCI_WORKDIR
> +	string "working directory"
> +	help
> +	  Working directory of the entrypoint process in the
> +	  container.
> +
> +config BR2_TARGET_ROOTFS_OCI_UID
> +	string "username or UID"
> +	default "0"
> +	help
> +	  The username or UID of user the process run as.
> +
> +config BR2_TARGET_ROOTFS_OCI_ENV_VARS
> +	string "environment variables"
> +	help
> +	  Default environment variables for the container.

 I've added here that variable assignments are space separated.

> +
> +config BR2_TARGET_ROOTFS_OCI_PORTS
> +	string "ports"
> +	help
> +	  Default set of ports to expose from a container running
> +	  this image in the following format:
> +
> +	  <port>/tcp, <port>/udp, <port> (same as <port>/tcp).
> +
> +config BR2_TARGET_ROOTFS_OCI_LABELS
> +	string "labels"
> +	help
> +	  Metadata in the format KEY=VALUE 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).
> +
> +config BR2_TARGET_ROOTFS_OCI_ARCHIVE
> +	bool "pack oci image into a tar archive"
> +	default n

 default n is not needed.

> +	help
> +	  Select whether the image should be packed into a TAR archive.
> +
> +endif
> diff --git a/fs/oci/oci.mk b/fs/oci/oci.mk
> new file mode 100644
> index 0000000000..09c3e88069
> --- /dev/null
> +++ b/fs/oci/oci.mk
> @@ -0,0 +1,99 @@
> +################################################################################
> +#
> +# Build the oci image
> +#
> +################################################################################
> +
> +ROOTFS_OCI_IMAGE_NAME = rootfs-oci
> +
> +ROOTFS_OCI_DEPENDENCIES = host-sloci-image
> +
> +# architecture
> +OCI_SLOCI_IMAGE_OPTS = --arch $(BR2_ARCH)

 That's unlikely to be correct... For example, the typical 32-bit Intel target
is i686 in Buildroot, not 386 as expected by OCI.

 The specification says it has to correspond to GOARCH - and we have that, in
GO_GOARCH. So I replaced it with that.

 Ideally, the Config.in option should also depend on
BR2_PACKAGE_HOST_GO_TARGET_ARCH_SUPPORTS. Unfortunately, that symbol includes a
dependency on BR2_PACKAGE_HOST_GO_BOOTSTRAP_ARCH_SUPPORTS, which is not needed
here. I decided that no sane person would try to build an OCI image for an
architecture which doesn't support containers, so I left it as is.


> +# architecture variant (typically used only for arm)
> +ifeq ($(BR2_ARM_CPU_HAS_ARM),y)
> +ifeq ($(BR2_ARM_CPU_ARMV5),y)
> +OCI_SLOCI_IMAGE_OPTS += --arch-variant v5
> +else ifeq ($(BR2_ARM_CPU_ARMV6),y)
> +OCI_SLOCI_IMAGE_OPTS += --arch-variant v6
> +else ifeq ($(BR2_ARM_CPU_ARMV7A),y)
> +OCI_SLOCI_IMAGE_OPTS += --arch-variant v7
> +else ifeq ($(BR2_ARM_CPU_ARMV8A),y)
> +OCI_SLOCI_IMAGE_OPTS += --arch-variant v8

 Same here, I replaced all that with

OCI_SLOCI_IMAGE_OPTS += $(and $(GO_GOARM),--arch-variant $(GO_GOARM))

> +endif
> +endif
> +
> +# entrypoint
> +OCI_ENTRYPOINT = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_ENTRYPOINT))
> +ifneq ($(OCI_ENTRYPOINT),)
> +OCI_SLOCI_IMAGE_OPTS += --entrypoint $(OCI_ENTRYPOINT)

 For consistency, I've added quotes around all options. It's a string so it may
contain spaces.


> +endif
> +
> +# entrypoint arguments
> +OCI_ENTRYPOINT_ARGS = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_ENTRYPOINT_ARGS))
> +ifneq ($(OCI_ENTRYPOINT_ARGS),)
> +OCI_SLOCI_IMAGE_OPTS += --cmd "$(OCI_ENTRYPOINT_ARGS)"
> +endif
> +
> +# author
> +OCI_AUTHOR = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_AUTHOR))
> +ifneq ($(OCI_AUTHOR),)
> +OCI_SLOCI_IMAGE_OPTS += --author "$(OCI_AUTHOR)"
> +endif
> +
> +# username or UID
> +OCI_UID = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_UID))
> +ifneq ($(OCI_UID),)
> +OCI_SLOCI_IMAGE_OPTS += --user $(OCI_UID)
> +endif
> +
> +# labels
> +OCI_LABELS = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_LABELS))
> +ifneq ($(OCI_LABELS),)
> +OCI_SLOCI_IMAGE_OPTS += \
> +	$(foreach label,$(OCI_LABELS),--label $(label))
> +endif
> +
> +# environment variables
> +OCI_ENV_VARS = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_ENV_VARS))
> +ifneq ($(OCI_ENV_VARS),)
> +OCI_SLOCI_IMAGE_OPTS += \
> +	$(foreach var,$(OCI_ENV_VARS),--env $(var))
> +endif
> +
> +# working directory
> +OCI_WORKDIR = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_WORKDIR))
> +ifneq ($(OCI_WORKDIR),)
> +OCI_SLOCI_IMAGE_OPTS += --working-dir $(OCI_WORKDIR)
> +endif
> +
> +# ports
> +OCI_PORTS = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_PORTS))
> +ifneq ($(OCI_PORTS),)
> +OCI_SLOCI_IMAGE_OPTS += \
> +	$(foreach port,$(OCI_PORTS),--port $(port))
> +endif
> +
> +# tag
> +OCI_TAG = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_TAG))
> +ifeq ($(OCI_TAG),)
> +# we need a tag, so if it is empty, it is safe to override here
> +# check-package OverriddenVariable
> +OCI_TAG = latest
> +endif

 This can also be simplified to

OCI_TAG = $(or $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_TAG)),latest)

> +
> +# enable tar archive
> +ifeq ($(BR2_TARGET_ROOTFS_OCI_ARCHIVE),y)
> +OCI_SLOCI_IMAGE_OPTS += --tar
> +endif
> +
> +define ROOTFS_OCI_CMD
> +	(cd $(BINARIES_DIR); \
> +		rm -rf $(ROOTFS_OCI_IMAGE_NAME)*
> +		$(HOST_DIR)/bin/sloci-image $(OCI_SLOCI_IMAGE_OPTS) $(TARGET_DIR) \
> +			$(ROOTFS_OCI_IMAGE_NAME):$(OCI_TAG)
> +	)

 The iamge name is just a file name, so the cd is not needed. I just added
$(BINARIES_DIR)/ in front and get the same result.

 I've also removed the ROOTFS_OCI_IMAGE_NAME, it serves no purpose IMHO.

 And i've removed the wildcard after the rm -rf. Only the directory needs to be
removed; if there's a tarball, it will simply be overwritten.

 Applied to master with all those fixed.

 Regards,
 Arnout

> +endef
> +
> +$(eval $(rootfs))
>
Peter Korsgaard Sept. 11, 2021, 1:29 p.m. UTC | #2 
>>>>> "Matthew" == Matthew Weber via buildroot <buildroot@busybox.net> writes:

 > From: Sergio Prado <sergio.prado@e-labworks.com>
 > 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:

Out of interest, what is the functional difference between this and just
doing docker import output/build/rootfs.tar <my-tag>?
Arnout Vandecappelle Sept. 11, 2021, 3:03 p.m. UTC | #3 
On 11/09/2021 15:29, Peter Korsgaard wrote:
>>>>>> "Matthew" == Matthew Weber via buildroot <buildroot@busybox.net> writes:
> 
>  > From: Sergio Prado <sergio.prado@e-labworks.com>
>  > 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:
> 
> Out of interest, what is the functional difference between this and just
> doing docker import output/build/rootfs.tar <my-tag>?

 "import" just creates a filesystem. An OCI image also has an entrypoint, an
environment, exposed ports, and a bunch of metadata.

 Regards,
 Arnout
Peter Korsgaard Sept. 11, 2021, 3:46 p.m. UTC | #4 
>>>>> "Arnout" == Arnout Vandecappelle <arnout@mind.be> writes:

 > On 11/09/2021 15:29, Peter Korsgaard wrote:
 >>>>>>> "Matthew" == Matthew Weber via buildroot <buildroot@busybox.net> writes:
 >> 
 >> > From: Sergio Prado <sergio.prado@e-labworks.com>
 >> > 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:
 >> 
 >> Out of interest, what is the functional difference between this and just
 >> doing docker import output/build/rootfs.tar <my-tag>?

 >  "import" just creates a filesystem. An OCI image also has an entrypoint, an
 > environment, exposed ports, and a bunch of metadata.

Ok. I guess you can do most if not all of those with the --change option
to docker import though:

https://docs.docker.com/engine/reference/commandline/import/
diff mbox series

Patch

diff --git a/fs/Config.in b/fs/Config.in
index 37a2aa21f8..eee5e26bb2 100644
--- a/fs/Config.in
+++ b/fs/Config.in
@@ -11,6 +11,7 @@  source "fs/f2fs/Config.in"
 source "fs/initramfs/Config.in"
 source "fs/iso9660/Config.in"
 source "fs/jffs2/Config.in"
+source "fs/oci/Config.in"
 source "fs/romfs/Config.in"
 source "fs/squashfs/Config.in"
 source "fs/tar/Config.in"
diff --git a/fs/oci/Config.in b/fs/oci/Config.in
new file mode 100644
index 0000000000..dd7112ea8a
--- /dev/null
+++ b/fs/oci/Config.in
@@ -0,0 +1,88 @@ 
+config BR2_TARGET_ROOTFS_OCI
+	bool "oci image"
+	help
+	  Build an OCI (Open Container Initiative) image.
+
+	  By default, the image is generated in a directory called
+	  rootfs-oci:
+
+	  $ cd output/images
+	  $ ls rootfs-oci/
+	  blobs  index.json  oci-layout
+
+	  You can push the image to a registry. Example using skopeo:
+
+	  $ skopeo copy --dest-creds <user>:<pass> \
+	           oci:rootfs-oci:<tag> docker://<user>/<image>[:tag]
+
+	  And pull/run it with docker:
+
+	  $ docker run -it <user>/<image>[:tag]
+
+if BR2_TARGET_ROOTFS_OCI
+
+config BR2_TARGET_ROOTFS_OCI_AUTHOR
+	string "author name and/or email address"
+	default "Buildroot"
+	help
+	  Name and/or email address of the person which created the
+	  image.
+
+config BR2_TARGET_ROOTFS_OCI_TAG
+	string "image tag"
+	default "latest"
+	help
+	  Tag to be used in the container image. If empty, 'latest' will
+	  be used by default.
+
+config BR2_TARGET_ROOTFS_OCI_ENTRYPOINT
+	string "entrypoint"
+	default "sh"
+	help
+	  Command to execute when the container starts.
+
+config BR2_TARGET_ROOTFS_OCI_ENTRYPOINT_ARGS
+	string "entrypoint arguments"
+	help
+	  Default arguments to the entrypoint of the container.
+
+config BR2_TARGET_ROOTFS_OCI_WORKDIR
+	string "working directory"
+	help
+	  Working directory of the entrypoint process in the
+	  container.
+
+config BR2_TARGET_ROOTFS_OCI_UID
+	string "username or UID"
+	default "0"
+	help
+	  The username or UID of user the process run as.
+
+config BR2_TARGET_ROOTFS_OCI_ENV_VARS
+	string "environment variables"
+	help
+	  Default environment variables for the container.
+
+config BR2_TARGET_ROOTFS_OCI_PORTS
+	string "ports"
+	help
+	  Default set of ports to expose from a container running
+	  this image in the following format:
+
+	  <port>/tcp, <port>/udp, <port> (same as <port>/tcp).
+
+config BR2_TARGET_ROOTFS_OCI_LABELS
+	string "labels"
+	help
+	  Metadata in the format KEY=VALUE 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).
+
+config BR2_TARGET_ROOTFS_OCI_ARCHIVE
+	bool "pack oci image into a tar archive"
+	default n
+	help
+	  Select whether the image should be packed into a TAR archive.
+
+endif
diff --git a/fs/oci/oci.mk b/fs/oci/oci.mk
new file mode 100644
index 0000000000..09c3e88069
--- /dev/null
+++ b/fs/oci/oci.mk
@@ -0,0 +1,99 @@ 
+################################################################################
+#
+# Build the oci image
+#
+################################################################################
+
+ROOTFS_OCI_IMAGE_NAME = rootfs-oci
+
+ROOTFS_OCI_DEPENDENCIES = host-sloci-image
+
+# architecture
+OCI_SLOCI_IMAGE_OPTS = --arch $(BR2_ARCH)
+
+# architecture variant (typically used only for arm)
+ifeq ($(BR2_ARM_CPU_HAS_ARM),y)
+ifeq ($(BR2_ARM_CPU_ARMV5),y)
+OCI_SLOCI_IMAGE_OPTS += --arch-variant v5
+else ifeq ($(BR2_ARM_CPU_ARMV6),y)
+OCI_SLOCI_IMAGE_OPTS += --arch-variant v6
+else ifeq ($(BR2_ARM_CPU_ARMV7A),y)
+OCI_SLOCI_IMAGE_OPTS += --arch-variant v7
+else ifeq ($(BR2_ARM_CPU_ARMV8A),y)
+OCI_SLOCI_IMAGE_OPTS += --arch-variant v8
+endif
+endif
+
+# entrypoint
+OCI_ENTRYPOINT = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_ENTRYPOINT))
+ifneq ($(OCI_ENTRYPOINT),)
+OCI_SLOCI_IMAGE_OPTS += --entrypoint $(OCI_ENTRYPOINT)
+endif
+
+# entrypoint arguments
+OCI_ENTRYPOINT_ARGS = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_ENTRYPOINT_ARGS))
+ifneq ($(OCI_ENTRYPOINT_ARGS),)
+OCI_SLOCI_IMAGE_OPTS += --cmd "$(OCI_ENTRYPOINT_ARGS)"
+endif
+
+# author
+OCI_AUTHOR = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_AUTHOR))
+ifneq ($(OCI_AUTHOR),)
+OCI_SLOCI_IMAGE_OPTS += --author "$(OCI_AUTHOR)"
+endif
+
+# username or UID
+OCI_UID = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_UID))
+ifneq ($(OCI_UID),)
+OCI_SLOCI_IMAGE_OPTS += --user $(OCI_UID)
+endif
+
+# labels
+OCI_LABELS = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_LABELS))
+ifneq ($(OCI_LABELS),)
+OCI_SLOCI_IMAGE_OPTS += \
+	$(foreach label,$(OCI_LABELS),--label $(label))
+endif
+
+# environment variables
+OCI_ENV_VARS = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_ENV_VARS))
+ifneq ($(OCI_ENV_VARS),)
+OCI_SLOCI_IMAGE_OPTS += \
+	$(foreach var,$(OCI_ENV_VARS),--env $(var))
+endif
+
+# working directory
+OCI_WORKDIR = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_WORKDIR))
+ifneq ($(OCI_WORKDIR),)
+OCI_SLOCI_IMAGE_OPTS += --working-dir $(OCI_WORKDIR)
+endif
+
+# ports
+OCI_PORTS = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_PORTS))
+ifneq ($(OCI_PORTS),)
+OCI_SLOCI_IMAGE_OPTS += \
+	$(foreach port,$(OCI_PORTS),--port $(port))
+endif
+
+# tag
+OCI_TAG = $(call qstrip,$(BR2_TARGET_ROOTFS_OCI_TAG))
+ifeq ($(OCI_TAG),)
+# we need a tag, so if it is empty, it is safe to override here
+# check-package OverriddenVariable
+OCI_TAG = latest
+endif
+
+# enable tar archive
+ifeq ($(BR2_TARGET_ROOTFS_OCI_ARCHIVE),y)
+OCI_SLOCI_IMAGE_OPTS += --tar
+endif
+
+define ROOTFS_OCI_CMD
+	(cd $(BINARIES_DIR); \
+		rm -rf $(ROOTFS_OCI_IMAGE_NAME)*
+		$(HOST_DIR)/bin/sloci-image $(OCI_SLOCI_IMAGE_OPTS) $(TARGET_DIR) \
+			$(ROOTFS_OCI_IMAGE_NAME):$(OCI_TAG)
+	)
+endef
+
+$(eval $(rootfs))