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author | Vyacheslav Yurkov <uvv.mail@gmail.com> | 2021-12-10 14:01:39 +0100 |
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committer | Richard Purdie <richard.purdie@linuxfoundation.org> | 2021-12-12 11:27:20 +0000 |
commit | 610ea808c8b5edb2826bda1f1c42a811bd4ba758 (patch) | |
tree | f48d78da7c562d9bc69e8ace8c5b4fbde773ed00 | |
parent | f9a2b08c07ff1270d5b3e8d72d17b6d5fde5bf96 (diff) | |
download | openembedded-core-contrib-610ea808c8b5edb2826bda1f1c42a811bd4ba758.tar.gz |
overlayfs-etc: mount etc as overlayfs
This class provides an image feature that mounts /etc as an overlayfs
file system. This is an extension for existing overlayfs class, which
doesn't support /etc
Signed-off-by: Alfred Schapansky <alfred.schapansky@avantys.de>
Signed-off-by: Vyacheslav Yurkov <uvv.mail@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
-rw-r--r-- | meta/classes/overlayfs-etc.bbclass | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/meta/classes/overlayfs-etc.bbclass b/meta/classes/overlayfs-etc.bbclass new file mode 100644 index 0000000000..4ced07ba11 --- /dev/null +++ b/meta/classes/overlayfs-etc.bbclass @@ -0,0 +1,76 @@ +# Class for setting up /etc in overlayfs +# +# In order to have /etc directory in overlayfs a special handling at early boot stage is required +# The idea is to supply a custom init script that mounts /etc before launching actual init program, +# because the latter already requires /etc to be mounted +# +# The configuration must be machine specific. You should at least set these three variables: +# OVERLAYFS_ETC_MOUNT_POINT ?= "/data" +# OVERLAYFS_ETC_FSTYPE ?= "ext4" +# OVERLAYFS_ETC_DEVICE ?= "/dev/mmcblk0p2" +# +# To control more mount options you should consider setting mount options: +# OVERLAYFS_ETC_MOUNT_OPTIONS ?= "defaults" +# +# The class provides two options for /sbin/init generation +# 1. Default option is to rename original /sbin/init to /sbin/init.orig and place generated init under +# original name, i.e. /sbin/init. It has an advantage that you won't need to change any kernel +# parameters in order to make it work, but it poses a restriction that package-management can't +# be used, becaause updating init manager would remove generated script +# 2. If you are would like to keep original init as is, you can set +# OVERLAYFS_ETC_USE_ORIG_INIT_NAME = "0" +# Then generated init will be named /sbin/preinit and you would need to extend you kernel parameters +# manually in your bootloader configuration. +# +# Regardless which mode you choose, update and migration strategy of configuration files under /etc +# overlay is out of scope of this class + +ROOTFS_POSTPROCESS_COMMAND += '${@bb.utils.contains("IMAGE_FEATURES", "overlayfs-etc", "create_overlayfs_etc_preinit;", "", d)}' +IMAGE_FEATURES_CONFLICTS_overlayfs-etc = "package-management" + +OVERLAYFS_ETC_MOUNT_POINT ??= "" +OVERLAYFS_ETC_FSTYPE ??= "" +OVERLAYFS_ETC_DEVICE ??= "" +OVERLAYFS_ETC_USE_ORIG_INIT_NAME ??= "1" +OVERLAYFS_ETC_MOUNT_OPTIONS ??= "defaults" +OVERLAYFS_ETC_INIT_TEMPLATE ??= "${COREBASE}/meta/files/overlayfs-etc-preinit.sh.in" + +python create_overlayfs_etc_preinit() { + overlayEtcMountPoint = d.getVar("OVERLAYFS_ETC_MOUNT_POINT") + overlayEtcFsType = d.getVar("OVERLAYFS_ETC_FSTYPE") + overlayEtcDevice = d.getVar("OVERLAYFS_ETC_DEVICE") + + if not overlayEtcMountPoint: + bb.fatal("OVERLAYFS_ETC_MOUNT_POINT must be set in your MACHINE configuration") + if not overlayEtcDevice: + bb.fatal("OVERLAYFS_ETC_DEVICE must be set in your MACHINE configuration") + if not overlayEtcFsType: + bb.fatal("OVERLAYFS_ETC_FSTYPE should contain a valid file system type on {0}".format(overlayEtcDevice)) + + with open(d.getVar("OVERLAYFS_ETC_INIT_TEMPLATE"), "r") as f: + PreinitTemplate = f.read() + + useOrigInit = oe.types.boolean(d.getVar('OVERLAYFS_ETC_USE_ORIG_INIT_NAME')) + preinitPath = oe.path.join(d.getVar("IMAGE_ROOTFS"), d.getVar("base_sbindir"), "preinit") + initBaseName = oe.path.join(d.getVar("base_sbindir"), "init") + origInitNameSuffix = ".orig" + + args = { + 'OVERLAYFS_ETC_MOUNT_POINT': overlayEtcMountPoint, + 'OVERLAYFS_ETC_MOUNT_OPTIONS': d.getVar('OVERLAYFS_ETC_MOUNT_OPTIONS'), + 'OVERLAYFS_ETC_FSTYPE': overlayEtcFsType, + 'OVERLAYFS_ETC_DEVICE': overlayEtcDevice, + 'SBIN_INIT_NAME': initBaseName + origInitNameSuffix if useOrigInit else initBaseName + } + + if useOrigInit: + # rename original /sbin/init + origInit = oe.path.join(d.getVar("IMAGE_ROOTFS"), initBaseName) + bb.debug(1, "rootfs path %s, init path %s, test %s" % (d.getVar('IMAGE_ROOTFS'), origInit, d.getVar("IMAGE_ROOTFS"))) + bb.utils.rename(origInit, origInit + origInitNameSuffix) + preinitPath = origInit + + with open(preinitPath, 'w') as f: + f.write(PreinitTemplate.format(**args)) + os.chmod(preinitPath, 0o755) +} |