1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
|
# Class for generation of overlayfs mount units
#
# It's often desired in Embedded System design to have a read-only rootfs.
# But a lot of different applications might want to have a read-write access to
# some parts of a filesystem. It can be especially useful when your update mechanism
# overwrites the whole rootfs, but you want your application data to be preserved
# between updates. This class provides a way to achieve that by means
# of overlayfs and at the same time keeping the base rootfs read-only.
#
# Usage example.
#
# Set a mount point for a partition overlayfs is going to use as upper layer
# in your machine configuration. Underlying file system can be anything that
# is supported by overlayfs. This has to be done in your machine configuration.
# QA check fails to catch file existence if you redefine this variable in your recipe!
#
# OVERLAYFS_MOUNT_POINT[data] ?= "/data"
#
# The class assumes you have a data.mount systemd unit defined in your
# systemd-machine-units recipe and installed to the image.
#
# Then you can specify writable directories on a recipe base
#
# OVERLAYFS_WRITABLE_PATHS[data] = "/usr/share/my-custom-application"
#
# To support several mount points you can use a different variable flag. Assume we
# want to have a writable location on the file system, but not interested where the data
# survive a reboot. Then we could have a mnt-overlay.mount unit for a tmpfs file system:
#
# OVERLAYFS_MOUNT_POINT[mnt-overlay] = "/mnt/overlay"
# OVERLAYFS_WRITABLE_PATHS[mnt-overlay] = "/usr/share/another-application"
#
# Note: the class does not support /etc directory itself, because systemd depends on it
REQUIRED_DISTRO_FEATURES += "systemd overlayfs"
inherit systemd features_check
python do_create_overlayfs_units() {
from oe.overlayfs import mountUnitName
CreateDirsUnitTemplate = """[Unit]
Description=Overlayfs directories setup
Requires={DATA_MOUNT_UNIT}
After={DATA_MOUNT_UNIT}
DefaultDependencies=no
[Service]
Type=oneshot
ExecStart=mkdir -p {DATA_MOUNT_POINT}/workdir{LOWERDIR} && mkdir -p {DATA_MOUNT_POINT}/upper{LOWERDIR}
RemainAfterExit=true
StandardOutput=journal
[Install]
WantedBy=multi-user.target
"""
MountUnitTemplate = """[Unit]
Description=Overlayfs mount unit
Requires={CREATE_DIRS_SERVICE}
After={CREATE_DIRS_SERVICE}
[Mount]
What=overlay
Where={LOWERDIR}
Type=overlay
Options=lowerdir={LOWERDIR},upperdir={DATA_MOUNT_POINT}/upper{LOWERDIR},workdir={DATA_MOUNT_POINT}/workdir{LOWERDIR}
[Install]
WantedBy=multi-user.target
"""
AllOverlaysTemplate = """[Unit]
Description=Groups all overlays required by {PN} in one unit
After={ALL_OVERLAYFS_UNITS}
Requires={ALL_OVERLAYFS_UNITS}
[Service]
Type=oneshot
ExecStart=/bin/true
RemainAfterExit=true
[Install]
WantedBy=local-fs.target
"""
def prepareUnits(data, lower):
from oe.overlayfs import helperUnitName
args = {
'DATA_MOUNT_POINT': data,
'DATA_MOUNT_UNIT': mountUnitName(data),
'CREATE_DIRS_SERVICE': helperUnitName(lower),
'LOWERDIR': lower,
}
bb.debug(1, "Generate systemd unit %s" % mountUnitName(lower))
with open(os.path.join(d.getVar('WORKDIR'), mountUnitName(lower)), 'w') as f:
f.write(MountUnitTemplate.format(**args))
bb.debug(1, "Generate helper systemd unit %s" % helperUnitName(lower))
with open(os.path.join(d.getVar('WORKDIR'), helperUnitName(lower)), 'w') as f:
f.write(CreateDirsUnitTemplate.format(**args))
def prepareGlobalUnit(dependentUnits):
from oe.overlayfs import allOverlaysUnitName
args = {
'ALL_OVERLAYFS_UNITS': " ".join(dependentUnits),
'PN': d.getVar('PN')
}
bb.debug(1, "Generate systemd unit with all overlays %s" % allOverlaysUnitName(d))
with open(os.path.join(d.getVar('WORKDIR'), allOverlaysUnitName(d)), 'w') as f:
f.write(AllOverlaysTemplate.format(**args))
mountUnitList = []
overlayMountPoints = d.getVarFlags("OVERLAYFS_MOUNT_POINT")
for mountPoint in overlayMountPoints:
bb.debug(1, "Process variable flag %s" % mountPoint)
for lower in d.getVarFlag('OVERLAYFS_WRITABLE_PATHS', mountPoint).split():
bb.debug(1, "Prepare mount unit for %s with data mount point %s" %
(lower, d.getVarFlag('OVERLAYFS_MOUNT_POINT', mountPoint)))
prepareUnits(d.getVarFlag('OVERLAYFS_MOUNT_POINT', mountPoint), lower)
mountUnitList.append(mountUnitName(lower))
# set up one unit, which depends on all mount units, so users can set
# only one dependency in their units to make sure software starts
# when all overlays are mounted
prepareGlobalUnit(mountUnitList)
}
# we need to generate file names early during parsing stage
python () {
from oe.overlayfs import strForBash, unitFileList
unitList = unitFileList(d)
for unit in unitList:
d.appendVar('SYSTEMD_SERVICE:' + d.getVar('PN'), ' ' + unit)
d.appendVar('FILES:' + d.getVar('PN'), ' ' + strForBash(unit))
d.setVar('OVERLAYFS_UNIT_LIST', ' '.join([strForBash(s) for s in unitList]))
}
do_install:append() {
install -d ${D}${systemd_system_unitdir}
for unit in ${OVERLAYFS_UNIT_LIST}; do
install -m 0444 ${WORKDIR}/${unit} ${D}${systemd_system_unitdir}
done
}
addtask create_overlayfs_units before do_install
|
