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d657c51f | 1 | systemd System and Service Manager |
31cee6f6 LP |
2 | |
3 | DETAILS: | |
4 | http://0pointer.de/blog/projects/systemd.html | |
5 | ||
6 | WEB SITE: | |
19d9372b | 7 | https://www.freedesktop.org/wiki/Software/systemd |
31cee6f6 LP |
8 | |
9 | GIT: | |
eb0914fc | 10 | git@github.com:systemd/systemd.git |
eb0914fc | 11 | https://github.com/systemd/systemd |
31cee6f6 LP |
12 | |
13 | MAILING LIST: | |
19d9372b | 14 | https://lists.freedesktop.org/mailman/listinfo/systemd-devel |
31cee6f6 LP |
15 | |
16 | IRC: | |
17 | #systemd on irc.freenode.org | |
18 | ||
19 | BUG REPORTS: | |
eb0914fc | 20 | https://github.com/systemd/systemd/issues |
31cee6f6 LP |
21 | |
22 | AUTHOR: | |
5430f7f2 LP |
23 | Lennart Poettering |
24 | Kay Sievers | |
25 | ...and many others | |
31cee6f6 | 26 | |
673eab9b | 27 | LICENSE: |
5430f7f2 | 28 | LGPLv2.1+ for all code |
a095315b KS |
29 | - except src/basic/MurmurHash2.c which is Public Domain |
30 | - except src/basic/siphash24.c which is CC0 Public Domain | |
85424725 KS |
31 | - except src/journal/lookup3.c which is Public Domain |
32 | - except src/udev/* which is (currently still) GPLv2, GPLv2+ | |
0490b440 | 33 | - except tools/chromiumos/* which is BSD-style |
673eab9b | 34 | |
31cee6f6 | 35 | REQUIREMENTS: |
dcce98a4 | 36 | Linux kernel >= 3.13 |
a0c3e16b | 37 | Linux kernel >= 4.2 for unified cgroup hierarchy support |
c2923fdc | 38 | Linux kernel >= 5.4 for signed Verity images support |
23aedd02 KS |
39 | |
40 | Kernel Config Options: | |
713bc0cf | 41 | CONFIG_DEVTMPFS |
d28315e4 | 42 | CONFIG_CGROUPS (it is OK to disable all controllers) |
713bc0cf KS |
43 | CONFIG_INOTIFY_USER |
44 | CONFIG_SIGNALFD | |
45 | CONFIG_TIMERFD | |
46 | CONFIG_EPOLL | |
41938693 | 47 | CONFIG_NET |
713bc0cf | 48 | CONFIG_SYSFS |
06d461ee | 49 | CONFIG_PROC_FS |
5d31974e | 50 | CONFIG_FHANDLE (libudev, mount and bind mount handling) |
713bc0cf | 51 | |
9c7f7d86 MG |
52 | Kernel crypto/hash API |
53 | CONFIG_CRYPTO_USER_API_HASH | |
54 | CONFIG_CRYPTO_HMAC | |
55 | CONFIG_CRYPTO_SHA256 | |
56 | ||
be2ea723 | 57 | udev will fail to work with the legacy sysfs layout: |
f28cbd03 | 58 | CONFIG_SYSFS_DEPRECATED=n |
713bc0cf KS |
59 | |
60 | Legacy hotplug slows down the system and confuses udev: | |
61 | CONFIG_UEVENT_HELPER_PATH="" | |
62 | ||
be2ea723 KS |
63 | Userspace firmware loading is not supported and should |
64 | be disabled in the kernel: | |
713bc0cf KS |
65 | CONFIG_FW_LOADER_USER_HELPER=n |
66 | ||
67 | Some udev rules and virtualization detection relies on it: | |
68 | CONFIG_DMIID | |
69 | ||
a5c724b2 KS |
70 | Support for some SCSI devices serial number retrieval, to |
71 | create additional symlinks in /dev/disk/ and /dev/tape: | |
72 | CONFIG_BLK_DEV_BSG | |
73 | ||
45a582d5 | 74 | Required for PrivateNetwork= in service units: |
13468826 | 75 | CONFIG_NET_NS |
b52a4a3b | 76 | Note that systemd-localed.service and other systemd units use |
45a582d5 | 77 | PrivateNetwork so this is effectively required. |
13468826 | 78 | |
0ca48bb0 | 79 | Required for PrivateUsers= in service units: |
87fe1707 LW |
80 | CONFIG_USER_NS |
81 | ||
713bc0cf KS |
82 | Optional but strongly recommended: |
83 | CONFIG_IPV6 | |
84 | CONFIG_AUTOFS4_FS | |
713bc0cf | 85 | CONFIG_TMPFS_XATTR |
0ceced3d | 86 | CONFIG_{TMPFS,EXT4_FS,XFS,BTRFS_FS,...}_POSIX_ACL |
f28cbd03 | 87 | CONFIG_SECCOMP |
fd74fa79 | 88 | CONFIG_SECCOMP_FILTER (required for seccomp support) |
3b920d78 | 89 | CONFIG_CHECKPOINT_RESTORE (for the kcmp() syscall) |
713bc0cf | 90 | |
f4e74be1 | 91 | Required for CPUShares= in resource control unit settings |
a21b4670 UTL |
92 | CONFIG_CGROUP_SCHED |
93 | CONFIG_FAIR_GROUP_SCHED | |
94 | ||
f4e74be1 | 95 | Required for CPUQuota= in resource control unit settings |
0acd5a08 WC |
96 | CONFIG_CFS_BANDWIDTH |
97 | ||
b1b96380 AJ |
98 | Required for IPAddressDeny= and IPAddressAllow= in resource control |
99 | unit settings | |
100 | CONFIG_CGROUP_BPF | |
101 | ||
f28cbd03 | 102 | For UEFI systems: |
f33016ff | 103 | CONFIG_EFIVAR_FS |
f28cbd03 KS |
104 | CONFIG_EFI_PARTITION |
105 | ||
c2923fdc LB |
106 | Required for signed Verity images support: |
107 | CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG | |
108 | ||
f4e74be1 LP |
109 | We recommend to turn off Real-Time group scheduling in the |
110 | kernel when using systemd. RT group scheduling effectively | |
111 | makes RT scheduling unavailable for most userspace, since it | |
112 | requires explicit assignment of RT budgets to each unit whose | |
113 | processes making use of RT. As there's no sensible way to | |
114 | assign these budgets automatically this cannot really be | |
115 | fixed, and it's best to disable group scheduling hence. | |
116 | CONFIG_RT_GROUP_SCHED=n | |
117 | ||
f5a93d5d LP |
118 | It's a good idea to disable the implicit creation of networking bonding |
119 | devices by the kernel networking bonding module, so that the | |
120 | automatically created "bond0" interface doesn't conflict with any such | |
582faeb4 DJL |
121 | device created by systemd-networkd (or other tools). Ideally there |
122 | would be a kernel compile-time option for this, but there currently | |
123 | isn't. The next best thing is to make this change through a modprobe.d | |
124 | drop-in. This is shipped by default, see modprobe.d/systemd.conf. | |
f5a93d5d | 125 | |
45a582d5 AJ |
126 | Required for systemd-nspawn: |
127 | CONFIG_DEVPTS_MULTIPLE_INSTANCES or Linux kernel >= 4.7 | |
128 | ||
77b6e194 LP |
129 | Note that kernel auditing is broken when used with systemd's |
130 | container code. When using systemd in conjunction with | |
19aadacf | 131 | containers, please make sure to either turn off auditing at |
77b6e194 LP |
132 | runtime using the kernel command line option "audit=0", or |
133 | turn it off at kernel compile time using: | |
134 | CONFIG_AUDIT=n | |
a7b1c397 LP |
135 | If systemd is compiled with libseccomp support on |
136 | architectures which do not use socketcall() and where seccomp | |
137 | is supported (this effectively means x86-64 and ARM, but | |
70a44afe | 138 | excludes 32-bit x86!), then nspawn will now install a |
a7b1c397 LP |
139 | work-around seccomp filter that makes containers boot even |
140 | with audit being enabled. This works correctly only on kernels | |
141 | 3.14 and newer though. TL;DR: turn audit off, still. | |
77b6e194 | 142 | |
3dd26f3e | 143 | glibc >= 2.16 |
3ede835a | 144 | libcap |
d6e80966 ZJS |
145 | libmount >= 2.30 (from util-linux) |
146 | (util-linux *must* be built without --enable-libmount-support-mtab) | |
6abfd303 | 147 | libseccomp >= 2.3.1 (optional) |
d47f6ca5 | 148 | libblkid >= 2.24 (from util-linux) (optional) |
a18535d9 | 149 | libkmod >= 15 (optional) |
3ede835a | 150 | PAM >= 1.1.2 (optional) |
c2923fdc | 151 | libcryptsetup (optional), >= 2.3.0 required for signed Verity images support |
3ede835a | 152 | libaudit (optional) |
19d5d4cb | 153 | libacl (optional) |
e71f5585 | 154 | libfdisk >= 2.33 (from util-linux) (optional) |
3ede835a | 155 | libselinux (optional) |
19d5d4cb | 156 | liblzma (optional) |
e0a1d4b0 | 157 | liblz4 >= 1.3.0 / 130 (optional) |
ef5924aa | 158 | libzstd >= 1.4.0 (optional) |
7b17a7d7 LP |
159 | libgcrypt (optional) |
160 | libqrencode (optional) | |
161 | libmicrohttpd (optional) | |
2cc86f09 | 162 | libpython (optional) |
87057e24 | 163 | libidn2 or libidn (optional) |
38e053c5 | 164 | gnutls >= 3.1.4 (optional, >= 3.6.0 is required to support DNS-over-TLS with gnutls) |
096cbdce | 165 | openssl >= 1.1.0 (optional, required to support DNS-over-TLS with openssl) |
5b244719 | 166 | elfutils >= 158 (optional) |
d79a2f5f | 167 | polkit (optional) |
781748af | 168 | tzdata >= 2014f (optional) |
72cdb3e7 | 169 | pkg-config |
8f968c73 | 170 | gperf |
72cdb3e7 ZJS |
171 | docbook-xsl (optional, required for documentation) |
172 | xsltproc (optional, required for documentation) | |
173 | python-lxml (optional, required to build the indices) | |
40f116f5 YW |
174 | python >= 3.5 |
175 | meson >= 0.46 (>= 0.49 is required to build position-independent executables) | |
176 | ninja | |
72cdb3e7 | 177 | gcc, awk, sed, grep, m4, and similar tools |
2cc86f09 | 178 | |
19aadacf JE |
179 | During runtime, you need the following additional |
180 | dependencies: | |
2cc86f09 | 181 | |
1d40ddbf | 182 | util-linux >= v2.27.1 required |
b895fa08 LP |
183 | dbus >= 1.4.0 (strictly speaking optional, but recommended) |
184 | NOTE: If using dbus < 1.9.18, you should override the default | |
185 | policy directory (--with-dbuspolicydir=/etc/dbus-1/system.d). | |
2cc86f09 | 186 | dracut (optional) |
d35f51ea | 187 | polkit (optional) |
3ede835a | 188 | |
3e609a8a ZJS |
189 | To build in directory build/: |
190 | meson build/ && ninja -C build | |
191 | ||
5238e957 | 192 | Any configuration options can be specified as -Darg=value... arguments |
3e609a8a ZJS |
193 | to meson. After the build directory is initially configured, meson will |
194 | refuse to run again, and options must be changed with: | |
195 | mesonconf -Darg=value... | |
196 | mesonconf without any arguments will print out available options and | |
197 | their current values. | |
198 | ||
199 | Useful commands: | |
200 | ninja -v some/target | |
201 | ninja test | |
202 | sudo ninja install | |
203 | DESTDIR=... ninja install | |
204 | ||
72cdb3e7 | 205 | A tarball can be created with: |
82627069 KS |
206 | git archive --format=tar --prefix=systemd-222/ v222 | xz > systemd-222.tar.xz |
207 | ||
19aadacf JE |
208 | When systemd-hostnamed is used, it is strongly recommended to |
209 | install nss-myhostname to ensure that, in a world of | |
210 | dynamically changing hostnames, the hostname stays resolvable | |
fff2e5b5 | 211 | under all circumstances. In fact, systemd-hostnamed will warn |
bf9e477c | 212 | if nss-myhostname is not installed. |
fff2e5b5 | 213 | |
01c8938e LP |
214 | nss-systemd must be enabled on systemd systems, as that's required for |
215 | DynamicUser= to work. Note that we ship services out-of-the-box that | |
216 | make use of DynamicUser= now, hence enabling nss-systemd is not | |
217 | optional. | |
218 | ||
1815dfbb LP |
219 | Note that the build prefix for systemd must be /usr. (Moreover, |
220 | packages systemd relies on — such as D-Bus — really should use the same | |
221 | prefix, otherwise you are on your own.) -Dsplit-usr=false (which is the | |
222 | default and does not need to be specified) is the recommended setting, | |
223 | and -Dsplit-usr=true should be used on systems which have /usr on a | |
224 | separate partition. | |
01c8938e | 225 | |
a2fc3d87 ZJS |
226 | Additional packages are necessary to run some tests: |
227 | - busybox (used by test/TEST-13-NSPAWN-SMOKE) | |
228 | - nc (used by test/TEST-12-ISSUE-3171) | |
229 | - python3-pyparsing | |
230 | - python3-evdev (used by hwdb parsing tests) | |
231 | - strace (used by test/test-functions) | |
e94681ad | 232 | - capsh (optional, used by test-execute) |
a2fc3d87 | 233 | |
a24c64f0 | 234 | USERS AND GROUPS: |
37495eed LP |
235 | Default udev rules use the following standard system group |
236 | names, which need to be resolvable by getgrnam() at any time, | |
237 | even in the very early boot stages, where no other databases | |
238 | and network are available: | |
239 | ||
2422bd21 | 240 | audio, cdrom, dialout, disk, input, kmem, kvm, lp, render, tape, tty, video |
37c0e8f3 | 241 | |
19aadacf | 242 | During runtime, the journal daemon requires the |
1a9ce3f7 | 243 | "systemd-journal" system group to exist. New journal files will |
19aadacf | 244 | be readable by this group (but not writable), which may be used |
a48a62a1 ZJS |
245 | to grant specific users read access. In addition, system |
246 | groups "wheel" and "adm" will be given read-only access to | |
247 | journal files using systemd-tmpfiles.service. | |
a24c64f0 | 248 | |
f959c5c6 YW |
249 | The journal remote daemon requires the |
250 | "systemd-journal-remote" system user and group to | |
37495eed LP |
251 | exist. During execution this network facing service will drop |
252 | privileges and assume this uid/gid for security reasons. | |
253 | ||
8d0e0ddd | 254 | Similarly, the network management daemon requires the |
323a2f0b LP |
255 | "systemd-network" system user and group to exist. |
256 | ||
8d0e0ddd | 257 | Similarly, the name resolution daemon requires the |
323a2f0b LP |
258 | "systemd-resolve" system user and group to exist. |
259 | ||
888e378d LP |
260 | Similarly, the coredump support requires the |
261 | "systemd-coredump" system user and group to exist. | |
262 | ||
a4a79605 | 263 | NSS: |
409093fe | 264 | systemd ships with four glibc NSS modules: |
a4a79605 | 265 | |
38ccb557 LP |
266 | nss-myhostname resolves the local hostname to locally configured IP |
267 | addresses, as well as "localhost" to 127.0.0.1/::1. | |
a4a79605 | 268 | |
38ccb557 LP |
269 | nss-resolve enables DNS resolution via the systemd-resolved DNS/LLMNR |
270 | caching stub resolver "systemd-resolved". | |
a4a79605 | 271 | |
409093fe | 272 | nss-mymachines enables resolution of all local containers registered |
38ccb557 | 273 | with machined to their respective IP addresses. |
a4a79605 | 274 | |
38ccb557 LP |
275 | nss-systemd enables resolution of users/group registered via the |
276 | User/Group Record Lookup API (https://systemd.io/USER_GROUP_API/), | |
277 | including all dynamically allocated service users. (See the | |
278 | DynamicUser= setting in unit files.) | |
a4a79605 | 279 | |
409093fe LP |
280 | To make use of these NSS modules, please add them to the "hosts:", |
281 | "passwd:" and "group:" lines in /etc/nsswitch.conf. The "resolve" | |
282 | module should replace the glibc "dns" module in this file (and don't | |
283 | worry, it chain-loads the "dns" module if it can't talk to resolved). | |
a4a79605 | 284 | |
409093fe LP |
285 | The four modules should be used in the following order: |
286 | ||
38ccb557 LP |
287 | passwd: compat systemd |
288 | group: compat systemd | |
a42d4f57 | 289 | hosts: files mymachines resolve [!UNAVAIL=return] dns myhostname |
a4a79605 | 290 | |
0f0467e6 MP |
291 | SYSV INIT.D SCRIPTS: |
292 | When calling "systemctl enable/disable/is-enabled" on a unit which is a | |
293 | SysV init.d script, it calls /usr/lib/systemd/systemd-sysv-install; | |
294 | this needs to translate the action into the distribution specific | |
295 | mechanism such as chkconfig or update-rc.d. Packagers need to provide | |
296 | this script if you need this functionality (you don't if you disabled | |
297 | SysV init support). | |
298 | ||
299 | Please see src/systemctl/systemd-sysv-install.SKELETON for how this | |
300 | needs to look like, and provide an implementation at the marked places. | |
301 | ||
21bc923a | 302 | WARNINGS: |
9e93f6f0 LP |
303 | systemd will warn during early boot if /usr is not already mounted at |
304 | this point (that means: either located on the same file system as / or | |
305 | already mounted in the initrd). While in systemd itself very little | |
306 | will break if /usr is on a separate, late-mounted partition, many of | |
307 | its dependencies very likely will break sooner or later in one form or | |
308 | another. For example, udev rules tend to refer to binaries in /usr, | |
309 | binaries that link to libraries in /usr or binaries that refer to data | |
310 | files in /usr. Since these breakages are not always directly visible, | |
311 | systemd will warn about this, since this kind of file system setup is | |
312 | not really supported anymore by the basic set of Linux OS components. | |
fc7a744c | 313 | |
47bc23c1 | 314 | systemd requires that the /run mount point exists. systemd also |
8f42ccd2 | 315 | requires that /var/run is a symlink to /run. |
47bc23c1 | 316 | |
aa167132 | 317 | For more information on this issue consult |
c6749ba5 | 318 | https://www.freedesktop.org/wiki/Software/systemd/separate-usr-is-broken |
aa167132 | 319 | |
d18cb393 ZJS |
320 | To run systemd under valgrind, compile with meson option |
321 | -Dvalgrind=true and have valgrind development headers installed | |
322 | (i.e. valgrind-devel or equivalent). Otherwise, false positives will be | |
323 | triggered by code which violates some rules but is actually safe. Note | |
324 | that valgrind generates nice output only on exit(), hence on shutdown | |
325 | we don't execve() systemd-shutdown. | |
2b671e95 | 326 | |
ba9e3fc4 | 327 | STABLE BRANCHES AND BACKPORTS: |
bfeb370a LP |
328 | Stable branches with backported patches are available in the |
329 | systemd-stable repo at https://github.com/systemd/systemd-stable. | |
330 | ||
331 | Stable branches are started for certain releases of systemd and named | |
332 | after them, e.g. v238-stable. Stable branches are managed by | |
333 | distribution maintainers on an as needed basis. See | |
334 | https://www.freedesktop.org/wiki/Software/systemd/Backports/ for some | |
335 | more information and examples. | |
94ac201a | 336 | |
ada64a0c LP |
337 | ENGINEERING AND CONSULTING SERVICES: |
338 | Kinvolk (https://kinvolk.io) offers professional engineering | |
339 | and consulting services for systemd. Please contact Chris Kühl | |
340 | <chris@kinvolk.io> for more information. |