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Commit | Line | Data |
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d657c51f | 1 | systemd System and Service Manager |
31cee6f6 | 2 | |
31cee6f6 | 3 | WEB SITE: |
2777a4a3 | 4 | https://systemd.io |
31cee6f6 LP |
5 | |
6 | GIT: | |
eb0914fc | 7 | git@github.com:systemd/systemd.git |
eb0914fc | 8 | https://github.com/systemd/systemd |
31cee6f6 LP |
9 | |
10 | MAILING LIST: | |
19d9372b | 11 | https://lists.freedesktop.org/mailman/listinfo/systemd-devel |
31cee6f6 LP |
12 | |
13 | IRC: | |
fb906b00 | 14 | #systemd on irc.libera.chat |
31cee6f6 LP |
15 | |
16 | BUG REPORTS: | |
eb0914fc | 17 | https://github.com/systemd/systemd/issues |
31cee6f6 | 18 | |
2777a4a3 ZJS |
19 | OLDER DOCUMENTATION: |
20 | ||
21 | http://0pointer.de/blog/projects/systemd.html | |
22 | https://www.freedesktop.org/wiki/Software/systemd | |
23 | ||
31cee6f6 | 24 | AUTHOR: |
5430f7f2 LP |
25 | Lennart Poettering |
26 | Kay Sievers | |
27 | ...and many others | |
31cee6f6 | 28 | |
673eab9b | 29 | LICENSE: |
7fe57498 | 30 | LGPL-2.1-or-later for all code, exceptions noted in LICENSES/README.md |
673eab9b | 31 | |
31cee6f6 | 32 | REQUIREMENTS: |
dcce98a4 | 33 | Linux kernel >= 3.13 |
a0c3e16b | 34 | Linux kernel >= 4.2 for unified cgroup hierarchy support |
c3080258 JK |
35 | Linux kernel >= 4.10 for cgroup-bpf egress and ingress hooks |
36 | Linux kernel >= 4.15 for cgroup-bpf device hook | |
37 | Linux kernel >= 4.17 for cgroup-bpf socket address hooks | |
38 | Linux kernel >= 5.3 for bounded-loops in BPF program | |
c2923fdc | 39 | Linux kernel >= 5.4 for signed Verity images support |
ec31dd5a | 40 | Linux kernel >= 5.7 for BPF links and the BPF LSM hook |
23aedd02 KS |
41 | |
42 | Kernel Config Options: | |
713bc0cf | 43 | CONFIG_DEVTMPFS |
d28315e4 | 44 | CONFIG_CGROUPS (it is OK to disable all controllers) |
713bc0cf KS |
45 | CONFIG_INOTIFY_USER |
46 | CONFIG_SIGNALFD | |
47 | CONFIG_TIMERFD | |
48 | CONFIG_EPOLL | |
8d186a35 | 49 | CONFIG_UNIX (it requires CONFIG_NET, but every other flag in it is not necessary) |
713bc0cf | 50 | CONFIG_SYSFS |
06d461ee | 51 | CONFIG_PROC_FS |
5d31974e | 52 | CONFIG_FHANDLE (libudev, mount and bind mount handling) |
713bc0cf | 53 | |
9c7f7d86 MG |
54 | Kernel crypto/hash API |
55 | CONFIG_CRYPTO_USER_API_HASH | |
56 | CONFIG_CRYPTO_HMAC | |
57 | CONFIG_CRYPTO_SHA256 | |
58 | ||
be2ea723 | 59 | udev will fail to work with the legacy sysfs layout: |
f28cbd03 | 60 | CONFIG_SYSFS_DEPRECATED=n |
713bc0cf KS |
61 | |
62 | Legacy hotplug slows down the system and confuses udev: | |
63 | CONFIG_UEVENT_HELPER_PATH="" | |
64 | ||
be2ea723 KS |
65 | Userspace firmware loading is not supported and should |
66 | be disabled in the kernel: | |
713bc0cf KS |
67 | CONFIG_FW_LOADER_USER_HELPER=n |
68 | ||
69 | Some udev rules and virtualization detection relies on it: | |
70 | CONFIG_DMIID | |
71 | ||
a5c724b2 KS |
72 | Support for some SCSI devices serial number retrieval, to |
73 | create additional symlinks in /dev/disk/ and /dev/tape: | |
74 | CONFIG_BLK_DEV_BSG | |
75 | ||
45a582d5 | 76 | Required for PrivateNetwork= in service units: |
13468826 | 77 | CONFIG_NET_NS |
b52a4a3b | 78 | Note that systemd-localed.service and other systemd units use |
45a582d5 | 79 | PrivateNetwork so this is effectively required. |
13468826 | 80 | |
0ca48bb0 | 81 | Required for PrivateUsers= in service units: |
87fe1707 LW |
82 | CONFIG_USER_NS |
83 | ||
713bc0cf KS |
84 | Optional but strongly recommended: |
85 | CONFIG_IPV6 | |
0c651d32 | 86 | CONFIG_AUTOFS_FS |
713bc0cf | 87 | CONFIG_TMPFS_XATTR |
0ceced3d | 88 | CONFIG_{TMPFS,EXT4_FS,XFS,BTRFS_FS,...}_POSIX_ACL |
f28cbd03 | 89 | CONFIG_SECCOMP |
fd74fa79 | 90 | CONFIG_SECCOMP_FILTER (required for seccomp support) |
560ace5d | 91 | CONFIG_KCMP (for the kcmp() syscall, used to be under CONFIG_CHECKPOINT_RESTORE before ~5.12) |
713bc0cf | 92 | |
f4e74be1 | 93 | Required for CPUShares= in resource control unit settings |
a21b4670 UTL |
94 | CONFIG_CGROUP_SCHED |
95 | CONFIG_FAIR_GROUP_SCHED | |
96 | ||
f4e74be1 | 97 | Required for CPUQuota= in resource control unit settings |
0acd5a08 WC |
98 | CONFIG_CFS_BANDWIDTH |
99 | ||
c3080258 JK |
100 | Required for IPAddressDeny=, IPAddressAllow=, IPIngressFilterPath=, |
101 | IPEgressFilterPath= in resource control unit settings | |
b1b96380 | 102 | unit settings |
c3080258 JK |
103 | CONFIG_BPF |
104 | CONFIG_BPF_SYSCALL | |
105 | CONFIG_BPF_JIT | |
106 | CONFIG_HAVE_EBPF_JIT | |
107 | CONFIG_CGROUP_BPF | |
108 | ||
43689840 MV |
109 | Required for SocketBind{Allow|Deny}=, RestrictNetworkInterfaces= in |
110 | resource control unit settings | |
c3080258 JK |
111 | CONFIG_BPF |
112 | CONFIG_BPF_SYSCALL | |
113 | CONFIG_BPF_JIT | |
114 | CONFIG_HAVE_EBPF_JIT | |
b1b96380 AJ |
115 | CONFIG_CGROUP_BPF |
116 | ||
f28cbd03 | 117 | For UEFI systems: |
f33016ff | 118 | CONFIG_EFIVAR_FS |
f28cbd03 KS |
119 | CONFIG_EFI_PARTITION |
120 | ||
c2923fdc LB |
121 | Required for signed Verity images support: |
122 | CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG | |
123 | ||
ec31dd5a ILG |
124 | Required for RestrictFileSystems= in service units: |
125 | CONFIG_BPF | |
126 | CONFIG_BPF_SYSCALL | |
127 | CONFIG_BPF_LSM | |
128 | CONFIG_DEBUG_INFO_BTF | |
129 | CONFIG_LSM="...,bpf" or kernel booted with lsm="...,bpf". | |
130 | ||
f4e74be1 LP |
131 | We recommend to turn off Real-Time group scheduling in the |
132 | kernel when using systemd. RT group scheduling effectively | |
133 | makes RT scheduling unavailable for most userspace, since it | |
134 | requires explicit assignment of RT budgets to each unit whose | |
135 | processes making use of RT. As there's no sensible way to | |
136 | assign these budgets automatically this cannot really be | |
137 | fixed, and it's best to disable group scheduling hence. | |
138 | CONFIG_RT_GROUP_SCHED=n | |
139 | ||
f5a93d5d LP |
140 | It's a good idea to disable the implicit creation of networking bonding |
141 | devices by the kernel networking bonding module, so that the | |
142 | automatically created "bond0" interface doesn't conflict with any such | |
582faeb4 DJL |
143 | device created by systemd-networkd (or other tools). Ideally there |
144 | would be a kernel compile-time option for this, but there currently | |
145 | isn't. The next best thing is to make this change through a modprobe.d | |
146 | drop-in. This is shipped by default, see modprobe.d/systemd.conf. | |
f5a93d5d | 147 | |
45a582d5 AJ |
148 | Required for systemd-nspawn: |
149 | CONFIG_DEVPTS_MULTIPLE_INSTANCES or Linux kernel >= 4.7 | |
150 | ||
e7b3f1a6 AZ |
151 | Required for systemd-oomd: |
152 | CONFIG_PSI | |
153 | ||
77b6e194 LP |
154 | Note that kernel auditing is broken when used with systemd's |
155 | container code. When using systemd in conjunction with | |
19aadacf | 156 | containers, please make sure to either turn off auditing at |
77b6e194 LP |
157 | runtime using the kernel command line option "audit=0", or |
158 | turn it off at kernel compile time using: | |
159 | CONFIG_AUDIT=n | |
a7b1c397 LP |
160 | If systemd is compiled with libseccomp support on |
161 | architectures which do not use socketcall() and where seccomp | |
162 | is supported (this effectively means x86-64 and ARM, but | |
70a44afe | 163 | excludes 32-bit x86!), then nspawn will now install a |
a7b1c397 LP |
164 | work-around seccomp filter that makes containers boot even |
165 | with audit being enabled. This works correctly only on kernels | |
166 | 3.14 and newer though. TL;DR: turn audit off, still. | |
77b6e194 | 167 | |
3dd26f3e | 168 | glibc >= 2.16 |
3ede835a | 169 | libcap |
d6e80966 ZJS |
170 | libmount >= 2.30 (from util-linux) |
171 | (util-linux *must* be built without --enable-libmount-support-mtab) | |
6abfd303 | 172 | libseccomp >= 2.3.1 (optional) |
d47f6ca5 | 173 | libblkid >= 2.24 (from util-linux) (optional) |
a18535d9 | 174 | libkmod >= 15 (optional) |
3ede835a | 175 | PAM >= 1.1.2 (optional) |
c2923fdc | 176 | libcryptsetup (optional), >= 2.3.0 required for signed Verity images support |
3ede835a | 177 | libaudit (optional) |
19d5d4cb | 178 | libacl (optional) |
c3080258 | 179 | libbpf >= 0.2.0 (optional) |
baec7d78 | 180 | libfdisk >= 2.32 (from util-linux) (optional) |
3ede835a | 181 | libselinux (optional) |
19d5d4cb | 182 | liblzma (optional) |
e0a1d4b0 | 183 | liblz4 >= 1.3.0 / 130 (optional) |
ef5924aa | 184 | libzstd >= 1.4.0 (optional) |
7b17a7d7 LP |
185 | libgcrypt (optional) |
186 | libqrencode (optional) | |
187 | libmicrohttpd (optional) | |
2cc86f09 | 188 | libpython (optional) |
87057e24 | 189 | libidn2 or libidn (optional) |
38e053c5 | 190 | gnutls >= 3.1.4 (optional, >= 3.6.0 is required to support DNS-over-TLS with gnutls) |
096cbdce | 191 | openssl >= 1.1.0 (optional, required to support DNS-over-TLS with openssl) |
5b244719 | 192 | elfutils >= 158 (optional) |
d79a2f5f | 193 | polkit (optional) |
781748af | 194 | tzdata >= 2014f (optional) |
72cdb3e7 | 195 | pkg-config |
8f968c73 | 196 | gperf |
72cdb3e7 ZJS |
197 | docbook-xsl (optional, required for documentation) |
198 | xsltproc (optional, required for documentation) | |
e0698c66 | 199 | python-jinja2 |
72cdb3e7 | 200 | python-lxml (optional, required to build the indices) |
40f116f5 | 201 | python >= 3.5 |
48538c19 | 202 | meson >= 0.53.2 (>= 0.54.0 is required to build with 'meson compile') |
40f116f5 | 203 | ninja |
44ff8df7 | 204 | gcc, awk, sed, grep, and similar tools |
c3080258 JK |
205 | clang >= 10.0, llvm >= 10.0 (optional, required to build BPF programs |
206 | from source code in C) | |
53f69d67 | 207 | gnu-efi >= 3.0.5 (optional, required for systemd-boot) |
2cc86f09 | 208 | |
19aadacf JE |
209 | During runtime, you need the following additional |
210 | dependencies: | |
2cc86f09 | 211 | |
1d40ddbf | 212 | util-linux >= v2.27.1 required |
b895fa08 LP |
213 | dbus >= 1.4.0 (strictly speaking optional, but recommended) |
214 | NOTE: If using dbus < 1.9.18, you should override the default | |
215 | policy directory (--with-dbuspolicydir=/etc/dbus-1/system.d). | |
2cc86f09 | 216 | dracut (optional) |
d35f51ea | 217 | polkit (optional) |
3ede835a | 218 | |
3e609a8a | 219 | To build in directory build/: |
8b08be40 | 220 | meson setup build/ && meson compile -C build/ |
3e609a8a | 221 | |
5238e957 | 222 | Any configuration options can be specified as -Darg=value... arguments |
3e609a8a ZJS |
223 | to meson. After the build directory is initially configured, meson will |
224 | refuse to run again, and options must be changed with: | |
5adfb06d | 225 | meson configure -Darg=value build/ |
226 | meson configure without any arguments will print out available options and | |
3e609a8a ZJS |
227 | their current values. |
228 | ||
229 | Useful commands: | |
8b08be40 LP |
230 | meson compile -v -C build/ some/target |
231 | meson test -C build/ | |
232 | sudo meson install -C build/ | |
233 | DESTDIR=... meson install -C build/ | |
3e609a8a | 234 | |
72cdb3e7 | 235 | A tarball can be created with: |
82627069 KS |
236 | git archive --format=tar --prefix=systemd-222/ v222 | xz > systemd-222.tar.xz |
237 | ||
19aadacf JE |
238 | When systemd-hostnamed is used, it is strongly recommended to |
239 | install nss-myhostname to ensure that, in a world of | |
240 | dynamically changing hostnames, the hostname stays resolvable | |
fff2e5b5 | 241 | under all circumstances. In fact, systemd-hostnamed will warn |
bf9e477c | 242 | if nss-myhostname is not installed. |
fff2e5b5 | 243 | |
01c8938e LP |
244 | nss-systemd must be enabled on systemd systems, as that's required for |
245 | DynamicUser= to work. Note that we ship services out-of-the-box that | |
246 | make use of DynamicUser= now, hence enabling nss-systemd is not | |
247 | optional. | |
248 | ||
1815dfbb LP |
249 | Note that the build prefix for systemd must be /usr. (Moreover, |
250 | packages systemd relies on — such as D-Bus — really should use the same | |
251 | prefix, otherwise you are on your own.) -Dsplit-usr=false (which is the | |
9afd5e7b ZJS |
252 | default and does not need to be specified) is the recommended setting. |
253 | -Dsplit-usr=true can be used to give a semblance of support for systems | |
254 | with programs installed split between / and /usr. Moving everything | |
255 | under /usr is strongly encouraged. | |
01c8938e | 256 | |
a2fc3d87 ZJS |
257 | Additional packages are necessary to run some tests: |
258 | - busybox (used by test/TEST-13-NSPAWN-SMOKE) | |
259 | - nc (used by test/TEST-12-ISSUE-3171) | |
260 | - python3-pyparsing | |
261 | - python3-evdev (used by hwdb parsing tests) | |
262 | - strace (used by test/test-functions) | |
e94681ad | 263 | - capsh (optional, used by test-execute) |
a2fc3d87 | 264 | |
a24c64f0 | 265 | USERS AND GROUPS: |
37495eed LP |
266 | Default udev rules use the following standard system group |
267 | names, which need to be resolvable by getgrnam() at any time, | |
268 | even in the very early boot stages, where no other databases | |
269 | and network are available: | |
270 | ||
2422bd21 | 271 | audio, cdrom, dialout, disk, input, kmem, kvm, lp, render, tape, tty, video |
37c0e8f3 | 272 | |
19aadacf | 273 | During runtime, the journal daemon requires the |
1a9ce3f7 | 274 | "systemd-journal" system group to exist. New journal files will |
19aadacf | 275 | be readable by this group (but not writable), which may be used |
a48a62a1 ZJS |
276 | to grant specific users read access. In addition, system |
277 | groups "wheel" and "adm" will be given read-only access to | |
278 | journal files using systemd-tmpfiles.service. | |
a24c64f0 | 279 | |
f959c5c6 YW |
280 | The journal remote daemon requires the |
281 | "systemd-journal-remote" system user and group to | |
37495eed LP |
282 | exist. During execution this network facing service will drop |
283 | privileges and assume this uid/gid for security reasons. | |
284 | ||
8d0e0ddd | 285 | Similarly, the network management daemon requires the |
323a2f0b LP |
286 | "systemd-network" system user and group to exist. |
287 | ||
8d0e0ddd | 288 | Similarly, the name resolution daemon requires the |
323a2f0b LP |
289 | "systemd-resolve" system user and group to exist. |
290 | ||
888e378d LP |
291 | Similarly, the coredump support requires the |
292 | "systemd-coredump" system user and group to exist. | |
293 | ||
a4a79605 | 294 | NSS: |
409093fe | 295 | systemd ships with four glibc NSS modules: |
a4a79605 | 296 | |
38ccb557 LP |
297 | nss-myhostname resolves the local hostname to locally configured IP |
298 | addresses, as well as "localhost" to 127.0.0.1/::1. | |
a4a79605 | 299 | |
38ccb557 LP |
300 | nss-resolve enables DNS resolution via the systemd-resolved DNS/LLMNR |
301 | caching stub resolver "systemd-resolved". | |
a4a79605 | 302 | |
409093fe | 303 | nss-mymachines enables resolution of all local containers registered |
38ccb557 | 304 | with machined to their respective IP addresses. |
a4a79605 | 305 | |
38ccb557 | 306 | nss-systemd enables resolution of users/group registered via the |
1d10005b | 307 | User/Group Record Lookup API (https://systemd.io/USER_GROUP_API), |
38ccb557 LP |
308 | including all dynamically allocated service users. (See the |
309 | DynamicUser= setting in unit files.) | |
a4a79605 | 310 | |
409093fe LP |
311 | To make use of these NSS modules, please add them to the "hosts:", |
312 | "passwd:" and "group:" lines in /etc/nsswitch.conf. The "resolve" | |
313 | module should replace the glibc "dns" module in this file (and don't | |
314 | worry, it chain-loads the "dns" module if it can't talk to resolved). | |
a4a79605 | 315 | |
409093fe LP |
316 | The four modules should be used in the following order: |
317 | ||
38ccb557 LP |
318 | passwd: compat systemd |
319 | group: compat systemd | |
a42d4f57 | 320 | hosts: files mymachines resolve [!UNAVAIL=return] dns myhostname |
a4a79605 | 321 | |
0f0467e6 MP |
322 | SYSV INIT.D SCRIPTS: |
323 | When calling "systemctl enable/disable/is-enabled" on a unit which is a | |
324 | SysV init.d script, it calls /usr/lib/systemd/systemd-sysv-install; | |
325 | this needs to translate the action into the distribution specific | |
326 | mechanism such as chkconfig or update-rc.d. Packagers need to provide | |
327 | this script if you need this functionality (you don't if you disabled | |
328 | SysV init support). | |
329 | ||
330 | Please see src/systemctl/systemd-sysv-install.SKELETON for how this | |
331 | needs to look like, and provide an implementation at the marked places. | |
332 | ||
21bc923a | 333 | WARNINGS: |
9e93f6f0 LP |
334 | systemd will warn during early boot if /usr is not already mounted at |
335 | this point (that means: either located on the same file system as / or | |
336 | already mounted in the initrd). While in systemd itself very little | |
337 | will break if /usr is on a separate, late-mounted partition, many of | |
338 | its dependencies very likely will break sooner or later in one form or | |
339 | another. For example, udev rules tend to refer to binaries in /usr, | |
340 | binaries that link to libraries in /usr or binaries that refer to data | |
341 | files in /usr. Since these breakages are not always directly visible, | |
342 | systemd will warn about this, since this kind of file system setup is | |
343 | not really supported anymore by the basic set of Linux OS components. | |
fc7a744c | 344 | |
47bc23c1 | 345 | systemd requires that the /run mount point exists. systemd also |
8f42ccd2 | 346 | requires that /var/run is a symlink to /run. |
47bc23c1 | 347 | |
aa167132 | 348 | For more information on this issue consult |
c6749ba5 | 349 | https://www.freedesktop.org/wiki/Software/systemd/separate-usr-is-broken |
aa167132 | 350 | |
d18cb393 ZJS |
351 | To run systemd under valgrind, compile with meson option |
352 | -Dvalgrind=true and have valgrind development headers installed | |
353 | (i.e. valgrind-devel or equivalent). Otherwise, false positives will be | |
354 | triggered by code which violates some rules but is actually safe. Note | |
355 | that valgrind generates nice output only on exit(), hence on shutdown | |
356 | we don't execve() systemd-shutdown. | |
2b671e95 | 357 | |
ba9e3fc4 | 358 | STABLE BRANCHES AND BACKPORTS: |
bfeb370a LP |
359 | Stable branches with backported patches are available in the |
360 | systemd-stable repo at https://github.com/systemd/systemd-stable. | |
361 | ||
362 | Stable branches are started for certain releases of systemd and named | |
363 | after them, e.g. v238-stable. Stable branches are managed by | |
364 | distribution maintainers on an as needed basis. See | |
365 | https://www.freedesktop.org/wiki/Software/systemd/Backports/ for some | |
366 | more information and examples. |