systemd-rhel

systemd-rhel copied to clipboard

systemd System and Service Manager

DETAILS: http://0pointer.de/blog/projects/systemd.html

WEB SITE: http://www.freedesktop.org/wiki/Software/systemd

GIT: git://anongit.freedesktop.org/systemd/systemd ssh://git.freedesktop.org/git/systemd/systemd

GITWEB: http://cgit.freedesktop.org/systemd/systemd

MAILING LIST: http://lists.freedesktop.org/mailman/listinfo/systemd-devel http://lists.freedesktop.org/mailman/listinfo/systemd-commits

IRC: #systemd on irc.freenode.org

BUG REPORTS: https://bugs.freedesktop.org/enter_bug.cgi?product=systemd

AUTHOR: Lennart Poettering Kay Sievers ...and many others

LICENSE: LGPLv2.1+ for all code - except sd-readahead.[ch] which is MIT - except src/shared/MurmurHash2.c which is Public Domain - except src/shared/siphash24.c which is CC0 Public Domain - except src/journal/lookup3.c which is Public Domain - except src/udev/* which is (currently still) GPLv2, GPLv2+

REQUIREMENTS: Linux kernel >= 3.7 Linux kernel >= 3.8 for Smack support

    Kernel Config Options:
      CONFIG_DEVTMPFS
      CONFIG_CGROUPS (it is OK to disable all controllers)
      CONFIG_INOTIFY_USER
      CONFIG_SIGNALFD
      CONFIG_TIMERFD
      CONFIG_EPOLL
      CONFIG_NET
      CONFIG_SYSFS
      CONFIG_PROC_FS
      CONFIG_FHANDLE (libudev, mount and bind mount handling)

    udev will fail to work with the legacy sysfs layout:
      CONFIG_SYSFS_DEPRECATED=n

    Legacy hotplug slows down the system and confuses udev:
      CONFIG_UEVENT_HELPER_PATH=""

    Userspace firmware loading is not supported and should
    be disabled in the kernel:
      CONFIG_FW_LOADER_USER_HELPER=n

    Some udev rules and virtualization detection relies on it:
      CONFIG_DMIID

    Support for some SCSI devices serial number retrieval, to
    create additional symlinks in /dev/disk/ and /dev/tape:
      CONFIG_BLK_DEV_BSG

    Required for PrivateNetwork and PrivateDevices in service units:
      CONFIG_NET_NS
      CONFIG_DEVPTS_MULTIPLE_INSTANCES
    Note that systemd-localed.service and other systemd units use
    PrivateNetwork and PrivateDevices so this is effectively required.

    Optional but strongly recommended:
      CONFIG_IPV6
      CONFIG_AUTOFS4_FS
      CONFIG_TMPFS_XATTR
      CONFIG_{TMPFS,EXT4,XFS,BTRFS_FS,...}_POSIX_ACL
      CONFIG_SECCOMP

    Required for CPUShares in resource control unit settings
      CONFIG_CGROUP_SCHED
      CONFIG_FAIR_GROUP_SCHED

    Required for CPUQuota in resource control unit settings
      CONFIG_CFS_BANDWIDTH

    For systemd-bootchart, several proc debug interfaces are required:
      CONFIG_SCHEDSTATS
      CONFIG_SCHED_DEBUG

    For UEFI systems:
      CONFIG_EFIVAR_FS
      CONFIG_EFI_PARTITION

    Note that kernel auditing is broken when used with systemd's
    container code. When using systemd in conjunction with
    containers, please make sure to either turn off auditing at
    runtime using the kernel command line option "audit=0", or
    turn it off at kernel compile time using:
      CONFIG_AUDIT=n
    If systemd is compiled with libseccomp support on
    architectures which do not use socketcall() and where seccomp
    is supported (this effectively means x86-64 and ARM, but
    excludes 32-bit x86!), then nspawn will now install a
    work-around seccomp filter that makes containers boot even
    with audit being enabled. This works correctly only on kernels
    3.14 and newer though. TL;DR: turn audit off, still.

    glibc >= 2.14
    libcap
    libmount >= 2.20 (from util-linux)
    libseccomp >= 1.0.0 (optional)
    libblkid >= 2.20 (from util-linux) (optional)
    libkmod >= 15 (optional)
    PAM >= 1.1.2 (optional)
    libcryptsetup (optional)
    libaudit (optional)
    libacl (optional)
    libselinux (optional)
    liblzma (optional)
    liblz4 >= 119 (optional)
    libgcrypt (optional)
    libqrencode (optional)
    libmicrohttpd (optional)
    libpython (optional)
    libidn (optional)
    gobject-introspection > 1.40.0 (optional)
    elfutils >= 158 (optional)
    make, gcc, and similar tools

    During runtime, you need the following additional
    dependencies:

    util-linux >= v2.19 (requires fsck -l, agetty -s),
                  v2.21 required for tests in test/
    dbus >= 1.4.0 (strictly speaking optional, but recommended)
    dracut (optional)
    PolicyKit (optional)

    When building from git, you need the following additional
    dependencies:

    docbook-xsl
    xsltproc
    automake
    autoconf
    libtool
    intltool
    gperf
    gtkdocize (optional)
    python (optional)
    python-lxml (optional, but required to build the indices)
    sphinx (optional)

    When systemd-hostnamed is used, it is strongly recommended to
    install nss-myhostname to ensure that, in a world of
    dynamically changing hostnames, the hostname stays resolvable
    under all circumstances. In fact, systemd-hostnamed will warn
    if nss-myhostname is not installed.

    To build HTML documentation for python-systemd using sphinx,
    please first install systemd (using 'make install'), and then
    invoke sphinx-build with 'make sphinx-<target>', with <target>
    being 'html' or 'latexpdf'. If using DESTDIR for installation,
    pass the same DESTDIR to 'make sphinx-html' invocation.

USERS AND GROUPS: Default udev rules use the following standard system group names, which need to be resolvable by getgrnam() at any time, even in the very early boot stages, where no other databases and network are available:

    audio, cdrom, dialout, disk, input, kmem, lp, tape, tty, video

    During runtime, the journal daemon requires the
    "systemd-journal" system group to exist. New journal files will
    be readable by this group (but not writable), which may be used
    to grant specific users read access. In addition, system
    groups "wheel" and "adm" will be given read-only access to
    journal files using systemd-tmpfiles.service.

    The journal gateway daemon requires the
    "systemd-journal-gateway" system user and group to
    exist. During execution this network facing service will drop
    privileges and assume this uid/gid for security reasons.

    Similarly, the NTP daemon requires the "systemd-timesync" system
    user and group to exist.

    Similarly, the network management daemon requires the
    "systemd-network" system user and group to exist.

    Similarly, the name resolution daemon requires the
    "systemd-resolve" system user and group to exist.

NSS: systemd ships with three NSS modules:

    nss-myhostname resolves the local hostname to locally
    configured IP addresses, as well as "localhost" to
    127.0.0.1/::1.

    nss-resolve enables DNS resolution via the systemd-resolved
    DNS/LLMNR caching stub resolver "systemd-resolved".

    nss-mymachines enables resolution of all local containers
    registered with machined to their respective IP addresses.

    To make use of these NSS modules, please add them to the
    "hosts: " line in /etc/nsswitch.conf. The "resolve" module
    should replace the glibc "dns" module in this file.

    The three modules should be used in the following order:

            hosts: files mymachines resolve myhostname

WARNINGS: systemd will warn you during boot if /etc/mtab is not a symlink to /proc/mounts. Please ensure that /etc/mtab is a proper symlink.

    systemd will warn you during boot if /usr is on a different
    file system than /. While in systemd itself very little will
    break if /usr is on a separate partition, many of its
    dependencies very likely will break sooner or later in one
    form or another. For example, udev rules tend to refer to
    binaries in /usr, binaries that link to libraries in /usr or
    binaries that refer to data files in /usr. Since these
    breakages are not always directly visible, systemd will warn
    about this, since this kind of file system setup is not really
    supported anymore by the basic set of Linux OS components.

    systemd requires that the /run mount point exists. systemd also
    requires that /var/run is a a symlink to /run.

    For more information on this issue consult
    http://freedesktop.org/wiki/Software/systemd/separate-usr-is-broken

    To run systemd under valgrind, compile with VALGRIND defined
    (e.g. ./configure CPPFLAGS='... -DVALGRIND=1'). Otherwise,
    false positives will be triggered by code which violates
    some rules but is actually safe.

ENGINEERING AND CONSULTING SERVICES: ENDOCODE https://endocode.com/ offers professional engineering and consulting services for systemd. Please contact Chris Kühl [email protected] for more information.