[Buildroot] [PATCH 00/20] system: properly handle systemd as init system

[Yann E. MORIN <yann.morin.1998@free.fr>]

Hello All!

This series is a proposal to fix our handling of systemd as an init
system.

Our default skeleton is not well suited for systemd:

  - we have /var/log a symlink to /tmp/log, but the way systemd starts
    hides the journals:
    - start systemd-journald, stores journals in /tmp/log/ (because of
      the redirection above)
    - mounts a tmpfs over /tmp, thus hidding the journals.

  - on a read-only rootfs, systemd expects /var to be read-write, which
    we do not provide.

All of this sounds trivial, but fixing it is definitely not.

The overall idea is that we need different skeletons, one for each type
of init systems: sysv, systemd, others (aka custom).

The skeleton package becomes a virtual package, that is provided by one
of four implementations:

  - skeleton-sysv or skeleton-systemd, as their names imply, for either
    SysV- or systemd-based systems, and which depend on skeleton-common;

  - skeleton-common, that provides base files and directories comon to
    all skeletons (except custom, below); skeleton-common is also a
    provider for the skeleton virtual package, for use with no-init (aka
    custom init) systems;

  - skeleton-custom, for user-provided custom skeleton, and of which we
    expect it is fully prepared; skeleton-custom does not depend on
    skeleton-common.

A series of runtime tests have also been added, running on the QEMU
vexpress:

    init system         rootfs      DHCP?
    -------------------------------------
    busybox             ext4        no
    busybox             ext4        eth0
    busybox             squashfs    no
    busybox             squashfs    eth0
  * systemd-ifupdown    ext4        eth0
    systemd-ifupdown    squashfs    eth0
 ** systemd-networkd    ext4        eth0
    systemd-networkd    squashfs    eth0
*** systemd-full        ext4        eth0
    systemd-full        squashfs    eth0
  + no-init             squashfs    no

    *   systemd-networkd: only what gets selected automatically when
        systemd is used as init system, with all other options unset;

    **  systemd-ifupdown: like systemd-networkd, but with networkd
        disabled, thus using ifupdown instead;

    *** systemd-full: all systemd options enabled, implies networkd;

    +   a shell is launched as init

Those new tests are not exhaustive, especially the systemd one; instead,
they just test basic features: what init is being used, and did we get
an IP adress for eth0? More tests can be added later on.

Changes v2 -> v3:
  - too much to note, mostly rewriten from scratch

Changes v1 -> v2:
  - enhance the commit logs


Regards,
Yann E. MORIN.


The following changes since commit bc801efacb298e2297024f83e960eaf8a45dd39f

  python-coherence: bump to the latest upstream commit (2017-07-17 11:28:58 +0200)


are available in the git repository at:

  git://git.buildroot.org/~ymorin/git/buildroot.git

for you to fetch changes up to 95f6965c48dbf2f754818e2bec1f2d3891015475

  support/testing: add runtime testing for init systems (2017-07-18 18:59:05 +0200)


----------------------------------------------------------------
Yann E. MORIN (20):
      support/tests: allow properly indented config fragment
      core/pkg-generic: add variable to skip skeleton dependency
      package/skeleton: add macro to rsync skeleton directory
      package/skeleton: make SKELETON_LIB_SYMLINK a macro
      system: provide package-wide system variables and macros
      system: move setting getty to the corresponding init systems
      system: move remounting / to the corresponding init systems
      system: with no init system, only allow custom skeleton
      package/skeleton: drop dependency on host-mkpasswd
      package/skeleton: select it rather than default to y
      package/skeleton: split out into skeleton-custom
      package/skeleton: split out into skeleton-common
      package/skeleton: make it a virtual package
      package/skeleton-common: simplify staging install
      package/skeleton: introduce sysv- and systemd-specific skeletons
      system: separate sysv and systemd parts of the skeleton
      sytem: no-init systems may use our default, common skeleton
      fs: add pre- and post-command hooks
      system: make systemd work on a read-only rootfs
      support/testing: add runtime testing for init systems

 Makefile                                           |   1 +
 fs/common.mk                                       |   4 +
 package/Config.in                                  |   4 +
 package/busybox/busybox.mk                         |  15 +-
 package/pkg-generic.mk                             |  11 +-
 package/skeleton-common/Config.in                  |  31 ++++
 package/skeleton-common/skeleton-common.mk         |  92 +++++++++
 package/skeleton-custom/Config.in                  |   6 +
 package/skeleton-custom/skeleton-custom.mk         | 107 +++++++++++
 package/skeleton-systemd/Config.in                 |   7 +
 package/skeleton-systemd/skeleton-systemd.mk       |  71 +++++++
 package/skeleton-sysv/Config.in                    |   7 +
 package/skeleton-sysv/skeleton-sysv.mk             |  22 +++
 {system => package/skeleton-sysv}/skeleton/dev/log |   0
 .../skeleton-sysv}/skeleton/dev/pts/.empty         |   0
 .../skeleton-sysv}/skeleton/dev/shm/.empty         |   0
 .../skeleton-sysv}/skeleton/etc/fstab              |   0
 .../skeleton-sysv}/skeleton/var/cache              |   0
 .../skeleton-sysv}/skeleton/var/lib/misc           |   0
 .../skeleton-sysv}/skeleton/var/lock               |   0
 {system => package/skeleton-sysv}/skeleton/var/log |   0
 {system => package/skeleton-sysv}/skeleton/var/run |   0
 .../skeleton-sysv}/skeleton/var/spool              |   0
 {system => package/skeleton-sysv}/skeleton/var/tmp |   0
 package/skeleton/Config.in                         |   8 +-
 package/skeleton/skeleton.mk                       | 206 +--------------------
 package/sysvinit/sysvinit.mk                       |  11 ++
 support/testing/infra/builder.py                   |   3 +-
 .../testing/tests/init/__init__.py                 |   0
 support/testing/tests/init/base.py                 |  47 +++++
 support/testing/tests/init/test_busybox.py         |  67 +++++++
 support/testing/tests/init/test_none.py            |  32 ++++
 support/testing/tests/init/test_systemd.py         | 145 +++++++++++++++
 system/Config.in                                   |  13 +-
 system/skeleton/dev/{pts => }/.empty               |   0
 system/system.mk                                   |  88 +++++++++
 36 files changed, 787 insertions(+), 211 deletions(-)
 create mode 100644 package/skeleton-common/Config.in
 create mode 100644 package/skeleton-common/skeleton-common.mk
 create mode 100644 package/skeleton-custom/Config.in
 create mode 100644 package/skeleton-custom/skeleton-custom.mk
 create mode 100644 package/skeleton-systemd/Config.in
 create mode 100644 package/skeleton-systemd/skeleton-systemd.mk
 create mode 100644 package/skeleton-sysv/Config.in
 create mode 100644 package/skeleton-sysv/skeleton-sysv.mk
 rename {system => package/skeleton-sysv}/skeleton/dev/log (100%)
 copy {system => package/skeleton-sysv}/skeleton/dev/pts/.empty (100%)
 rename {system => package/skeleton-sysv}/skeleton/dev/shm/.empty (100%)
 rename {system => package/skeleton-sysv}/skeleton/etc/fstab (100%)
 rename {system => package/skeleton-sysv}/skeleton/var/cache (100%)
 rename {system => package/skeleton-sysv}/skeleton/var/lib/misc (100%)
 rename {system => package/skeleton-sysv}/skeleton/var/lock (100%)
 rename {system => package/skeleton-sysv}/skeleton/var/log (100%)
 rename {system => package/skeleton-sysv}/skeleton/var/run (100%)
 rename {system => package/skeleton-sysv}/skeleton/var/spool (100%)
 rename {system => package/skeleton-sysv}/skeleton/var/tmp (100%)
 copy system/skeleton/dev/pts/.empty => support/testing/tests/init/__init__.py (100%)
 create mode 100644 support/testing/tests/init/base.py
 create mode 100644 support/testing/tests/init/test_busybox.py
 create mode 100644 support/testing/tests/init/test_none.py
 create mode 100644 support/testing/tests/init/test_systemd.py
 rename system/skeleton/dev/{pts => }/.empty (100%)
 create mode 100644 system/system.mk

-- 
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| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
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