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Enhance docs rendering; update documentation

Enhanced rendering of docs, expanded introductory section.

Documented `perm` module, alphabetically sorted documenation for
modules, replaced dead recorded demo links with new links,
documented apt package blacklisting capability.

Change-Id: Ifd889efe73287c13d839ab40b1a78ffa357fd00e
changes/44/638144/18
Roman Gorshunov 3 years ago
parent
commit
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  2. 42
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  3. 390
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@ -52,6 +52,7 @@ ChangeLog
*~
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# Files created by releasenotes build
releasenotes/build

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README.rst

@ -1,22 +1,52 @@
==========
Divingbell
==========
|Doc Status|
Introduction
============
Divingbell is a lightweight solution for:
1. Bare metal configuration management for a few very targeted use cases
2. Bare metal package manager orchestration
1. Bare metal configuration management for a few very targeted use
cases via the following modules:
- *apparmor*
- *ethtool*
- *exec* (run arbitrary scripts)
- system *limits*
- *mounts*
- permissions (*perm*)
- *sysctl* values
- basic user account management (*uamlite*)
2. Bare metal package manager orchestration using *apt* module
What problems does it solve?
----------------------------
The needs identified for Divingbell were:
1. To plug gaps in day 1 tools (e.g., Drydock) for node configuration
1. To plug gaps in day 1 tools (e.g., `Drydock`_) for node configuration
2. To provide a day 2 solution for managing these configurations going forward
3. [Future] To provide a day 2 solution for system level host patching
.. include-marker
Documentation
-------------
=============
Find more documentation for Divingbell on `Read the Docs`_.
Further Reading
===============
`Airship`_.
Find more documentation for Divingbell on
`Read the Docs <https://airship-divingbell.readthedocs.io/>`_.
.. |Doc Status| image:: https://readthedocs.org/projects/airship-divingbell/badge/?version=latest
:target: https://airship-divingbell.readthedocs.io/
:alt: Documentation Status
.. _Read the Docs: https://airship-divingbell.readthedocs.io
.. _Drydock: https://airship-drydock.readthedocs.io
.. _Airship: https://www.airshipit.org

390
doc/source/index.rst

@ -14,139 +14,96 @@
License for the specific language governing permissions and limitations
under the License.
Divingbell
==========
Divingbell is a lightweight solution for:
1. Bare metal configuration management for a few very targeted use cases
2. Bare metal package manager orchestration
What problems does it solve?
----------------------------
The needs identified for Divingbell were:
1. To plug gaps in day 1 tools (e.g., Drydock) for node configuration
2. To provide a day 2 solution for managing these configurations going forward
3. [Future] To provide a day 2 solution for system level host patching
.. include:: ../../README.rst
:end-before: include-marker
Design and Implementation
-------------------------
=========================
Divingbell daemonsets run as privileged containers which mount the host
Divingbell DaemonSets run as privileged containers which mount the host
filesystem and chroot into that filesystem to enforce configuration and package
state. (The `diving bell <http://bit.ly/2hSXlai>`_ analogue can be thought of as something that descends
into the deeps to facilitate work done down below the surface.)
state, or executes scripts in a namespace of ``systemd`` (PID=1). (The
`diving bell <http://bit.ly/2hSXlai>`_ analogue can be thought of as something
that descends into the deeps to facilitate work done down below the surface).
We use the daemonset construct as a way of getting a copy of each pod on every
We use the DaemonSet construct as a way of getting a copy of each pod on every
node, but the work done by this chart's pods behaves like an event-driven job.
In practice this means that the chart internals run once on pod startup,
followed by an infinite sleep such that the pods always report a "Running"
status that k8s recognizes as the healthy (expected) result for a daemonset.
status that k8s recognizes as the healthy (expected) result for a DaemonSet.
In order to keep configuration as isolated as possible from other systems that
manage common files like /etc/fstab and /etc/sysctl.conf, Divingbell daemonsets
manage all of their configuration in separate files (e.g. by writing unique
files to /etc/sysctl.d or defining unique Systemd units) to avoid potential
conflicts. Another example is limit management, Divingbell daemonset writes
separate files to /etc/security/limits.d.
manage common files like ``/etc/fstab`` and ``/etc/sysctl.conf``, Divingbell
DaemonSets manage all of their configuration in separate files (e.g. by writing
unique files to ``/etc/sysctl.d`` or defining unique Systemd units) to avoid
potential conflicts. Another example is ``limits`` management, where Divingbell
DaemonSets write separate files to ``/etc/security/limits.d``.
To maximize robustness and utility, the daemonsets in this chart are made to be
To maximize robustness and utility, the DaemonSets in this chart are made to be
idempotent. In addition, they are designed to implicitly restore the original
system state after previously defined states are undefined. (e.g., removing a
previously defined mount from the yaml manifest, with no record of the original
mount in the updated manifest).
Lifecycle management
--------------------
====================
This chart's daemonsets will be spawned by Armada. They run in an event-driven
fashion: the idempotent automation for each daemonset will only re-run when
This chart's DaemonSets will be spawned by `Armada`_. They run in an event-driven
fashion: the idempotent automation for each DaemonSet only re-runs when
Armada spawns/respawns the container, or if information relevant to the host
changes in the configmap.
Daemonset configs
-----------------
sysctl
^^^^^^
DaemonSet configs
=================
Used to manage host level sysctl tunables. Ex::
conf:
sysctl:
net/ipv4/ip_forward: 1
net/ipv6/conf/all/forwarding: 1
limits
^^^^^^
Used to manage host level limits. Ex::
conf:
limits:
nofile:
domain: 'root'
type: 'soft'
item: 'nofile'
value: '101'
core_dump:
domain: '0:'
type: 'hard'
item: 'core'
value: 0
Previous values of newly set limits are backed up to /var/divingbell/limits
mounts
^^^^^^
apparmor
--------
used to manage host level mounts (outside of those in /etc/fstab). Ex::
Used to manage host level apparmor profiles/rules. Ex.::
conf:
mounts:
mnt:
mnt_tgt: /mnt
device: tmpfs
type: tmpfs
options: 'defaults,noatime,nosuid,nodev,noexec,mode=1777,size=1024M'
ethtool
^^^^^^^
Used to manage host level NIC tunables. Ex::
apparmor:
complain_mode: "true"
profiles:
profile-1: |
#include <tunables/global>
/usr/sbin/profile-1 {
#include <abstractions/apache2-common>
#include <abstractions/base>
#include <abstractions/nis>
conf:
ethtool:
ens3:
tx-tcp-segmentation: off
tx-checksum-ip-generic: on
capability dac_override,
capability dac_read_search,
capability net_bind_service,
capability setgid,
capability setuid,
uamlite
^^^^^^^
/data/www/safe/* r,
deny /data/www/unsafe/* r,
}
profile-2: |
#include <tunables/global>
/usr/sbin/profile-2 {
#include <abstractions/apache2-common>
#include <abstractions/base>
#include <abstractions/nis>
Used to manage host level local user accounts, their SSH keys, and their sudo
access. Ex::
capability dac_override,
capability dac_read_search,
capability net_bind_service,
capability setgid,
capability setuid,
conf:
uamlite:
purge_expired_users: false
users:
- user_name: testuser
user_crypt_passwd: $6$...
user_sudo: true
user_sshkeys:
- ssh-rsa AAAAB3N... key1-comment
- ssh-rsa AAAAVY6... key2-comment
/data/www/safe/* r,
deny /data/www/unsafe/* r,
}
apt
^^^
---
``apt`` daemonset does package management. It is able to install a package of
``apt`` DaemonSet does package management. It is able to install a package of
a specific version (or upgrade an existing one to requested version). Version
is optional, and if not provided the latest available package is installed.
is optional, and if not provided, the latest available package is installed.
It can also remove packages that were previously installed by divingbell (it is
done by excluding the packages you want to remove from the configuration).
Here is an example configuration for it::
@ -158,7 +115,15 @@ Here is an example configuration for it::
version: <VERSION1>
- name: <PACKAGE2>
It is also possible to provide debconf settings for packages the following
There is a possibility to blacklist packages, e.g. ``telnetd`` and ``nis``::
conf:
apt:
blacklistpkgs:
- name: telnetd
- name: nis
It is also possible to provide ``debconf`` settings for packages the following
way::
conf:
@ -170,10 +135,21 @@ way::
question_type: boolean
answer: false
ethtool
-------
Used to manage host level NIC tunables. Ex.::
conf:
ethtool:
ens3:
tx-tcp-segmentation: off
tx-checksum-ip-generic: on
exec
^^^^
----
Used to execute scripts on nodes, ex::
Used to execute scripts on nodes in ``systemd`` (PID=1) namespace, for ex.::
exec:
002-script2.sh:
@ -195,112 +171,146 @@ Used to execute scripts on nodes, ex::
echo env: $env1 $env2 $env3
Scripts are executed in alphanumeric order with the key names used. Therefore
in this example, 001-script1.sh runs first, followed by 002-script2.sh.
in this example, ``001-script1.sh`` runs first, followed by ``002-script2.sh``.
Targeting of directives to specific nodes by hostname or node label is
achievable by use of the overrides capability described below.
achievable by the use of the overrides capability described below.
The following set of options are fully implemeneted::
The following set of options is fully implemeneted:
``rerun_policy`` may be optionally set to ``always``, ``never``, or
- ``rerun_policy`` may optionally be set to ``always``, ``never``, or
``once_successfully`` for a given script. That script would always be rerun,
never be rerun, or rerun until the first successful execution respectively.
Default value is ``always``. This is tracked via a hash of the dict object
for the script (i.e. script name, script data, script args, script env, etc).
If any of that info changes, so will the hash, and it will be seen as a new
object which will be executed regardless of this setting.
``script_timeout`` may optionally be set to the number of seconds to wait for
- ``script_timeout`` may optionally be set to the number of seconds to wait for
script completion before termination. Default value is ``1800`` (30 min).
``rerun_interval`` may be optionally set to the number of seconds to wait
- ``rerun_interval`` may optionally be set to the number of seconds to wait
between rerunning a given script which ran successfully the previous time.
Default value is ``infinite``.
``retry_interval`` may be optionally set to the number of seconds to wait
- ``retry_interval`` may optionally be set to the number of seconds to wait
between rerunning a given script which did not run successfully the previous
time. Default behavior is to match the ``rerun_interval``.
The following set of options are partially implemeneted::
The following set of options is partially implemeneted:
``blocking_policy`` may optionally be set to ``background``, ``foreground``,
- ``blocking_policy`` may optionally be set to ``background``, ``foreground``,
or ``foreground_halt_pod_on_failure`` for a given script. This may be used to
run a script in the background (running in parallel, i.e. non-blocking) or
in the foreground (blocking). In either case, a failure of the script does
not cause a failure (crashloop) of the pod. The third option may be used
not cause a failure (CrashLoop) of the pod. The third option may be used
where the reverse behavior is desired (i.e., it would not proceed with
running the next script in the sequence until the current script ran
successfully). ``background`` option is not yet implemeneted. Default value
Deafult value is ``foreground``.
is ``foreground``.
The following set of options are not yet implemeneted::
The following set of options is not yet implemeneted:
``rerun_interval_persist`` may be optionally set to ``false`` for a given
- ``rerun_interval_persist`` may optionally be set to ``false`` for a given
script. This makes the script execute on pod/node startup regardless of the
interval since the last successful execution. Default value is ``true``.
``rerun_max_count`` may be optionally set to the maximum number of times a
- ``rerun_max_count`` may optionally be set to the maximum number of times a
succeeding script should be retried. Successful exec count does not persist
through pod/node restart. Default value is ``infinite``.
``retry_interval_persist`` may be optionally set to ``false`` for a given
- ``retry_interval_persist`` may optionally be set to ``false`` for a given
script. This makes the script execute on pod/node startup, regardless of the
time since the last execution. Default value is ``true``.
``retry_max_count`` may be optionally set to the maximum number of times a
- ``retry_max_count`` may optionally be set to the maximum number of times a
failing script should be retried. Failed exec count does not persist
through pod/node restart. Default value is ``infinite``.
apparmor
^^^^^^^^
limits
------
Used to manage host level apparmor profiles/rules, Ex::
Used to manage host level limits. Ex.::
conf:
limits:
nofile:
domain: 'root'
type: 'soft'
item: 'nofile'
value: '101'
core_dump:
domain: '0:'
type: 'hard'
item: 'core'
value: 0
Previous values of newly set limits are backed up to ``/var/divingbell/limits``.
mounts
------
Used to manage host level mounts (outside of those in ``/etc/fstab``). Ex.::
conf:
apparmor:
complain_mode: "true"
profiles:
profile-1: |
#include <tunables/global>
/usr/sbin/profile-1 {
#include <abstractions/apache2-common>
#include <abstractions/base>
#include <abstractions/nis>
mounts:
mnt:
mnt_tgt: /mnt
device: tmpfs
type: tmpfs
options: 'defaults,noatime,nosuid,nodev,noexec,mode=1777,size=1024M'
capability dac_override,
capability dac_read_search,
capability net_bind_service,
capability setgid,
capability setuid,
perm
----
/data/www/safe/* r,
deny /data/www/unsafe/* r,
}
profile-2: |
#include <tunables/global>
/usr/sbin/profile-2 {
#include <abstractions/apache2-common>
#include <abstractions/base>
#include <abstractions/nis>
Used to manage permissions. Ex.::
capability dac_override,
capability dac_read_search,
capability net_bind_service,
capability setgid,
capability setuid,
conf:
perms:
-
path: '/etc/shadow'
owner: 'root'
group: 'shadow'
permissions: '0640'
-
path: '/etc/passwd'
owner: 'root'
group: 'root'
permissions: '0644'
Module supports ``rerun_policy`` and ``rerun_interval`` options (like in
``exec`` module). Previous values of newly set permissions are backed up to
``/var/divingbell/perm``.
/data/www/safe/* r,
deny /data/www/unsafe/* r,
}
sysctl
------
Used to manage host level sysctl tunables. Ex.::
conf:
sysctl:
net/ipv4/ip_forward: 1
net/ipv6/conf/all/forwarding: 1
uamlite
-------
Used to manage host level local user accounts, their SSH keys, and their sudo
access. Ex.::
conf:
uamlite:
purge_expired_users: false
users:
- user_name: testuser
user_crypt_passwd: $6$...
user_sudo: true
user_sshkeys:
- ssh-rsa AAAAB3N... key1-comment
- ssh-rsa AAAAVY6... key2-comment
Operations
----------
==========
Setting apparmor profiles
^^^^^^^^^^^^^^^^^^^^^^^^^
-------------------------
The way apparmor loading/unloading implemented is through saving
settings to a file and than running ``apparmor_parser`` command.
The daemonset supports both enforcement and complain mode,
The DaemonSet supports both enforcement and complain mode,
enforcement being the default. To request complain mode for the
profiles, add ``complain_mode: "true"`` nested under apparmor entry.
@ -330,7 +340,7 @@ net_bind_service), but not both. Such problems are hard to debug, so
caution needed while setting configs up.
Setting user passwords
^^^^^^^^^^^^^^^^^^^^^^
----------------------
Including ``user_crypt_passwd`` to set a user password is optional.
@ -352,7 +362,7 @@ network access is unavailable, console username/password access will be the only
login option.
Setting user sudo
^^^^^^^^^^^^^^^^^
-----------------
Including ``user_sudo`` to set user sudo access is optional. The default value
is ``false``.
@ -361,7 +371,7 @@ At least one user must be defined with sudo access in order for the built-in
``ubuntu`` account to be disabled.
SSH keys
^^^^^^^^
--------
Including ``user_sshkeys`` for defining one or more user SSH keys is optional.
@ -380,7 +390,7 @@ At least one user must be defined with an SSH key and sudo in order for the
built-in ``ubuntu`` account to be disabled.
Purging expired users
^^^^^^^^^^^^^^^^^^^^^
---------------------
Including the ``purge_expired_users`` key-value pair is optional. The default
value is ``false``.
@ -392,23 +402,23 @@ maintain UID consistency (in the event the same accounts gets re-added later,
they regain access to their home directory files without UID mismatching).
Node specific configurations
----------------------------
============================
Although we expect these daemonsets to run indiscriminately on all nodes in the
Although we expect these DaemonSets to run indiscriminately on all nodes in the
infrastructure, we also expect that different nodes will need to be given a
different set of data depending on the node role/function. This chart supports
establishing value overrides for nodes with specific label value pairs and for
targeting nodes with specific hostnames. The overridden configuration is merged
with the normal config data, with the override data taking precedence.
The chart will then generate one daemonset for each host and label override, in
addition to a default daemonset for which no overrides are applied.
Each daemonset generated will also exclude from its scheduling criteria all
other hosts and labels defined in other overrides for the same daemonset, to
ensure that there is no overlap of daemonsets (i.e., one and only one daemonset
The chart will then generate one DaemonSet for each host and label override, in
addition to a default DaemonSet for which no overrides are applied.
Each DaemonSet generated will also exclude from its scheduling criteria all
other hosts and labels defined in other overrides for the same DaemonSet, to
ensure that there is no overlap of DaemonSets (i.e., one and only one DaemonSet
of a given type for each node).
Overrides example with sysctl daemonset::
Overrides example with sysctl DaemonSet::
conf:
sysctl:
@ -459,7 +469,8 @@ Caveats:
contained both of the defined labels.
Dev Environment with Vagrant
----------------------------
============================
The point of Dev env to prepare working environment for development.
Vagrantfile allows to run on working copy with modifications
@ -471,6 +482,29 @@ but do not delete the pods and other stuff. You have:
3. your not committed test runs in prepared env
Recorded Demo
-------------
A recorded demo of using Divingbell can be found `here <https://asciinema.org/a/beJQZpRPdOctowW0Lxkxrhz17>`_.
=============
Here are a few demo recording of Divingbell in action:
- Divingbell limits module:
`link <https://asciinema.org/a/209619>`__,
`link <https://asciinema.org/a/211450>`__ (with overrides)
- Divingbell sysctl module:
`link <https://asciinema.org/a/209667>`__,
`link <https://asciinema.org/a/211433>`__ (with overrides)
- Divingbell perms module:
`link <https://asciinema.org/a/209509>`__,
`link <https://asciinema.org/a/213125>`__ (with overrides)
Further Reading
===============
`Airship`_.
.. |Doc Status| image:: https://readthedocs.org/projects/airship-divingbell/badge/?version=latest
:target: https://airship-divingbell.readthedocs.io/
:alt: Documentation Status
.. _Read the Docs: https://airship-divingbell.readthedocs.io
.. _Drydock: https://airship-drydock.readthedocs.io
.. _Airship: https://www.airshipit.org
.. _Armada: https://airship-armada.readthedocs.io
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