forked from dan/liminix
outline of the missing doc sections
This commit is contained in:
parent
dece70b336
commit
17035ca3b7
|
@ -0,0 +1,15 @@
|
|||
System Administration
|
||||
#####################
|
||||
|
||||
..
|
||||
- administration guide
|
||||
|
||||
- what you can do on a running system
|
||||
- s6-rc commands
|
||||
|
||||
- writable filesystem: min-copy-closure, min-collect-garbage,
|
||||
liminix-rebuild
|
||||
|
||||
- full flash:
|
||||
how to do the two-step thing
|
||||
flash from OpenWrt
|
|
@ -140,3 +140,18 @@ the `oneshot` or `longrun` functions:
|
|||
Services may have dependencies: as you see above in the ``cowsayd``
|
||||
example, it depends on some service called ``config.services.lan``,
|
||||
meaning that it won't be started until that other service is up.
|
||||
|
||||
..
|
||||
TODO: explain service outputs
|
||||
|
||||
..
|
||||
TODO: outputs that change, and services that poll other services
|
||||
|
||||
Module implementation
|
||||
*********************
|
||||
|
||||
..
|
||||
TODO: make your own modules
|
||||
|
||||
* how a module exposes services
|
||||
* defining types
|
||||
|
|
|
@ -0,0 +1,336 @@
|
|||
Development
|
||||
###########
|
||||
|
||||
As a developer working on Liminix, or implementing a service or
|
||||
module, you probably want to test your changes more conveniently
|
||||
than by building and flashing a new image every time. This section
|
||||
documents various affordances for iteration and experiments.
|
||||
|
||||
In general, packages and tools that run on the "build" machine are
|
||||
available in the ``buildEnv`` derivation and can most easily
|
||||
be added to your environment by running :command:`nix-shell`.
|
||||
|
||||
|
||||
|
||||
Emulated devices
|
||||
****************
|
||||
|
||||
Liminix has a ``qemu`` device, which generates images suitable for
|
||||
running on your build machine using the free `QEMU machine emulator <http://www.qemu.org>`_.
|
||||
This is useful for developing userland without needing to keep
|
||||
flashing or messing with U-Boot: it also enables testing against
|
||||
emulated network peers using `QEMU socket networking <https://wiki.qemu.org/Documentation/Networking#Socket>`_,
|
||||
which may be preferable to letting Liminix loose on your actual LAN.
|
||||
To build it,
|
||||
|
||||
.. code-block:: console
|
||||
|
||||
nix-build -I liminix-config=path/to/your/configuration.nix --arg device "import ./devices/qemu" -A outputs.default
|
||||
|
||||
In a ``buildEnv`` nix-shell, you can use the :command:`mips-vm` command
|
||||
to run Qemu with appropriate options. It connects the Liminix
|
||||
serial console and the `QEMU monitor <https://www.qemu.org/docs/master/system/monitor.html>`_ to stdin/stdout. Use ^P (not ^A) to switch to the monitor.
|
||||
|
||||
.. code-block:: console
|
||||
|
||||
nix-shell --run "mips-vm result/vmlinux result/squashfs"
|
||||
|
||||
If you run with ``--background /path/to/some/directory`` as the first
|
||||
parameter, it will fork into the background and open Unix sockets in
|
||||
that directory for console and monitor. Use :command:`connect-vm`
|
||||
(also in the ``buildEnv`` environment) to connect to either of these
|
||||
sockets, and ^O to disconnect.
|
||||
|
||||
Networking
|
||||
==========
|
||||
|
||||
VMs can network with each other using QEMU
|
||||
socket networking. We observe these conventions, so that we can run
|
||||
multiple emulated instances and have them wired up to each other in
|
||||
the right way:
|
||||
|
||||
* multicast 230.0.0.1:1234 : access (interconnect between router and "isp")
|
||||
* multicast 230.0.0.1:1235 : lan
|
||||
* multicast 230.0.0.1:1236 : world (the internet)
|
||||
|
||||
A VM started with :command:`mips-vm` is connected to "lan" and "access", and
|
||||
the emulated border network gateway (see below) runs PPPoE and is
|
||||
connected to "access" and "world".
|
||||
|
||||
Border Network Gateway
|
||||
----------------------
|
||||
|
||||
In pkgs/routeros there is a derivation to install and configure
|
||||
`Mikrotik RouterOS <https://mikrotik.com/software>`_ as a PPPoE access
|
||||
concentrator connected to the ``access`` and ``world`` networks, so that
|
||||
Liminix PPPoE client support can be tested without actual hardware.
|
||||
|
||||
This is made available as the :command:`routeros` command in
|
||||
``buildEnv``, so you can do something like::
|
||||
|
||||
mkdir ros-sockets
|
||||
nix-shell
|
||||
nix-shell$ routeros ros-sockets
|
||||
nix-shell$ connect-vm ./ros-sockets/console
|
||||
|
||||
to start it and connect to it. Note that by default it runs in the
|
||||
background. It is connected to "access" and "world" virtual networks
|
||||
and runs a PPPoE service on "access" - so a Liminix VM with a
|
||||
PPPOE client can connect to it and thus reach the virtual internet.
|
||||
[ check, but pretty sure this is not the actual internet ]
|
||||
|
||||
`Liminix does not provide RouterOS licences and it is your own
|
||||
responsibility if you use this to ensure you're compliant with the
|
||||
terms of Mikrotik's licencing. It may be supplemented or replaced in
|
||||
time with configurations for RP-PPPoE and/or Accel PPP.`
|
||||
|
||||
Hardware devices
|
||||
****************
|
||||
|
||||
How you get your image onto hardware will vary according to the
|
||||
device, but is likely to involve taking it apart to add wires to
|
||||
serial console pads/headers, then using U-Boot to fetch images over
|
||||
TFTP. The OpenWrt documentation has a `good explanation <https://openwrt.org/docs/techref/hardware/port.serial>`_ of what you may expect to find on
|
||||
the device.
|
||||
|
||||
There is a rudimentary TFTP server bundled with the system which runs
|
||||
from the command line, has an allowlist for client connections, and
|
||||
follows symlinks, so you can have your device download images direct
|
||||
from the :file:`./result` directory without exposing :file:`/nix/store/` to the
|
||||
internet or mucking about copying files to :file:`/tftproot`. If the
|
||||
permitted device is to be given the IP address 192.168.8.251 you might
|
||||
do something like this:
|
||||
|
||||
.. code-block:: console
|
||||
|
||||
nix-shell --run "tufted -a 192.168.8.251 result"
|
||||
|
||||
Now add the device and server IP addresses to your configuration:
|
||||
|
||||
.. code-block:: nix
|
||||
|
||||
boot.tftp = {
|
||||
serverip = "192.168.8.111";
|
||||
ipaddr = "192.168.8.251";
|
||||
};
|
||||
|
||||
and then build the derivation for ``outputs.default`` or
|
||||
``outputs.flashimage`` (for which it will be an alias on any device
|
||||
where this is applicable). You should find it has created
|
||||
|
||||
* :file:`result/firmware.bin` which is the file you are going to flash
|
||||
* :file:`result/flash.scr` which is a set of instructions to U-Boot to
|
||||
download the image and write it to flash after erasing the appropriate
|
||||
flash partition.
|
||||
|
||||
.. NOTE::
|
||||
|
||||
TTL serial connections typically have no form of flow control and
|
||||
so don't always like having massive chunks of text pasted into
|
||||
them - and U-Boot may drop characters while it's busy. So don't
|
||||
necessarily expect to copy-paste the whole of :file:`boot.scr` into
|
||||
a terminal emulator and have it work just like that. You may need
|
||||
to paste each line one at a time, or even retype it.
|
||||
|
||||
|
||||
For a faster edit-compile-test cycle, you can build a TFTP-bootable
|
||||
image instead of flashing. In your device configuration add
|
||||
|
||||
.. code-block:: nix
|
||||
|
||||
imports = [
|
||||
./modules/tftpboot.nix
|
||||
];
|
||||
|
||||
and then build ``outputs.tftpboot``. This creates a file in
|
||||
``result/`` called ``boot.scr``, which you can copy and paste into
|
||||
U-Boot to transfer the kernel and filesystem over TFTP and boot the
|
||||
kernel from RAM.
|
||||
|
||||
|
||||
Networking
|
||||
==========
|
||||
|
||||
You probably don't want to be testing a device that might serve DHCP,
|
||||
DNS and routing protocols on the same LAN as you (or your colleagues,
|
||||
employees, or family) are using for anything else, because it will
|
||||
interfere. You also might want to test the device against an
|
||||
"upstream" connection without having to unplug your regular home
|
||||
router from the internet so you can borrow the cable/fibre/DSL.
|
||||
|
||||
``bordervm`` is included for this purpose. You will need
|
||||
|
||||
* a Linux machine with a spare (PCI or USB) ethernet device which you can dedicate to Liminix
|
||||
|
||||
* an L2TP service such as https://www.aa.net.uk/broadband/l2tp-service/
|
||||
|
||||
You need to "hide" the Ethernet device from the host - for PCI this
|
||||
means configuring it for VFIO passthru; for USB you need to unload the
|
||||
module(s) it uses. I have this segment in configuration.nix which you
|
||||
may be able to adapt:
|
||||
|
||||
.. code-block:: nix
|
||||
|
||||
boot = {
|
||||
kernelParams = [ "intel_iommu=on" ];
|
||||
kernelModules = [
|
||||
"kvm-intel" "vfio_virqfd" "vfio_pci" "vfio_iommu_type1" "vfio"
|
||||
];
|
||||
|
||||
postBootCommands = ''
|
||||
# modprobe -i vfio-pci
|
||||
# echo vfio-pci > /sys/bus/pci/devices/0000:01:00.0/driver_override
|
||||
'';
|
||||
blacklistedKernelModules = [
|
||||
"r8153_ecm" "cdc_ether"
|
||||
];
|
||||
};
|
||||
services.udev.extraRules = ''
|
||||
SUBSYSTEM=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="8153", OWNER="dan"
|
||||
'';
|
||||
|
||||
Then
|
||||
you can execute :command:`run-border-vm` in a ``buildEnv`` shell,
|
||||
which starts up QEMU using the NixOS configuration in
|
||||
:file:`bordervm-configuration.nix`.
|
||||
|
||||
In this VM
|
||||
|
||||
* your Liminix checkout is mounted under :file:`/home/liminix/liminix`
|
||||
|
||||
* TFTP is listening on the ethernet device and serving
|
||||
:file:`/home/liminix/liminix`. The server IP address is 10.0.0.1
|
||||
|
||||
* a PPPOE-L2TP relay is running on the same ethernet card. When the
|
||||
connected Liminix device makes PPPoE requests, the relay spawns
|
||||
L2TPv2 Access Concentrator sessions to your specified L2TP LNS.
|
||||
Note that authentication is expected at the PPP layer not the L2TP
|
||||
layer, so the PAP/CHAP credentials provided by your L2TP service can
|
||||
be configured into your test device - bordervm doesn't need to know
|
||||
about them.
|
||||
|
||||
To configure bordervm, you need a file called :file:`bordervm.conf.nix`
|
||||
which you can create by copying and appropriately editing :file:`bordervm.conf-example.nix`
|
||||
|
||||
.. note::
|
||||
|
||||
If you make changes to the bordervm configuration after executing
|
||||
:command:`run-border-vm`, you need to remove the :file:`border.qcow2` disk
|
||||
image file otherwise the changes won't get picked up.
|
||||
|
||||
|
||||
Running tests
|
||||
*************
|
||||
|
||||
You can run all of the tests by evaluating :file:`ci.nix`, which is the
|
||||
input I use in Hydra. Note that it expects Nixpkgs stable `and` unstable
|
||||
as inputs, because it builds the qemu device against both.
|
||||
|
||||
.. code-block:: console
|
||||
|
||||
nix-build --argstr liminix `pwd` --arg nixpkgs "<nixpkgs>" \
|
||||
--argstr unstable `pwd`/../unstable-nixpkgs/ ci.nix
|
||||
|
||||
To run a single named test, use the ``-A`` flag. For example, ``-A pppoe``
|
||||
|
||||
|
||||
|
||||
|
||||
Troubleshooting
|
||||
***************
|
||||
|
||||
Diagnosing unexpectedly large images
|
||||
====================================
|
||||
|
||||
Sometimes you can add a package and it causes the image size to balloon
|
||||
because it has dependencies on other things you didn't know about. Build the
|
||||
``outputs.manifest`` attribute, which is a JSON representation of the
|
||||
filesystem, and you can run :command:`nix-store --query` on it.
|
||||
|
||||
.. code-block:: console
|
||||
|
||||
nix-build -I liminix-config=path/to/your/configuration.nix \
|
||||
--arg device "import ./devices/qemu" -A outputs.manifest \
|
||||
-o manifest
|
||||
nix-store -q --tree manifest
|
||||
|
||||
|
||||
Contributing
|
||||
************
|
||||
|
||||
Contributions are welcome, though in these early days there may be a
|
||||
bit of back and forth involved before patches are merged:
|
||||
Please get in touch somehow `before` you invest a lot of time into a
|
||||
code contribution I haven't asked for. Just so I know it's expected
|
||||
and you're not wasting time doing something I won't accept or have
|
||||
already started on.
|
||||
|
||||
|
||||
Nix language style
|
||||
==================
|
||||
|
||||
This section describes some Nix language style points that we
|
||||
attempt to adhere to in this repo.
|
||||
|
||||
* favour ``callPackage`` over raw ``import`` for calling derivations
|
||||
or any function that may generate one - any code that might need
|
||||
``pkgs`` or parts of it.
|
||||
|
||||
* prefer ``let inherit (quark) up down strange charm`` over
|
||||
``with quark``, in any context where the scope is more than a single
|
||||
expression or there is more than one reference to ``up``, ``down``
|
||||
etc. ``with pkgs; [ foo bar baz]`` is OK,
|
||||
``with lib; stdenv.mkDerivation { ... }`` is usually not.
|
||||
|
||||
* ``<liminix>`` is defined only when running tests, so don't refer to it
|
||||
in "application" code
|
||||
|
||||
* the parameters to a derivation are sorted alphabetically, except for
|
||||
``lib``, ``stdenv`` and maybe other non-package "special cases"
|
||||
|
||||
* indentation is whatever emacs nix-mode says it is.
|
||||
|
||||
* where a ``let`` form defines multiple names, put a newline after the
|
||||
token ``let``, and indent each name two characters
|
||||
|
||||
* to decide whether some code should be a package or a module?
|
||||
Packages are self-contained - they live in ``/nix/store/eeeeeee-name``
|
||||
and don't directly change system behaviour by their presence or
|
||||
absense. modules can add to
|
||||
``/etc`` or ``/bin`` or other global state, create services, all that
|
||||
side-effecty stuff. Generally it should be a package unless it
|
||||
can't be.
|
||||
|
||||
|
||||
|
||||
Copyright
|
||||
=========
|
||||
|
||||
The Nix code in Liminix is MIT-licenced (same as Nixpkgs), but the
|
||||
code it combines from other places (e.g. Linux, OpenWrt) may have a
|
||||
variety of licences. I have no intention of asking for copyright
|
||||
assignment: just like when submitting to the Linux kernel you retain
|
||||
the copyright on the code you contribute.
|
||||
|
||||
|
||||
Code of Conduct
|
||||
===============
|
||||
|
||||
Please govern yourself in Liminix project venues according to the
|
||||
`Code of Conduct <https://gti.telent.net/dan/liminix/src/commit/7bcf6b15c3fdddafeda13f65b3cd4a422dc52cd3/CODE-OF-CONDUCT.md>`_
|
||||
|
||||
|
||||
Where to send patches
|
||||
=====================
|
||||
|
||||
|
||||
Liminix' primary repo is https://gti.telent.net/dan/liminix but you
|
||||
can't send code there directly because it doesn't have open registrations.
|
||||
|
||||
* There's a `mirror on Github <https://github.com/telent/liminix>`_ for
|
||||
convenience and visibility: you can open PRs against that
|
||||
|
||||
* or, you can send me your patch by email using `git send-email <https://git-send-email.io/>`_
|
||||
|
||||
* or in the future, some day, we will have federated Gitea using
|
||||
ActivityPub.
|
|
@ -7,6 +7,8 @@ Liminix
|
|||
|
||||
tutorial
|
||||
configuration
|
||||
admin
|
||||
development
|
||||
|
||||
|
||||
Indices and tables
|
||||
|
|
Loading…
Reference in New Issue