https://github.com/troglobit/br2-finit-demo

Demo of Finit (FastInit) in Buildroot
https://github.com/troglobit/br2-finit-demo

buildroot buildroot-external buildroot-external-tree buildroot-layer finit init-system

Last synced: 12 months ago
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Demo of Finit (FastInit) in Buildroot

• Host: GitHub
• URL: https://github.com/troglobit/br2-finit-demo
• Owner: troglobit
• Created: 2022-12-19T18:01:10.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2024-01-09T07:29:19.000Z (over 2 years ago)
• Last Synced: 2025-04-02T19:51:44.450Z (about 1 year ago)
• Topics: buildroot, buildroot-external, buildroot-external-tree, buildroot-layer, finit, init-system
• Language: Shell
• Homepage: https://troglobit.com/post/2022-12-26-buildroot-demo-of-fastinit-finit/
• Size: 168 KB
• Stars: 7
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
Buildroot Demo with Fast Init

=============================



This is an example of how FastInit ([Finit][1]) can be used with Buildroot

instead of the default BusyBox init, or systemd.

The provided defconfig (see below) is the default Buildroot Qemu x86_64

defconfig with Finit enabled as the default system init.  The kernel is

the same as Buildroot, targeting only a basic Qemu PC machine.  The root

filesystem (ext4) is built around BusyBox, with the following changes:

 - Disable BusyBox init

 - Disable BusyBox poweroff/halt/reboot commands (for init)

 - Enable mount helpers (for fstab tricks later)

 - Enable a few services: `httpd`, `ntpd`, `udhcpd`, `dnsd`, `telnetd`, ...

The rest of this tree is basically just glue to make everything fit in

with the Buildroot external concept, as described in the [excellent

manual][3].  Check it out for helpful hints and how to extend on this

demo with more services, or even customize it for your own project.

> Notice the use of an external, `br2-ext-finit`, providing only the

> necessary Finit package(s) and a root skeleton with a wide range of

> service configurations.  If you already have a Buildroot system, it

> comes with all you need to get up and running.

Build

-----

To build, first clone this repository to your host system, change to

the top-level directory, activate the defconfig and make:

    git clone https://github.com/troglobit/br2-finit-demo.git

    cd br2-finit-demo/

    make qemu_x86_64_defconfig

    make

The resulting image files are placed `output/images/` and a Qemu host

program is available in `output/host/bin/`.

> The host requirements are the same as Buildroot proper, for details,

> see 

Run

---

The `external.mk` file extends Buildroot with a `run` command that calls

the Qemu host program with the generated image files:

    make run

It boots fairly quick provided you have an x86_64 host computer.  See

the `initctl` tool (below) to control Finit.

Default login is `root`, no password.

> **Note:** use `Ctrl-a x` to exit qemu, and `Ctrl-a c` to toggle console/monitor

Usage

-----

Finit is controlled by its helper tool `initctl`:

    initctl help

Brings up the available commands.  Check what is running right now:

    initctl status   # default command, you can omit 'status'

Show available .conf snippets that start services:

    initctl ls

Configuration files are in `/etc/finit.conf` and `/etc/finit.d/*`, the

latter support Apache-like `available/` and `enabled/` configuration

snippets.

Try enabling some services (not a lot is enabled in the defconfig, add

more with `make menuconfig` or `make busybox-menuconfig`) like:

    initctl enable telnetd

Try `initctl ls` again, it's now listed in the set of enabled services.

But it's not yet running ... (check with `initctl status`).  This is

because we may want to roll out multiple changes to a system before

activating them.  To activate we tell Finit to reload its configuration.

    initctl reload

Verify it is now running.  For more detailed information about telnetd:

    initctl status telnetd

Try killing telnetd and check the status again.  You can now see that

Finit has already restarted it for you (`Restarts: 1 (1/10)`).  Kill it

a few more times to see what happens.  When a service reaches its max

restart count Finit will no longer try to restart it automatically --

something is obviously not right with the service.  You will have to

restart it manually, which clears the restart counter.  Notice how the

total restarts counter continues counting.

Access

------

To be able to run Qemu unprivileged, without sudo, the guest runs in

user networking mode.  Meaning the guest is hidden behind a NAT and

regular services cannot be reached without a port forward.

When calling `make run` the following ports are forwarded from the guest

to the host's 80xx port range:

| **Service** | **Guest port** | **Host port** |

|-------------|----------------|---------------|

| FTP         | 21             | tcp/8021      |

| SSH         | 22             | tcp/8022      |

| Telnet      | 23             | tcp/8023      |

| HTTP        | 80             | tcp/8080      |

So, to test login via telnet from your host:

    telnet localhost 8023

or if you want test the web server (enabled by default):

    x-www-browser http://localhost:8080       # Debian/Ubuntu/Mint shortcut

You can even reach it from another host on your LAN by replacing the

`localhost` name with the name, or IP address, of the host you are

running Qemu on.

Fin

---

There is of course a lot more to cover.  Please let me know if you are

curious about some other aspect that would be suitable for a blog post.

There is also a [discussion forum][2] open for general questions about

[Finit][1].

[1]: https://github.com/troglobit/finit#introduction

[2]: https://github.com/troglobit/finit/discussions

[3]: https://buildroot.org/downloads/manual/manual.html