Runit on Ivon's Blog

Manage auto-starting services: how to use Termux-services & Termux:Boot

infoivonblog.nkfjt@aleeas.com (Ivon Huang) — Mon, 18 Nov 2024 06:00:00 +0800

Manage auto-startup services in Termux.

Here I share two Termux extensions. The first is Termux-services, which manages services after the Termux app is started. The second is Termux:Boot, which configures Termux services to start automatically after Android boots.

Why would you need Termux-services?

If you want to start and stop services in Termux, and configure services to start automatically after opening the app, but Termux has no Systemd, are you stuck writing auto-start services into ~/.bashrc or ~/.profile, then killing processes with the kill command when you want to stop them?

At this point, Termux-services is a pretty good tool.

Termux-services lets you use a set of commands to control service execution, so you can freely start and stop services. It is very useful for programs that need daemons, such as sshd, apache2, and bitcoin, which can be started automatically through Termux-services after the Termux app opens.

Termux-services uses “runit” to manage system services. This is a very simple init service manager, now used by only a small number of Linux distributions. Speaking of Linux distributions that use runit, the most famous are probably Artix Linux and Void Linux.

First I will introduce how to use Termux-service, then explain how to use Termux: Boot.

1. Termux-services auto-start
#

Install the Termux-services package

pkg install termux-services

When installing some packages, Termux will also install runit service files. The files for all services are located at $PREFIX/var/service/sv.
For example, after installing the openssh package, Termux-services will automatically install the SSHD service file. $PREFIX/var/service/sv/sshd/run defines the command executed after the service starts, and $PREFIX/var/service/sv/sshd/down defines the command executed after the service stops.
To start and stop the SSHD service, use the following commands:

# Start
sv up sshd

# Stop
sv down sshd

# Auto-start after opening the app 
sv-enable sshd

# Disable auto-start after opening the app 
sv-disable sshd

By analogy, if you want to execute other programs after Termux starts, create a service file in the same way. Refer to the official runit templates when writing scripts. I will use running a custom script as an example:

# Edit content
echo "echo 'Hello world' ">> ~/run.sh
chmod +x ~/run.sh

# Add service file
vim $PREFIX/var/service/sv/myscript/run

# Fill in:
bash ~/run.sh

# Configure auto-start after starting the Termux app
sv-enable myscript

2. Termux:Boot auto-start on boot
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Termux:Boot automatically executes the scripts you write after the Android system boots.

Actually, you do not have to use it together with Termux-service. Termux:Boot can call Termux to execute arbitrary commands, but I think system services are better managed centrally. So the architecture becomes: first add the services you want to run through Termux-services, then use Termux:Boot to automatically start Termux, and all the services you wrote will start with it.

Install the Termux: Boot APK
Tap the icon once to launch it, so it will start automatically after boot

Solutions when Termux proot cannot use the systemctl command

infoivonblog.nkfjt@aleeas.com (Ivon Huang) — Sat, 31 Aug 2024 23:00:00 +0800

Systemd is an init program. Almost all Linux distributions use Systemd to manage system services, and common commands include systemctl, journalctl, and so on.

However, Termux cannot use Systemd. If you run commands related to systemctl start inside a Termux proot-distro or chroot container environment, you will see this error: System has not been booted with systemd as init system (PID 1). Can't operate. Failed to connect to bus: Host is down

This is because the container environment does not support Systemd.

There is actually no real solution, unless the Termux development team learns from Microsoft WSL and finds a way to make Systemd run. However, we do have some alternatives to address this problem.

Method 1: Start the program directly from the executable path
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First, understand that Systemd is just an init program for managing system services. It is responsible for starting programs after Linux boots and letting users turn programs on and off. But simply starting a program does not actually require systemctl.

For example, to start the SSH service in proot Debian, the Systemd way is to run the following command:

sudo systemctl start sshd

If we find Systemd’s service file /etc/systemd/system/sshd.service (most Systemd service files are here), we will see that what follows ExecStart= is the command it really executes:

[Service]
EnvironmentFile=-/etc/default/ssh
ExecStartPre=/usr/sbin/sshd -t
ExecStart=/usr/sbin/sshd -D

Therefore, the SSH service can be started directly with this command and run in the background:

mkdir -p /run/sshd

/usr/sbin/sshd -D

Note: programs inside Termux proot-distro cannot use ports below 1000. When logging in to proot-distro, add the --fix-low-ports parameter to redirect SSH port 22 to 2022.

If you want to automatically start a specific program after logging in to proot-distro, the simplest way is to add the command you want to run to ~/.bashrc in the user’s home directory.

Method 2: Switch to a distribution that uses OpenRC
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OpenRC and runit are more traditional init programs. They are not as complex as Systemd, and they can run and manage services in proot. Users unfamiliar with OpenRC commands can refer to the Systemd and OpenRC command comparison table below.

At present, the proot-distro distribution that uses OpenRC is Alpine Linux, while Artix Linux and Void Linux use runit.

Install Alpine Linux

proot-distro install alpine
proot-distro login alpine

Install the OpenRC package

apk add openrc

After that, append this command when logging in to proot, and the OpenRC program will start

proot-distro login alpine --fix-low-ports -- /bin/ash -c "/sbin/openrc default; /bin/ash -l"

After that, you can use OpenRC to manage services. For example, SSH can be managed with the rc-service command, without typing the executable path

sudo rc-service sshd start

You can also configure the SSH service to start automatically after logging in to proot-distro.

sudo rc-update add sshd

Method 3: Run a full Linux system virtual machine
#

The ultimate solution is to emulate a full Linux system so that Systemd can run.

Runit on Ivon's Blog

Manage auto-starting services: how to use Termux-services & Termux:Boot

1. Termux-services auto-start #

2. Termux:Boot auto-start on boot #

Solutions when Termux proot cannot use the systemctl command

Method 1: Start the program directly from the executable path #

Method 2: Switch to a distribution that uses OpenRC #

Method 3: Run a full Linux system virtual machine #

1. Termux-services auto-start
#

2. Termux:Boot auto-start on boot
#

Method 1: Start the program directly from the executable path
#

Method 2: Switch to a distribution that uses OpenRC
#

Method 3: Run a full Linux system virtual machine
#