Summary

Flutter is one of the mobile app frameworks developed by Google which supports both Android and iOS. It is cross-platform and being advanced to be applied to other platforms. Their official website says:

Flutter transforms the app development process. Build, test, and deploy beautiful mobile, web, desktop, and embedded apps from a single codebase.

On May 12, 2022, its latest major version, 3 was released.

I built the dev env on Devuan GNU+Linux, a fork of Debian without systemd. It resembles my past trial on Artix Linux.

This post shows how I did it.
It is manual installation without Debian package management system (apt-get etc.). However, it isn't complicated thanks to the officially distributed packages.

Environment

OS: Devuan 4 (Chimaera)
App Framework: Flutter 3
Programming Language: Dart
IDE: Android Studio 2022.3.1.18

Tutorial

All doas from OpenBSD's can be replaced with sudo.

Get Android Studio (IDE)

Install it and configure. This post may be helpful.

Install dependencies

Run:

$ doas apt install cmake clang ninja-build libgtk-3-dev

Get Flutter and Dart SDK

Flutter

Get the .tar.xz package in "Install Flutter manually" in the official docs.

Then run to extract:

$ tar xJf flutter_linux_3.xx.xx-stable.tar.xz

Dart SDK

Get the .zip package in "Stable channel" in "Dart SDK archive" in the official.

Then extract all from it.

Set up `PATH` environment variable

Update PATH to let them available in IDE:

$ export PATH=(readlink -f dart-sdk/bin):"$PATH"
$ export PATH=(readlink -f flutter/bin):"$PATH"

The order above is important: First dart-sdk comes and then flutter does. It means we should be careful that flutter should be resolved earlier than dart.
Otherwise, you will meet the warning from flutter doctor:

! Warning: `dart` on your path resolves to
  /(...)/dart-sdk/bin/dart, which is not inside your current
  Flutter SDK checkout at /(...)/flutter. Consider adding
  /(...)/flutter/bin to the front of your path.

How to update `PATH` at login (Optional)

Well, it should be useful to add them to PATH environment variable at login.
It's done, for example, by editing ~/.profile.

export PATH="$HOME/(...)/dart-sdk/bin:$PATH"
export PATH="$HOME/(...)/flutter/bin:$PATH"

In addition, with multiple variables to be added, a list as below and for-loop statement are also available.

for x in \
    $HOME/(...)/(something to be added) \
    $HOME/(...)/dart-sdk \
    $HOME/(...)/flutter
do
    if [ -d "$x" ] ; then
        PATH="$x/bin:$PATH"
    fi
done

Set up `CHROME_EXECUTABLE` in case of Chromium used (Optional)

In order to pass tests by flutter doctor perfectly, you must have either Google Chrome or defined CHROME_EXECUTABLE.
Chromium was my choice and thus I ran:

$ export CHROME_EXECUTABLE=/usr/bin/chromium

Configure IDE

Open "Settings" in "File" in the top menus and choose "Plugins".

Install "Flutter" and "Dart".

You will see warning on Flutter. It has to be accepted:

After Flutter plugin installed, you will be required to "Restart" IDE.

Next, we have to install Android SDK Command-line Tools.

Open "Settings" again and go to "Languages & Frameworks" > "Android SDK" > "SDK Tools".
Check "Android SDK Command-line Tools (latest)" and click "OK"s.

The download will begin and finish after a while:

Run `flutter doctor`

You have two tasks left: Agree to the Android licenses, and validate your environment.

They are done by flutter doctor, one of the flutter commands.
Open terminal and run to deal with the first task:

$ flutter doctor --android-licenses

You will be asked if agree to each of them.

Next, run to validate:

$ flutter doctor

Printed out as below ?

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.10.6, on Devuan GNU/Linux 4 (chimaera) 5.10.0-23-amd64, locale
    en_US.UTF-8)
[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
[✓] Chrome - develop for the web
[✓] Linux toolchain - develop for Linux desktop
[✓] Android Studio (version 2022.3)
[✓] Connected device (2 available)
[✓] Network resources

• No issues found!

Congratulations 🎉🎉

Opt out telemetry by Flutter (Optional)

Additionally, if you want to opt it out, run:

$ flutter --disable-telemetry
Analytics reporting disabled.

Create a Flutter project

Now we are ready. Let's create your first project !!

Start Android Studio and click "New Flutter Project".

After validating the paths of flutter and dart, click "Next":

Enter and confirm the project information, and click "Create":

After a little short, the creation will be completed.

Shall we run the default demo ? Start the virtual device in "Device Manager":

Then run the app by clicking the green triangle button at a little right to the center in the second-top bar.
Alternatively, push Shift + F10, or click [Run] - [Run 'app'] in the top menus.

Your flutter app is here !!

Editing examples

The below is a small trial to customize it: Changed the title phrase and also color theme. (Line 31, 34)

Build executable for Android mobile

Here is another small trial. You can build APK or App Bundle:

...and deliver it easily ;)

Conclusion

You got ready to develop Flutter apps. I hope you enjoy the cross-platform development 💫

Besides, there may be other ways to install them, although there doesn't seem no such Flatpak packages in Flathub. For example, some scenario to use some release channel or Docker / Podman. Additionally, when you use a different Linux distro where systemd is adopted and therefore can do Snaps (Snapd), you have another possibility.

🎶 🎵 🎸 Happy development 🥁 🎶 🎵

Flutter 3 on Devuan 4: Getting started