Is it possible to generate linux .rpm packages from flutter linux app? - linux

Question

As far as I know, Flutter for linux app only targets snap packaging format.
Is it possible to generate .rpm and .deb (cross-linux platform) software packages from the flutter build?
Kindly post any help on how to package a flutter-linux app as RPM package

Answer 1

Building RPMs and DEBs is doable, but a pretty involved process. I will try to outline the basic process for RPM's as best as I can. The process of making a DEB is mostly the same with a few differences. I will stick to RPM's for now.
The main thing which is a pain is that to build packages you need specific tools which are only available on the distros. So if you want to do this cross platform (generate a RPM on a ubuntu machine for example) we need to use Docker.
Create a Dockerfile which in which we will install the rpm-build package which contains all tools to build RPMs.
FROM centos:7
RUN yum install -y -q rpm-build
Build this dockerfile and remember the docker image, we will need it later.
Execute the following command mkdir -p build/{BUILD,RPMS,SOURCES,SPECS,SRPMS}. This will create the directory structure required for rpmbuild
Create a .spec file, this file is a config file for the rpmbuild command and place it in the build/SPECS directory. The contents of this file are very specific to the what the package has to do. RPMs are very flexible and can do lots of stuff ranging from just copying files to running complex bash scripts on the target machine to perform compilation on the target machine and perform complex installations. Here are some guides which I found useful: package guide, fedora guide, and redhat guide.
Download the files you want to package, often they are distributed as tarballs and place it in the build/SOURCES directory.
Now we can execute the following command docker run --rm -v $(pwd)/build:/rpmbuild {name of image} /bin/bash -c "cd /rpmbuild && rpmbuild --define '_topdir /rpmbuild' -ba SPECS/flutter.spec"
I will break the command down.
docker run --rm -v $(pwd)/build:/rpmbuild {name of image} - we start a container from the image we created earlier, and mount the build dir in which our .spec and .tar.gz are located so the container can see them. --rm cleans up the container after we are done since we don't need it after the first command.
/bin/bash -c - this is a trick since we need to execute 2 command inside the docker container, if we don't do this our shell will thing the && is meant after the docker command and not passed to the container.
"cd /rpmbuild && rpmbuild --define '_topdir /rpmbuild' -ba SPECS/flutter.spec" - move to the mounted build directory and build the RPM package. the -ba option tells rpmbuild to build both the binary and source packages in case you want the source package as well.
If all went well your should now have an .rpm file in the build/RPMS and a source package in the build/SRPMS directory.
For DEB the process is almost the same, except you need a debian or ubuntu docker image, you use the dpkg-deb command to build and you need a control file instead of a .spec file(same purpose different format)

Answer 2

I will also go over some of the key parts of building rpm packages for flutter applications in case the previous answer was ambiguous.
I have already written an article going into details but here I will only highlight the key parts. You can find the article here
Also for simplicity of explanation, I will be using cool-app as an example throughout this post.
1- Run flutter build linux to get the Linux build inside the build folder in your project root directory.
2- Copy your bundle folder someplace else and there, rename it according to app-name-version semantic. e.g. cool-app-1.0.0
3- Create a .desktop file. e.g. cool-app.desktop will look like the following :
[Desktop Entry]
Name=My Cool App
Comment=A cool app that does everything
Exec=/usr/bin/cool-app/cool-app
Icon=/usr/bin/cool-app/data/flutter_assets/assets/icon.svg
Terminal=false
Type=Application
Categories=Utility;
change the properties accordingly and place the .desktop file inside cool-app-1.0.0 directory
4- run mkdir -p rpmbuild/{BUILD,RPMS,SOURCES,SPECS,SRPMS} in your home directory.
5- copy the cool-app-1.0.0 directory to ~/rpmbuild/SOURCES.
Due to a problem that as the time of writing this still persists, the rpath for lib*_plugin.so files point to user's build tree path which results in rpmbuild failure.
6- Run patchelf --print-rpath * inside cool-app-1.0.0/lib and check the output. If the output contains a path from your home directory, run patchelf --set-rpath '$ORIGIN' * to fix the rpaths, then check again. now all paths must be $ORIGIN. (This was the way I was able to fix it, not sure if it's the best solution)
You can check this github issue for further information.
7- cd into ~/rpmbuild/SOURCES and run tar --create --file cool-app-1.0.0.tar.gz cool-app-1.0.0 to create a tar.gz file.
8- Create a file named cool-app.spec inside ~/rpmbuild/SPECS directory.
Sample cool-app.spec file :
Name: cool-app
Version: 1.0.0
Release: 1%{?dist}
Summary: Very cool app
BuildArch: x86_64
URL: https://github.com/CoolDev/cool-app
License: GPLv3
Source0: %{name}-%{version}.tar.gz
Requires: bash
%description
A very cool app that does everything
%prep
%setup -q
%install
rm -rf $RPM_BUILD_ROOT
mkdir -p $RPM_BUILD_ROOT/%{_bindir}/%{name}
cp %{name} $RPM_BUILD_ROOT/%{_bindir}/%{name}
cp -R lib $RPM_BUILD_ROOT/%{_bindir}/%{name}
cp -R data $RPM_BUILD_ROOT/%{_bindir}/%{name}
desktop-file-install %{name}.desktop
%clean
rm -rf $RPM_BUILD_ROOT
%files
%{_bindir}/%{name}
/usr/share/applications/
You could use the same template and only change Name,Version,Summery,Release,BuildArch,URL,License,%description and you will most likely be fine.
I went over the spec file in more detail in my article mentioned in the beginning of this post.
9- run rpmbuild --bb cool-app.spec to get your rpm file inside ~/rpmbuild/RPMS directory.