Converting Flatpak applications with ll-pica: concepts and a worked approach

Author:克亮 · Original source: https://bbs.deepin.org/post/291716

---

What is pica? How to use pica?

Official document introduction: https://linyaps.org.cn/guide/ll-pica/introduction.html

ll-pica is a set of tools for converting application packages in different formats (deb, AppImage, Flatpak) into Linyaps (Linglong) format application packages. The toolset consists of binaries and scripts, forming a complete application package conversion ecosystem.

deepin V23-25 system can open the terminal by right-clicking and typing apt download linglong-pica to obtain the installation deb package

The latest version of the current repository is linglong-pica_1.2.4-1+u005_amd64.deb

We can unpack the deb package through the dpkg-deb -R command to find out what is inside (it contains binary files and related scripts)

1. ll-pica – Main tool for converting DEB packages into Linyaps applications (layer, uab-offline package)
2. ll-pica-flatpak – For converting Flatpak apps into Linyaps apps
3. ll-appimage-convert – For converting AppImage apps into Linyaps apps
4. ll-convert-tool – A helper script that provides various utility functions

DEB package conversion (ll-pica)/AppImage application conversion (ll-appimage-convert)/Flatpak application conversion (ll-pica-flatpak)

DEB package conversion (ll-pica)

https://linyaps.org.cn/guide/ll-pica/convert.html

AppImage application conversion (ll-appimage-convert)

https://linyaps.org.cn/guide/ll-appimage-convert/convert-appimage.html

Flatpak application conversion (ll-pica-flatpak)

https://linyaps.org.cn/guide/ll-flatpak-convert/convert-flatpak.html

Let’s focus on learning and understanding how to use ll-pica-flatpak convert to convert flatpak applications into Linyaps applications

Detailed explanation of the working principle of ll-pica-flatpak convert

1. Initialization and configuration-(the first run is a bit long)

1. Environment settings ：
   • Set Flathub cache directory: $HOME/.cache/linglong-pica-flathub
   • Setup configuration file: $HOME/.pica/ll-pica-flatpak-config.json
   • Set reference file: $HOME/.pica/ll-pica-flatpak-refs.txt
2. Parameter handling ：
   • Receive application ID
   • Handle optional parameters:
     • --base : Specify the base image name
     • --base-version : Specify the base image version
     • --version : Specify application version
     • --build : Whether to build UAB package
     • --layer : Whether to export the installation package in layer format The format of
3. Initialize ostree repository ：
   • Create ostree repository: ostree init --repo="$FLATHUB_CACHE" --mode bare-user-only
   • Add Flathub remote repository: ostree --repo="$FLATHUB_CACHE" remote add --if-not-exists --no-sign-verify flathub "$FLATHUB_URL"

2. Application acquisition and extraction

1. Generate reference cache ：
   • Generate reference cache if referenced file does not exist: ll-pica-flatpak-utils generate_ref_cache
2. Pull application ：
   • Use ostree to pull applications: ostree --repo="$FLATHUB_CACHE" pull "$REF"
   • Among them $REF is: flathub:app/$APPID/$ARCH/stable
3. Checkout application ：
   • Create working directory: mkdir -p "$WORKDIR"
   • Checkout application: ostree --repo="$FLATHUB_CACHE" checkout "$REF" "$WORKDIR/flatpak"

3. Metadata extraction and processing

1. Extract Flatpak metadata ：
   • Extract commands from metadata files: grep '^command=' $WORKDIR/flatpak/metadata
   • Extract runtime information: grep '^runtime=' "$WORKDIR"/flatpak/metadata
2. Determine Linyaps base image ：
   • Generate Linyaps base image name based on Flatpak runtime: org.deepin.base.flatpak.$(echo "$FLATPAK_RUNTIME"|awk -F'.' '{print $2}')
   • Generate base image version: Convert Flatpak runtime version to Linyaps version format

4. Path adjustment

1. Handling desktop files ：
   • Find all .desktop files
   • Extract Exec lines
   • will /app Path replaced with /opt/apps/$APPID/files
2. Determine binary file path ：
   • Extract binary file names from Exec lines
   • Determine final path based on path type (absolute/relative)

5. Generate Linyaps configuration file

1. Create linglong.yaml

2. Create profile file

6. Build and Export

1. Build UAB package ：
   • If specified --build option, execute: ll-builder build
2. Export ：
   • If specified --layer option, execute: ll-builder export --layer
   • Otherwise execute: ll-builder export

After extensive application testing, it was found that ostree Pulling the application takes longer than expected and is very unstable. To solve this problem. I made several plans and shared my journey with you as follows:

For novices, they must first configure the Flatpak store locally and open the website https://flathub.org/zh-Hans Install Flatpak according to your own distribution, here we use Deepin for demonstration.

Install Flatpak

sudo apt install flatpak

Add Flathub repository

flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo

Replace with domestic mirror——(Here are two domestic high-speed mirror sites of Shanghai Jiao Tong University- Siyuan – Zhiyuan ）

sudo flatpak remote-modify flathub --url=https://mirror.sjtu.edu.cn/flathub

sudo flatpak remote-modify flathub --url=https://mirrors.sjtug.sjtu.edu.cn/flathub

If you want to restore the official source:

flatpak remote-modify flathub --url=https://dl.flathub.org/repo

If you want to view the details of the flatpak repository

flatpak remotes --show-details

At this point, the introduction to Flatpak has been completed. If there are any mistakes, please teach me more!

Method 1: Change the default repository in the Flathub cache directory config to the domestic mirror site of Shanghai Jiao Tong University) as shown below

Add several very important commands and share them here

1. Linyapsbase and runtime query methods

Show latest version only

ll-cli search . --type=runtime

View all versions in the repository

ll-cli search . --type=runtime --show-all-version

The red box below is the Linyaps base image name generated based on Flatpak runtime.

(If some flatpak applications do not have a corresponding runtime version, you can manually modify the version number in linglong.yaml to test whether it can run normally)

2.Flatpak queries the metadata information of the application (no need to install the application locally)

flatpak remote-info [远程仓库名] [应用ID]

For example, I want to query an application with the ID net.nokyan.Resources. Enter the following command in the terminal.

flatpak remote-info flathub net.nokyan.Resources