How to pass flutter build arguments to snapcraft command when building flutter app using snapcraft?

kimmy214 · May 12, 2024, 1:33am

name: app_name
version: 1.0.0
summary: My App description.
description: My App description.
icon: snap/gui/app_name.png
title: AppName
contact: support@mail.com
license: MIT
architectures:
  - build-on: [ amd64 ]
  - build-on: [ arm64 ]

confinement: strict
base: core22
grade: stable

slots:
  dbus-app_name: # adjust accordingly to your app name
    interface: dbus
    bus: session
    name: app.app_name # adjust accordingly to your app name and

apps:
  app_name:
    command: app_name
    extensions: [gnome] # gnome includes the libraries required by flutter
    plugs:
      - network
    slots:
      - dbus-app_name
parts:
  app_name:
    source: .
    plugin: flutter
    flutter-target: lib/main.dart # The main entry-point file of the application

baldeuniversel · May 12, 2024, 8:47am

Hi ! @kimmy214 .

What’s the goal ?

kimmy214 · May 12, 2024, 9:08am

Thanks for the reply. Also a big thanks to the ubuntu-flutter-community channel on discord. The purpose is to customize the parameters of flutter build linux.

This problem has been solved, the solution is as follows.

1、Update snapcraft.yaml

parts:
  app_name:
    source: .
    plugin: flutter
    flutter-target: lib/main.dart # The main entry-point file of the application
    override-build: |
      cp -r build/linux/*/release/bundle/* $CRAFT_PART_INSTALL/

2、I run flutter build linux --release --dart-define-from-file=.env --verbose --target lib/main.dart in the root directory of the flutter project, and then run snapcraft --verbose --output app_name.snap

baldeuniversel · May 12, 2024, 9:19am

Well ! @kimmy214 .

So, you can close this topic .

kimmy214 · May 12, 2024, 9:35am

Sorry, I can’t find the close button. If possible, could you help close it?

baldeuniversel · May 12, 2024, 9:53am

@kimmy214 Click on the three dotted lines next to the solution you shared with me, then press solution. And voila.

kimmy214 · May 12, 2024, 10:08am

Is it this button? After clicking, an additional delete button will be displayed.

baldeuniversel · May 12, 2024, 10:45am

@kimmy214 It’s already done !

The Solution box is checked.

soumyaDghosh · May 12, 2024, 11:31am

This needs a little bit update, if you just run override-build without using the flutter build commands, the app will not build, it’ll just execute the cp command, which in turn would find empty files.

kimmy214 · May 12, 2024, 11:49am

I’m a newbie in snapcraft and I don’t understand what you mean, can you elaborate? Is there something wrong with this solution of mine?

soumyaDghosh · May 12, 2024, 12:03pm

as I explained in the discord channel, override-build is used only to use some different commands. A quick example

override-build: |
  echo "hello"

output:

hello

override-build: |
  craftctl default
  echo "hello"

output:

# the built script set  by the plugin runs
hello

override-build: |
  echo "hello"
  craftctl default

output:

hello

# build script set  by the plugin runs

kimmy214 · May 12, 2024, 12:29pm

I understand what you mean is that it is best to execute the flutter build linux command in the override-build block, otherwise execute this line of code cp -r build/linux/*/release/bundle/* $CRAFT_PART_INSTALL/ , it is possible to copy an empty file to the directory corresponding to $CRAFT_PART_INSTALL

soumyaDghosh · May 12, 2024, 12:41pm

That folder will not be there if it’s not built. So, the copy will fail eventually.

kimmy214 · May 12, 2024, 1:21pm

I also want to execute the flutter build linux command in the override-build block, but I face two problems:

As you said in the discord channel, First it builds flutter in the pull stage, but I don’t know about the built-in environment variables(such as the installation directory of flutter) and how to get the value of the plug-in’s configuration parameters (such as flutter-target) in the build stage, and I didn’t find the documentation so I can’t run the flutter script
I need to get the environment variables from the CI/CD system and then pass them to the flutter build linux command. How do I get the environment variables in CI/CD in the override-build block? Taking GitHub Actions as an example, does it look like this?

1,

jobs:
   snap:
     name: Create snap
     runs-on: ubuntu-latest
     steps:
       - name: Build snap
         run: |
           # https://snapcraft.io/docs/flutter-applications
           snapcraft --output app_name.snap
         env:
           TEST_ENV_BASE64: ${{ secrets.TEST_ENV_BASE64 }}

2,

parts:
   app_name:
     source: .
     plugin: flutter
     flutter-target: lib/main.dart # The main entry-point file of the application
     override-build: |
       echo "$TEST_ENV_BASE64" | base64 --decode > .env
       flutter build linux --dart-define-from-file=.env
       cp -r build/linux/*/release/bundle/* $CRAFT_PART_INSTALL/

soumyaDghosh · May 12, 2024, 2:47pm

https://snapcraft.io/docs/flutter-plugin

You can have build-environment which you can use. eg:

parts:
  app:
    build-environment:
      - TEST_ENV_BASE64: #set it here if it's static

kimmy214 · May 12, 2024, 3:43pm

Thank you very much for your help.

1.1、In the ‘override-build’ block, I can get all the environment variables by executing the ‘env’ command. I also found that the flutter installation directory has been added to the path, but when executing ‘flutter build linux’, the error ‘flutter: command not found’ is reported.

1.2、I configured ‘parts.app_name.flutter-target’ in ‘snapcraft.yaml’, so how can I get this value in the ‘override-build’ block? I didn’t find a solution in the document link you gave me.

2、This can’t be written in plain text in a config file, because my project is open source. it’s not static, so ‘build-environment’ doesn’t work, I’ve tried that.

KhazAkar · May 12, 2024, 3:58pm

1.1 - Does flutter installation is set in user .profile/.bashrc? If so, you need to source it within override-build 2. It can be generated on the fly with some simple scripting eventually.

kimmy214 · May 13, 2024, 1:54pm

Thank you very much. It works for me.

parts:
  app_name:
    source: .
    plugin: flutter
    # flutter-target: lib/main.dart # The main entry-point file of the application
    build-environment:
      - FLUTTER_REPO: https://github.com/flutter/flutter.git
      - FLUTTER_CHANNEL: stable
      - FLUTTER_TARGET: lib/main.dart
      - TARGET_PLATFORM: linux-x64
    override-build: |
      # https://github.com/canonical/snapcraft/blob/main/snapcraft/parts/plugins/flutter_plugin.py
      PG_FLUTTER_BUILD_DIR="$CRAFT_PART_BUILD/flutter-distro"
      if [ -d "$PG_FLUTTER_BUILD_DIR" ]; then
        echo "$PG_FLUTTER_BUILD_DIR"
        rm -rf $PG_FLUTTER_BUILD_DIR
      fi
      git clone --depth 1 -b $FLUTTER_CHANNEL $FLUTTER_REPO $PG_FLUTTER_BUILD_DIR
      flutter doctor -v
      flutter precache --linux
      flutter pub get
      flutter build linux --release --dart-define-from-file=.env --target-platform $TARGET_PLATFORM --target $FLUTTER_TARGET
      cp -r build/linux/*/release/bundle/* $CRAFT_PART_INSTALL/