How I Moved Flutter Android Builds to GitHub Actions (Low-Spec PC)

Background

I'm building an Android app with Flutter as a side project.

My development machine is a Celeron N4500 / 4GB RAM laptop. Running flutter build apk locally meant the fan would spin up, the PC would freeze for other tasks, and builds took 10+ minutes. Disk space was also getting tight.

I moved the build process to GitHub Actions. Now I just push code and download the APK when the cloud build finishes.

The Workflow

Local: edit code → git push
GitHub Actions: flutter build apk --release → save APK as Artifact
Local: gh run download → upload APK to Google Play Console

No local Android SDK required.

Setup

1. Encode your keystore to base64

Your signing keystore needs to be stored as a GitHub Secret. First, encode it:

import base64
with open('android/app/upload-keystore.jks', 'rb') as f:
    print(base64.b64encode(f.read()).decode('utf-8'))

Copy the output string.

2. Add GitHub Secrets

Go to your repo's Settings → Secrets and variables → Actions and add these four secrets:

Secret	Value
KEYSTORE_BASE64	The base64 string from above
STORE_PASSWORD	Your keystore password
KEY_PASSWORD	Your key password
KEY_ALIAS	Your key alias (e.g. upload)

3. Create the workflow file

Create .github/workflows/android-build.yml:

name: Android Build

on:
  push:
    branches:
      - master
  workflow_dispatch:

jobs:
  build:
    runs-on: ubuntu-latest
    timeout-minutes: 30

    steps:
      - name: Checkout code
        uses: actions/checkout@v4

      - name: Set up Java 17
        uses: actions/setup-java@v4
        with:
          java-version: '17'
          distribution: 'temurin'

      - name: Set up Flutter
        uses: subosito/flutter-action@v2
        with:
          channel: 'stable'
          cache: true

      - name: Install dependencies
        run: flutter pub get

      - name: Decode keystore
        run: |
          echo "${{ secrets.KEYSTORE_BASE64 }}" | base64 --decode > android/app/upload-keystore.jks

      - name: Create key.properties
        run: |
          cat > android/key.properties << EOF
          storePassword=${{ secrets.STORE_PASSWORD }}
          keyPassword=${{ secrets.KEY_PASSWORD }}
          keyAlias=${{ secrets.KEY_ALIAS }}
          storeFile=upload-keystore.jks
          EOF

      - name: Build release APK
        run: flutter build apk --release

      - name: Upload APK
        uses: actions/upload-artifact@v4
        with:
          name: release-apk
          path: build/app/outputs/flutter-apk/app-release.apk
          retention-days: 7

4. Download the APK

After the build completes, download using GitHub CLI:

# Check the latest run ID
gh run list --repo your-username/your-repo --limit 3

# Download APK
gh run download <RUN_ID> --repo your-username/your-repo --dir ./apk-output

Or download directly from the GitHub Actions page → click the run → scroll to Artifacts.

Tips

Match your branch name

Make sure the branch name in on: push: branches: matches your actual default branch. Some repos use main, others use master.

Keep keystore out of git

# .gitignore
*.jks
*.keystore
key.properties

Never commit your keystore. Using GitHub Secrets keeps the signing process secure even in cloud builds.

First build is slower

The first run downloads Flutter and all dependencies (~15 min). Subsequent builds use subosito/flutter-action's cache and are significantly faster.

Comparison

	Local build	GitHub Actions
Build time	10+ min (low-spec PC)	~15 min first run, faster after
CPU/fan	Maxed out	Zero
Disk usage	build/ folder bloats	Zero
Android SDK needed	Yes	No

If you're on a low-spec machine or just want a cleaner local environment, this setup works well.