The signing key and the pre-release tick are the two things that silently make an update invisible, and neither is guessable from the code. Co-Authored-By: Claude <noreply@anthropic.com>
110 lines
4.6 KiB
Markdown
110 lines
4.6 KiB
Markdown
# Publishing an OTA release
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How to ship an update the car will install by itself. Written for whoever does this
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next — probably me, having forgotten the details.
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## What the updater actually looks for
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`OtaUpdater.check()` reads `https://api.github.com/repos/fatihdonmezdev/MG4ABRP/releases`
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and walks **every** entry, keeping the highest version rather than the first match. A
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release is a candidate only if all of these hold:
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| Requirement | Where it is enforced | What happens otherwise |
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|---|---|---|
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| Marked **pre-release** | `release.optBoolean("prerelease")` | Skipped entirely |
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| Asset name contains `unstable` | `name.contains("unstable")` | Asset ignored |
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| Asset name ends `-<version>.apk` | `ASSET_VERSION` regex | No version, asset ignored |
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| Version strictly higher than installed | `isNewer()` | Nothing to do, reports "Güncel" |
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| Download host on the allowlist | `isAllowedUrl()` | Refused and logged |
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| APK signed with the **same certificate** as the running app | `signatureMatchesRunningApp()` | Deleted, never installed |
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The last one is the one that bites. The car runs a platform-signed build; an APK signed
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with a debug key — or anyone else's key — is downloaded, rejected and deleted. Sign every
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release with the same platform key or the update silently never lands.
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The version comes from the **asset filename**, not the git tag. The tag can stay
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`unstable` forever and be moved; the filename is what identifies a build.
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## Release checklist
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1. **Raise the version.** `app/build.gradle`, `defaultConfig`:
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```gradle
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versionCode 20 // must increase — Android orders updates by this, not by name
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versionName "2.2.3"
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```
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The unstable flavour appends its own suffix, so `2.2.3` becomes `2.2.3.0-unstable`.
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Check what the installed build reports before picking a number: the app's About
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dialog shows it, and `isNewer` compares numerically segment by segment.
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2. **Build.**
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```bash
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./gradlew :app:assembleUnstableDebug
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```
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3. **Sign with the platform key.** Options come *before* the input APK — apksigner
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rejects the other order.
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```bash
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BT=~/Android/Sdk/build-tools/35.0.0
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KEYS=~/Desktop/Coding/LUMINA/DriveHub_Kamera/tools
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"$BT/zipalign" -f 4 \
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app/build/outputs/apk/unstable/debug/app-unstable-debug.apk aligned.apk
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"$BT/apksigner" sign \
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--key "$KEYS/platform.pk8" \
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--cert "$KEYS/platform.x509.pem" \
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--out FatihsMG4-unstable-2.2.3.apk \
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aligned.apk
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rm aligned.apk
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```
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The output filename **is** the version the updater reads. Name it
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`FatihsMG4-unstable-<version>.apk` and nothing else.
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4. **Verify the signer** before uploading. It must say `CN=Android`:
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```bash
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"$BT/apksigner" verify --print-certs FatihsMG4-unstable-2.2.3.apk | grep DN:
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```
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5. **Publish.** On github.com/fatihdonmezdev/MG4ABRP → Releases → Draft a new release:
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- tag: `unstable` (reuse it; the rolling tag is the design)
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- **tick "Set as a pre-release"** ← the whole thing is inert without this
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- attach the signed APK
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6. **Install it.** Open the app on the head unit and press the refresh button in the top
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bar. Expected toast: `Güncellendi: 2.2.3 — yeniden başlatın`.
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## When it says something else
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| Toast | Meaning |
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|---|---|
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| `Güncel (2.2.2.0-unstable)` | No release beat the installed version. Check the pre-release tick and the asset filename. |
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| `İndirme başarısız` | Release found, download did not complete. Usually no network. |
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| `Kurulum reddedildi (imza uyuşmuyor?)` | Signed with the wrong key — rebuild and re-sign with `platform.pk8`. |
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| `Güncelleme kontrolü başarısız` | The check threw. `adb logcat -s EVABRP.Update OtaUpdater` if a cable is available; otherwise the in-app Log page. |
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## Untested
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`OtaUpdater.install()` shells out to `/system/bin/pm install -r`, which only a
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platform-signed app may call. That is what this build is, so it should work — but it has
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never actually run on the car. If installs are refused with a signature that *does* match,
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the fallback is an `ACTION_INSTALL_PACKAGE` intent, which asks the driver to confirm
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instead of installing silently.
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## Why the check is manual
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The refresh button is the only trigger. `UpdateHook.checkInBackground(this)` also runs on
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app start, but the app is rarely launched — the upload service does the work, and the
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driver does not open the UI on every trip. The button is there so an update can be pulled
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deliberately rather than waiting for a launch that may not come.
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The upload service does **not** check for updates on its tick. Installing a new APK
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restarts the process, and doing that mid-drive would interrupt the telemetry the service
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exists to send.
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