Docker build env for windows/android

docker/build-env/README.md

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+# Build environments
+
+Dockerfiles that pin the same toolchain CI uses, so a developer can
+reproduce a CI build locally without installing platform SDKs on their
+workstation. The version pins in each `Dockerfile` must stay in lockstep
+with `.github/workflows/`.
+
+## `android/`
+
+Mirrors `.github/workflows/mobile-build-validation.yml` (`android_build`
+job). Carries Go 1.25.5, Adopt JDK 11, Android cmdline-tools 8512546,
+NDK 23.1.7779620 and gomobile pinned at the CI commit. Use it to
+produce `netbird.aar` from `./client/android`:
+
+```bash
+docker build -t netbird/build-android docker/build-env/android
+docker run --rm -v "$PWD:/src" -w /src netbird/build-android \
+    gomobile bind \
+    -o netbird.aar \
+    -javapkg=io.netbird.gomobile \
+    -ldflags="-checklinkname=0 \
+              -X golang.zx2c4.com/wireguard/ipc.socketDirectory=/data/data/io.netbird.client/cache/wireguard \
+              -X github.com/netbirdio/netbird/version.version=local" \
+    ./client/android
+```
+
+To build the full Android APK, bind-mount the `android-client` repo as
+well and run its own `./gradlew assembleDebug` from inside the
+container (the gradle wrapper ships with `android-client`).
+
+## `windows-cross/`
+
+Cross-compiles Windows binaries from Linux using `mingw-w64`. Lets you
+verify that `GOOS=windows go build ./...` compiles cleanly without
+needing a Windows VM. Cannot run Windows tests — the `golang-test-windows`
+CI job executes on a native `windows-latest` runner with wintun.dll
+and PsExec, neither of which lives under Linux containers.
+
+```bash
+docker build -t netbird/build-windows docker/build-env/windows-cross
+docker run --rm -v "$PWD:/src" -w /src netbird/build-windows \
+    bash -c 'GOOS=windows GOARCH=amd64 go build ./...'
+```
+
+## What is NOT here
+
+- **iOS / macOS**: cannot legally run macOS in Docker (Apple EULA),
+  and Xcode is not redistributable. The `ios_build` CI job uses a
+  `macos-latest` GitHub runner; locally you need a real Mac.
+
+- **Native Windows tests**: see note above. The Linux+mingw image
+  builds, it does not execute Windows-host code paths
+  (registry, wintun, services, PsExec workflows).
+
+When CI version pins change, update the corresponding `ARG` lines in
+the Dockerfiles and the README's table of versions.

docker/build-env/android/Dockerfile

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+# Android build environment.
+#
+# Mirrors the toolchain pinned by .github/workflows/mobile-build-validation.yml
+# so a `gomobile bind` against ./client/android in this image produces the
+# same netbird.aar that CI builds.
+#
+# Tooling versions (must stay in sync with the CI workflow):
+#   - Ubuntu 22.04 (matches the ubuntu-latest GitHub runner)
+#   - Go 1.25.5 (matches go.mod)
+#   - Adopt JDK 11 (matches actions/setup-java@v3 java-version: 11, distribution: adopt)
+#   - Android SDK cmdline-tools 8512546
+#   - Android NDK 23.1.7779620
+#   - gomobile commit v0.0.0-20251113184115-a159579294ab
+#
+# Usage (from the netbird repo root):
+#
+#   docker build -t netbird/build-android docker/build-env/android
+#
+#   # bind the netbird checkout in and run the same gomobile command CI runs
+#   docker run --rm -v "$PWD:/src" -w /src netbird/build-android \
+#       gomobile bind \
+#       -o netbird.aar \
+#       -javapkg=io.netbird.gomobile \
+#       -ldflags="-checklinkname=0 \
+#                 -X golang.zx2c4.com/wireguard/ipc.socketDirectory=/data/data/io.netbird.client/cache/wireguard \
+#                 -X github.com/netbirdio/netbird/version.version=local" \
+#       ./client/android
+#
+# To build the full APK, mount the android-client repo too and run
+# `./gradlew assembleDebug` from /android-client (this image carries
+# gradle's prerequisites JDK + Android SDK but not the gradle wrapper —
+# that ships with android-client).
+
+FROM ubuntu:22.04
+
+ARG DEBIAN_FRONTEND=noninteractive
+
+# Versions — bump in lockstep with .github/workflows/mobile-build-validation.yml.
+ARG GO_VERSION=1.25.5
+ARG ANDROID_CMDLINE_TOOLS_VERSION=8512546
+ARG ANDROID_NDK_VERSION=23.1.7779620
+ARG GOMOBILE_VERSION=v0.0.0-20251113184115-a159579294ab
+
+ENV ANDROID_HOME=/opt/android-sdk
+ENV ANDROID_NDK_HOME=${ANDROID_HOME}/ndk/${ANDROID_NDK_VERSION}
+ENV JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
+ENV GOPATH=/go
+ENV GOTOOLCHAIN=local
+ENV CGO_ENABLED=0
+ENV PATH=${GOPATH}/bin:/usr/local/go/bin:${ANDROID_HOME}/cmdline-tools/latest/bin:${ANDROID_HOME}/platform-tools:${JAVA_HOME}/bin:${PATH}
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        ca-certificates \
+        curl \
+        unzip \
+        git \
+        openjdk-11-jdk-headless \
+        build-essential \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Go (matches go.mod). actions/setup-go fetches the same tarball.
+RUN curl -fsSL "https://go.dev/dl/go${GO_VERSION}.linux-amd64.tar.gz" \
+        | tar -C /usr/local -xz \
+    && go version
+
+# Install Android SDK command-line tools, accept licenses, install NDK.
+RUN mkdir -p "${ANDROID_HOME}/cmdline-tools" \
+    && curl -fsSL -o /tmp/cmdline.zip \
+        "https://dl.google.com/android/repository/commandlinetools-linux-${ANDROID_CMDLINE_TOOLS_VERSION}_latest.zip" \
+    && unzip -q /tmp/cmdline.zip -d "${ANDROID_HOME}/cmdline-tools" \
+    && mv "${ANDROID_HOME}/cmdline-tools/cmdline-tools" "${ANDROID_HOME}/cmdline-tools/latest" \
+    && rm /tmp/cmdline.zip \
+    && yes | sdkmanager --licenses > /dev/null \
+    && sdkmanager --install "ndk;${ANDROID_NDK_VERSION}" "platform-tools" > /dev/null
+
+# Install gomobile at the same commit CI pins. Don't run `gomobile init` here:
+# `init` resolves the NDK at runtime, do it on the first bind in the mounted
+# workspace so the cache lands on the host volume.
+RUN GOBIN=/usr/local/bin go install "golang.org/x/mobile/cmd/gomobile@${GOMOBILE_VERSION}" \
+    && gomobile version
+
+WORKDIR /src
+
+# Default entrypoint is a plain shell so the image is composable: callers pass
+# the full gomobile / gradle command they want to run.
+CMD ["/bin/bash"]

docker/build-env/windows-cross/Dockerfile

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+# Windows-cross build environment.
+#
+# Cross-compiles Windows .exe targets from a Linux container using
+# mingw-w64. Mirrors the toolchain set used by
+# .github/workflows/golang-test-windows.yml insofar as that is possible
+# without a Windows kernel.
+#
+# IMPORTANT — what this image CAN do:
+#   - `GOOS=windows go build ./...` to validate that Windows builds compile
+#   - CGO Windows cross-compile via x86_64-w64-mingw32-gcc when CGO_ENABLED=1
+#     (matches CI's choco-installed mingw-w64)
+#
+# IMPORTANT — what this image CANNOT do:
+#   - Run Windows binaries (no Windows kernel under Docker on Linux).
+#   - Replicate the CI's `go test` runs which execute on a real
+#     windows-latest runner (wintun.dll, PsExec, registry, etc.).
+#     Use the CI for that or a native Windows VM.
+#
+# Usage (from the netbird repo root):
+#
+#   docker build -t netbird/build-windows docker/build-env/windows-cross
+#
+#   # Cross-compile a static client (.exe) from Linux:
+#   docker run --rm -v "$PWD:/src" -w /src netbird/build-windows \
+#       bash -c 'CGO_ENABLED=1 GOOS=windows GOARCH=amd64 \
+#           CC=x86_64-w64-mingw32-gcc CXX=x86_64-w64-mingw32-g++ \
+#           go build -o netbird.exe ./client'
+#
+#   # Just validate that everything *compiles* on Windows (no CGO):
+#   docker run --rm -v "$PWD:/src" -w /src netbird/build-windows \
+#       bash -c 'GOOS=windows GOARCH=amd64 go build ./...'
+#
+# Tooling versions (keep in sync with go.mod and any future explicit pin
+# documented in golang-test-windows.yml):
+#   - Ubuntu 22.04
+#   - Go 1.25.5 (matches go.mod)
+#   - mingw-w64 (Ubuntu package — pin further if drift becomes a problem)
+
+FROM ubuntu:22.04
+
+ARG DEBIAN_FRONTEND=noninteractive
+ARG GO_VERSION=1.25.5
+
+ENV GOPATH=/go
+ENV GOTOOLCHAIN=local
+ENV PATH=${GOPATH}/bin:/usr/local/go/bin:${PATH}
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        ca-certificates \
+        curl \
+        git \
+        build-essential \
+        mingw-w64 \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Go (matches go.mod).
+RUN curl -fsSL "https://go.dev/dl/go${GO_VERSION}.linux-amd64.tar.gz" \
+        | tar -C /usr/local -xz \
+    && go version
+
+WORKDIR /src
+
+CMD ["/bin/bash"]