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mikrotik-tailscale/Dockerfile
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2026-06-16 02:01:02 +00:00

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Docker

# syntax=docker/dockerfile:1.24.0@sha256:87999aa3d42bdc6bea60565083ee17e86d1f3339802f543c0d03998580f9cb89
# =============================================================================
# Multi-architecture build
# =============================================================================
# Supported MikroTik Container architectures (build with `docker buildx`):
# linux/amd64 x86 / CHR
# linux/arm64 RB5009, CCR2xxx, hAP ax3, L009, Chateau (most modern)
# linux/arm/v7 ARMv7: hAP ac2, RB3011, RB4011, RB1100AHx4
#
# NOT supported here: ARMv5 (hEX Refresh / hAP ax S, EN7562CT CPU). ARMv5 has
# no Alpine/musl base image, so it cannot use the musl + scratch design below;
# it would need a glibc (Debian) base and produces a much larger image. See
# README for details if you need it.
#
# Both the Go (Tailscale) stage and the C (busybox) stage cross-compile: they
# always run NATIVELY on the build host ($BUILDPLATFORM) and produce binaries
# for $TARGETPLATFORM. This eliminates QEMU emulation entirely from the build,
# which is the main source of slowness in multi-arch builds. Only the final
# scratch stage pulls in the target-arch-specific layers (CA certs, busybox
# rootfs) which are just file copies with no emulated execution.
#
# Cross-compilation for C (busybox) is provided by tonistiigi/xx, which
# configures clang+lld as a cross-compiler and installs musl headers for the
# target arch via xx-apk.
# =============================================================================
# xx: Dockerfile cross-compilation helpers (provides xx-clang, xx-apk, etc.)
# =============================================================================
# renovate: datasource=docker depName=tonistiigi/xx versioning=docker
FROM --platform=$BUILDPLATFORM tonistiigi/xx:1.9.0@sha256:c64defb9ed5a91eacb37f96ccc3d4cd72521c4bd18d5442905b95e2226b0e707 AS xx
# =============================================================================
# Stage 1: Build Tailscale combined binary (cross-compiled, runs natively)
# =============================================================================
FROM --platform=$BUILDPLATFORM golang:1.26.4-alpine@sha256:f1ddd9fe14fffc091dd98cb4bfa999f32c5fc77d2f2305ea9f0e2595c5437c14 AS builder
# renovate: datasource=github-releases depName=tailscale packageName=tailscale/tailscale versioning=semver
ARG TAILSCALE_VERSION=v1.98.5
# Provided automatically by buildx for the target platform.
ARG TARGETOS
ARG TARGETARCH
ARG TARGETVARIANT
RUN apk add --no-cache \
git \
upx \
ca-certificates
# Clone the exact release tag (no full history)
RUN git clone --depth 1 --branch ${TAILSCALE_VERSION} \
https://github.com/tailscale/tailscale.git /src/tailscale
WORKDIR /src/tailscale
# Inject a stderr verbosity filter into the tailscaled package.
#
# With logtail compiled out (ts_omit_logtail), tailscaled never installs
# logpolicy (see `if buildfeatures.HasLogTail` in cmd/tailscaled/tailscaled.go),
# so log output goes raw to stderr: the [v1]/[v2] verbosity tags embedded in
# messages are neither parsed nor filtered, and --verbose has NO effect. The
# result is constant log spam in the RouterOS container log (filter
# "Accept: TCP" verdicts, "netcheck: [v1] report", "wg: [v2]" handshakes and
# keepalives) — see tailscale/tailscale#12158 and #1548.
#
# The injected file (build-tagged ts_omit_logtail, so it's a no-op if logtail
# is ever re-enabled) registers a log writer in init() that drops lines
# carrying a [v1]+ tag, restoring the equivalent of logtail's StderrLevel=0
# default. Setting TS_LOG_VERBOSITY=1 (or higher) in the container environment
# disables the filter at runtime for debugging — no rebuild needed.
COPY patches/stderr_verbosity_filter.go cmd/tailscaled/
# Patch net/tstun/wrap.go: fix panic("unreachable") in invertGSOChecksum for
# ts_omit_netstack builds.
#
# invertGSOChecksum is a gVisor/GSO helper that inverts a transport-layer
# checksum before/after SNAT when gVisor hands us a segment with a partial
# checksum (NeedsCsum=true). It is only meaningful when netstack (gVisor) is
# compiled in (HasNetstack=true).
#
# The function correctly guards its body with:
# if !buildfeatures.HasNetstack { panic("unreachable") }
#
# When built with ts_omit_netstack, HasNetstack is a const false, so that guard
# evaluates to `if true { panic(...) }` — the function always panics.
#
# The problem: invertGSOChecksum is called unconditionally from injectedRead()
# (twice, around pc.snat()), even for the res.data path where res.packet==nil
# and gso is a zero-value netstack_GSO (NeedsCsum=false). The HasNetstack
# guard in the res.packet branch does NOT protect these calls.
#
# As a result, any code path that injects an outbound packet via InjectOutbound()
# — which happens when enabling exit-node use (Tailscale sends TSMP messages
# and synthesizes packets through the TUN injection path) — hits injectedRead
# with res.data!=nil, calls invertGSOChecksum, and crashes with:
# panic: unreachable
# tailscale.com/net/tstun.invertGSOChecksum(...)
# tailscale.com/net/tstun.(*Wrapper).injectedRead(...) wrap.go:1077
#
# Fix: replace the `panic("unreachable")` with a `return` in invertGSOChecksum.
# When HasNetstack=false (ts_omit_netstack), a zero-value netstack_GSO always
# has NeedsCsum=false, so the function is correctly a no-op anyway. This matches
# what the function would do if the rest of its body ran: NeedsCsum=false → return.
#
# The sed expression targets the function precisely: it matches the three-line
# sequence that opens invertGSOChecksum's HasNetstack guard, and replaces only
# the panic line with return. The pattern is stable across minor reformats
# because it anchors on the literal function comment and the specific panic string.
#
# See tailscale/tailscale issue for context (no upstream fix as of v1.98.5):
# panic happens when using exit-node via a ts_omit_netstack build.
RUN sed -i \
-e '/func invertGSOChecksum/,/^}/ s/\t\tpanic("unreachable")/\t\treturn/' \
net/tstun/wrap.go
# Build a minimal combined binary (tailscale CLI + tailscaled daemon in one file).
#
# Tag strategy — ALLOWLIST, not blocklist:
# 1. cmd/featuretags --min --add=osrouter generates the full ts_omit_* set
# (identical to build_dist.sh --extra-small), omitting every optional feature.
# 2. We pipe that through sed to REMOVE the ts_omit_ tags for the features
# we explicitly want, leaving everything else omitted.
# 3. We prepend ts_include_cli (combined daemon+CLI binary).
#
# This means any NEW ts_omit_* tag added in a future Tailscale release will
# automatically be omitted — we only get features we consciously opt into.
#
# Features opted in (removed from the omit list):
# advertiseexitnode — run as exit node for the tailnet
# advertiseroutes — advertise LAN subnets to the tailnet
# useexitnode — route router's own traffic via a remote exit node
# useroutes — accept routes advertised by other tailnet nodes
# dns — MagicDNS; configure MikroTik DNS to forward
# *.ts.net → 100.100.100.100; use --no-dns daemon
# flag to skip writing /etc/resolv.conf
# portmapper — NAT-PMP / PCP / UPnP to punch through upstream NAT
# listenrawdisco — raw sockets for more robust disco/NAT-traversal
# health — health subsystem required by 'tailscale status'
# iptables — Linux iptables support for routing rules
# unixsocketidentity — REQUIRED for the CLI to talk to the daemon. Without it,
# the localapi can't verify a request arrived over the
# trusted unix socket, so PermitRead/PermitWrite are
# always false and EVERY CLI call (status, up, set, ...)
# returns "access denied" (tailscale/tailscale#17873).
# ipnbus — IPN bus watch. Without it, 'tailscale up' cannot wait
# for completion: it fires config at the daemon and
# returns immediately ("built with ts_omit_ipnbus; not
# waiting for completion") WITHOUT printing the auth URL
# or confirming success. Including it makes interactive
# 'up' behave normally (blocks, prints login URL).
#
# Everything else remains omitted, including (rationale):
# clientupdate — DELIBERATELY removed. The built-in updater would download
# the FULL official upstream tailscale binary (tens of MB,
# with all features) directly onto the device, defeating the
# entire point of this minimal build and risking filling the
# 16 MB flash. It also can't update a binary baked into a
# read-only container image. Updates are instead delivered by
# rebuilding/republishing this image (CI) and pulling the new
# image only when it actually changed (see the RouterOS
# update script). This keeps the on-device footprint minimal
# and the update path controlled, reproducible, and flash-safe.
# cachenetmap — DELIBERATELY omitted. It ONLY persists the netmap to disk so
# the node can come online from the last-known config after a
# COLD START while the control plane is simultaneously
# unreachable. The in-memory netmap is NOT gated by this tag:
# a running daemon that loses its control connection keeps its
# map and can still reach known peers (data path is direct
# WireGuard/DERP, not via control). The only loss is the narrow
# reboot-during-control-outage case. In exchange we avoid disk
# writes on every netmap delta (frequent on busy tailnets),
# which is exactly the flash wear we want to avoid.
# logtail — no persistent log writes to flash; also pass
# --no-logs-no-support at runtime
# netstack+gro — userspace networking; router uses kernel TUN
# ssh — not needed; access via MikroTik SSH + tailscale CLI
# all GUI/desktop/cloud/k8s features — irrelevant for a headless router
RUN mkdir -p /out && \
ALL_OMIT=$(GOOS= GOARCH= go run ./cmd/featuretags --min --add=osrouter) && \
TAGS=$(echo "ts_include_cli,${ALL_OMIT}" | \
sed \
-e 's/ts_omit_advertiseexitnode,\{0,1\}//g' \
-e 's/ts_omit_advertiseroutes,\{0,1\}//g' \
-e 's/ts_omit_useexitnode,\{0,1\}//g' \
-e 's/ts_omit_useroutes,\{0,1\}//g' \
-e 's/ts_omit_dns,\{0,1\}//g' \
-e 's/ts_omit_portmapper,\{0,1\}//g' \
-e 's/ts_omit_listenrawdisco,\{0,1\}//g' \
-e 's/ts_omit_health,\{0,1\}//g' \
-e 's/ts_omit_iptables,\{0,1\}//g' \
-e 's/ts_omit_unixsocketidentity,\{0,1\}//g' \
-e 's/ts_omit_ipnbus,\{0,1\}//g' \
-e 's/,$//' \
) && \
echo "Build tags: ${TAGS}" && \
# Map Docker's TARGETARCH/TARGETVARIANT to Go's GOARCH/GOARM.
# For arm/v7 -> GOARM=7 (hardfloat). Other arches leave GOARM unset.
GOARM="" && \
if [ "${TARGETARCH}" = "arm" ]; then \
case "${TARGETVARIANT}" in \
v7) GOARM=7 ;; \
v6) GOARM=6 ;; \
v5) GOARM=5 ;; \
*) GOARM=7 ;; \
esac; \
fi && \
echo "Cross-compiling: GOOS=${TARGETOS:-linux} GOARCH=${TARGETARCH} GOARM=${GOARM}" && \
CGO_ENABLED=0 GOOS=${TARGETOS:-linux} GOARCH=${TARGETARCH} GOARM=${GOARM} \
go build \
-tags "${TAGS}" \
-gcflags="all=-l" \
-ldflags="-s -w" \
-trimpath \
-o /out/tailscale.combined \
./cmd/tailscaled
# Compress with UPX LZMA.
# Expected: ~14 MB raw → ~3.8 MB compressed (with -gcflags=all=-l)
RUN upx --lzma --best /out/tailscale.combined
# Lay out the final /usr/local/bin HERE (binary + argv[0] symlinks) so the final
# stage can bring it in with a SINGLE COPY layer. Creating the symlinks with a
# `RUN` in the final scratch stage instead would force overlayfs to copy-up the
# whole directory — duplicating the ~3 MB binary into another layer and roughly
# doubling the extracted on-disk size on RouterOS (overlay layers are extracted
# separately). Building it in one place keeps it to one copy.
RUN mkdir -p /out/usrlocalbin && \
mv /out/tailscale.combined /out/usrlocalbin/tailscale.combined && \
ln -s /usr/local/bin/tailscale.combined /out/usrlocalbin/tailscale && \
ln -s /usr/local/bin/tailscale.combined /out/usrlocalbin/tailscaled
# Entrypoint wrapper: enable IP forwarding inside the container's network
# namespace, then exec tailscaled. tailscaled does NOT reliably enable IPv6
# forwarding itself in a container netns ("IPv6 forwarding is disabled" warning),
# which silently breaks advertised IPv6 subnet routes. The sysctls ARE writable
# from inside a RouterOS container, so we set both here. Written in the builder
# stage so it ships in the same single /usr/local/bin COPY layer (preserves the
# overlayfs single-copy property). `exec` keeps tailscaled as PID 1.
RUN printf '%s\n' \
'#!/bin/sh' \
'# Enable IPv4/IPv6 forwarding. Required for advertised subnet routes and' \
'# exit-node functionality.' \
'for f in /proc/sys/net/ipv4/ip_forward /proc/sys/net/ipv6/conf/all/forwarding; do' \
' if [ -w "$f" ]; then echo 1 > "$f" 2>/dev/null || echo "warn: could not write $f"; fi' \
'done' \
'exec /usr/local/bin/tailscaled "$@"' \
> /out/usrlocalbin/entrypoint.sh && \
chmod +x /out/usrlocalbin/entrypoint.sh
# =============================================================================
# Stage 2: Custom minimal busybox (cross-compiled, runs natively on build host)
# =============================================================================
# The official busybox:musl image ships all ~404 applets at ~1.24 MB. For a
# debug shell on a flash-constrained router we only need ~100 applets, so we
# build a static busybox from source with a curated applet set, then UPX it
# down to ~230 kB on disk.
#
# UPX is normally dangerous with busybox: the ash shell's standalone applet
# dispatch re-execs /proc/self/exe, which UPX breaks, so typed commands fail
# (https://github.com/upx/upx/issues/248, closed as "invalid"). We sidestep
# this by building WITHOUT the standalone/nofork features (see
# busybox-applets.config) and providing an explicit /bin/<applet> symlink
# farm. Commands then resolve via the ordinary PATH -> symlink -> argv[0]
# dispatch, which works fine under UPX. The cost is a fork+exec per command,
# acceptable for an occasional debug shell. RouterOS stores the EXTRACTED
# rootfs on disk (overlayfs), so the ~190 kB UPX saving is real on-disk space.
#
# This stage runs NATIVELY on the build host (--platform=$BUILDPLATFORM) and
# cross-compiles busybox for the target architecture using clang+lld via the
# tonistiigi/xx helpers. This eliminates QEMU emulation from the busybox build,
# which was the main source of slowness for arm64/arm/v7 targets.
#
# Cross-compilation setup:
# - xx-apk installs musl-dev and linux-headers for the TARGET arch under
# /<triple> (a secondary sysroot), while clang/lld/upx/make stay native.
# - xx-clang --setup-target-triple creates <triple>-clang / <triple>-cc
# aliases in PATH that busybox's Makefile picks up via CROSS_COMPILE.
# - Busybox make receives:
# CROSS_COMPILE=<triple>- → picks up <triple>-clang (from xx aliases)
# CC=clang → use clang (aliased target via CROSS_COMPILE)
# HOSTCC=gcc → compile host helper tools with native gcc
# - upx (native x86_64 binary) can compress target-arch binaries since UPX
# operates on the ELF file format regardless of the target ISA.
#
# Applet symlink probing: for native-arch builds the probe runs directly;
# for cross-compiled binaries we use QEMU user-mode emulation (from binfmt)
# only for this one lightweight probe step (busybox --help per applet), not
# for the compile itself. The probe can alternatively be skipped by using
# a pre-enumerated applet list, but the current approach is simpler.
FROM --platform=$BUILDPLATFORM alpine:3.24.0@sha256:a2d49ea686c2adfe3c992e47dc3b5e7fa6e6b5055609400dc2acaeb241c829f4 AS busybox
# Copy xx cross-compilation helpers (xx-clang, xx-apk, xx-info, etc.)
COPY --from=xx / /
# renovate: datasource=docker depName=busybox versioning=docker
ARG BUSYBOX_VERSION=1.38.0
# Target platform ARGs (provided automatically by buildx).
ARG TARGETPLATFORM
ARG TARGETARCH
ARG TARGETVARIANT
# Native build tools (clang/lld for cross-compiling; gcc/make/upx run natively).
# xx-apk installs the target-arch sysroot: musl-dev (C library headers + CRT),
# gcc (provides crtbeginS.o/crtendS.o and libgcc needed by clang on Alpine),
# and linux-headers (required by busybox for <linux/*.h> / <net/*.h>).
RUN apk add --no-cache \
clang \
lld \
llvm \
gcc \
make \
wget \
bzip2 \
perl \
upx && \
xx-apk add --no-cache musl-dev gcc linux-headers
RUN wget -q https://busybox.net/downloads/busybox-${BUSYBOX_VERSION}.tar.bz2 \
&& tar xf busybox-${BUSYBOX_VERSION}.tar.bz2
WORKDIR /busybox-${BUSYBOX_VERSION}
# allnoconfig = every feature OFF; then enable only the curated applet set.
COPY busybox-applets.config /tmp/applets.config
# Set up xx cross-compiler aliases (<triple>-clang, <triple>-cc, etc.) and
# build busybox.
#
# Key make variables:
# ARCH — busybox ARCH; must match the cross-target, not the build
# host. busybox's Makefile would otherwise read SUBARCH from
# `uname -m` (the BUILD host's arch) which is wrong when
# cross-compiling. We map TARGETARCH to busybox's arch name.
# busybox uses -include arch/$(ARCH)/Makefile; missing arch
# dirs are silently ignored, so any value is safe.
# CC — busybox defaults to $(CROSS_COMPILE)gcc. We override CC to
# the full <triple>-clang path so it resolves to the xx alias
# (which sets --target and --sysroot for the cross-compiler).
# Setting CC= avoids needing a <triple>-gcc symlink.
# HOSTCC — native compiler for host-side build tools (scripts/kconfig,
# gen_build_files, etc.); must NOT be the cross-compiler.
# SKIP_STRIP — defer stripping to after symlink probing (we strip below
# with llvm-strip, which handles any target ELF arch).
RUN xx-clang --setup-target-triple && \
CROSS=$(xx-info triple) && \
# Map TARGETARCH to the busybox ARCH value.
case "${TARGETARCH}" in \
amd64) BUSYBOX_ARCH=x86_64 ;; \
arm64) BUSYBOX_ARCH=aarch64 ;; \
arm) BUSYBOX_ARCH=arm ;; \
*) BUSYBOX_ARCH=${TARGETARCH} ;; \
esac && \
make allnoconfig ARCH="${BUSYBOX_ARCH}" && \
while read -r sym; do \
case "$sym" in ''|\#*) continue ;; esac; \
if grep -q "^# CONFIG_${sym} is not set" .config; then \
sed -i "s/^# CONFIG_${sym} is not set/CONFIG_${sym}=y/" .config; \
elif ! grep -q "^CONFIG_${sym}=y" .config; then \
echo "CONFIG_${sym}=y" >> .config; \
fi; \
done < /tmp/applets.config && \
yes "" | make oldconfig ARCH="${BUSYBOX_ARCH}" >/dev/null 2>&1 && \
make -j"$(nproc)" \
ARCH="${BUSYBOX_ARCH}" \
CROSS_COMPILE="${CROSS}-" \
CC="${CROSS}-clang" \
HOSTCC=gcc \
SKIP_STRIP=y \
>/dev/null 2>&1 && \
llvm-strip busybox
# Lay out a minimal rootfs with busybox + an applet symlink per applet.
# Symlinks (argv[0] dispatch) are how busybox selects an applet and make the
# applets resolvable via $PATH from inside the shell. We derive the applet
# names from the build .config: a symbol is an applet if its lowercase name
# resolves to a runnable applet (busybox returns "applet not found" on stderr
# for non-applet symbols like FEATURE_* / STATIC, which we filter out).
# We generate symlinks from the UNCOMPRESSED binary (so the probe is reliable),
# then UPX-compress the binary in place afterwards.
#
# Note: probing cross-compiled binaries requires binfmt/QEMU user-mode. This
# is only a lightweight per-applet help-flag check, not a full emulated build.
# If QEMU is unavailable in CI, replace the probe with a static applet list.
RUN mkdir -p /rootfs/bin && \
grep '^CONFIG_.*=y' .config \
| sed -e 's/^CONFIG_//' -e 's/=y$//' \
| tr 'A-Z' 'a-z' \
| while read -r app; do \
if ! ./busybox "$app" --help 2>&1 | grep -q "applet not found"; then \
ln -sf /bin/busybox /rootfs/bin/"$app"; \
fi; \
done && \
ln -sf /bin/busybox /rootfs/bin/sh && \
echo "Applet symlinks created: $(ls /rootfs/bin | wc -l)" && \
upx --lzma --best busybox && \
cp busybox /rootfs/bin/busybox
# =============================================================================
# Stage 3: Final runtime image
# =============================================================================
FROM scratch
# Release version (the git tag, e.g. v1.98.3-mt.1), injected by CI at build
# time. This is the value the MikroTik update cronjob compares against the
# registry to decide whether to recreate the container: it changes ONLY on a
# meaningful release (Tailscale bump -> mt.1, or a manual mt.N), never on a
# build-system-only rebuild. Defaults to "dev" for local builds.
ARG OCI_VERSION=dev
# OCI image annotations. org.opencontainers.image.version is the canonical place
# for the release version and is what the router reads back from the registry.
LABEL org.opencontainers.image.title="mikrotik-tailscale" \
org.opencontainers.image.description="Minimal Tailscale image for MikroTik RouterOS Container" \
org.opencontainers.image.source="https://gitea.lumpiasty.xyz/lumpiasty/mikrotik-tailscale" \
org.opencontainers.image.version="${OCI_VERSION}"
# Custom static busybox + applet symlinks (provides /bin/sh and utilities)
COPY --from=busybox /rootfs/ /
# CA certificates (needed to reach Tailscale coordination server)
COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
# Combined Tailscale binary + its argv[0] symlinks, in a single layer (built in
# the builder stage to avoid overlayfs copy-up duplicating the binary — see the
# builder stage comment).
COPY --from=builder /out/usrlocalbin/ /usr/local/bin/
# Ensure /usr/local/bin and busybox dirs are on PATH for interactive shells
ENV PATH=/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
# -----------------------------------------------------------------------------
# Volume layout (to be created by deploy script):
#
# /var/lib/tailscale — persistent state (authkey, node identity)
# → bind-mount to MikroTik disk storage
# → survives reboots, written infrequently (only on
# auth / key rotation / prefs change)
# → netmap is NOT cached to disk (cachenetmap is
# omitted), so this dir sees no per-netmap writes
#
# /var/run/tailscale — runtime socket dir
# → tmpfs, lost on reboot (expected)
# -----------------------------------------------------------------------------
VOLUME ["/var/lib/tailscale"]
# entrypoint.sh enables IP forwarding (incl. IPv6) in the container netns, then
# exec's tailscaled with the CMD flags below as its arguments.
ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]
# Default flags:
# --no-logs-no-support disables logtail uploads (logtail binary code is
# omitted, but the flag also suppresses any remaining
# log buffering and prevents the daemon from trying
# to write log files)
# --state persistent node identity / authkey storage
# --socket CLI communication socket (on tmpfs)
# --statedir var root (derpmap cache, certs, etc.); no netmap
# disk cache here since cachenetmap is omitted
CMD ["--no-logs-no-support", \
"--state=/var/lib/tailscale/tailscaled.state", \
"--socket=/var/run/tailscale/tailscaled.sock", \
"--statedir=/var/lib/tailscale"]