diff --git a/Dockerfile b/Dockerfile index 118f35b..d96090c 100644 --- a/Dockerfile +++ b/Dockerfile @@ -157,6 +157,25 @@ RUN mkdir -p /out/usrlocalbin && \ 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 (best-effort; sysctls are writable inside' \ + '# a RouterOS container netns). 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 # ============================================================================= @@ -274,7 +293,9 @@ ENV PATH=/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin # ----------------------------------------------------------------------------- VOLUME ["/var/lib/tailscale"] -ENTRYPOINT ["/usr/local/bin/tailscaled"] +# 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 diff --git a/docs/DESIGN.md b/docs/DESIGN.md index 7755d40..07d4be4 100644 --- a/docs/DESIGN.md +++ b/docs/DESIGN.md @@ -70,8 +70,21 @@ in a future release stays omitted until deliberately added to the Dockerfile. saves a real ~195 kB of flash (424 kB → 229 kB), not just transfer size. The final image is built `FROM scratch` — there is no base distro layer. -It contains only the busybox binary + applet symlinks, the CA bundle, and -the Tailscale binary. +It contains only the busybox binary + applet symlinks, the CA bundle, the +Tailscale binary, and a tiny `entrypoint.sh`. + +### Entrypoint: IP forwarding + +`ENTRYPOINT` is a small `entrypoint.sh` that enables IPv4 and IPv6 forwarding +(`net.ipv4.ip_forward`, `net.ipv6.conf.all.forwarding`) in the container's +network namespace, then `exec`s `tailscaled` (so the daemon stays PID 1). This +is necessary because `tailscaled` does **not** reliably enable IPv6 forwarding +itself inside a container netns — it logs "IPv6 forwarding is disabled" and +advertised IPv6 subnet routes silently fail. The sysctls are writable from +inside a RouterOS container, so the entrypoint sets them directly; no +host-side or `/container` configuration is required. The script is created in +the builder stage so it ships in the same single `/usr/local/bin` `COPY` layer +(preserving the [single-copy property](#avoiding-overlayfs-layer-duplication)). ### Avoiding overlayfs layer duplication diff --git a/docs/USAGE.md b/docs/USAGE.md index e8e9a27..74640e3 100644 --- a/docs/USAGE.md +++ b/docs/USAGE.md @@ -95,7 +95,8 @@ The daemon is now running but **not yet authenticated**. ### 5. Authenticate -> This image runs `tailscaled` directly and does **not** bundle Tailscale's +> This image runs `tailscaled` via a tiny entrypoint (which enables IP +forwarding, then `exec`s the daemon) and does **not** bundle Tailscale's `containerboot` wrapper, so the `TS_AUTHKEY` environment variable is **not** read automatically. You authenticate with `tailscale up --authkey=...` after the container starts. @@ -119,6 +120,12 @@ The node now appears in your Tailscale admin console. Approve the advertised routes / exit node there. Because the auth state is written to the persisted `tailscaled.state`, you only do this once — it survives reboots and updates. +> **IP forwarding** (IPv4 and IPv6) is enabled automatically by the container's +> entrypoint, so advertised subnet routes and exit-node traffic work without any +> extra `sysctl`/`/container` configuration. (IPv6 forwarding in particular is +> not reliably enabled by `tailscaled` itself inside a container network +> namespace, so the entrypoint sets it explicitly.) + ### 6. Enable automatic updates First, edit the `CONFIG` block at the top of `routeros/update-tailscale.rsc` if