ci: Add nix build w/ smoketest. (closes #111)

docker: Add target for nix build. (#111)

Signed-off-by: Jason Volk <jason@zemos.net>

docker/Dockerfile.nix

@@ -0,0 +1,87 @@
+# syntax = docker/dockerfile:1.11-labs
+
+FROM input AS nix-base
+ARG sys_name
+ARG sys_version
+ARG sys_target
+
+WORKDIR /
+COPY --link --from=input . .
+RUN \
+--mount=type=cache,dst=/nix,sharing=shared \
+--mount=type=cache,dst=/root/.cache/nix,sharing=shared \
+--mount=type=cache,dst=/root/.local/state/nix,sharing=shared \
+<<EOF
+	set -eux
+	curl --proto '=https' --tlsv1.2 -L https://nixos.org/nix/install > nix-install
+	sh ./nix-install --daemon
+	rm nix-install
+EOF
+
+
+FROM nix-base AS build-nix
+ARG sys_name
+ARG sys_version
+ARG sys_target
+
+WORKDIR /usr/src/tuwunel
+COPY --link --from=source /usr/src/tuwunel .
+RUN \
+--mount=type=cache,dst=/nix,sharing=shared \
+--mount=type=cache,dst=/root/.cache/nix,sharing=shared \
+--mount=type=cache,dst=/root/.local/state/nix,sharing=shared \
+<<EOF
+	set -eux
+	nix-build \
+		--cores 0 \
+		--max-jobs $(nproc) \
+		--log-format raw \
+		.
+
+	cp -afRL --copy-contents result /opt/tuwunel
+EOF
+
+
+FROM build-nix AS smoke-nix
+ARG sys_name
+ARG sys_version
+ARG sys_target
+
+WORKDIR /
+COPY --link --from=build-nix . .
+
+WORKDIR /opt/tuwunel
+ENV TUWUNEL_DATABASE_PATH="/tmp/smoketest.db"
+ENV TUWUNEL_LOG="info"
+RUN \
+--mount=type=cache,dst=/nix,sharing=shared \
+--mount=type=cache,dst=/root/.cache/nix,sharing=shared \
+--mount=type=cache,dst=/root/.local/state/nix,sharing=shared \
+<<EOF
+    set -eux
+    bin/tuwunel \
+        -Otest='["smoke"]' \
+        -Oserver_name=\"localhost\" \
+        -Odatabase_path=\"${TUWUNEL_DATABASE_PATH}\"
+
+    rm -rf "${TUWUNEL_DATABASE_PATH}"
+EOF
+
+
+FROM build-nix AS nix-pkg
+ARG sys_name
+ARG sys_version
+ARG sys_target
+
+WORKDIR /
+COPY --link --from=build-nix . .
+
+WORKDIR /usr/src/tuwunel
+RUN \
+--mount=type=cache,dst=/nix,sharing=shared \
+--mount=type=cache,dst=/root/.cache/nix,sharing=shared \
+--mount=type=cache,dst=/root/.local/state/nix,sharing=shared \
+<<EOF
+	set -eux
+    #TODO: extract derivation?
+EOF