Add simple Dockerfile for local/development builds

.dockerignore

@@ -2,5 +2,5 @@
 !cmd/
 !go.mod
 !go.sum
-!scripts/bashbrew-arch-to-goenv.sh
+!scripts/
 !vendor/

Dockerfile

@@ -0,0 +1,29 @@
+FROM tianon/docker-tianon
+
+SHELL ["bash", "-Eeuo", "pipefail", "-xc"]
+
+RUN apt-get update; \
+	apt-get install -y --no-install-recommends \
+		golang-go \
+	; \
+	rm -rf /var/lib/apt/lists/*
+
+WORKDIR /usr/src/bashbrew
+COPY go.mod go.sum ./
+COPY cmd cmd
+COPY vendor vendor
+RUN export CGO_ENABLED=0; \
+	go build -mod vendor -v -o /usr/local/bin/bashbrew ./cmd/bashbrew; \
+	rm -r ~/.cache/go-build; \
+	bashbrew --help > /dev/null
+
+ENV BASHBREW_CACHE /bashbrew-cache
+# make sure our default cache dir exists and is writable by anyone (similar to /tmp)
+RUN mkdir -p "$BASHBREW_CACHE"; \
+	chmod 1777 "$BASHBREW_CACHE"
+# (this allows us to decide at runtime the exact uid/gid we'd like to run as)
+
+VOLUME $BASHBREW_CACHE
+
+COPY scripts/bashbrew-entrypoint.sh /usr/local/bin/
+ENTRYPOINT ["bashbrew-entrypoint.sh"]