[lbry] ci: update Dockerfile

Dockerfile

@@ -0,0 +1,39 @@
+# This Dockerfile builds lbcwallet from source and creates a small (55 MB) docker container based on alpine linux.
+#
+# Clone this repository and run the following command to build and tag a fresh lbcwallet amd64 container:
+#
+# docker build . -t yourregistry/lbcwallet
+#
+# You can use the following command to buid an arm64v8 container:
+#
+# docker build . -t yourregistry/lbcwallet --build-arg ARCH=arm64v8
+#
+# For more information how to use this docker image visit:
+# https://github.com/lbryio/lbcwallet/tree/master/docs
+#
+# 9244  Mainet Wallet RPC port
+
+ARG ARCH=amd64
+
+FROM golang:1.18.2 AS build-container
+
+ARG ARCH
+
+ADD . /app
+WORKDIR /app
+RUN set -ex \
+  && if [ "${ARCH}" = "amd64" ]; then export GOARCH=amd64; fi \
+  && if [ "${ARCH}" = "arm32v7" ]; then export GOARCH=arm; fi \
+  && if [ "${ARCH}" = "arm64v8" ]; then export GOARCH=arm64; fi \
+  && echo "Compiling for $GOARCH" \
+  && go install -v . ./cmd/...
+
+FROM $ARCH/debian:bullseye-20220418-slim
+
+COPY --from=build-container /go/bin /bin
+
+VOLUME ["/root/.lbcwallet"]
+
+EXPOSE 9244
+
+ENTRYPOINT ["lbcwallet"]