Docker release

Makefile

@@ -38,14 +38,22 @@ endif
 
 DOCKER_TOOLS = docker run \
   --rm \
-  -v $(shell bash -c "go env GOCACHE || (mkdir -p /tmp/go-cache; echo /tmp/go-cache)"):/tmp/build/.cache \
-  -v $(shell bash -c "go env GOMODCACHE || (mkdir -p /tmp/go-modcache; echo /tmp/go-modcache)"):/tmp/build/.modcache \
+  -v $(shell bash -c "go env GOCACHE 2>/dev/null || (mkdir -p /tmp/go-cache; echo /tmp/go-cache)"):/tmp/build/.cache \
+  -v $(shell bash -c "go env GOMODCACHE 2>/dev/null || (mkdir -p /tmp/go-modcache; echo /tmp/go-modcache)"):/tmp/build/.modcache \
   -v $$(pwd):/build loop-tools
 
-GREEN := "\\033[0;32m"
-NC := "\\033[0m"
+DOCKER_RELEASE_BUILDER = docker run \
+  --rm \
+  -v $(shell bash -c "go env GOCACHE 2>/dev/null || (mkdir -p /tmp/go-cache; echo /tmp/go-cache)"):/tmp/build/.cache \
+  -v $(shell bash -c "go env GOMODCACHE 2>/dev/null || (mkdir -p /tmp/go-modcache; echo /tmp/go-modcache)"):/tmp/build/.modcache \
+  -v $$(pwd):/repo \
+  -e LOOPBUILDSYS='$(buildsys)' \
+  loop-release-builder
+
+GREEN=\033[0;32m
+NC=\033[0m
 define print
-	echo $(GREEN)$1$(NC)
+	@printf '%b%s%b\n' '${GREEN}' $1 '${NC}'
 endef
 
 # ============
@@ -71,6 +79,13 @@ install:
 	$(GOINSTALL) -tags="${tags}" $(LDFLAGS) $(PKG)/cmd/loop
 	$(GOINSTALL) -tags="${tags}" $(LDFLAGS) $(PKG)/cmd/loopd
 
+# docker-release: Same as release.sh but within a docker container to support
+# reproducible builds on any platform.
+docker-release: docker-release-builder
+	@$(call print, "Building release binaries in docker.")
+	@if [ "$(tag)" = "" ]; then echo "Must specify tag=<commit_or_tag>!"; exit 1; fi
+	$(DOCKER_RELEASE_BUILDER) bash release.sh $(tag)
+
 rpc:
 	@$(call print, "Compiling protos.")
 	cd ./swapserverrpc; ./gen_protos_docker.sh
@@ -131,6 +146,10 @@ docker-tools:
 	@$(call print, "Building tools docker image.")
 	docker build -q -t loop-tools $(TOOLS_DIR)
 
+docker-release-builder:
+	@$(call print, "Building release builder docker image.")
+	docker build -q -t loop-release-builder -f release.Dockerfile .
+
 mod-tidy:
 	@$(call print, "Tidying modules.")
 	$(GOMOD) tidy

README.md

@@ -125,3 +125,8 @@ git clone https://github.com/lightninglabs/loop.git
 cd loop/cmd
 go install ./...
 ```
+
+## Reproducible builds
+
+If you want to build release files yourself, follow
+[the guide](./docs/release.md).

docs/release.md

@@ -0,0 +1,107 @@
+# Reproducible Builds
+
+## Building with Docker
+
+To create a Loop release with binaries that are identical to an official
+release, run the following command (available since release `v0.31.3-beta`):
+
+```bash
+make docker-release tag=<tag-of-release>
+```
+
+This command will create a directory named `loop-<tag-of-release>` containing
+the source archive, vendored dependencies, and the built binaries packaged in
+`.tar.gz` or `.zip` format. It also creates a manifest file with `SHA-256`
+checksums for all release files.
+
+For example:
+
+```bash
+make docker-release tag=v0.31.3-beta
+```
+
+This will create the release artifacts in the `loop-v0.31.3-beta` directory.
+
+If you want to build from an untagged commit, first check it out, then use the
+output of `git describe --abbrev=10` as the tag:
+
+```bash
+git describe --abbrev=10
+# v0.31.2-beta-135-g35d0fa26ac
+
+make docker-release tag=v0.31.2-beta-135-g35d0fa26ac
+```
+
+You can filter the target platforms to speed up the build process. For example,
+to build only for `linux-amd64`:
+
+```bash
+make docker-release buildsys=linux-amd64 tag=v0.31.3-beta
+```
+
+Or for multiple platforms:
+
+```bash
+make docker-release buildsys='linux-amd64 windows-amd64' tag=v0.31.3-beta
+```
+
+Note: inside Docker the current directory is mapped as `/repo` and it might
+mention `/repo` as parts of file paths.
+
+## Building on the Host
+
+You can also build a release on your host system without Docker. You will need
+to install the Go version specified in the `go.mod` file, as well as a few
+other tools:
+
+```bash
+sudo apt-get install build-essential git make zip perl gpg
+```
+
+You can [download](https://go.dev/dl/) and unpack Go somewhere and set variable
+`GO_CMD=/path/to/go` (path to Go binary of the needed version).
+
+If you already have another Go version, you can install the Go version needed
+for a release using the following commands:
+
+```bash
+$ go version
+go version go1.25.0 linux/amd64
+$ go install golang.org/dl/go1.24.6@latest
+$ go1.24.6 download
+Unpacking /home/user/sdk/go1.24.6/go1.24.6.linux-amd64.tar.gz ...
+Success. You may now run 'go1.24.6'
+$ go1.24.6 version
+go version go1.24.6 linux/amd64
+
+$ GO_CMD=/home/user/go/bin/go1.24.6 ./release.sh v0.31.3
+```
+
+On MacOS, you will need to install GNU tar and GNU gzip, which can be done with
+`brew`:
+
+```bash
+brew install gnu-tar gzip
+```
+
+Add GPG key of Alex Bosworth to verify release tag signature:
+```bash
+gpg --keyserver keys.openpgp.org --recv-keys DE23E73BFA8A0AD5587D2FCDE80D2F3F311FD87E
+```
+
+Then, run the `release.sh` script directly:
+
+```bash
+./release.sh <tag-of-release>
+```
+
+To filter the target platforms, pass them as a space-separated list in the
+`LOOPBUILDSYS` environment variable:
+
+```bash
+LOOPBUILDSYS='linux-amd64 windows-amd64' ./release.sh v0.31.3-beta
+```
+
+This will produce the same artifacts in a `loop-<tag-of-release>` directory as
+the `make docker-release` command. The latter simply runs the `release.sh`
+script inside a Docker container.

release.Dockerfile

@@ -0,0 +1,23 @@
+FROM golang:1.24.6
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    git ca-certificates zip gpg && rm -rf /var/lib/apt/lists/*
+
+# Add GPG key of Alex Bosworth to verify release tag signature.
+RUN gpg --keyserver keys.openpgp.org \
+    --recv-keys DE23E73BFA8A0AD5587D2FCDE80D2F3F311FD87E
+
+# Mark the repo directory safe for git. User ID may be different inside
+# Docker and Git might refuse to work without this setting.
+RUN git config --global --add safe.directory /repo
+RUN git config --global --add safe.directory /repo/.git
+
+# Set GO build time environment variables.
+ENV GOCACHE=/tmp/build/.cache \
+    GOMODCACHE=/tmp/build/.modcache
+
+# Create directories to which host's Go caches are mounted.
+RUN mkdir -p /tmp/build/.cache /tmp/build/.modcache \
+    && chmod -R 777 /tmp/build/
+
+WORKDIR /repo