An Idea how to add x86_64-unknown-linux-musl build target

[LouneCode]

Add x86_64-unknown-linux-musl build target

Will be done as follows. At first clone this repository.

git clone https://github.com/chirpstack/chirpstack-mqtt-forwarder.git

Copy the following lines to the add_cross-compile-target_x86_64.patch file (should be in the UTF-8 format).

diff --git a/.cargo/config.toml b/.cargo/config.toml
index ff7c12a..565ff2f 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -1,3 +1,13 @@
+[target.x86_64-unknown-linux-musl]
+  rustflags = [
+    "-C", "target-feature=+crt-static",
+    "-C", "link-arg=-s",
+    "-C", "link-arg=-lc",
+    "-C", "link-arg=-lgcc",
+    "-L", "native=/usr/local/x86_64-linux-musl-target/lib",
+    "-l", "static=stdc++",
+  ]
+
 [target.aarch64-unknown-linux-musl]
   rustflags = [
     "-C", "target-feature=+crt-static",
diff --git a/Cargo.lock b/Cargo.lock
index e65efaa..e78b2d0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -954,6 +954,15 @@ version = "1.18.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dd8b5dd2ae5ed71462c540258bedcb51965123ad7e7ccf4b9a8cafaa4a63576d"
 
+[[package]]
+name = "openssl-src"
+version = "300.1.5+3.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "559068e4c12950d7dcaa1857a61725c0d38d4fc03ff8e070ab31a75d6e316491"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "openssl-sys"
 version = "0.9.93"
@@ -962,6 +971,7 @@ checksum = "db4d56a4c0478783083cfafcc42493dd4a981d41669da64b4572a2a089b51b1d"
 dependencies = [
  "cc",
  "libc",
+ "openssl-src",
  "pkg-config",
  "vcpkg",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 5eaf3f5..404aee0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -35,7 +35,8 @@ hex = "0.4"
 base64 = "0.21"
 rand = "0.8"
 pbjson-types = "0.5"
-paho-mqtt = { version = "0.12", features = ["ssl", "build_bindgen"] }
+# See features section: "paho-mqtt:build_bindgen" or "paho-mqtt:vendored-ssl"
+paho-mqtt = { version = "0.12", features = ["ssl"] } 
 handlebars = "4.4"
 tokio = { version = "1.32", features = [
     "macros",
@@ -54,9 +55,11 @@ zmq = { version = "0.10", optional = true }
 dotenv = "0.15"
 
 [features]
-default = ["semtech_udp", "concentratord"]
+default = ["semtech_udp", "concentratord", "paho-mqtt/build_bindgen"]
 semtech_udp = []
 concentratord = ["zmq"]
+paho_mqtt_vendored_ssl = ["paho-mqtt/vendored-ssl"]
+paho_mqtt_bindgen_ssl = ["paho-mqtt/build_bindgen"]
 
 # Debian packaging.
 [package.metadata.deb]
diff --git a/Cross.toml b/Cross.toml
index 4300cba..98e7d79 100644
--- a/Cross.toml
+++ b/Cross.toml
@@ -1,3 +1,6 @@
+[target.x86_64-unknown-linux-musl]
+dockerfile="cross/Dockerfile.x86_64-unknown-linux-musl"
+
 [target.aarch64-unknown-linux-musl]
 dockerfile="cross/Dockerfile.aarch64-unknown-linux-musl"
 
diff --git a/Makefile b/Makefile
index abf5e0a..d95cdbb 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,8 @@ build: build-aarch64-unknown-linux-musl \
 	build-armv5te-unknown-linux-musleabi \
 	build-armv7-unknown-linux-musleabihf \
 	build-mips-unknown-linux-musl \
-	build-mipsel-unknown-linux-musl
+	build-mipsel-unknown-linux-musl \
+	build-x86_64-unknown-linux-musl
 
 build-aarch64-unknown-linux-musl:
 	cross build --target aarch64-unknown-linux-musl --release
@@ -17,18 +18,22 @@ build-armv7-unknown-linux-musleabihf:
 	cross build --target armv7-unknown-linux-musleabihf --release
 
 build-mips-unknown-linux-musl:
-	cross build --target mips-unknown-linux-musl --release --no-default-features --features semtech_udp
+	cross build --target mips-unknown-linux-musl --release --no-default-features --features semtech_udp,paho_mqtt_bindgen_ssl
 
 build-mipsel-unknown-linux-musl:
-	cross build --target mipsel-unknown-linux-musl --release --no-default-features --features semtech_udp
+	cross build --target mipsel-unknown-linux-musl --release --no-default-features --features semtech_udp,paho_mqtt_bindgen_ssl	
+
+build-x86_64-unknown-linux-musl:
+	cross build --target x86_64-unknown-linux-musl --release --no-default-features --features semtech_udp,concentratord,paho_mqtt_vendored_ssl
 
 # Build distributable binaries for all targets.
 dist: dist-aarch64-unknown-linux-musl \
 	dist-armv5te-unknown-linux-musleabi \
 	dist-armv7-unknown-linux-musleabihf \
 	dist-mips-unknown-linux-musl \
-	dist-mipsel-unknown-linux-musl
-
+	dist-mipsel-unknown-linux-musl \
+	dist-x86_64-unknown-linux-musl
+	
 dist-aarch64-unknown-linux-musl: build-aarch64-unknown-linux-musl package-aarch64-unknown-linux-musl
 
 dist-armv5te-unknown-linux-musleabi: build-armv5te-unknown-linux-musleabi package-armv5te-unknown-linux-musleabi
@@ -39,6 +44,8 @@ dist-mips-unknown-linux-musl: build-mips-unknown-linux-musl package-mips-unknown
 
 dist-mipsel-unknown-linux-musl: build-mipsel-unknown-linux-musl package-mipsel-unknown-linux-musl
 
+dist-x86_64-unknown-linux-musl: build-x86_64-unknown-linux-musl package-x86_64-unknown-linux-musl
+
 # Package the compiled binaries
 package-aarch64-unknown-linux-musl:
 	$(eval PKG_VERSION := $(shell cargo metadata --no-deps --format-version 1 | jq -r '.packages[0].version'))
@@ -68,6 +75,17 @@ package-mips-unknown-linux-musl: package-dragino
 
 package-mipsel-unknown-linux-musl: package-rak-ramips-24kec
 
+package-x86_64-unknown-linux-musl:
+	$(eval PKG_VERSION := $(shell cargo metadata --no-deps --format-version 1 | jq -r '.packages[0].version'))
+	mkdir -p dist
+
+	# .tar.gz
+	tar -czvf dist/chirpstack-mqtt-forwarder_$(PKG_VERSION)_x86_64.tar.gz -C target/x86_64-unknown-linux-musl/release chirpstack-mqtt-forwarder
+
+	# .deb
+	cargo deb --target x86_64-unknown-linux-musl --no-build --no-strip
+	cp target/x86_64-unknown-linux-musl/debian/*.deb ./dist	
+
 # Gateway specific packaging.
 package-dragino:
 	cd packaging/vendor/dragino/mips_24kc && ./package.sh
diff --git a/cross/Dockerfile.x86_64-unknown-linux-musl b/cross/Dockerfile.x86_64-unknown-linux-musl
new file mode 100644
index 0000000..f78bef4
--- /dev/null
+++ b/cross/Dockerfile.x86_64-unknown-linux-musl
@@ -0,0 +1,30 @@
+FROM ghcr.io/cross-rs/x86_64-unknown-linux-musl:latest
+
+ENV OPENSSL_VERSION=3.1.2
+ENV OPENSSL_TARGET=linux-x86_64
+ENV MUSL_PREFIX=x86_64-linux-musl
+ENV OPENSSL_STATIC=1
+
+RUN apt-get update && \
+    apt-get --assume-yes install \
+    protobuf-compiler \
+    libprotobuf-dev \
+    pkg-config \
+    libssl-dev
+
+RUN echo "Building OpenSSL" && \
+    cd /tmp && \
+    curl -fLO "https://www.openssl.org/source/openssl-$OPENSSL_VERSION.tar.gz" && \
+    tar xvzf "openssl-$OPENSSL_VERSION.tar.gz" && cd "openssl-$OPENSSL_VERSION" && \
+    env CC=$MUSL_PREFIX-gcc ./Configure no-shared no-zlib -fPIC --prefix=/usr/local/$MUSL_PREFIX-target -DOPENSSL_NO_SECURE_MEMORY $OPENSSL_TARGET && \
+    env C_INCLUDE_PATH=/usr/local/$MUSL_PREFIX/include/ make depend && \
+    env C_INCLUDE_PATH=/usr/local/$MUSL_PREFIX/include/ make && \
+    make install_sw && \
+    rm -r /tmp/*
+
+RUN echo "Copy libstdc++" && \
+    mkdir -p /usr/local/$MUSL_PREFIX-target/lib && \
+    cp /usr/local/$MUSL_PREFIX/lib/libstdc++* /usr/local/$MUSL_PREFIX-target/lib
+
+
+ENV PKG_CONFIG_PATH=/usr/local/$MUSL_PREFIX-target/lib/pkgconfig
\ No newline at end of file

Patch repository

And next, patch the chirpstack-mqtt-forwarder repository.

$ cd ./chirpstack-mqtt-forwarder
$ git apply --ignore-space-change --ignore-whitespace add_cross-compile-target_x86_64.patch  

The command may display warnings. don't panic...

/home/lab/add_cross-compile-target_x86_6
[target.x86_64-unknown-linux-musl]
/home/lab/add_cross-compile-target_x86_6
  rustflags = [
/home/lab/add_cross-compile-target_x86_6
    "-C", "target-feature=+crt-static",
/home/lab/add_cross-compile-target_x86_6
    "-C", "link-arg=-s",
/home/lab/add_cross-compile-target_x86_6
    "-C", "link-arg=-lc",
warning: squelched 42 whitespace errors
warning: 47 lines add whitespace errors.

...It's OK.

Build

$ make clean
$ make build

Optional command $ docker system prune -a cleans all unused images from docker repository. You been warned.

$ docker system prune -a

Changes shortly

• Makefile - add x86_64-unknown-linux-musl build instructions
• cross.toml - add [target.x86_64-unknown-linux-musl]
• cross/Dockerfile.x86_64-unknown-linux-musl - A new Docker build file
• .cargo/config.toml - [target.x86_64-unknown-linux-musl] compilation flags

In the Cargo.toml is used the features of dependencies to control how to ssl of the paho-mqtt package will be built (paho_mqtt_vendored_ssl and paho_mqtt_bindgen_ss features).
For more details see Cargo book, feature

[features]
default = ["semtech_udp", "concentratord", "paho-mqtt/build_bindgen"]
semtech_udp = []
concentratord = ["zmq"]
paho_mqtt_vendored_ssl = ["paho-mqtt/vendored-ssl"]
paho_mqtt_bindgen_ssl = ["paho-mqtt/build_bindgen"]

A build parameters in the Make file controls how to ssl layer will be built for paho_mqtt package. Simplified building logics is described in examples below:

Makefile:

cross build --target aarch64-unknown-linux-musl --release

Cargo will build paho_mqtt with following fetures: paho-mqtt = { version = "0.12", features = ["ssl","build_bindgen"] } by using default features of the Cargo.toml file.

cross build --target x86_64-unknown-linux-musl --release --no-default-features --features semtech_udp,concentratord,paho_mqtt_vendored_ssl

Cargo will build paho_mqtt with following features: paho-mqtt = { version = "0.12", features = ["ssl","vendored-ssl"] }

Hints:

• paho.mqtt.rust
• Build failure – missing pkg-config #250
• Unable to cross compile for musl #1627

Let's do IoT better

[LouneCode]

And the usual simple way works well ; ) ; ) ; ) cargo build --release on the x86_64 platform. There is no need to use cross command to build the code.

[LouneCode]

Case is closed ;)