chore: Add Dockerfile and instructions for building ruby gem locally

ruby-sdk/Dockerfile

@@ -0,0 +1,30 @@
+FROM ruby:3.3
+
+ARG WORKDIR
+
+RUN apt-get update && apt-get install -y \
+    curl \
+    build-essential \
+    libssl-dev \
+    zlib1g-dev \
+    && apt-get clean && rm -rf /var/lib/apt/lists/*
+
+RUN apt-get install ca-certificates curl
+RUN install -m 0755 -d /etc/apt/keyrings
+RUN curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
+RUN chmod a+r /etc/apt/keyrings/docker.asc
+
+RUN echo \
+  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian \
+  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
+  tee /etc/apt/sources.list.d/docker.list > /dev/null
+RUN apt-get update
+RUN apt-get install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
+
+WORKDIR $WORKDIR
+
+RUN gem install rb_sys
+
+COPY build.sh ./
+
+CMD ["/bin/bash", "./build.sh"]

ruby-sdk/README.md

@@ -43,3 +43,15 @@ Make sure you remove the override before updating `Cargo.lock`. Otherwise, the l
 * Bump versions in `ruby-sdk/lib/eppo_client/version.rb` and `ruby-sdk/ext/eppo_client/Cargo.toml`
 * Run `cargo update --workspace --verbose` to update `Cargo.lock`
 * Run `bundle` to update `Gemfile.lock`
+
+
+## Building native libs
+
+```
+docker build --build-arg WORKDIR=$(pwd) -t ruby-sdk-builder .
+mkdir -p rust/cargo/registry
+docker run --rm -it \
+  -v /var/run/docker.sock:/var/run/docker.sock \
+  -v /tmp:/tmp -v \
+  $(pwd)/rust:$(pwd)/rust ruby-sdk-builder
+```

ruby-sdk/build.sh

@@ -0,0 +1,11 @@
+set -e
+export RUST_INSTALL_PATH=./rust
+mkdir -p $RUST_INSTALL_PATH
+export RUSTUP_HOME=$RUST_INSTALL_PATH/rustup
+export CARGO_HOME=$RUST_INSTALL_PATH/cargo
+export PATH=$CARGO_HOME/bin:$PATH
+export RB_SYS_DOCK_CACHE_DIR=./cache
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+rustup install stable
+rustup default stable
+rb-sys-dock --platform aarch64-linux-musl --mount-toolchains --ruby-versions 3.3 -V --build -V

ruby-sdk/ext/eppo_client/Cargo.toml

@@ -12,7 +12,7 @@ crate-type = ["cdylib"]
 
 [dependencies]
 env_logger = { version = "0.11.3", features = ["unstable-kv"] }
-eppo_core = { version = "=5.0.0", features = ["vendored"] }
+eppo_core = { version = "=4.1.1", features = ["vendored"] }
 log = { version = "0.4.21", features = ["kv_serde"] }
 magnus = { version = "0.6.4" }
 serde = { version = "1.0.203", features = ["derive"] }