looorent/hackmation-rust-brainfuck-cli repository overview

⁠hackmation-rust-brainfuck-cli

A Brainfuck interpreter written in Rust (zero dependencies, pure std), packaged as a minimal Docker image built entirely inside Docker. No Rust toolchain is needed on the host.

Semantics:

• 30000-cell tape of wrapping u8 cells.
• Moving the pointer outside the tape is an error (no undefined behavior).
• , reads one byte from stdin; on EOF it sets the current cell to 0.
• . writes one byte to stdout. Stdout only ever contains program output.
• Unbalanced brackets are rejected before execution: message on stderr, non-zero exit code.

⁠Usage

The first positional argument is the Brainfuck source:

docker run --rm looorent/hackmation-rust-brainfuck-cli \
  '++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.'
# Hello World!

Program input for , comes from stdin (note -i):

echo -n 'hi' | docker run --rm -i looorent/hackmation-rust-brainfuck-cli ',[.,]'
# hi

Reading the program from a file instead of argv:

docker run --rm -v "$PWD:/w" looorent/hackmation-rust-brainfuck-cli -f /w/program.bf

⁠Prerequisites

Docker only. Compiling, testing, and packaging all happen inside the build. No rustup, no cargo, nothing installed on the host.

⁠Building the image

docker build -t looorent/hackmation-rust-brainfuck-cli .

⁠Publishing

The image name already carries the Docker Hub namespace, so pushing is:

docker login   # once, as looorent
docker push looorent/hackmation-rust-brainfuck-cli:latest

For another registry, retag first, e.g. docker tag looorent/hackmation-rust-brainfuck-cli ghcr.io/<owner>/hackmation-rust-brainfuck-cli:latest.

⁠How the image stays small

• The final stage is FROM scratch: it contains a single file, the binary.
• The build stage runs on rust:1-alpine, where the host target is *-unknown-linux-musl, so the binary is statically linked and needs no libc at runtime. The target is never hardcoded, so the build works on amd64 and arm64 alike.
• The release profile in Cargo.toml minimizes binary size: opt-level = "z", lto = true, codegen-units = 1, strip = true, panic = "abort".

Result: an image well under 1 MB.

⁠Running the tests

Unit tests live in src/interpreter.rs and run inside Docker via the test build stage:

docker build --target test --progress=plain .