Dockerfile

# Dockerfile for rJMX-Exporter
# Multi-stage build for minimal production image
#
# Build: docker build -t rjmx-exporter .
# Run:   docker run -v ./config.yaml:/config.yaml rjmx-exporter

# =============================================================================
# Stage 1: Build
# =============================================================================
FROM rust:1.83-alpine AS builder

# Install build dependencies
RUN apk add --no-cache \
    musl-dev \
    openssl-dev \
    openssl-libs-static \
    pkgconfig

# Create app directory
WORKDIR /app

# Copy manifests first for better layer caching
COPY Cargo.toml Cargo.lock ./

# Create dummy src and benches to build dependencies
# (Cargo.toml references [[bench]] entries that must exist for manifest parsing)
RUN mkdir -p src benches && \
    echo 'fn main() { println!("Dummy"); }' > src/main.rs && \
    echo '' > src/lib.rs && \
    echo 'fn main() {}' > benches/collector_bench.rs && \
    echo 'fn main() {}' > benches/memory_bench.rs && \
    echo 'fn main() {}' > benches/startup_bench.rs && \
    echo 'fn main() {}' > benches/scrape_latency_bench.rs

# Build dependencies (this layer is cached)
RUN cargo build --release --target x86_64-unknown-linux-musl && \
    rm -rf src benches && \
    rm -rf target/x86_64-unknown-linux-musl/release/deps/rjmx* && \
    rm -rf target/x86_64-unknown-linux-musl/release/deps/librjmx* && \
    rm -rf target/x86_64-unknown-linux-musl/release/.fingerprint/rjmx*

# Copy actual source code
COPY src ./src
COPY benches ./benches

# Build the actual binary (touch files to ensure cache invalidation)
RUN touch src/lib.rs src/main.rs && \
    cargo build --release --target x86_64-unknown-linux-musl && \
    strip target/x86_64-unknown-linux-musl/release/rjmx-exporter

# =============================================================================
# Stage 2: Runtime
# =============================================================================
FROM alpine:3.19

# Labels
LABEL org.opencontainers.image.title="rJMX-Exporter"
LABEL org.opencontainers.image.description="High-performance JMX metrics exporter written in Rust"
LABEL org.opencontainers.image.source="https://github.com/jsoonworld/rJMX-Exporter"
LABEL org.opencontainers.image.licenses="MIT OR Apache-2.0"

# Install runtime dependencies (CA certificates for HTTPS)
RUN apk add --no-cache ca-certificates tzdata && \
    adduser -D -H -s /sbin/nologin rjmx

# Copy binary from builder
COPY --from=builder /app/target/x86_64-unknown-linux-musl/release/rjmx-exporter /usr/local/bin/

# Use non-root user
USER rjmx

# Expose metrics port
EXPOSE 9090

# Health check
HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
    CMD wget --no-verbose --tries=1 --spider http://localhost:9090/health || exit 1

# Default entrypoint
ENTRYPOINT ["/usr/local/bin/rjmx-exporter"]
CMD ["-c", "/config.yaml"]