# Multi-stage build for minimal final image

FROM alpine:3.20 AS builder

# Install build dependencies

RUN apk add --no-cache \

build-base \

autoconf \

automake \

libpcap-dev \

pcre2-dev \

libnet-dev

# Copy source code

WORKDIR /build

COPY . .

# Build ngrep

RUN ./configure --enable-ipv6 --enable-pcre2 --enable-tcpkill --prefix=/usr && \

make && \

make install DESTDIR=/install

# Final minimal image

FROM alpine:3.20

# Install only runtime dependencies

RUN apk add --no-cache \

libpcap \

pcre2 \

libnet

# Copy built binary from builder

COPY --from=builder /install/usr/bin/ngrep /usr/bin/ngrep

COPY --from=builder /install/usr/share/man/man8/ngrep.8 /usr/share/man/man8/ngrep.8

# ngrep needs to run as root or with NET_CAP_RAW capability

# Alpine uses musl libc which is smaller than glibc

USER root

ENTRYPOINT ["/usr/bin/ngrep"]

CMD ["-h"]