Verify and document systemcrypto functionality on Alpine Linux

[dagood]

I don't know off the top of my head:

• Does systemcrypto work on Alpine?
• If you build an app on Alpine with cgo (like you must with systemcrypto), does it link against musl?
• Does musl have similar versioning issues as glibc?
• If you build against an old glibc, will that work better with Alpine glibc compatability workaround packages? (Or the same?)

This is a tracking issue to figure these out and add it to any applicable documentation.

[gdams]

I ran some quick tests here:

I create an Alpine Dockerfile:

FROM alpine:latest

# Dependencies for cgo + OpenSSL
RUN apk add --no-cache gcc musl-dev make

# Install Microsoft Go toolset
WORKDIR /usr/local
ADD https://aka.ms/golang/release/latest/go1.25.linux-arm64.tar.gz go.tar.gz
RUN tar -xzf go.tar.gz && rm go.tar.gz
ENV PATH=/usr/local/go/bin:$PATH

# Verify version
RUN go version

WORKDIR /src
RUN go mod init example.com/testapp

RUN cat > main.go <<'EOF'
package main

import (
    "crypto/sha256"
    "fmt"
)

func main() {
    data := []byte("hello world")
    sum := sha256.Sum256(data)
    fmt.Printf("SHA256: %x\n", sum)
}
EOF

RUN go build -o app .

CMD ["./app"]

I then built it with docker build -t alpine-test . and then checked the output of ldd

docker run alpine-test ldd ./app
        /lib/ld-musl-aarch64.so.1 (0xffffb5190000)
        libc.musl-aarch64.so.1 => /lib/ld-musl-aarch64.so.1 (0xffffb5190000)

So yes, If you build an app on Alpine with cgo (including systemcrypto), it links against musl.