Fly.io example demonstrating libsodium use failure. Launch with `fly launch` and see the logs for the error.

config.nims

switch("gc", "orc")
switch("d", "nimDebugDlOpen")

when defined(linux):
  import os
  switch("dynlibOverride", "libsodium")
  switch("cincludes", "/usr/include")
  switch("clibdir", "/usr/lib")
  switch("passL", "-lsodium")

Dockerfile

# -- Stage 1 -- #
FROM nimlang/nim:1.6.10-alpine@sha256:408ebac99ad2d170a59e7a09c10e82e7336cf71fa38c7a1322aaa598a54d32c2 as builder
WORKDIR /app
RUN apk update && apk add libsodium-static libsodium musl-dev
RUN nimble install -y libsodium
COPY . .
RUN nim c -o:testapp main.nim
RUN ls -al

# -- Stage 2 -- #
FROM alpine:3.13.12@sha256:16fd981ddc557fd3b38209d15e7ee8e3e6d9d4d579655e8e47243e2c8525b503
WORKDIR /root/
RUN apk update && apk add libressl3.1-libcrypto
COPY --from=builder /app/testapp /usr/local/bin/
CMD ["/usr/local/bin/testapp"]

main.nim

import std/asynchttpserver
import std/asyncdispatch

import libsodium/sodium

proc main {.async.} =
  # libsodium test
  try:
    echo "Attempting crypto_pwhash_str..."
    echo crypto_pwhash_str("some text")
    echo "ok"
  except:
    echo "Failed crypto_pwhash_str: ", getCurrentExceptionMsg()

  # webserver to keep fly happy
  var server = newAsyncHttpServer()
  proc cb(req: Request) {.async.} =
    let headers = {"Content-type": "text/plain; charset=utf-8"}
    await req.respond(Http200, "Hello World", headers.newHttpHeaders())

  server.listen(Port(8080))
  while true:
    if server.shouldAcceptRequest():
      await server.acceptRequest(cb)

waitFor main()