build.sh runs npm run build on macOS, so only the host's sharp binary (darwin-arm64) got traced into the standalone output. The container runs node:20-alpine (Linux, musl libc), which cannot load that binary - the server crashed at runtime, causing a 502 even though the docker build itself succeeded. npm pack can fetch another platform's prebuilt sharp/libvips tarballs without an install-time OS check, so build.sh now pulls the linux-musl x64 and arm64 builds directly into build/node_modules and drops the now-unused host binary.
@img/sharp-linuxmusl-x64
Prebuilt sharp for use with Linux (musl) x64.
Licensing
Copyright 2013 Lovell Fuller and others.
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at https://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.