pds implicitly requires sse4.2

[mounirlamouri]

I've been battling for a bit trying to understand why the pds service was crashing on startup on my server. After investigations, I found out that the root cause was that pds requires a CPU with sse4.2 which my server (old Atom) doesn't support.

For background, these are the symptoms:

• the docker instance would start but pds would keep dying and restarting
• error message in /var/log/messages

kernel: traps: node[23207] trap invalid opcode ip:7f22afe5cec3 sp:7ffc11f4e2e0 error:0 in libvips-cpp.so.42[7f22af6a4000+a69000]

After some research, it appears that libvips is used by sharp which is directly included by atproto/pds (package.json).

I would suggest to either:

• Document that SSE4.2 is required, may by doing a check in the installer with the output of lscpu, OR
• Change the dependency to not prevent CPUs too old to support sse4.2 to be unable to run PDS.

[mounirlamouri]

It happens that sharp will use the system libvips by checking for the vips-cpp package using pkg-config. The simpler solution here, which would improve the portability and the security of the container would be to install vips-cpp on the image so when the install phase happens, sharp will use it. It does increase the time it takes to build the image because of the new packages to install and the time it takes to then build the C++ files that sharp uses. However, it's possible to only copy the libraries and reduce the actual impact on the image size.

I have it working locally and will send a PR soon.