These should be considered experimental in nature and will be limited to Node 8 and 10 (the official Node 6 Alpine images are based on v3.4, which is missing pthread_setname_np support amongst other things).
Here's an example CI build using Alpine 3.8 https://travis-ci.org/lovell/sharp/jobs/430178777
v0.21.0 now available with pre-built sharp and libvips binaries for musl. Requires Node 8+ and tested on Alpine v3.8.
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v0.21.0 now available with pre-built sharp and libvips binaries for musl. Requires Node 8+ and tested on Alpine v3.8.