Install postgres extension PGXN "fatal error: unistd.h: No such file or directory" - postgresql

Question

I need to sync some postgres tables with elasticsearch and come to conclusion that the best solution for my case is the one described here. Unfortunately I'm still failing to install required postgres extension amqp.
I use docker so I start from image postgres:13-alpine.
Here is how my Dockerfile looks like so far:
FROM postgres:13-alpine
ENV POSTGRES_DB ''
ENV POSTGRES_USER ''
ENV POSTGRES_PASSWORD ''
RUN apk update \
&& apk add py-pip make gcc \
&& pip install pgxnclient
Then when you enter the container and try to run pgxn install pg_amqp you will get following error.
bash-5.1# pgxn install pg_amqp
INFO: best version: pg_amqp 0.3.0
INFO: saving /tmp/tmpgjtefhgh/pg_amqp-0.3.0.zip
INFO: unpacking: /tmp/tmpgjtefhgh/pg_amqp-0.3.0.zip
INFO: building extension
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wimplicit-fallthrough=3 -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -Wno-format-truncation -Wno-stringop-truncation -O2 -fPIC -I. -I./ -I/usr/local/include/postgresql/server -I/usr/local/include/postgresql/internal -D_GNU_SOURCE -I/usr/include/libxml2 -c -o src/pg_amqp.o src/pg_amqp.c
src/pg_amqp.c:36:10: fatal error: unistd.h: No such file or directory
36 | #include <unistd.h>
| ^~~~~~~~~~
compilation terminated.
make: *** [<builtin>: src/pg_amqp.o] Error 1
ERROR: command returned 2: make PG_CONFIG=/usr/local/bin/pg_config all
It seems that I am out of the ideas what to do with that. Any help?

Answer 1

You are missing the musl C library (libc) implementation: musl-dev
RUN apk update \
&& apk add py-pip make gcc musl-dev \
&& pip install pgxnclient