I am not so sure what have I did wrongly, I was trying to install the set_user extension in the postgresql-16 which was installed in the alpine linux docker file. Here are the steps I did:

1. Pull alpine docker image

   docker pull alpine
   

2. Run the docker image and access to the docker container

   docker run -t -d b0c9d60fc5e3
   docker exec -it 3df8d7b4b26696de73a2a8cc508e3315c0702529bb7c546f03b6a3d7fc1212ad sh
   

3. Install postgresql16 and start the service

   apk add postgresql16
   mkdir /run/postgresql
   chown postgres:postgres /run/postgresql/
   su postgres
   mkdir /var/lib/postgresql/data
   chmod 0700 /var/lib/postgresql/data
   initdb -D /var/lib/postgresql/data
   pg_ctl start -D /var/lib/postgresql/data
   

4. Import the folder into the docker container
5. cd to the set_user folder inside the docker container then type "make", producing this PNG file as output

I will encountered an error

Makefile:25: /usr/lib/postgresql16/pgxs/src/makefiles/pgxs.mk: No such file or directory
make: *** No rule to make target '/usr/lib/postgresql16/pgxs/src/makefiles/pgxs.mk'.  Stop.

error when I want to install the set_user.