How to I install Puma on Ubuntu 16.04 with rails 2.3.5 and Ruby 1.8.7?

Question

I'm trying to deploy Fedena 2.3 (projectfedena.org) on Ubuntu 16.04, and its built with Ruby 1.8.7 on Rails 2.3.5. I've been able to install it and run with script/server, but now I'm trying to deploy it using Puma+Nginx and as soon as I run gem install puma 3.6.2 (any version above it requires Ruby > 1.8.7), it gives me this error. Does anyone know how i can fix it?

user@server:~/development$ gem install puma -v 3.6.2
Building native extensions.  This could take a while...
ERROR:  Error installing puma:
    ERROR: Failed to build gem native extension.

/home/user/.rvm/rubies/ruby-1.8.7-head/bin/ruby extconf.rb
checking for BIO_read() in -lcrypto... yes
checking for SSL_CTX_new() in -lssl... yes
checking for openssl/bio.h... yes
creating Makefile

make
gcc -I. -I. -I/home/user/.rvm/rubies/ruby-1.8.7-head/lib/ruby/1.8/x86_64-linux -I. -DHAVE_OPENSSL_BIO_H    -fPIC -O2 -fno-tree-dce -fno-optimize-sibling-calls  -fPIC   -c http11_parser.c
gcc -I. -I. -I/home/user/.rvm/rubies/ruby-1.8.7-head/lib/ruby/1.8/x86_64-linux -I. -DHAVE_OPENSSL_BIO_H    -fPIC -O2 -fno-tree-dce -fno-optimize-sibling-calls  -fPIC   -c puma_http11.c
gcc -I. -I. -I/home/user/.rvm/rubies/ruby-1.8.7-head/lib/ruby/1.8/x86_64-linux -I. -DHAVE_OPENSSL_BIO_H    -fPIC -O2 -fno-tree-dce -fno-optimize-sibling-calls  -fPIC   -c mini_ssl.c
mini_ssl.c:4:26: fatal error: ruby/version.h: No such file or directory
 #include <ruby/version.h>
                          ^
compilation terminated.
make: *** [mini_ssl.o] Error 1


Gem files will remain installed in /home/user/.rvm/gems/ruby-1.8.7-head/gems/puma-3.6.2 for inspection.
Results logged to /home/user/.rvm/gems/ruby-1.8.7-head/gems/puma-3.6.2/ext/puma_http11/gem_make.out

Answer 1

The last puma version to officially support Ruby 1.8.7 is 2.16.0

https://github.com/puma/puma/blob/master/History.md#2160--2016-01-27

https://github.com/puma/puma/blob/master/History.md#300--2016-02-25 states

Ruby pre-2.0 is no longer supported

Answer 2

Running

gem install puma -v 3.4.0

works for my ruby 1.8.7. Try installing this puma version instead