[GR-18163] Document OPENSSL_PREFIX and test Fedora 36 (#2660)

PullRequest: truffleruby/3364

Author: eregon

doc/user/installing-libssl.md

@@ -7,13 +7,20 @@ permalink: /reference-manual/ruby/Installinglibssl/
 # Installing `libssl`
 
 TruffleRuby provides the `openssl` module but not the native `libssl` system library that the module uses.
-TruffleRuby supports both versions 1.0.2 and 1.1.0.
+TruffleRuby supports libssl versions 1.0.2 and 1.1.0 (not 3.0.0 currently).
 
 If you experience `openssl`-related errors, it might help to recompile the `openssl` module by running `lib/truffle/post_install_hook.sh`.
 This is done automatically by Ruby managers, and mentioned in the post-install message when installing TruffleRuby via `gu install` in GraalVM.
 
+To compile TruffleRuby against a non-system `libssl`, set `OPENSSL_PREFIX` while installing TruffleRuby:
+```bash
+export OPENSSL_PREFIX=/path/to/my/openssl-1.1.0
+```
+
 ### RedHat-based: Fedora, Oracle Linux, etc
 
+On Fedora 36, use `openssl1.1-devel` instead.
+
 ```bash
 sudo dnf install openssl-devel
 ```

lib/truffle/truffle/openssl-prefix.rb

@@ -8,6 +8,10 @@
 
 # Set OPENSSL_PREFIX in ENV to find the OpenSSL headers
 
+module Truffle
+  OPENSSL_PREFIX_WAS_SET = ENV.key?('OPENSSL_PREFIX')
+end
+
 search_homebrew = -> homebrew {
   if prefix = "#{homebrew}/opt/[email protected]" and Dir.exist?(prefix)
     prefix

src/main/c/openssl/extconf.rb

@@ -110,7 +110,7 @@ def find_openssl_library
 
 # TruffleRuby: do not perform all checks again if extconf.h already exists
 extconf_h = "#{__dir__}/extconf.h"
-if File.exist?(extconf_h) && File.mtime(extconf_h) >= File.mtime(__FILE__ )
+if File.exist?(extconf_h) && File.mtime(extconf_h) >= File.mtime(__FILE__ ) && !Truffle::OPENSSL_PREFIX_WAS_SET
   $extconf_h = extconf_h
 else
 ### START of checks

tool/docker-configs.yaml

@@ -39,6 +39,13 @@ fedora28:
   locale:
   <<: *rpm
 
+fedora36:
+  base: fedora:36
+  install: RUN dnf install -y
+  locale: glibc-langpack-en
+  <<: *rpm
+  openssl: openssl1.1-devel
+
 fedora34:
   base: fedora:34
   install: RUN dnf install -y