[Backport] Clarify optional libraries and allow optionally disabling them (#453)

`libcurl` & `libcairo` are also optional and their usage can now be optionally disabled (along with `libmemcached` & `librados`.)

* No longer test macOS Autotools building

Author: hummeltech

.github/workflows/build-and-test.yml

@@ -171,9 +171,6 @@ jobs:
         on_default_branch:
           - ${{ contains(github.ref, 'master') || contains(github.ref, 'develop') || contains(github.ref, 'CI') }}
         include:
-          - os: macos-14
-            build_system: Autotools
-            compiler: LLVM
           - os: macos-14
             build_system: CMake
             compiler: LLVM

CMakeLists.txt

@@ -25,9 +25,13 @@ set(CMAKE_CXX_STANDARD 11 CACHE STRING "Sets the C++ standard.")
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(THREADS_PREFER_PTHREAD_FLAG ON)
 
+set(CMAKE_INSTALL_MODULESDIR CACHE PATH "Apache HTTP Server module installation directory")
 set(ENABLE_MAN ON CACHE BOOL "Build man pages")
 set(ENABLE_TESTS OFF CACHE BOOL "Build test suite")
-set(CMAKE_INSTALL_MODULESDIR CACHE PATH "Apache HTTP Server module installation directory")
+set(USE_CAIRO ON CACHE BOOL "Add cairo support if available (for `store_ro_composite.c` backend)")
+set(USE_CURL ON CACHE BOOL "Add curl support if available (for `store_ro_http_proxy.c` backend)")
+set(USE_MEMCACHED ON CACHE BOOL "Add memcached support if available (for `store_memcached.c` backend)")
+set(USE_RADOS ON CACHE BOOL "Add rados support if available (for `store_rados.c` backend)")
 
 #-----------------------------------------------------------------------------
 #
@@ -38,23 +42,32 @@ set(CMAKE_INSTALL_MODULESDIR CACHE PATH "Apache HTTP Server module installation
 include(GNUInstallDirs)
 
 # Packages
-find_package(CURL)
 find_package(ICU REQUIRED uc)
 find_package(Threads REQUIRED)
 
 find_package(APR REQUIRED)
-find_package(CAIRO REQUIRED)
 find_package(GLIB REQUIRED)
 find_package(HTTPD REQUIRED)
 find_package(INIPARSER REQUIRED)
 find_package(LIBMAPNIK REQUIRED)
-find_package(LIBMEMCACHED)
-find_package(LIBRADOS)
 
 if(LIBMAPNIK_VERSION VERSION_GREATER_EQUAL 4)
   set(CMAKE_CXX_STANDARD 17)
 endif()
 
+if(USE_CURL)
+  find_package(CURL)
+endif()
+if(USE_CAIRO)
+  find_package(CAIRO)
+endif()
+if(USE_MEMCACHED)
+  find_package(LIBMEMCACHED)
+endif()
+if(USE_RADOS)
+  find_package(LIBRADOS)
+endif()
+
 # Programs
 find_program(APXS_EXECUTABLE apxs REQUIRED)
 

README.rst

@@ -22,19 +22,19 @@ Dependencies
 ------------
 
 * `Supported Operating Systems`
-    * `GNU/Linux` (works best on Debian or Ubuntu)
     * `FreeBSD`
+    * `GNU/Linux`
     * `macOS`
 * `Supported Build Systems`
-    * `GNU Autotools <https://www.gnu.org/software/software.html>`__
     * `CMake <https://cmake.org/>`__
+    * `GNU Autotools <https://www.gnu.org/software/software.html>`__
 * `Runtime/Build Dependencies`
     * `Apache 2 HTTP webserver <https://httpd.apache.org/>`__
-    * `Mapnik <https://mapnik.org/>`__
-    * `Cairo 2D graphics library  <https://cairographics.org/>`__
-    * `Curl library (SSL variant) <https://curl.haxx.se/>`__
-    * `Iniparser library <https://github.com/ndevilla/iniparser>`__
+    * `Cairo 2D graphics library (optional) <https://cairographics.org/>`__
+    * `Curl library (optional) <https://curl.haxx.se/>`__
     * `GLib library <https://gitlab.gnome.org/GNOME/glib>`__
+    * `Iniparser library <https://github.com/ndevilla/iniparser>`__
+    * `Mapnik library <https://mapnik.org/>`__
     * `Memcached library (optional) <https://libmemcached.org/>`__
     * `RADOS library (optional) <https://docs.ceph.com/en/latest/rados/api/librados/>`__