CentOS 7: When building Mapnik, the configure step does not find optional dependencies like libpng-devel, libjpeg-devel, etc

I am trying to build/install Mapnik (3.0.10) on a CentOS 7 system and I am having trouble getting all the dependencies in place and recognized. I have installed gcc/g++ compiler from the gcc6 series to ensure c++14 support, which Mapnik needs. If I point directly to my new gcc and poll its version I get this: [root@raven ~]# /usr/local/bin/gcc --version gcc (GCC) 6.5.0 Copyright (C) 2017 Free Software Foundat/..snip.. Next I temporarily overrode the $CC and $CXX environment variables so the updated compiler would be used for subsequent builds, then I installed Boost 1.69.0 from source, like this. Note that this actually installs a second Boost, so the --prefix parameter establishes where this alternative Boost will install to: export CC=/usr/local/bin/gcc export CXX=/usr/local/bin/g++ cd /root/downloads wget https://dl.bintray.com/boostorg/release/1.69.0/source/boost_1_69_0.tar.gz tar -xzf boost_1_* cd boost_1_* ./bootstrap.sh --prefix=/opt/boost ./b2 install --prefix=/opt/boost --with=all Now, if I check /opt/boost, I see what I expect.. [root@raven ~]# dir /opt/boost/ include lib Finally I get to installing Mapnik itself. I'm basically using the approach noted here . However, I've already got several of the dependencies in place due to previously installing GDAL and PostGIS. But, when I run Mapnik's .configure step, it fails to find my optional dependencies. For example, I built proj from source and know exactly where it is.. [root@raven ~]# dir /usr/proj49/ bin include lib share And ldconfig finds it too.. [root@raven mapnik-v3.0.10]# ldconfig -p | grep libproj libproj.so.12 (libc6,x86-64) => /usr/proj49/lib/libproj.so.12 libproj.so.0 (libc6,x86-64) => /lib64/libproj.so.0 libproj.so (libc6,x86-64) => /usr/proj49/lib/libproj.so libproj.so (libc6,x86-64) => /lib64/libproj.so So I specify my alternative Boost location as well as PROJ_LIBS and PROJ_INCLUDES as .configure parameters.....but it still fails to find proj? Here's some abridged output. Note that it finds my Boost, as specified, but it fails to find proj, in spite of the config params.. [root@raven ~]# cd /root/downloads/mapnik-v3.0.10 [root@raven mapnik-v3.0.10]# ./configure BOOST_LIBS=/opt/boost/lib BOOST_INCLUDES=/opt/boost/includes PROJ_LIBS=/usr/proj49/lib PROJ_INCLUDES=/usr/proj49/include ..snip.. Searching for boost libs and headers... (cached) Found boost libs: /opt/boost/lib Found boost headers: /opt/boost/include Checking for C++ header file boost/version.hpp... yes Checking for Boost version >= 1.47... yes Found boost lib version... 1_69 ..snip.. Checking for C library proj... no Could not find optional header or shared library for proj ..snip.. Most of the optional dependencies seem to be similarly overlooked—libpng-devel, libjpeg-devel, sqlite3, the tiff stuff, proj, etc. And most of those are package installs, not source builds. As we'll be using this server for quite some time I would like to have the latest Mapnik with its full complement of support (especially for proj, png, and jpeg). It's especially vexing that my proj install isn't tying in, because I know exactly where it is and provided Mapnik those parameters. I apologize for the long noisy read, but does anyone see what I am missing? [**Update**: 4.24.19 5pm] Ok, I may have figured it out. I was hoping it had something to do with environment/shell setup, rather than having to build all dependencies from source with the same compiler, and stumbled onto an old post where a "Dom Lehr" recommended modifying the LD_LIBRARY_PATH environment variable to include specifically /usr/local/lib. Well, I tried that, and it didn't solve the problem. However, I optimistically expanded the parameter values to include some additional locations, and now I can complete the .configure step with all dependencies recognized. Here's how I did it.. vi /etc/profile.d/sh.local # Add colon-separated paths to the LD_LIBRARY_PATH variable like this.. export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib:/usr/local/lib64:/usr/lib:/usr/lib64: I added everything I could think of where I found seemingly related .so files. Save the file, then.. /sbin/ldconfig ldconfig Then I logged out of my terminal session and logged back in to refresh the shell. Then double-checked that it worked: [root@raven mapnik-v3.0.10]# echo $LD_LIBRARY_PATH /opt/remi/php70/root/usr/lib64::/usr/local/lib:/usr/local/lib64:/usr/lib:/usr/lib64: It did. So I refreshed my temporary compiler arguments, went to the Mapnik source folder, and re-ran the .configure instruction, and it worked without issue.. export CC=/usr/local/bin/gcc export CXX=/usr/local/bin/g++ cd /root/downloads/mapnik-v3.0.10 ./configure BOOST_LIBS=/opt/boost/lib BOOST_INCLUDES=/opt/boost/includes And it worked. Now, whether it will build without issue is still a mystery, but this seems to have done the trick! Well I spoke to soon. Now make fails with.. > >&&’ scons: *** [src/json/mapnik_json_geometry_grammar.o] Error 1 scons: building terminated because of errors. make: *** [src/json/libmapnik-json.a] Error 2 ....which is in-line with a lot of others posts I've found where folks are having trouble with mismatched compiler/dependency issues. Back to the drawing board.