Changed environment handling in automake

.env.default

@@ -0,0 +1,4 @@
+server_name=yacswa.home
+public_dir=/srv/yacswa.home
+nginx_dir=/etc/nginx
+nginx_config=yacswa.home.conf

configure

@@ -665,7 +665,11 @@ enable_option_checking
 '
       ac_precious_vars='build_alias
 host_alias
-target_alias'
+target_alias
+server_name
+public_dir
+nginx_dir
+nginx_config'
 
 
 # Initialize some variables set by options.
@@ -1281,6 +1285,17 @@ if test -n "$ac_init_help"; then
    esac
   cat <<\_ACEOF
 
+Some influential environment variables:
+  server_name The hostname of the target server
+  public_dir  The directory where public html files should be installed
+  nginx_dir   The nginx config directory containing sites_available and
+              sites_enabled
+  nginx_config
+              The name to give the nginx config file in sites_available
+
+Use these variables to override the choices made by 'configure' or to help
+it to find libraries and programs with nonstandard names/locations.
+
 Report bugs to <me@bradymcd.ca>.
 _ACEOF
 ac_status=$?
@@ -1724,14 +1739,15 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
 # Pull in environment variables
-server_name=yacswa.home
 
-public_dir=/srv/yacswa.home
 
-nginx_dir=/etc/nginx/
 
-nginx_config=yacswa.home.conf
 
+# Default values
+test "$server_name" || server_name=yacswa.home
+test "$public_dir" || public_dir=/srv/yacswa.home
+test "$nginx_dir" || nginx_dir=/etc/nginx/
+test "$nginx_config" || nginx_config=yacswa.home.conf
 
 # Checks for programs.
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether ${MAKE-make} sets \$(MAKE)" >&5

configure.in

@@ -5,10 +5,15 @@ AC_PREREQ([2.72])
 AC_INIT([Yet Another Covid Statistics Web App], [1.0], [me@bradymcd.ca])
 
 # Pull in environment variables
-AC_SUBST([server_name], [yacswa.home])
-AC_SUBST([public_dir], [/srv/yacswa.home])
-AC_SUBST([nginx_dir], [/etc/nginx/])
-AC_SUBST([nginx_config], [yacswa.home.conf])
+AC_ARG_VAR([server_name], [The hostname of the target server])
+AC_ARG_VAR([public_dir], [The directory where public html files should be installed])
+AC_ARG_VAR([nginx_dir], [The nginx config directory containing sites_available and sites_enabled])
+AC_ARG_VAR([nginx_config], [The name to give the nginx config file in sites_available])
+# Default values
+test "$server_name" || server_name=yacswa.home
+test "$public_dir" || public_dir=/srv/yacswa.home
+test "$nginx_dir" || nginx_dir=/etc/nginx/
+test "$nginx_config" || nginx_config=yacswa.home.conf
 
 # Checks for programs.
 AC_PROG_MAKE_SET