Allow building with missing beast/mongoose if web server is disabled.

CMakeLists.txt

@@ -1009,7 +1009,6 @@ set(NSCP_DEF_PLUGIN_LIB
     ${PLUGIN_API_TARGET}
 )
 
-set(ALL_LIB_NAMES)
 message(STATUS "Adding libraries")
 file(
     GLOB ALL_LIB_PROJECTS
@@ -1035,10 +1034,6 @@ foreach(CURRENT_LIB ${ALL_LIB_PROJECTS})
     endif()
     message(STATUS " + Library: ${CURRENT_LIB_PATH} (${CURRENT_LIB_NAME})")
     add_subdirectory("${CURRENT_LIB_PATH}")
-    set(ALL_LIB_NAMES
-        ${ALL_LIB_NAMES}
-        ${CURRENT_LIB_NAME}
-    )
 endforeach(
     CURRENT_LIB
     ${ALL_LIB_PROJECTS}

build/cmake/dependencies.cmake

@@ -86,38 +86,46 @@ set(NSCP_WEB_BACKEND
 )
 set_property(CACHE NSCP_WEB_BACKEND PROPERTY STRINGS mongoose beast)
 
+# Decide whether the nscp_mongoose web library can be built. It is only
+# built when the selected backend's dependencies are satisfied:
+#   mongoose -> the vendored mongoose source is found
+#   beast    -> OpenSSL is available (ServerBeastImpl includes Boost.Asio
+#               SSL headers, which need OpenSSL headers/libs at compile time
+#               even when TLS is not enabled at runtime)
+# When they are not, we skip building nscp_mongoose rather than failing the
+# whole configure; modules/WEBServer/CMakeLists.txt raises a targeted error
+# if it is asked to build without the library.
+set(NSCP_MONGOOSE_AVAILABLE FALSE)
 if(NSCP_WEB_BACKEND STREQUAL "mongoose")
     find_package(Mongoose)
-    # Surface a clear error here instead of letting MONGOOSE_INCLUDE_DIR-NOTFOUND
-    # propagate into source lists (`${MONGOOSE_INCLUDE_DIR}/mongoose.c`), which
-    # otherwise fails much later with a cryptic "Cannot find source file".
-    if(NOT MONGOOSE_FOUND)
+    if(MONGOOSE_FOUND)
+        set(NSCP_MONGOOSE_AVAILABLE TRUE)
+    else()
         message(
-            FATAL_ERROR
-            "NSCP_WEB_BACKEND=mongoose requires the vendored mongoose source.\n"
-            "Either set MONGOOSE_SOURCE_DIR (see build.md), or switch to the\n"
-            "Beast backend with -DNSCP_WEB_BACKEND=beast (the default on Linux\n"
-            "CI builds)."
+            STATUS
+            "NSCP_WEB_BACKEND=mongoose but the vendored mongoose source was not "
+            "found; nscp_mongoose (and the WEBServer module) will not be built. "
+            "Set MONGOOSE_SOURCE_DIR (see build.md), or switch to the Beast "
+            "backend with -DNSCP_WEB_BACKEND=beast (the default on Linux CI "
+            "builds)."
         )
     endif()
 elseif(NSCP_WEB_BACKEND STREQUAL "beast")
     # Beast is header-only; the Boost components (coroutine + context)
     # needed by ServerBeastImpl are added below.
-    # ServerBeastImpl also includes Boost.Asio SSL headers, which require
-    # OpenSSL headers/libs at compile time even when TLS is not enabled at
-    # runtime. Fail during configure instead of producing a later compile
-    # error from missing openssl/ssl.h or unresolved SSL symbols.
-    if(NOT OPENSSL_FOUND)
+    if(OPENSSL_FOUND)
+        set(NSCP_MONGOOSE_AVAILABLE TRUE)
+        message(STATUS "WEB backend: Boost.Beast (mongoose download skipped)")
+    else()
         message(
-            FATAL_ERROR
-            "NSCP_WEB_BACKEND=beast requires OpenSSL.\n"
-            "ServerBeastImpl includes Boost.Asio SSL headers, so OpenSSL must\n"
-            "be available at configure/build time even if TLS is not enabled\n"
-            "at runtime.\n"
+            STATUS
+            "NSCP_WEB_BACKEND=beast but OpenSSL was not found; nscp_mongoose "
+            "(and the WEBServer module) will not be built. ServerBeastImpl "
+            "includes Boost.Asio SSL headers, so OpenSSL must be available at "
+            "configure/build time even if TLS is not enabled at runtime. "
             "Install/configure OpenSSL, or switch to -DNSCP_WEB_BACKEND=mongoose."
         )
     endif()
-    message(STATUS "WEB backend: Boost.Beast (mongoose download skipped)")
 else()
     message(FATAL_ERROR "Unknown NSCP_WEB_BACKEND='${NSCP_WEB_BACKEND}' (expected mongoose | beast)")
 endif()
@@ -132,8 +140,14 @@ endif()
 # unused work — and would force the package list (libboost-coroutine,
 # libboost-context on Debian; analogous on RPM) on environments that
 # only ever build the mongoose backend (typically Windows).
+#
+# Gate on NSCP_MONGOOSE_AVAILABLE too: when the Beast backend is selected but
+# its dependencies are missing (e.g. OpenSSL not found) the web library is
+# skipped, so ServerBeastImpl is never compiled. Requesting coroutine/context
+# as *required* COMPONENTS below would then turn an optional, disabled web
+# build into a hard Boost.Coroutine/Context requirement and fail configure.
 set(_nscp_extra_boost_components)
-if(NSCP_WEB_BACKEND STREQUAL "beast")
+if(NSCP_WEB_BACKEND STREQUAL "beast" AND NSCP_MONGOOSE_AVAILABLE)
     list(APPEND _nscp_extra_boost_components coroutine context)
 endif()
 

libs/mongoose-cpp/CMakeLists.txt

@@ -1,6 +1,19 @@
 cmake_minimum_required(VERSION 3.10)
 project(nscp_mongoose)
 
+# Only build the library when the selected web backend's dependencies are
+# satisfied (see NSCP_MONGOOSE_AVAILABLE in build/cmake/dependencies.cmake).
+# When they are not, skip the target entirely; the WEBServer module raises a
+# targeted error if it is asked to build without it.
+if(NOT NSCP_MONGOOSE_AVAILABLE)
+    message(
+        STATUS
+        "Skipping nscp_mongoose: NSCP_WEB_BACKEND='${NSCP_WEB_BACKEND}' "
+        "dependencies are not satisfied."
+    )
+    return()
+endif()
+
 # Backend-independent sources.
 set(SOURCES
     Controller.cpp
@@ -24,8 +37,10 @@ set(SOURCES
 if(NSCP_WEB_BACKEND STREQUAL "beast")
     list(APPEND SOURCES ServerBeastImpl.cpp)
     add_definitions(-DNSCP_WEB_BACKEND_BEAST)
-else()
+elseif(NSCP_WEB_BACKEND STREQUAL "mongoose")
     list(APPEND SOURCES ServerMongooseImpl.cpp ${MONGOOSE_INCLUDE_DIR}/mongoose.c)
+else()
+    message(FATAL_ERROR "Unknown NSCP_WEB_BACKEND='${NSCP_WEB_BACKEND}' (expected mongoose | beast)")
 endif()
 
 if(WIN32)

modules/WEBServer/CMakeLists.txt

@@ -4,6 +4,22 @@ set(TARGET WEBServer)
 
 project(${TARGET})
 
+# WEBServer links against nscp_mongoose, which is only built when the selected
+# web backend's dependencies are satisfied (see NSCP_MONGOOSE_AVAILABLE in
+# build/cmake/dependencies.cmake). Fail with a clear message here instead of a
+# cryptic "target nscp_mongoose not found" later. Disable this module with
+# -DBUILD_MODULE_WEBServer=OFF if you cannot provide the backend.
+if(NOT TARGET nscp_mongoose)
+    message(
+        FATAL_ERROR
+        "WEBServer requires the nscp_mongoose library, which was not built "
+        "because the NSCP_WEB_BACKEND='${NSCP_WEB_BACKEND}' web backend's "
+        "dependencies are not satisfied. Provide the backend dependencies "
+        "(mongoose source, or OpenSSL for beast), switch NSCP_WEB_BACKEND, "
+        "or disable this module with -DBUILD_MODULE_WEBServer=OFF."
+    )
+endif()
+
 CREATE_MODULE(SRCS ${CMAKE_CURRENT_SOURCE_DIR} ${CMAKE_CURRENT_BINARY_DIR})
 
 set(SRCS

tests/CMakeLists.txt

@@ -453,6 +453,11 @@ NSCP_CREATE_TEST(
         ${CMAKE_SOURCE_DIR}/modules/IcingaClient
 )
 
+# The mongoose wrapper tests link against nscp_mongoose, which is only built
+# when the selected web backend's dependencies are satisfied (see
+# NSCP_MONGOOSE_AVAILABLE in build/cmake/dependencies.cmake). Skip the test
+# when the library is not built rather than failing on a missing target.
+if(TARGET nscp_mongoose)
 set(MONGOOSE_CPP_DIR ${CMAKE_SOURCE_DIR}/libs/mongoose-cpp)
 
 # Shared (backend-independent) test sources.
@@ -565,6 +570,7 @@ if(WIN32)
         COMMAND_EXPAND_LISTS
     )
 endif()
+endif() # TARGET nscp_mongoose
 
 set(SETTINGS_INI_TEST_SOURCES
     ${NSCP_INCLUDEDIR}/settings/impl/settings_ini_test.cpp