manager: add install config module

This new module allows Manager to use Meson-configured paths (generally
inside the install prefix). It will allow us to add functionality to
e.g. check for Lua modules during config validation.

Author: Oto Šťáva

manager/knot_resolver_install_config.py.in

@@ -0,0 +1,9 @@
+# This generated file is kept outside of the knot_resolver_manager module
+# because it may sometimes (when debugging) reside in another Python module
+# search path. Since Python does not merge module directories it finds on
+# multiple paths, it just uses the first one it finds, we need to keep this
+# separate.
+
+lib_dir = "@lib_dir@"
+bin_dir = "@bin_dir@"
+sbin_dir = "@sbin_dir@"

manager/knot_resolver_manager/constants.py

@@ -1,8 +1,14 @@
+import importlib.util
 import logging
 from pathlib import Path
 from typing import TYPE_CHECKING, Optional
 
-from knot_resolver_manager.utils import which
+# Install config is semi-optional - only needed to actually run Manager, but not
+# for its unit tests.
+if importlib.util.find_spec("knot_resolver_install_config"):
+    import knot_resolver_install_config as install_config
+else:
+    install_config = None
 
 if TYPE_CHECKING:
     from knot_resolver_manager.config_store import ConfigStore
@@ -20,11 +26,13 @@
 
 
 def kresd_executable() -> Path:
-    return which.which("kresd")
+    assert install_config is not None
+    return Path(install_config.sbin_dir) / "kresd"
 
 
 def kres_gc_executable() -> Path:
-    return which.which("kres-cache-gc")
+    assert install_config is not None
+    return Path(install_config.sbin_dir) / "kres-cache-gc"
 
 
 def kresd_cache_dir(config: "KresConfig") -> Path:

manager/meson.build

@@ -1,8 +1,18 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 build_manager = false
+generate_manager_install_config = false
 
 if get_option('manager') != 'disabled'
+    build_manager = true
+    generate_manager_install_config = true
+endif
+
+if get_option('manager_install_config') == 'enabled'
+    generate_manager_install_config = true
+endif
+
+if build_manager or generate_manager_install_config
     message('--- manager dependencies ---')
 
     pymod = import('python')
@@ -13,14 +23,30 @@ if get_option('manager') != 'disabled'
         error('At least Python 3.6 is required.')
     elif py3_deps.returncode() != 0
         error(py3_deps.stderr().strip())
-    else
-        message('all dependencies found')
-        build_manager = true
     endif
 
+    message('all dependencies found')
+
     message('----------------------------')
 endif
 
+if generate_manager_install_config
+    manager_install_config = configuration_data()
+    manager_install_config.set('lib_dir', lib_dir)
+    manager_install_config.set('bin_dir', bin_dir)
+    manager_install_config.set('sbin_dir', sbin_dir)
+
+    install_config = configure_file(
+        input: 'knot_resolver_install_config.py.in',
+        output: 'knot_resolver_install_config.py',
+        configuration: manager_install_config,
+    )
+
+    py3.install_sources(
+        install_config,
+    )
+endif
+
 if build_manager
 
     # shell completion
@@ -34,4 +60,6 @@ if build_manager
         sources: 'etc/knot-resolver/config.yaml',
         install_dir: etc_dir,
     )
-endif
+
+endif
+

manager/scripts/_env.sh

@@ -30,6 +30,7 @@ fi
 
 # update PATH with node_modules
 PATH="$PATH:$gitroot/node_modules/.bin"
+PYTHONPATH="$PYTHONPATH"
 
 # fail even on unbound variables
 set -o nounset
@@ -44,9 +45,13 @@ function build_kresd {
 	echo
 	pushd ..
 	mkdir -p manager/.build_kresd manager/.install_kresd
-	meson manager/.build_kresd --prefix=$(realpath manager/.install_kresd) --default-library=static --buildtype=debug
+	meson manager/.build_kresd \
+		--prefix=$(realpath manager/.install_kresd) \
+		--default-library=static \
+		--buildtype=debug \
+		-Dmanager_install_config=enabled
 	ninja -C manager/.build_kresd
 	ninja install -C manager/.build_kresd
-	export PATH="$(realpath manager/.install_kresd)/sbin:$PATH"
+	export PYTHONPATH="$(realpath manager/.install_kresd/lib/python*/site-packages):$PYTHONPATH"
 	popd
 }

manager/scripts/run

@@ -41,4 +41,5 @@ fi
 
 export KRES_MANAGER_CONFIG
 export KRES_MANAGER_API_SOCK
-python3 -m knot_resolver_manager $@
+export PYTHONPATH
+python3 -m knot_resolver_manager "$@"

meson_options.txt

@@ -137,6 +137,17 @@ option(
   description: 'build manager and its features',
 )
 
+option(
+  'manager_install_config',
+  type: 'combo',
+  choices: [
+    'enabled',
+    'disabled',
+  ],
+  value: 'disabled',
+  description: 'generate install config for the manager (without building the manager itself)',
+)
+
 option(
   'utils',
   type: 'combo',