S allius/issue217 2 (#230)

* add some reader classes to get the configuration

* adapt unittests

* get config from json or toml file

* loop over all config readers to get the configuration

* rename config test files

* use relative paths for coverage test in vscode

* do not throw an error for missing config files

* remove obsolete tests

* use dotted key notation for pv sub dictonary

* log config reading progress

* remove create_config_toml.py

* remove obsolete tests for the ha_addon

* disable mosquitto tests if the server is down

* ignore main method for test coverage

* increase test coverage

* pytest-cov: use relative_files only on github, so coverage will work with vscode locally

* remove unneeded imports

* add missing test cases

* disable branch coverage, cause its not reachable

app/src/cnf/config_read_env.py

@@ -0,0 +1,25 @@
+'''Config Reader module which handles config values from the environment'''
+
+import os
+from cnf.config import ConfigIfc
+
+
+class ConfigReadEnv(ConfigIfc):
+    '''Reader for environment values of the configuration'''
+
+    def get_config(self) -> dict:
+        conf = {}
+        data = [
+            ('mqtt.host', 'MQTT_HOST'),
+            ('mqtt.port', 'MQTT_PORT'),
+            ('mqtt.user', 'MQTT_USER'),
+            ('mqtt.passwd', 'MQTT_PASSWORD'),
+        ]
+        for key, env_var in data:
+            val = os.getenv(env_var)
+            if val:
+                self._extend_key(conf, key, val)
+        return conf
+
+    def descr(self):
+        return "Read environment"