Add configuration validation with jsonschema

Signed-off-by: Julien Riou <julien@riou.xyz>

.pre-commit-config.yaml

@@ -11,6 +11,8 @@ repos:
         args: ['--remove']
       - id: requirements-txt-fixer
       - id: trailing-whitespace
+      - id: check-json
+      - id: check-yaml
   - repo: https://gitlab.com/pycqa/flake8
     rev: master
     hooks:

README.md

@@ -17,14 +17,14 @@ git clone https://github.com/jouir/notify-by-telegram.git /opt/notify-by-telegra
 
 Install dependencies using the package manager:
 ```
-sudo apt install python3-jinja2 python3-requests
+sudo apt install python3-jinja2 python3-requests python3-jsonschema
 ```
 
 ## Configuration
 
 Copy and update the configuration file example:
 ```
-cp -p config.json.example telegram.json
+cp -p config.example.json telegram.json
 vim telegram.json
 sudo mv telegram.json /etc/nagios4/telegram.json
 sudo chown root:nagios /etc/nagios4/telegram.json

TODO.txt

@@ -1,3 +1,2 @@
-Use JSON schema to validate configuration file
 Add pre-commit Dockerfile and a doc to easily lint the code
 Add requirements.txt file

config.schema.json

@@ -0,0 +1,21 @@
+{
+  "type": "object",
+  "properties": {
+    "chat_id": {
+      "type": "number"
+    },
+    "auth_key": {
+      "type": "string"
+    },
+    "host_template": {
+      "type": "string"
+    },
+    "service_template": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "chat_id",
+    "auth_key"
+  ]
+}

notify-by-telegram.py

@@ -6,8 +6,10 @@ import os
 
 import requests
 from jinja2 import Environment, FileSystemLoader
+from jsonschema import validate
 
 logger = logging.getLogger(__name__)
+absolute_path = os.path.split(os.path.abspath(__file__))[0]
 
 
 class InvalidConfigException(Exception):
@@ -60,9 +62,9 @@ def read_config(filename=None):
 def validate_config(config):
     if config is None:
         raise InvalidConfigException('config is not a dict')
-    for key in ['chat_id', 'auth_key']:
+    with open(os.path.join(absolute_path, 'config.schema.json'), 'r') as fd:
-        if key not in config:
+        schema = json.loads(fd.read())
-            raise InvalidConfigException(f'missing "{key}" key in config')
+        validate(instance=config, schema=schema)
 
 
 def setup_logging(args):
@@ -82,7 +84,6 @@ def generate_payload(chat_id, message_type, message_variables, template_file_nam
     # define jinja template name
     if not template_file_name:
         template_name = 'host.md.j2' if message_type == 'host' else 'service.md.j2'
-        absolute_path = os.path.split(os.path.abspath(__file__))[0]
         template_file_name = os.path.join(absolute_path, 'templates', template_name)
     template_path = os.path.dirname(os.path.abspath(template_file_name))
     template_name = os.path.basename(os.path.abspath(template_file_name))