Adding linux_config_files snmp script to monitor configuration file updates (#453)

snmp/linux_config_files.py

@@ -0,0 +1,173 @@
+#!/usr/bin/env python
+#
+# Name: linux_config_files Script
+# Author: bnerickson <bnerickson87@gmail.com> w/SourceDoctor's certificate.py script forming
+#         the base of the vast majority of this one.
+# Version: 1.0
+# Description: This is a simple script to parse "pkg_tool_cmd" output for ingestion into
+#              LibreNMS via the linux_config_files application.  Additional distribution
+#              support may be added.
+# Installation:
+#     1. Copy this script to /etc/snmp/ and make it executable:
+#         chmod +x /etc/snmp/linux_config_files.py
+#     2. Edit your snmpd.conf and include:
+#         extend linux_config_files /etc/snmp/linux_config_files.py
+#     3. (Optional, if RPM-based) Create a /etc/snmp/linux_config_files.json file and specify:
+#           a.) "pkg_system" - String designating the distribution name of the system.  At
+#                              the moment only "rpm" is supported.
+#           b.) "pkg_tool_cmd" - String path to the package tool binary ["/sbin/rpmconf"]
+#         ```
+#         {
+#             "pkg_system": "rpm",
+#             "pkg_tool_cmd": "/bin/rpmconf",
+#         }
+#         ```
+#     4. Restart snmpd and activate the app for desired host.
+
+import json
+import subprocess
+import sys
+
+CONFIG_FILE = "/etc/snmp/linux_config_files.json"
+PKG_SYSTEM = "rpm"
+PKG_TOOL_ARGS = {"rpm": ["--all", "--test"]}
+PKG_TOOL_CMD = {"rpm": "/sbin/rpmconf"}
+
+
+def error_handler(error_name, err):
+    """
+    error_handler(): Common error handler for config/output parsing and
+                     command execution.
+    Inputs:
+        error_name: String describing the error handled.
+        err: The error message in its entirety.
+    Outputs:
+        None
+    """
+    output_data = {
+        "errorString": "%s: '%s'" % (error_name, err),
+        "error": 1,
+        "version": 1,
+        "data": [],
+    }
+    print(json.dumps(output_data))
+    sys.exit(1)
+
+
+def config_file_parser():
+    """
+    config_file_parser(): Parses the config file (if it exists) and extracts the
+                          necessary parameters.
+
+    Inputs:
+        None
+    Outputs:
+        pkg_system: The package management used by the system.
+        pkg_tool_cmd: The full package tool command to execute.
+    """
+    pkg_system = PKG_SYSTEM
+    pkg_tool_cmd = [PKG_TOOL_CMD[pkg_system]]
+
+    # Load configuration file if it exists
+    try:
+        with open(CONFIG_FILE, "r") as json_file:
+            config_file = json.load(json_file)
+            if "pkg_system" in config_file:
+                pkg_system = config_file["pkg_system"].strip().lower()
+            pkg_tool_cmd = (
+                [config_file["pkg_tool_cmd"].strip().lower()]
+                if "pkg_tool_cmd" in config_file
+                else [PKG_TOOL_CMD[pkg_system]]
+            )
+    except FileNotFoundError:
+        pass
+    except (KeyError, PermissionError, OSError, json.decoder.JSONDecodeError) as err:
+        error_handler("Config File Error", err)
+
+    # Create and return pkg_system & full pkg_tool_cmd command.
+    pkg_tool_cmd.extend(PKG_TOOL_ARGS[pkg_system])
+    return pkg_system, pkg_tool_cmd
+
+
+def command_executor(pkg_system, pkg_tool_cmd):
+    """
+    command_executor(): Execute the pkg_tool_cmd command and return the output.
+
+    Inputs:
+        pkg_system: The package management used by the system.
+        pkg_tool_cmd: The full package tool command to execute.
+    Outputs:
+        poutput: The stdout of the executed command (empty byte-string if error).
+    """
+    poutput = None
+    try:
+        # Execute pkg_tool_cmd command
+        poutput = subprocess.check_output(
+            pkg_tool_cmd,
+            stdin=None,
+            stderr=subprocess.PIPE,
+        )
+    except (subprocess.CalledProcessError, OSError) as err:
+        # Per rpmconf man page, an error code of 5 indicates there are conf file
+        # to merge, so disregard that error code.
+        if err.returncode != 5 or pkg_system != "rpm":
+            error_handler("Command Execution Error", err)
+        poutput = err.output
+    return poutput
+
+
+def output_parser(pkg_system, cmd_output):
+    """
+    output_parser(): Parses stdout of executed command and returns updated dictionary
+                     with parsed data.
+
+    Inputs:
+        pkg_system: The package management used by the system.
+        cmd_output: stdout of the executed command.
+    Outputs:
+        output_data: Dictionary updated with parsed data.
+    """
+    output_data = {
+        "errorString": "",
+        "error": 0,
+        "version": 1,
+        "data": {"number_of_confs": None},
+    }
+
+    if pkg_system == "rpm":
+        if not cmd_output:
+            output_data["data"]["number_of_confs"] = 0
+        else:
+            output_data["data"]["number_of_confs"] = len(
+                cmd_output.decode("utf-8").strip().split("\n")
+            )
+
+    return output_data
+
+
+def main():
+    """
+    main(): main function that delegates config file parsing, command execution,
+            and unit stdout parsing.  Then it prints out the expected json output
+            for the pkg_tool_cmd application.
+
+    Inputs:
+        None
+    Outputs:
+        None
+    """
+    # Parse configuration file.
+    pkg_system, pkg_tool_cmd = config_file_parser()
+
+    # Execute pkg_tool_cmd command and parse output.
+    cmd_output = command_executor(pkg_system, pkg_tool_cmd)
+
+    # Parse command output.
+    output_data = output_parser(pkg_system, cmd_output)
+
+    # Print json dumps of dictionary.
+    print(json.dumps(output_data))
+
+
+if __name__ == "__main__":
+    main()