Add script to shot tempalte coverage

* Add a script to compare the defined metrics with those used in the
  Zabbix template.

* Add a Makefile target to run the above script.

.gitignore

@@ -8,3 +8,4 @@ missing
 __pycache__
 venv
 build
+.coverage

Makefile

@@ -19,6 +19,12 @@ RPM_VERSION := $(VERSION)-$(RPM_RELEASE)
 DEB_VERSION := $(VERSION)~rc$(RELEASE)
 endif
 
+# Python stuff
+PYTHON ?= python3
+PYLINT ?= pylint
+BLACK ?= black
+
+HAVE_COVERAGE := $(shell $(PYTHON) -c 'import coverage' 2>/dev/null && echo yes)
 
 # Where packages are built
 BUILD_DIR := build
@@ -38,7 +44,7 @@ SUPPORTED := ubuntu-20.04 \
 # These targets are the main ones to use for most things.
 ##
 
-.PHONY: all clean tgz test query-tests install-common install-openrc install-systemd
+.PHONY: all clean tgz lint format test query-tests install-common install-openrc install-systemd
 
 all: package-all
 
@@ -80,14 +86,35 @@ tgz:
 clean:
 	rm -rf $(BUILD_DIR)
 
+# Check for lint
+lint:
+	$(PYLINT) src/pgmon.py
+	$(PYLINT) src/test_pgmon.py
+	$(BLACK) --check --diff src/pgmon.py
+	$(BLACK) --check --diff src/test_pgmon.py
+
+# Format the code using black
+format:
+	$(BLACK) src/pgmon.py
+	$(BLACK) src/test_pgmon.py
+
 # Run unit tests for the script
 test:
-	cd src ; python3 -m unittest
+ifeq ($(HAVE_COVERAGE),yes)
+	cd src ; $(PYTHON) -m coverage run -m unittest && python3 -m coverage report -m
+else
+	cd src ; $(PYTHON) -m unittest
+endif
 
 # Run query tests
 query-tests:
 	cd tests ; ./run-tests.sh
 
+# Compare the sample metrics with the Zabbix template
+template-coverage:
+	$(PYTHON) zabbix_templates/coverage.py sample-config/pgmon-metrics.yml zabbix_templates/pgmon_templates.yaml
+
+
 # Install the script at the specified base directory (common components)
 install-common:
 	# Set up directories

pylintrc

@@ -0,0 +1,4 @@
+[MASTER]
+py-version=3.5
+
+disable=fixme

sample-config/pgmon-metrics.yml

@@ -18,6 +18,7 @@ metrics:
     query:
       0: >
         SELECT host(client_addr) || '_' || regexp_replace(application_name, '[ ,]', '_', 'g') AS repid,
+               application_name,
                client_addr,
                state
         FROM pg_stat_replication
@@ -229,7 +230,19 @@ metrics:
         SELECT COUNT(*) FILTER (WHERE has_sequence_privilege(c.oid, 'SELECT,USAGE')) AS visible_sequences,
                COUNT(*) AS total_sequences
         FROM pg_class AS c
-        WHERE relkind = 'S';
+        WHERE relkind = 'S'
+
+  locks:
+    type: row
+    query:
+      0:
+        SELECT COUNT(*) AS total,
+               SUM(CASE WHEN granted THEN 1 ELSE 0 END) AS granted
+        FROM pg_locks
+      90400: >
+        SELECT COUNT(*) AS total,
+               COUNT(*) FILTER (WHERE granted) AS granted
+        FROM pg_locks
 
 
   ##

src/pgmon.py

@@ -1,105 +1,147 @@
 #!/usr/bin/env python3
+"""
+pgmon is a monitoring intermediary that sits between a PostgreSQL cluster and a monitoring systen
+that is capable of parsing JSON responses over an HTTP connection.
+"""
+
+# pylint: disable=too-few-public-methods
 
-import yaml
 import json
 import time
 import os
 import sys
-
+import signal
 import argparse
 import logging
+import re
+
+from decimal import Decimal
+
+from urllib.parse import urlparse, parse_qs
+
+from contextlib import contextmanager
 
 from datetime import datetime, timedelta
 
+from http.server import BaseHTTPRequestHandler
+from http.server import ThreadingHTTPServer
+
+from threading import Lock
+
+import yaml
+
 import psycopg2
 from psycopg2.extras import RealDictCursor
 from psycopg2.pool import ThreadedConnectionPool
 
-from contextlib import contextmanager
-
-import signal
-from threading import Thread, Lock, Semaphore
-
-from http.server import BaseHTTPRequestHandler, HTTPServer
-from http.server import ThreadingHTTPServer
-from urllib.parse import urlparse, parse_qs
-
 import requests
-import re
 
-from decimal import Decimal
 
 VERSION = "1.0.4"
 
-# Configuration
-config = {}
 
-# Dictionary of current PostgreSQL connection pools
-connections_lock = Lock()
-connections = {}
+class Context:
+    """
+    The global context for connections, config, version, nad IPC
+    """
 
-# Dictionary of unhappy databases.  Keys are database names, value is the time
-# the database was determined to be unhappy plus the cooldown setting.  So,
-# basically it's the time when we should try to connect to the database again.
-unhappy_cooldown = {}
+    # Configuration
+    config = {}
 
-# Version information
-cluster_version = None
-cluster_version_next_check = None
-cluster_version_lock = Lock()
+    # Dictionary of current PostgreSQL connection pools
+    connections_lock = Lock()
+    connections = {}
 
-# PostgreSQL latest version information
-latest_version = None
-latest_version_next_check = None
-latest_version_lock = Lock()
-release_supported = None
+    # Dictionary of unhappy databases.  Keys are database names, value is the time
+    # the database was determined to be unhappy plus the cooldown setting.  So,
+    # basically it's the time when we should try to connect to the database again.
+    unhappy_cooldown = {}
 
-# Running state (used to gracefully shut down)
-running = True
+    # Version information
+    cluster_version = None
+    cluster_version_next_check = None
+    cluster_version_lock = Lock()
 
-# The http server object
-httpd = None
+    # PostgreSQL latest version information
+    latest_version = None
+    latest_version_next_check = None
+    latest_version_lock = Lock()
+    release_supported = None
 
-# Where the config file lives
-config_file = None
+    # Running state (used to gracefully shut down)
+    running = True
 
-# Configure logging
-log = logging.getLogger(__name__)
-formatter = logging.Formatter(
-    "%(asctime)s - %(levelname)s - %(filename)s: %(funcName)s() line %(lineno)d: %(message)s"
-)
-console_log_handler = logging.StreamHandler()
-console_log_handler.setFormatter(formatter)
-log.addHandler(console_log_handler)
+    # The http server object
+    httpd = None
+
+    # Where the config file lives
+    config_file = None
+
+    # Configure logging
+    log = logging.getLogger(__name__)
+
+    @classmethod
+    def init_logging(cls):
+        """
+        Actually initialize the logging framework.  Since we don't ever instantiate the Context
+        class, this provides a way to make a few modifications to the log handler.
+        """
+
+        formatter = logging.Formatter(
+            "%(asctime)s - %(levelname)s - %(filename)s: "
+            "%(funcName)s() line %(lineno)d: %(message)s"
+        )
+        console_log_handler = logging.StreamHandler()
+        console_log_handler.setFormatter(formatter)
+        cls.log.addHandler(console_log_handler)
 
 
 # Error types
 class ConfigError(Exception):
-    pass
+    """
+    Error type for all config related errors.
+    """
 
 
 class DisconnectedError(Exception):
-    pass
+    """
+    Error indicating a previously active connection to the database has been disconnected.
+    """
 
 
 class UnhappyDBError(Exception):
-    pass
+    """
+    Error indicating that a database the code has been asked to connect to is on the unhappy list.
+    """
 
 
 class UnknownMetricError(Exception):
-    pass
+    """
+    Error indicating that an undefined metric was requested.
+    """
 
 
 class MetricVersionError(Exception):
-    pass
+    """
+    Error indicating that there is no suitable query for a metric that was requested for the
+    version of PostgreSQL being monitored.
+    """
 
 
 class LatestVersionCheckError(Exception):
-    pass
+    """
+    Error indicating that there was a problem retrieving or parsing the latest version information.
+    """
+
+
+class InvalidDataError(Exception):
+    """
+    Error indicating query results were somehow invalid
+    """
 
 
 # Default config settings
-default_config = {
+DEFAULT_CONFIG = {
     # The address the agent binds to
     "address": "127.0.0.1",
     # The port the agent listens on for requests
@@ -177,6 +219,60 @@ def update_deep(d1, d2):
     return d1
 
 
+def validate_metric(path, name, metric):
+    """
+    Validate a metric definition from a given file.  If any query definitions come from external
+    files, the metric dict will be updated with the actual query.
+
+    Params:
+        path: path to the file which contains this definition
+        name: name of the metric
+        metric: the dictionary containing the metric definition
+    """
+    # Validate return types
+    try:
+        if metric["type"] not in ["value", "row", "column", "set"]:
+            raise ConfigError(
+                "Invalid return type: {} for metric {} in {}".format(
+                    metric["type"], name, path
+                )
+            )
+    except KeyError as e:
+        raise ConfigError(
+            "No type specified for metric {} in {}".format(name, path)
+        ) from e
+
+    # Ensure queries exist
+    query_dict = metric.get("query", {})
+    if not isinstance(query_dict, dict):
+        raise ConfigError(
+            "Query definition should be a dictionary, got: {} for metric {} in {}".format(
+                query_dict, name, path
+            )
+        )
+
+    if len(query_dict) == 0:
+        raise ConfigError("Missing queries for metric {} in {}".format(name, path))
+
+    # Read external sql files and validate version keys
+    config_base = os.path.dirname(path)
+    for vers, query in metric["query"].items():
+        try:
+            int(vers)
+        except Exception as e:
+            raise ConfigError(
+                "Invalid version: {} for metric {} in {}".format(vers, name, path)
+            ) from e
+
+        # Read in the external query and update the definition in the metricdictionary
+        if query.startswith("file:"):
+            query_path = query[5:]
+            if not query_path.startswith("/"):
+                query_path = os.path.join(config_base, query_path)
+            with open(query_path, "r", encoding="utf-8") as f:
+                metric["query"][vers] = f.read()
+
+
 def read_config(path, included=False):
     """
     Read a config file.
@@ -185,61 +281,21 @@ def read_config(path, included=False):
         path: path to the file to read
         included: is this file included by another file?
     """
+
     # Read config file
-    log.info("Reading log file: {}".format(path))
-    with open(path, "r") as f:
+    Context.log.info("Reading log file: %s", path)
+    with open(path, "r", encoding="utf-8") as f:
         try:
             cfg = yaml.safe_load(f)
         except yaml.parser.ParserError as e:
-            raise ConfigError("Inavlid config file: {}: {}".format(path, e))
-
-    # Since we use it a few places, get the base directory from the config
-    config_base = os.path.dirname(path)
+            raise ConfigError("Inavlid config file: {}: {}".format(path, e)) from e
 
     # Read any external queries and validate metric definitions
     for name, metric in cfg.get("metrics", {}).items():
-        # Validate return types
-        try:
-            if metric["type"] not in ["value", "row", "column", "set"]:
-                raise ConfigError(
-                    "Invalid return type: {} for metric {} in {}".format(
-                        metric["type"], name, path
-                    )
-                )
-        except KeyError:
-            raise ConfigError(
-                "No type specified for metric {} in {}".format(name, path)
-            )
-
-        # Ensure queries exist
-        query_dict = metric.get("query", {})
-        if type(query_dict) is not dict:
-            raise ConfigError(
-                "Query definition should be a dictionary, got: {} for metric {} in {}".format(
-                    query_dict, name, path
-                )
-            )
-
-        if len(query_dict) == 0:
-            raise ConfigError("Missing queries for metric {} in {}".format(name, path))
-
-        # Read external sql files and validate version keys
-        for vers, query in metric["query"].items():
-            try:
-                int(vers)
-            except:
-                raise ConfigError(
-                    "Invalid version: {} for metric {} in {}".format(vers, name, path)
-                )
-
-            if query.startswith("file:"):
-                query_path = query[5:]
-                if not query_path.startswith("/"):
-                    query_path = os.path.join(config_base, query_path)
-                with open(query_path, "r") as f:
-                    metric["query"][vers] = f.read()
+        validate_metric(path, name, metric)
 
     # Read any included config files
+    config_base = os.path.dirname(path)
     for inc in cfg.get("include", []):
         # Prefix relative paths with the directory from the current config
         if not inc.startswith("/"):
@@ -250,34 +306,37 @@ def read_config(path, included=False):
     # config
     if included:
         return cfg
-    else:
-        new_config = {}
-        update_deep(new_config, default_config)
-        update_deep(new_config, cfg)
 
-        # Minor sanity checks
-        if len(new_config["metrics"]) == 0:
-            log.error("No metrics are defined")
-            raise ConfigError("No metrics defined")
+    new_config = {}
+    update_deep(new_config, DEFAULT_CONFIG)
+    update_deep(new_config, cfg)
 
-        # Validate the new log level before changing the config
-        if new_config["log_level"].upper() not in [
-            "DEBUG",
-            "INFO",
-            "WARNING",
-            "ERROR",
-            "CRITICAL",
-        ]:
-            raise ConfigError("Invalid log level: {}".format(new_config["log_level"]))
+    # Minor sanity checks
+    if len(new_config["metrics"]) == 0:
+        Context.log.error("No metrics are defined")
+        raise ConfigError("No metrics defined")
 
-        global config
-        config = new_config
+    # Validate the new log level before changing the config
+    if new_config["log_level"].upper() not in [
+        "DEBUG",
+        "INFO",
+        "WARNING",
+        "ERROR",
+        "CRITICAL",
+    ]:
+        raise ConfigError("Invalid log level: {}".format(new_config["log_level"]))
 
-        # Apply changes to log level
-        log.setLevel(logging.getLevelName(config["log_level"].upper()))
+    Context.config = new_config
+
+    # Apply changes to log level
+    Context.log.setLevel(logging.getLevelName(Context.config["log_level"].upper()))
+
+    # Return the config (mostly to make pylint happy, but also in case I opt to remove the side
+    # effect and make this more functional.
+    return Context.config
 
 
-def signal_handler(sig, frame):
+def signal_handler(sig, frame):  # pylint: disable=unused-argument
     """
     Function for handling signals
 
@@ -288,19 +347,22 @@ def signal_handler(sig, frame):
 
     # Signal everything to shut down
     if sig in [signal.SIGINT, signal.SIGTERM, signal.SIGQUIT]:
-        log.info("Shutting down ...")
-        global running
-        running = False
-        if httpd is not None:
-            httpd.socket.close()
+        Context.log.info("Shutting down ...")
+        Context.running = False
+        if Context.httpd is not None:
+            Context.httpd.socket.close()
 
     # Signal a reload
     if sig == signal.SIGHUP:
-        log.warning("Received config reload signal")
-        read_config(config_file)
+        Context.log.warning("Received config reload signal")
+        read_config(Context.config_file)
 
 
 class ConnectionPool(ThreadedConnectionPool):
+    """
+    Threaded connection pool that has a context manager.
+    """
+
     def __init__(self, dbname, minconn, maxconn, *args, **kwargs):
         # Make sure dbname isn't different in the kwargs
         kwargs["dbname"] = dbname
@@ -309,7 +371,14 @@ class ConnectionPool(ThreadedConnectionPool):
         self.name = dbname
 
     @contextmanager
-    def connection(self, timeout=None):
+    def connection(self, timeout):
+        """
+        Connection context manager for our connection pool.  This will attempt to retrieve a
+        connection until the timeout is reached.
+
+        Params:
+            timeout: how long to keep trying to get a connection bedore giving up
+        """
         conn = None
         timeout_time = datetime.now() + timedelta(timeout)
         # We will continue to try to get a connection slot until we time out
@@ -333,34 +402,37 @@ class ConnectionPool(ThreadedConnectionPool):
 def get_pool(dbname):
     """
     Get a database connection pool.
+
+    Params:
+        dbname: the name of the database for which a connection pool should be returned.
     """
     # Check if the db is unhappy and wants to be left alone
-    if dbname in unhappy_cooldown:
-        if unhappy_cooldown[dbname] > datetime.now():
+    if dbname in Context.unhappy_cooldown:
+        if Context.unhappy_cooldown[dbname] > datetime.now():
             raise UnhappyDBError()
 
     # Create a connection pool if it doesn't already exist
-    if dbname not in connections:
-        with connections_lock:
+    if dbname not in Context.connections:
+        with Context.connections_lock:
             # Make sure nobody created the pool while we were waiting on the
             # lock
-            if dbname not in connections:
-                log.info("Creating connection pool for: {}".format(dbname))
+            if dbname not in Context.connections:
+                Context.log.info("Creating connection pool for: %s", dbname)
                 # Actually create the connection pool
-                connections[dbname] = ConnectionPool(
+                Context.connections[dbname] = ConnectionPool(
                     dbname,
-                    int(config["min_pool_size"]),
-                    int(config["max_pool_size"]),
+                    int(Context.config["min_pool_size"]),
+                    int(Context.config["max_pool_size"]),
                     application_name="pgmon",
-                    host=config["dbhost"],
-                    port=config["dbport"],
-                    user=config["dbuser"],
-                    connect_timeout=int(config["connect_timeout"]),
-                    sslmode=config["ssl_mode"],
+                    host=Context.config["dbhost"],
+                    port=Context.config["dbport"],
+                    user=Context.config["dbuser"],
+                    connect_timeout=int(Context.config["connect_timeout"]),
+                    sslmode=Context.config["ssl_mode"],
                 )
             # Clear the unhappy indicator if present
-            unhappy_cooldown.pop(dbname, None)
-    return connections[dbname]
+            Context.unhappy_cooldown.pop(dbname, None)
+    return Context.connections[dbname]
 
 
 def handle_connect_failure(pool):
@@ -368,8 +440,8 @@ def handle_connect_failure(pool):
     Mark the database as being unhappy so we can leave it alone for a while
     """
     dbname = pool.name
-    unhappy_cooldown[dbname] = datetime.now() + timedelta(
-        seconds=int(config["reconnect_cooldown"])
+    Context.unhappy_cooldown[dbname] = datetime.now() + timedelta(
+        seconds=int(Context.config["reconnect_cooldown"])
     )
 
 
@@ -400,41 +472,67 @@ def json_encode_special(obj):
     """
     if isinstance(obj, Decimal):
         return float(obj)
-    raise TypeError(f'Cannot serialize object of {type(obj)}')
+    raise TypeError("Cannot serialize object of {}".format(type(obj)))
+
+
+def json_encode_result(return_type, res):
+    """
+    Return a json string encoding of the results of a query.
+
+    params:
+        return_type: the expected structure to return.  One of:
+                     value, row, column, set
+        res: the query results
+
+    returns: a json string form of the results
+
+    raises:
+        ConfigError: when an invalid return_type is given
+        InvalidDataError: when the query results don't match the return type
+    """
+    try:
+        if return_type == "value":
+            if len(res) == 0:
+                return ""
+            return str(list(res[0].values())[0])
+
+        if return_type == "row":
+            return json.dumps(
+                res[0] if len(res) > 0 else {}, default=json_encode_special
+            )
+
+        if return_type == "column":
+            return json.dumps(
+                [list(r.values())[0] for r in res], default=json_encode_special
+            )
+
+        if return_type == "set":
+            return json.dumps(res, default=json_encode_special)
+    except IndexError as e:
+        raise InvalidDataError(e) from e
+
+    # If we got to this point, the return type is invalid
+    raise ConfigError("Invalid query return type: {}".format(return_type))
 
 
 def run_query_no_retry(pool, return_type, query, args):
     """
     Run the query with no explicit retry code
     """
-    with pool.connection(float(config["connect_timeout"])) as conn:
+    with pool.connection(float(Context.config["connect_timeout"])) as conn:
         try:
             with conn.cursor(cursor_factory=RealDictCursor) as curs:
                 curs.execute(query, args)
                 res = curs.fetchall()
 
-                if return_type == "value":
-                    if len(res) == 0:
-                        return ""
-                    return str(list(res[0].values())[0])
-                elif return_type == "row":
-                    if len(res) == 0:
-                        return "[]"
-                    return json.dumps(res[0], default=json_encode_special)
-                elif return_type == "column":
-                    if len(res) == 0:
-                        return "[]"
-                    return json.dumps([list(r.values())[0] for r in res], default=json_encode_special)
-                elif return_type == "set":
-                    return json.dumps(res, default=json_encode_special)
-        except:
+                return json_encode_result(return_type, res)
+        except Exception as e:
             dbname = pool.name
-            if dbname in unhappy_cooldown:
-                raise UnhappyDBError()
-            elif conn.closed != 0:
-                raise DisconnectedError()
-            else:
-                raise
+            if dbname in Context.unhappy_cooldown:
+                raise UnhappyDBError() from e
+            if conn.closed != 0:
+                raise DisconnectedError() from e
+            raise
 
 
 def run_query(pool, return_type, query, args):
@@ -455,7 +553,7 @@ def run_query(pool, return_type, query, args):
     try:
         return run_query_no_retry(pool, return_type, query, args)
     except DisconnectedError:
-        log.warning("Stale PostgreSQL connection found ... trying again")
+        Context.log.warning("Stale PostgreSQL connection found ... trying again")
         # This sleep is an annoying hack to give the pool workers time to
         # actually mark the connection, otherwise it can be given back in the
         # next connection() call
@@ -463,9 +561,9 @@ def run_query(pool, return_type, query, args):
         time.sleep(1)
         try:
             return run_query_no_retry(pool, return_type, query, args)
-        except:
+        except Exception as e:
             handle_connect_failure(pool)
-            raise UnhappyDBError()
+            raise UnhappyDBError() from e
 
 
 def get_cluster_version():
@@ -473,40 +571,39 @@ def get_cluster_version():
     Get the PostgreSQL version if we don't already know it, or if it's been
     too long sice the last time it was checked.
     """
-    global cluster_version
-    global cluster_version_next_check
 
     # If we don't know the version or it's past the recheck time, get the
     # version from the database.  Only one thread needs to do this, so they all
     # try to grab the lock, and then make sure nobody else beat them to it.
     if (
-        cluster_version is None
-        or cluster_version_next_check is None
-        or cluster_version_next_check < datetime.now()
+        Context.cluster_version is None
+        or Context.cluster_version_next_check is None
+        or Context.cluster_version_next_check < datetime.now()
     ):
-        with cluster_version_lock:
+        with Context.cluster_version_lock:
             # Only check if nobody already got the version before us
             if (
-                cluster_version is None
-                or cluster_version_next_check is None
-                or cluster_version_next_check < datetime.now()
+                Context.cluster_version is None
+                or Context.cluster_version_next_check is None
+                or Context.cluster_version_next_check < datetime.now()
             ):
-                log.info("Checking PostgreSQL cluster version")
-                pool = get_pool(config["dbname"])
-                cluster_version = int(
+                Context.log.info("Checking PostgreSQL cluster version")
+                pool = get_pool(Context.config["dbname"])
+                Context.cluster_version = int(
                     run_query(pool, "value", "SHOW server_version_num", None)
                 )
-                cluster_version_next_check = datetime.now() + timedelta(
-                    seconds=int(config["version_check_period"])
+                Context.cluster_version_next_check = datetime.now() + timedelta(
+                    seconds=int(Context.config["version_check_period"])
                 )
-                log.info("Got PostgreSQL cluster version: {}".format(cluster_version))
-                log.debug(
-                    "Next PostgreSQL cluster version check will be after: {}".format(
-                        cluster_version_next_check
-                    )
+                Context.log.info(
+                    "Got PostgreSQL cluster version: %s", Context.cluster_version
+                )
+                Context.log.debug(
+                    "Next PostgreSQL cluster version check will be after: %s",
+                    Context.cluster_version_next_check,
                 )
 
-    return cluster_version
+    return Context.cluster_version
 
 
 def version_num_to_release(version_num):
@@ -519,8 +616,7 @@ def version_num_to_release(version_num):
     """
     if version_num // 10000 < 10:
         return version_num // 10000 + (version_num % 10000 // 100 / 10)
-    else:
-        return version_num // 10000
+    return version_num // 10000
 
 
 def parse_version_rss(raw_rss, release):
@@ -528,7 +624,7 @@ def parse_version_rss(raw_rss, release):
     Parse the raw RSS from the versions.rss feed to extract the latest version of
     PostgreSQL that's availabe for the cluster being monitored.
 
-    This sets these global variables:
+    This sets these Context variables:
         latest_version
         release_supported
 
@@ -538,8 +634,6 @@ def parse_version_rss(raw_rss, release):
         raw_rss: The raw rss text from versions.rss
         release: The PostgreSQL release we care about (ex: 9.2, 14)
     """
-    global latest_version
-    global release_supported
 
     # Regular expressions for parsing the RSS document
     version_line = re.compile(
@@ -559,75 +653,75 @@ def parse_version_rss(raw_rss, release):
             version = m.group(1)
             parts = list(map(int, version.split(".")))
             if parts[0] < 10:
-                latest_version = int(
+                Context.latest_version = int(
                     "{}{:02}{:02}".format(parts[0], parts[1], parts[2])
                 )
             else:
-                latest_version = int("{}00{:02}".format(parts[0], parts[1]))
+                Context.latest_version = int("{}00{:02}".format(parts[0], parts[1]))
         elif release_found:
             # The next line after the version tells if the version is supported
             if unsupported_line.match(line):
-                release_supported = False
+                Context.release_supported = False
             else:
-                release_supported = True
+                Context.release_supported = True
             break
 
     # Make sure we actually found it
     if not release_found:
         raise LatestVersionCheckError("Current release ({}) not found".format(release))
 
-    log.info(
-        "Got latest PostgreSQL version: {} supported={}".format(
-            latest_version, release_supported
-        )
+    Context.log.info(
+        "Got latest PostgreSQL version: %s supported=%s",
+        Context.latest_version,
+        Context.release_supported,
     )
-    log.debug(
-        "Next latest PostgreSQL version check will be after: {}".format(
-            latest_version_next_check
-        )
+    Context.log.debug(
+        "Next latest PostgreSQL version check will be after: %s",
+        Context.latest_version_next_check,
     )
 
 
 def get_latest_version():
     """
-    Get the latest supported version of the major PostgreSQL release running on the server being monitored.
+    Get the latest supported version of the major PostgreSQL release running on the server being
+    monitored.
     """
 
-    global latest_version_next_check
-
     # If we don't know the latest version or it's past the recheck time, get the
     # version from the PostgreSQL RSS feed.  Only one thread needs to do this, so
     # they all try to grab the lock, and then make sure nobody else beat them to it.
     if (
-        latest_version is None
-        or latest_version_next_check is None
-        or latest_version_next_check < datetime.now()
+        Context.latest_version is None
+        or Context.latest_version_next_check is None
+        or Context.latest_version_next_check < datetime.now()
     ):
         # Note: we get the cluster version here before grabbing the latest_version_lock
         #       lock so it's not held while trying to talk with the DB.
         release = version_num_to_release(get_cluster_version())
 
-        with latest_version_lock:
+        with Context.latest_version_lock:
             # Only check if nobody already got the version before us
             if (
-                latest_version is None
-                or latest_version_next_check is None
-                or latest_version_next_check < datetime.now()
+                Context.latest_version is None
+                or Context.latest_version_next_check is None
+                or Context.latest_version_next_check < datetime.now()
             ):
-                log.info("Checking latest PostgreSQL version")
-                latest_version_next_check = datetime.now() + timedelta(
-                    seconds=int(config["latest_version_check_period"])
+                Context.log.info("Checking latest PostgreSQL version")
+                Context.latest_version_next_check = datetime.now() + timedelta(
+                    seconds=int(Context.config["latest_version_check_period"])
                 )
 
                 # Grab the RSS feed
-                raw_rss = requests.get("https://www.postgresql.org/versions.rss")
+                raw_rss = requests.get(
+                    "https://www.postgresql.org/versions.rss", timeout=30
+                )
                 if raw_rss.status_code != 200:
-                    raise LatestVersionCheckError("code={}".format(r.status_code))
+                    raise LatestVersionCheckError("code={}".format(raw_rss.status_code))
 
-                # Parse the RSS body and set global variables
+                # Parse the RSS body and set Context variables
                 parse_version_rss(raw_rss.text, release)
 
-    return latest_version
+    return Context.latest_version
 
 
 def sample_metric(dbname, metric_name, args, retry=True):
@@ -636,9 +730,9 @@ def sample_metric(dbname, metric_name, args, retry=True):
     """
     # Get the metric definition
     try:
-        metric = config["metrics"][metric_name]
-    except KeyError:
-        raise UnknownMetricError("Unknown metric: {}".format(metric_name))
+        metric = Context.config["metrics"][metric_name]
+    except KeyError as e:
+        raise UnknownMetricError("Unknown metric: {}".format(metric_name)) from e
 
     # Get the connection pool for the database, or create one if it doesn't
     # already exist.
@@ -653,8 +747,7 @@ def sample_metric(dbname, metric_name, args, retry=True):
     # Execute the quert
     if retry:
         return run_query(pool, metric["type"], query, args)
-    else:
-        return run_query_no_retry(pool, metric["type"], query, args)
+    return run_query_no_retry(pool, metric["type"], query, args)
 
 
 def test_queries():
@@ -662,12 +755,17 @@ def test_queries():
     Run all of the metric queries against a database and check the results
     """
     # We just use the default db for tests
-    dbname = config["dbname"]
+    dbname = Context.config["dbname"]
     # Loop through all defined metrics.
-    for name, metric in config["metrics"].items():
+    for name, metric in Context.config["metrics"].items():
         # If the metric has arguments to use while testing, grab those
         args = metric.get("test_args", {})
-        print("Testing {} [{}]".format(name, ", ".join(["{}={}".format(key, value) for key, value in args.items()])))
+        print(
+            "Testing {} [{}]".format(
+                name,
+                ", ".join(["{}={}".format(key, value) for key, value in args.items()]),
+            )
+        )
         # When testing against a docker container, we may end up connecting
         # before the service is truly up (it restarts during the initialization
         # phase).  To cope with this, we'll allow a few connection failures.
@@ -704,9 +802,8 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
         """
         Override to suppress standard request logging
         """
-        pass
 
-    def do_GET(self):
+    def do_GET(self):  # pylint: disable=invalid-name
         """
         Handle a request.  This is just a wrapper around the actual handler
         code to keep things more readable.
@@ -714,7 +811,7 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
         try:
             self._handle_request()
         except BrokenPipeError:
-            log.error("Client disconnected, exiting handler")
+            Context.log.error("Client disconnected, exiting handler")
 
     def _handle_request(self):
         """
@@ -727,7 +824,6 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
 
         if metric_name == "agent_version":
             self._reply(200, VERSION)
-            return
         elif metric_name == "latest_version_info":
             try:
                 get_latest_version()
@@ -735,46 +831,40 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
                     200,
                     json.dumps(
                         {
-                            "latest": latest_version,
-                            "supported": 1 if release_supported else 0,
+                            "latest": Context.latest_version,
+                            "supported": 1 if Context.release_supported else 0,
                         }
                     ),
                 )
             except LatestVersionCheckError as e:
-                log.error("Failed to retrieve latest version information: {}".format(e))
+                Context.log.error(
+                    "Failed to retrieve latest version information: %s", e
+                )
                 self._reply(503, "Failed to retrieve latest version info")
-            return
+        else:
+            # Note: parse_qs returns the values as a list.  Since we always expect
+            #       single values, just grab the first from each.
+            args = {key: values[0] for key, values in parsed_query.items()}
 
-        # Note: parse_qs returns the values as a list.  Since we always expect
-        #       single values, just grab the first from each.
-        args = {key: values[0] for key, values in parsed_query.items()}
+            # Get the dbname.  If none was provided, use the default from the
+            # config.
+            dbname = args.get("dbname", Context.config["dbname"])
 
-        # Get the dbname.  If none was provided, use the default from the
-        # config.
-        dbname = args.get("dbname", config["dbname"])
-
-        # Sample the metric
-        try:
-            self._reply(200, sample_metric(dbname, metric_name, args))
-            return
-        except UnknownMetricError as e:
-            log.error("Unknown metric: {}".format(metric_name))
-            self._reply(404, "Unknown metric")
-            return
-        except MetricVersionError as e:
-            log.error(
-                "Failed to find a version of {} for {}".format(metric_name, version)
-            )
-            self._reply(404, "Unsupported version")
-            return
-        except UnhappyDBError as e:
-            log.info("Database {} is unhappy, please be patient".format(dbname))
-            self._reply(503, "Database unavailable")
-            return
-        except Exception as e:
-            log.error("Error running query: {}".format(e))
-            self._reply(500, "Unexpected error: {}".format(e))
-            return
+            # Sample the metric
+            try:
+                self._reply(200, sample_metric(dbname, metric_name, args))
+            except UnknownMetricError:
+                Context.log.error("Unknown metric: %s", metric_name)
+                self._reply(404, "Unknown metric")
+            except MetricVersionError:
+                Context.log.error("Failed to find an query version for %s", metric_name)
+                self._reply(404, "Unsupported version")
+            except UnhappyDBError:
+                Context.log.info("Database %s is unhappy, please be patient", dbname)
+                self._reply(503, "Database unavailable")
+            except Exception as e:  # pylint: disable=broad-exception-caught
+                Context.log.error("Error running query: %s", e)
+                self._reply(500, "Unexpected error: {}".format(e))
 
     def _reply(self, code, content):
         """
@@ -787,7 +877,14 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
         self.wfile.write(bytes(content, "utf-8"))
 
 
-if __name__ == "__main__":
+def main():
+    """
+    Main application routine
+    """
+
+    # Initialize the logging framework
+    Context.init_logging()
+
     # Handle cli args
     parser = argparse.ArgumentParser(
         prog="pgmon", description="A PostgreSQL monitoring agent"
@@ -808,33 +905,35 @@ if __name__ == "__main__":
     args = parser.parse_args()
 
     # Set the config file path
-    config_file = args.config_file
+    Context.config_file = args.config_file
 
     # Read the config file
-    read_config(config_file)
+    read_config(Context.config_file)
 
     # Run query tests and exit if test mode is enabled
     if args.test:
-        errors = test_queries()
-        if errors > 0:
+        if test_queries() > 0:
             sys.exit(1)
-        else:
-            sys.exit(0)
+        sys.exit(0)
 
     # Set up the http server to receive requests
-    server_address = (config["address"], config["port"])
-    httpd = ThreadingHTTPServer(server_address, SimpleHTTPRequestHandler)
+    server_address = (Context.config["address"], Context.config["port"])
+    Context.httpd = ThreadingHTTPServer(server_address, SimpleHTTPRequestHandler)
 
     # Set up the signal handler
     signal.signal(signal.SIGINT, signal_handler)
     signal.signal(signal.SIGHUP, signal_handler)
 
     # Handle requests.
-    log.info("Listening on port {}...".format(config["port"]))
-    while running:
-        httpd.handle_request()
+    Context.log.info("Listening on port %s...", Context.config["port"])
+    while Context.running:
+        Context.httpd.handle_request()
 
     # Clean up PostgreSQL connections
     # TODO: Improve this ... not sure it actually closes all the connections cleanly
-    for pool in connections.values():
+    for pool in Context.connections.values():
         pool.close()
+
+
+if __name__ == "__main__":
+    main()

zabbix_templates/coverage.py

@@ -0,0 +1,129 @@
+#!/usr/bin/env python3
+
+# Compare the items defined in a Zabbix template with the metrics defined in a config file.
+
+import sys
+
+import yaml
+
+# Special built in metrics
+SPECIAL = {
+    "agent_version",
+    "latest_version_info"
+}
+
+
+class NonMetricItemError(Exception):
+    """
+    A given item does not directly use a metric
+    """
+
+
+def read_metrics(file):
+    """
+    Read the metrics from a config file and return the list of names
+
+    params:
+        file: the name of the file to read
+
+    returns:
+        list of metric named defined in the file
+
+    raises:
+        yaml.parser.ParserError: invalid yaml file
+    """
+    names = set()
+    config = None
+
+    with open(file, "r", encoding="utf-8") as f:
+        config = yaml.safe_load(f)
+
+    try:
+        for m in config["metrics"].keys():
+            names.add(m)
+    except KeyError:
+        pass
+
+    return names
+
+
+def extract_metric(item):
+    """
+    Extract the metric from an item definition
+
+    params:
+        item: the item/discovery/prototype definition dict
+
+    returns:
+        the name of the metric used in the item
+
+    raises:
+        NonMetricItemError: the item does not directly use a metric
+    """
+    try:
+        if item["type"] == "HTTP_AGENT":
+            url = item["url"]
+            if url.startswith("http://localhost:{$AGENT_PORT}"):
+                return url.split("/")[-1]
+    except KeyError:
+        raise NonMetricItemError()
+
+    raise NonMetricItemError()
+
+
+def read_template(file):
+    """
+    Read the items from a Zabbix template and return the list of metric names
+
+    params:
+        file: the name of the file to read
+
+    returns:
+        list of metric named used in the file
+
+    raises:
+        yaml.parser.ParserError: invalid yaml file
+    """
+    names = set()
+    config = None
+
+    with open(file, "r", encoding="utf-8") as f:
+        config = yaml.safe_load(f)
+
+    try:
+        for template in config["zabbix_export"]["templates"]:
+            for item in template["items"]:
+                try:
+                    names.add(extract_metric(item))
+                except NonMetricItemError:
+                    pass
+
+            for rule in template["discovery_rules"]:
+                try:
+                    names.add(extract_metric(rule))
+                except NonMetricItemError:
+                    pass
+
+                for proto in rule["item_prototypes"]:
+                    try:
+                        names.add(extract_metric(proto))
+                    except NonMetricItemError:
+                        pass
+    except KeyError:
+        pass
+
+    return names
+
+
+if __name__ == '__main__':
+    config_file = sys.argv[1]
+    config_metrics = read_metrics(config_file)
+
+    template_file = sys.argv[2]
+    template_metrics = read_template(template_file) - SPECIAL
+
+    config_only = config_metrics - template_metrics
+    template_only = template_metrics - config_metrics
+
+    print("Config only: {}".format(sorted(list(config_only))))
+    print("Template only: {}".format(sorted(list(template_only))))

zabbix_templates/pgmon_templates.yaml

@@ -167,7 +167,8 @@ zabbix_export:
                 operator: NOT_MATCHES_REGEX
                 formulaid: A
           lifetime: 30d
-          enabled_lifetime_type: DISABLE_NEVER
+          enabled_lifetime_type: DISABLE_AFTER
+          enabled_lifetime: 1d
           item_prototypes:
             - uuid: a30babe4a6f4440bba2a3ee46eff7ce2
               name: 'Time spent executing statements on {#DBNAME}'
@@ -982,6 +983,9 @@ zabbix_export:
           type: DEPENDENT
           key: pgmon_discover_io_backend_types
           delay: '0'
+          lifetime: 30d
+          enabled_lifetime_type: DISABLE_AFTER
+          enabled_lifetime: 1h
           item_prototypes:
             - uuid: b1ac2e56b30f4812bf33ce973ef16b10
               name: 'I/O Evictions by {#BACKEND_TYPE}'
@@ -1572,8 +1576,15 @@ zabbix_export:
           type: HTTP_AGENT
           key: pgmon_discover_rep
           delay: 10m
+          filter:
+            conditions:
+              - macro: '{#APPLICATION_NAME}'
+                value: '^pg_[0-9]+_sync_[0-9]+_[0-9]+$'
+                operator: NOT_MATCHES_REGEX
+                formulaid: A
           lifetime: 30d
-          enabled_lifetime_type: DISABLE_NEVER
+          enabled_lifetime_type: DISABLE_AFTER
+          enabled_lifetime: 7d
           item_prototypes:
             - uuid: 3a5a60620e6a4db694e47251148d82f5
               name: 'Flush lag for {#REPID}'
@@ -1775,6 +1786,8 @@ zabbix_export:
                   value: Raw
           url: 'http://localhost:{$AGENT_PORT}/discover_rep'
           lld_macro_paths:
+            - lld_macro: '{#APPLICATION_NAME}'
+              path: $.application_name
             - lld_macro: '{#CLIENT_ADDR}'
               path: $.client_addr
             - lld_macro: '{#REPID}'
@@ -1786,6 +1799,15 @@ zabbix_export:
           type: HTTP_AGENT
           key: pgmon_discover_slots
           delay: 10m
+          filter:
+            conditions:
+              - macro: '{#SLOT_NAME}'
+                value: '^pg_[0-9]+_sync_[0-9]+_[0-9]+$'
+                operator: NOT_MATCHES_REGEX
+                formulaid: A
+          lifetime: 30d
+          enabled_lifetime_type: DISABLE_AFTER
+          enabled_lifetime: 7d
           item_prototypes:
             - uuid: 536c5f82e3074ddfbfd842b3a2e8d46c
               name: 'Slot {#SLOT_NAME} - Confirmed Flushed Bytes Lag'