wip

requirements.yml

@@ -1,2 +1,4 @@
-psycopg
+psycopg2
 pyyaml
+llfuse
+requests

sample-config/pgmon.yml

@@ -1,8 +1,22 @@
-# The address the agent binds to
-#address: 127.0.0.1
+# # The name for this agent instance (controles the FUSE directory name)
+#name: pgmon
 
-# The port the agent listens on for requests
-#port: 5400
+# Mode to set on FUSE files (in octal)
+#fuse_mode: 0o400
+
+# Owner to set on FUSE files
+#fuse_owner: zabbix
+fuse_owner: james
+
+# Group to set on FUSE files
+#fuse_group: zabbix
+fuse_group: james
+
+# User the agent runs as
+agent_user: james
+
+# Groupthe agent runs as
+agent_group: james
 
 # Min PostgreSQL connection pool size (per database)
 #min_pool_size: 0
@@ -16,21 +30,28 @@
 # Log level for stderr logging (see https://docs.python.org/3/library/logging.html#logging-levels)
 # Possible values are: debug, info, warning, error, critical
 #log_level: 'error'
+log_level: 'info'
+
+# Base directory for FUSE file system
+fuse_base: /tmp/pgmon
 
 # Database user to connect as
 #dbuser: 'postgres'
 
 # Database host
 #dbhost: '/var/run/postgresql'
+dbhost: 127.0.0.1
 
 # Database port
 #dbport: 5432
+dbport: 54315
 
 # Default database to connect to when none is specified for a metric
 #dbname: 'postgres'
 
 # SSL connection mode
 #ssl_mode: require
+ssl_mode: allow
 
 # Timeout for getting a connection slot from a pool
 #pool_slot_timeout: 5

src/pgmon.py

@@ -14,6 +14,9 @@ import signal
 import argparse
 import logging
 import re
+import stat
+import errno
+import requests
 
 from decimal import Decimal
 
@@ -23,9 +26,6 @@ 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
@@ -34,7 +34,10 @@ import psycopg2
 from psycopg2.extras import RealDictCursor
 from psycopg2.pool import ThreadedConnectionPool
 
-import requests
+from pwd import getpwnam
+from grp import getgrnam
+
+import llfuse
 
 
 VERSION = "1.1.0-rc1"
@@ -71,9 +74,6 @@ class Context:
     # Running state (used to gracefully shut down)
     running = True
 
-    # The http server object
-    httpd = None
-
     # Where the config file lives
     config_file = None
 
@@ -142,10 +142,20 @@ class InvalidDataError(Exception):
 
 # Default config settings
 DEFAULT_CONFIG = {
-    # The address the agent binds to
-    "address": "127.0.0.1",
-    # The port the agent listens on for requests
-    "port": 5400,
+    # The name for this agent instance (controles the FUSE directory name)
+    "name": "pgmon",
+    # Base directory for FUSE file system
+    "fuse_base": "/run/pgmon",
+    # Mode to set on FUSE files (in octal)
+    "fuse_mode": 0o400,
+    # Owner to set on FUSE files
+    "fuse_owner": "zabbix",
+    # Group to set on FUSE files
+    "fuse_group": "zabbix",
+    # The user the agent runs as
+    "agent_user": "pgmon",
+    # The group the agent runs as
+    "agent_group": "pgmon",
     # Min PostgreSQL connection pool size (per database)
     "min_pool_size": 0,
     # Max PostgreSQL connection pool size (per database)
@@ -349,11 +359,9 @@ def signal_handler(sig, frame):  # pylint: disable=unused-argument
     if sig in [signal.SIGINT, signal.SIGTERM, signal.SIGQUIT]:
         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:
+    if sig in [signal.SIGHUP, signal.SIGUSR1]:
         Context.log.warning("Received config reload signal")
         read_config(Context.config_file)
 
@@ -792,89 +800,253 @@ def test_queries():
     return 0
 
 
-class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
+class PGMonFuse(llfuse.Operations):
     """
-    This is our request handling server.  It is responsible for listening for
+    This is our FUSE filesystem for requests from Zabbix.  It is responsible for listening for
     requests, processing them, and responding.
     """
 
-    def log_request(self, code="-", size="-"):
-        """
-        Override to suppress standard request logging
-        """
+    def __init__(self):
+        super().__init__()
+        self.builtin = ["agent_version", "latest_version_info", "sleep"]
+        self.update_files()
 
-    def do_GET(self):  # pylint: disable=invalid-name
+        # Dictionary holdig context information for open file handles
+        self.inodes = dict()
+        self.file_handles = dict()
+
+    @staticmethod
+    def gen_attrs(inode, is_dir):
+
+        attrs = llfuse.EntryAttributes()
+        if is_dir:
+            attrs.st_mode = Context.config["fuse_mode"] | stat.S_IXUSR | stat.S_IFDIR
+        else:
+            attrs.st_mode = Context.config["fuse_mode"] | stat.S_IFREG
+        attrs.st_nlink = 1
+        attrs.st_size = 1024
+        attrs.st_uid = getpwnam(Context.config["fuse_owner"]).pw_uid
+        attrs.st_gid = getgrnam(Context.config["fuse_group"]).gr_gid
+
+        attrs.st_ino = inode
+
+        return attrs
+
+    def update_files(self):
+        self.files = self.builtin + sorted(list(Context.config["metrics"].keys()))
+
+    @staticmethod
+    def path_to_inode(path):
         """
-        Handle a request.  This is just a wrapper around the actual handler
-        code to keep things more readable.
+        Provide a consistent inode for a given file
         """
+        return hash(path) & 0xFFFFFFFFFFFFFFFF
+
+    def lookup(self, inode_p, name, ctx=None):
+        """ """
+        print(f"Lookup called with: inode_p={inode_p} name={name}")
+
+        # We only have a single level, so if the parent inode is anything else
+        # then it doesn't exist
+        if inode_p != llfuse.ROOT_INODE:
+            raise llfuse.FUSEError(errno.ENOENT)
+
+        # Generate the inode for this file (ie: query + args)
+        inode = self.path_to_inode(name)
+
+        # Get the file info if we already have it, create it otherwise
         try:
-            self._handle_request()
-        except BrokenPipeError:
-            Context.log.error("Client disconnected, exiting handler")
+            file = self.inodes[inode]
+        except KeyError:
+            # Separate out the name components
+            parts = name.decode("utf-8").split(":", 1)
+            base_name = parts[0]
+            try:
+                arg_str = parts[1]
+            except IndexError:
+                arg_str = ""
 
-    def _handle_request(self):
-        """
-        Request handler
-        """
-        # Parse the URL
-        parsed_path = urlparse(self.path)
-        metric_name = parsed_path.path.strip("/")
-        parsed_query = parse_qs(parsed_path.query)
+            # Make sure it's a valid request
+            if base_name not in self.files:
+                raise llfuse.FUSEError(errno.ENOENT)
 
+            # Split any key/value args
+            args = {}
+            for arg in arg_str.split(","):
+                if arg == "":
+                    continue
+                print(f"Splitting: {arg}")
+                key, value = arg.split("=", 1)
+                args[key] = value
+
+            file = {
+                "name": base_name,
+                "args": args,
+                "error": None,
+                "attrs": None,
+                "count": 0,
+            }
+
+            self.inodes[inode] = file
+
+        if not file["attrs"]:
+            # Fuse shouldn't be calling this for the base directory, so it
+            # should be safe to assume we're dealing with a file.
+            file["attrs"] = self.gen_attrs(inode, False)
+
+        # Increase the lookup count
+        file["count"] += 1
+
+        return file["attrs"]
+
+    def getattr(self, inode, ctx=None):
+        print(f"getattr called with: inode={inode}")
+
+        if inode == llfuse.ROOT_INODE:
+            # If we're looking at the directory itself
+            return self.gen_attrs(inode, True)
+
+        try:
+            return self.inodes[inode]["attrs"]
+        except KeyError:
+            print(f"Getattr called without a lookup first for: inode={inode}")
+            raise llfuse.FUSEError(errno.ENOENT)
+
+    def opendir(self, inode, ctx):
+        """
+        Note: We only allow one directory level
+        """
+        print(f"opendir called with: inode={inode}")
+
+        if inode != llfuse.ROOT_INODE:
+            raise llfuse.FUSEError(errno.ENOENT)
+        return inode
+
+    def readdir(self, fh, off):
+        print(f"readdir called with: fh={fh} off={off}")
+
+        # Something has gone wrong if this was called for anything other than the top level directory
+        assert fh == llfuse.ROOT_INODE
+
+        for i, entry in enumerate(self.files[off:]):
+            print(f" yielding: {entry.encode('utf8')}")
+            yield (
+                entry.encode("utf-8"),
+                self.lookup(llfuse.ROOT_INODE, entry.encode("utf-8")),
+                i + off + 1,
+            )
+
+    def new_file_handle(self, inode=None):
+        """
+        Pick an unused file handle (int) and create an entry in file_handles for it
+
+        returns: the file handle number
+        """
+        # Find the first unused number
+        new_fh = 0
+        for fh in sorted(self.file_handles.keys()):
+            if new_fh == fh:
+                new_fh += 1
+            else:
+                break
+
+        # Create the empty entry in the
+        self.file_handles[new_fh] = {
+            "inode": inode,
+            "data": None,
+        }
+
+        return new_fh
+
+    def open(self, inode, flags, ctx):
+        print(f"open called with: inode={inode} flags={flags}")
+
+        fh = self.new_file_handle(inode)
+
+        # Get the data associated with the file handle
+        file = self.file_handles[fh]
+
+        # Get the data associated with the file name and parameters
+        data = self.inodes[inode]
+
+        # Pull out the things we need to run the query
+        metric_name = data["name"]
+        metric_args = data["args"]
+
+        # Populate the data for the file
         if metric_name == "agent_version":
-            self._reply(200, VERSION)
+            file["data"] = VERSION.encode("utf-8")
+        elif metric_name == "sleep":
+            seconds = metric_args.get("seconds", "10")
+            with llfuse.lock_released:
+                time.sleep(int(seconds))
+            file["data"] = seconds.encode("utf-8")
         elif metric_name == "latest_version_info":
             try:
                 get_latest_version()
-                self._reply(
-                    200,
-                    json.dumps(
-                        {
-                            "latest": Context.latest_version,
-                            "supported": 1 if Context.release_supported else 0,
-                        }
-                    ),
-                )
+                file["data"] = json.dumps(
+                    {
+                        "latest": Context.latest_version,
+                        "supported": 1 if Context.release_supported else 0,
+                    }
+                ).encode("utf-8")
             except LatestVersionCheckError as e:
                 Context.log.error(
                     "Failed to retrieve latest version information: %s", e
                 )
-                self._reply(503, "Failed to retrieve latest version info")
+                file["data"] = "ERROR: Failed to retrieve latest version info".encode(
+                    "utf-8"
+                )
         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()}
-
             # Get the dbname.  If none was provided, use the default from the
             # config.
-            dbname = args.get("dbname", Context.config["dbname"])
+            dbname = metric_args.get("dbname", Context.config["dbname"])
 
             # Sample the metric
             try:
-                self._reply(200, sample_metric(dbname, metric_name, args))
+                file["data"] = sample_metric(dbname, metric_name, metric_args).encode(
+                    "utf-8"
+                )
             except UnknownMetricError:
                 Context.log.error("Unknown metric: %s", metric_name)
-                self._reply(404, "Unknown metric")
+                file["data"] = "ERROR: Unknown metric".encode("utf-8")
             except MetricVersionError:
                 Context.log.error("Failed to find an query version for %s", metric_name)
-                self._reply(404, "Unsupported version")
+                file["data"] = "ERROR: Unsupported version".encode("utf-8")
             except UnhappyDBError:
                 Context.log.info("Database %s is unhappy, please be patient", dbname)
-                self._reply(503, "Database unavailable")
+                file["data"] = "ERROR: Database unavailable".encode("utf-8")
             except Exception as e:  # pylint: disable=broad-exception-caught
                 Context.log.error("Error running query: %s", e)
-                self._reply(500, "Unexpected error: {}".format(e))
+                file["data"] = "ERROR: Unexpected error: {}".format(e).encode("utf-8")
 
-    def _reply(self, code, content):
-        """
-        Send a reply to the client
-        """
-        self.send_response(code)
-        self.send_header("Content-type", "application/json")
-        self.end_headers()
+        return fh
 
-        self.wfile.write(bytes(content, "utf-8"))
+    def read(self, fh, off, size):
+        print(f"read called with: fh={fh} off={off} size={size}")
+
+        file = self.file_handles[fh]
+
+        return file["data"][off : off + size]
+
+    def forget(self, inode_list):
+        """
+        Note: Per the dcumenation, this function must not raise an exception!
+        """
+        print(f"forget called with: inode_list={inode_list}")
+
+        for inode, nlookup in inode_list:
+            try:
+                self.inodes[inode]["count"] -= nlookup
+                if self.inodes[inode]["count"] <= 0:
+                    del self.inodes[inode]
+            except Exception as e:
+                Context.log.error("Error forgetting inode %s: %s", inode, e)
+
+    def release(self, fh):
+        print(f"release called with: fh={fh}")
+
+        del self.file_handles[fh]
 
 
 def main():
@@ -916,23 +1088,44 @@ def main():
             sys.exit(1)
         sys.exit(0)
 
-    # Set up the http server to receive requests
-    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)
+    signal.signal(signal.SIGUSR1, signal_handler)
 
-    # Handle requests.
-    Context.log.info("Listening on port %s...", Context.config["port"])
-    while Context.running:
-        Context.httpd.handle_request()
+    # Ensure the mount point exists
+    if not os.path.exists(Context.config["fuse_base"]):
+        os.makedirs(Context.config["fuse_base"])
+
+    # Create the FUSE filesystem
+    pgmon_fuse = PGMonFuse()
+    fuse_options = set(llfuse.default_options)
+    fuse_options.add("fsname=pgmon")
+    # fuse_options.add('direct_io')
+    # if options.debug_fuse:
+    #    fuse_options.add('allow_others')
+    try:
+        llfuse.init(pgmon_fuse, Context.config["fuse_base"], fuse_options)
+    except:
+        llfuse.close()
+        return -1
+
+    try:
+        llfuse.main(workers=1)
+    except:
+        llfuse.close()
+        raise
+
+    llfuse.close()
 
     # Clean up PostgreSQL connections
     # TODO: Improve this ... not sure it actually closes all the connections cleanly
     for pool in Context.connections.values():
-        pool.close()
+        pool.closeall()
+
+    logging.shutdown()
+
+    print("Good bye.")
 
 
 if __name__ == "__main__":