wip

requirements.yml

@@ -1,3 +1,4 @@
 psycopg2
 pyyaml
-fusepy
+llfuse
+requests

sample-config/pgmon.yml

@@ -44,6 +44,7 @@ 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'

src/pgmon.py

@@ -15,6 +15,8 @@ import argparse
 import logging
 import re
 import stat
+import errno
+import requests
 
 from decimal import Decimal
 
@@ -35,7 +37,7 @@ from psycopg2.pool import ThreadedConnectionPool
 from pwd import getpwnam
 from grp import getgrnam
 
-from fuse import FUSE, Operations, LoggingMixIn, fuse_exit
+import llfuse
 
 
 VERSION = "1.1.0-rc1"
@@ -141,7 +143,7 @@ class InvalidDataError(Exception):
 # Default config settings
 DEFAULT_CONFIG = {
     # The name for this agent instance (controles the FUSE directory name)
-    "name": 'pgmon',
+    "name": "pgmon",
     # Base directory for FUSE file system
     "fuse_base": "/run/pgmon",
     # Mode to set on FUSE files (in octal)
@@ -798,69 +800,203 @@ def test_queries():
     return 0
 
 
-class PGMonFuse(LoggingMixIn, Operations):
+class PGMonFuse(llfuse.Operations):
     """
     This is our FUSE filesystem for requests from Zabbix.  It is responsible for listening for
     requests, processing them, and responding.
     """
 
     def __init__(self):
-        self.builtin = ['agent_version', 'latest_version_info']
+        super().__init__()
+        self.builtin = ["agent_version", "latest_version_info", "sleep"]
+        self.update_files()
 
+        # 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
 
-    def getattr(self, path, fh=None):
-        attrs = {
-            'st_mode': (Context.config['fuse_mode'] | stat.S_IFREG),
-            'st_nlink': 1,
-            'st_size': 1024,
-            'st_uid': getpwnam(Context.config['fuse_owner']).pw_uid,
-            'st_gid': getgrnam(Context.config['fuse_group']).gr_gid,
-        }
-        if path == "/":
-            # If we're looking at the directory itself, add execute permissions for the owner and identify it as a directory
-            attrs['st_mode'] = Context.config['fuse_mode'] | stat.S_IXUSR | stat.S_IFDIR
         return attrs
 
-    def readdir(self, path, fh):
-        return ['.', '..'] + self.builtin + list(Context.config["metrics"].keys())
+    def update_files(self):
+        self.files = self.builtin + sorted(list(Context.config["metrics"].keys()))
 
-#    def open(self, path, fh):
-#        fh.direct_io = 1
-#        pass
+    @staticmethod
+    def path_to_inode(path):
+        """
+        Provide a consistent inode for a given file
+        """
+        return hash(path) & 0xFFFFFFFFFFFFFFFF
 
-    def read(self, path, size, offset, fh):
-        # Split the path into the expected components: /<metric>/<arg1>/<arg2>/...
-        parts = path.split('/')
+    def lookup(self, inode_p, name, ctx=None):
+        """ """
+        print(f"Lookup called with: inode_p={inode_p} name={name}")
 
-        # Note: the first element will be empty.  If we got less than two, we
-        #       don't have a valid request.
-        if len(parts) < 2:
-            return ''.encode('utf-8')
+        # 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)
 
-        res = None
-        metric_name = parts[1]
-        metric_args = {}
+        # Generate the inode for this file (ie: query + args)
+        inode = self.path_to_inode(name)
 
-        for arg in parts[2:]:
-            key, value = arg.split('=')
-            metric_args[key] = value
+        # Get the file info if we already have it, create it otherwise
+        try:
+            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 = ""
 
+            # 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":
-            res = 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()
-                res = json.dumps(
+                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
                 )
-                res = "ERROR: Failed to retrieve latest version info"
+                file["data"] = "ERROR: Failed to retrieve latest version info".encode(
+                    "utf-8"
+                )
         else:
             # Get the dbname.  If none was provided, use the default from the
             # config.
@@ -868,21 +1004,49 @@ class PGMonFuse(LoggingMixIn, Operations):
 
             # Sample the metric
             try:
-                res = sample_metric(dbname, metric_name, metric_args)
+                file["data"] = sample_metric(dbname, metric_name, metric_args).encode(
+                    "utf-8"
+                )
             except UnknownMetricError:
                 Context.log.error("Unknown metric: %s", metric_name)
-                res = "ERROR: 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)
-                res = "ERROR: Unsupported version"
+                file["data"] = "ERROR: Unsupported version".encode("utf-8")
             except UnhappyDBError:
                 Context.log.info("Database %s is unhappy, please be patient", dbname)
-                res = "ERROR: 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)
-                res = "ERROR: Unexpected error: {}".format(e)
+                file["data"] = "ERROR: Unexpected error: {}".format(e).encode("utf-8")
 
-        return res.encode('utf-8')
+        return fh
+
+    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():
@@ -934,7 +1098,25 @@ def main():
         os.makedirs(Context.config["fuse_base"])
 
     # Create the FUSE filesystem
-    FUSE(PGMonFuse(), Context.config["fuse_base"], foreground=True, default_permissions=True)
+    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
@@ -945,5 +1127,6 @@ def main():
 
     print("Good bye.")
 
+
 if __name__ == "__main__":
     main()