queue_exporter as subproject. checks only queue. lesser dependencies, lesser footprint.

README.adoc

@@ -4,6 +4,16 @@ postfix_exporter
 Collects continuesly events from postfix and dovecot via journald.
 Exports the collected event-counters and the currently count of queued messages.
 
+queue_exporter
+==============
+
+If you only want to check the count of mails in queue, use the `queue_exporter` in the subdirectory.
+It has lesser dependencies and a smaller footprint:
+
+* No journald, no ffi, no puma
+* ffi and puma need a compiler, which you do not need to install
+* Instead of puma, use simple rackup, which provides a simpler webserver.
+
 Usage
 -----
 

queue_exporter/Gemfile

@@ -0,0 +1,4 @@
+source 'https://rubygems.org'
+
+gem 'prometheus-client'
+gem 'rack'

queue_exporter/Gemfile.lock

@@ -0,0 +1,15 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    prometheus-client (4.0.0)
+    rack (3.0.0)
+
+PLATFORMS
+  x86_64-linux
+
+DEPENDENCIES
+  prometheus-client
+  rack
+
+BUNDLED WITH
+   2.3.9

queue_exporter/config.ru

@@ -0,0 +1,48 @@
+require 'rack'
+require 'socket'
+
+showqpath = '/var/spool/postfix/public/showq'
+prometheus = Prometheus::Client.registry
+metrics = OpenStruct.new(
+	queued: prometheus.gauge( :postfix_queued, docstring: "Queued mails per queue and sender/recipient", labels: %i[queue sender recipient]),
+)
+
+def determine_domain str
+	case str
+	when /@([^.]+\.(?:(?:co|ac)\.)?[^.]+)\.?\z/
+		$1
+	when /\.([^.]+\.(?:(?:co|ac)\.)?[^.]+)\?.\z/
+		"any.#$1"
+	when 'MAILER-DAEMON'
+		'MAILER-DAEMON'
+	else
+		'any'
+	end
+end
+
+run lambda {|env|
+	req = Rack::Request.new env
+	case req.path
+	when "/metrics"
+		showq = ''
+		UNIXSocket.open showqpath do |s|
+			while '' != (r = s.read)
+				showq += r
+			end
+		end
+		showq =
+			showq.split( "\x00\x00").map do |x|
+				y = x.split "\x00"
+				y.push ''  if y.length.odd?
+				Hash[*y]
+			end
+		showq.group_by do |e|
+			{queue: e['queue_name'], sender: determine_domain( e['sender']), recipient: determine_domain( e['recipient'])}
+		end.each do |labels, entries|
+			metrics.queued.set entries.length, labels: labels  if labels and labels[:queue]
+		end
+		[200, {"Content-Type" => "text/plain"}, [Prometheus::Client::Formats::Text.marshal( prometheus)]]
+	else
+		[404, {"Content-Type" => "text/plain"}, ["Not found\nYou want to try /metrics?\n"]]
+	end
+}

queue_exporter/gemset.nix

@@ -0,0 +1,22 @@
+{
+  prometheus-client = {
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "11k1r8mfr0bnd574yy08wmpzbgq8yqw3shx7fn5f6hlmayacc4bh";
+      type = "gem";
+    };
+    version = "4.0.0";
+  };
+  rack = {
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "1772yq480iffns36zisgsnaxf6cr6r7m8v7y14cwlpaqbnzdnyhr";
+      type = "gem";
+    };
+    version = "3.0.0";
+  };
+}

queue_exporter/queue_exporter.service.erb

@@ -0,0 +1,16 @@
+<% require 'pathname'; path = Pathname.new( __FILE__).expand_path.dirname %>
+[Unit]
+Description=Postfix Queue exporter
+Documentation=https://git.denkn.at/deac/postfix_exporter
+After=network.target
+
+[Service]
+Restart=always
+User=postfix_exporter
+WorkingDirectory=<%=path%>
+ExecStart=<%=`which bundle`.chomp%> exec rackup --bind 'tcp://[::]:9124' --environment production --tag queue_exporter
+ExecReload=/bin/kill -USR1 $MAINPID
+KillMode=mixed
+
+[Install]
+WantedBy=multi-user.target

queue_exporter/shell.nix

@@ -0,0 +1,21 @@
+with (import <nixpkgs> {});
+let
+  env = bundlerEnv {
+    name = "queue_exporter-bundler-env";
+    inherit ruby;
+    gemfile  = ./Gemfile;
+    lockfile = ./Gemfile.lock;
+    gemset   = ./gemset.nix;
+  };
+in stdenv.mkDerivation {
+  name = "queue-exporter";
+  buildInputs = [ pkgs.ruby env env.gems.rack ];
+  #buildPhase = ''
+  #  echo "Build queue_exporter
+  #  mkdir -p "$out/lib"
+  #  for f in ${pkgs.systemd}/lib/libsystemd*
+  #  do
+  #    ln -s "$f" "$out/lib/"
+  #  done
+  #'';
+}