Class: PrometheusExporter::Server::WebServer

Inherits:
Object
  • Object
show all
Defined in:
lib/prometheus_exporter/server/web_server.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts) ⇒ WebServer

Returns a new instance of WebServer.



12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
 
# File 'lib/prometheus_exporter/server/web_server.rb', line 12

def initialize(opts)
  @port = opts[:port] || PrometheusExporter::DEFAULT_PORT
  @bind = opts[:bind] || PrometheusExporter::DEFAULT_BIND_ADDRESS
  @collector = opts[:collector] || Collector.new
  @timeout = opts[:timeout] || PrometheusExporter::DEFAULT_TIMEOUT
  @verbose = opts[:verbose] || false
  @auth = opts[:auth]
  @realm = opts[:realm] || PrometheusExporter::DEFAULT_REALM

  @metrics_total = PrometheusExporter::Metric::Counter.new("collector_metrics_total", "Total metrics processed by exporter web.")

  @sessions_total = PrometheusExporter::Metric::Counter.new("collector_sessions_total", "Total send_metric sessions processed by exporter web.")

  @bad_metrics_total = PrometheusExporter::Metric::Counter.new("collector_bad_metrics_total", "Total mis-handled metrics by collector.")

  @metrics_total.observe(0)
  @sessions_total.observe(0)
  @bad_metrics_total.observe(0)

  @access_log, @logger = nil
  log_target = opts[:log_target]

  if @verbose
    @access_log = [
      [$stderr, WEBrick::AccessLog::COMMON_LOG_FORMAT],
      [$stderr, WEBrick::AccessLog::REFERER_LOG_FORMAT],
    ]
    @logger = WEBrick::Log.new(log_target || $stderr)
  else
    @access_log = []
    @logger = WEBrick::Log.new(log_target || "/dev/null")
  end

  @logger.info "Using Basic Authentication via #{@auth}" if @verbose && @auth

  @server = WEBrick::HTTPServer.new(
    Port: @port,
    BindAddress: @bind,
    Logger: @logger,
    AccessLog: @access_log,
  )

  @server.mount_proc '/' do |req, res|
    res['Content-Type'] = 'text/plain; charset=utf-8'
    if req.path == '/metrics'
      authenticate(req, res) if @auth

      res.status = 200
      if req.header["accept-encoding"].to_s.include?("gzip")
        sio = StringIO.new
        collected_metrics = metrics
        begin
          writer = Zlib::GzipWriter.new(sio)
          writer.write(collected_metrics)
        ensure
          writer.close
        end
        res.body = sio.string
        res.header["content-encoding"] = "gzip"
      else
        res.body = metrics
      end
    elsif req.path == '/send-metrics'
      handle_metrics(req, res)
    elsif req.path == '/ping'
      res.body = 'PONG'
    else
      res.status = 404
      res.body = "Not Found! The Prometheus Ruby Exporter only listens on /ping, /metrics and /send-metrics"
    end
  end
end

Instance Attribute Details

#collector ⇒ Object (readonly)

Returns the value of attribute collector.



10
11
12
 
# File 'lib/prometheus_exporter/server/web_server.rb', line 10

def collector
  @collector
end

Instance Method Details

#add_gauge(name, help, value) ⇒ Object 



161
162
163
164
165
 
# File 'lib/prometheus_exporter/server/web_server.rb', line 161

def add_gauge(name, help, value)
  gauge = PrometheusExporter::Metric::Gauge.new(name, help)
  gauge.observe(value)
  gauge
end

#authenticate(req, res) ⇒ Object 



167
168
169
170
171
172
 
# File 'lib/prometheus_exporter/server/web_server.rb', line 167

def authenticate(req, res)
  htpasswd = WEBrick::HTTPAuth::Htpasswd.new(@auth)
  basic_auth = WEBrick::HTTPAuth::BasicAuth.new({ Realm: @realm, UserDB: htpasswd, Logger: @logger })

  basic_auth.authenticate(req, res)
end

#get_rss ⇒ Object 



155
156
157
158
159
 
# File 'lib/prometheus_exporter/server/web_server.rb', line 155

def get_rss
  @pagesize ||= `getconf PAGESIZE`.to_i rescue 4096
  @pid ||= Process.pid
  File.read("/proc/#{@pid}/statm").split(' ')[1].to_i * @pagesize rescue 0
end

#handle_metrics(req, res) ⇒ Object 



85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
 
# File 'lib/prometheus_exporter/server/web_server.rb', line 85

def handle_metrics(req, res)
  @sessions_total.observe
  req.body do |block|
    begin
      @metrics_total.observe
      @collector.process(block)
    rescue => e
      if @verbose
        @logger.error "\n\n#{e.inspect}\n#{e.backtrace}\n\n"
      end
      @bad_metrics_total.observe
      res.body = "Bad Metrics #{e}"
      res.status = e.respond_to?(:status_code) ? e.status_code : 500
      return
    end
  end

  res.body = "OK"
  res.status = 200
end

#metrics ⇒ Object 



120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
 
# File 'lib/prometheus_exporter/server/web_server.rb', line 120

def metrics
  metric_text = nil
  begin
    Timeout::timeout(@timeout) do
      metric_text = @collector.prometheus_metrics_text
    end
  rescue Timeout::Error
    # we timed out ... bummer
    @logger.error "Generating Prometheus metrics text timed out"
  end

  metrics = []

  metrics << add_gauge(
    "collector_working",
    "Is the master process collector able to collect metrics",
    metric_text && metric_text.length > 0 ? 1 : 0
  )

  metrics << add_gauge(
    "collector_rss",
    "total memory used by collector process",
    get_rss
  )

  metrics << @metrics_total
  metrics << @sessions_total
  metrics << @bad_metrics_total

  <<~TEXT
  #{metrics.map(&:to_prometheus_text).join("\n\n")}
  #{metric_text}
  TEXT
end

#start ⇒ Object 



106
107
108
109
110
111
112
113
114
 
# File 'lib/prometheus_exporter/server/web_server.rb', line 106

def start
  @runner ||= Thread.start do
    begin
      @server.start
    rescue => e
      @logger.error "Failed to start prometheus collector web on port #{@port}: #{e}"
    end
  end
end

#stop ⇒ Object 



116
117
118
 
# File 'lib/prometheus_exporter/server/web_server.rb', line 116

def stop
  @server.shutdown
end