Implement Prometheus metrics

Dockerfile

@@ -56,6 +56,7 @@ COPY src .
 COPY package.json ../
 
 EXPOSE 8191
+EXPOSE 8192
 
 # dumb-init avoids zombie chromium processes
 ENTRYPOINT ["/usr/bin/dumb-init", "--"]

README.md

@@ -227,7 +227,7 @@ This is the same as `request.get` but it takes one more param:
 ## Environment variables
 
 | Name               | Default                | Notes                                                                                                                                                         |
-|-----------------|------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|--------------------|------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | LOG_LEVEL          | info                   | Verbosity of the logging. Use `LOG_LEVEL=debug` for more information.                                                                                         |
 | LOG_HTML           | false                  | Only for debugging. If `true` all HTML that passes through the proxy will be logged to the console in `debug` level.                                          |
 | CAPTCHA_SOLVER     | none                   | Captcha solving method. It is used when a captcha is encountered. See the Captcha Solvers section.                                                            |
@@ -237,12 +237,40 @@ This is the same as `request.get` but it takes one more param:
 | TEST_URL           | https://www.google.com | FlareSolverr makes a request on start to make sure the web browser is working. You can change that URL if it is blocked in your country.                      |
 | PORT               | 8191                   | Listening port. You don't need to change this if you are running on Docker.                                                                                   |
 | HOST               | 0.0.0.0                | Listening interface. You don't need to change this if you are running on Docker.                                                                              |
+| PROMETHEUS_ENABLED | false                  | Enable Prometheus exporter. See the Prometheus section below.                                                                                                 |
+| PROMETHEUS_PORT    | 8192                   | Listening port for Prometheus exporter. See the Prometheus section below.                                                                                     |
 
 Environment variables are set differently depending on the operating system. Some examples:
 * Docker: Take a look at the Docker section in this document. Environment variables can be set in the `docker-compose.yml` file or in the Docker CLI command.
 * Linux: Run `export LOG_LEVEL=debug` and then start FlareSolverr in the same shell.
 * Windows: Open `cmd.exe`, run `set LOG_LEVEL=debug` and then start FlareSolverr in the same shell.
 
+## Prometheus exporter
+
+The Prometheus exporter for FlareSolverr is disabled by default. It can be enabled with the environment variable `PROMETHEUS_ENABLED`. If you are using Docker make sure you expose the `PROMETHEUS_PORT`.
+
+Example metrics:
+```shell
+# HELP flaresolverr_request_total Total requests with result
+# TYPE flaresolverr_request_total counter
+flaresolverr_request_total{domain="nowsecure.nl",result="solved"} 1.0
+# HELP flaresolverr_request_created Total requests with result
+# TYPE flaresolverr_request_created gauge
+flaresolverr_request_created{domain="nowsecure.nl",result="solved"} 1.690141657157109e+09
+# HELP flaresolverr_request_duration Request duration in seconds
+# TYPE flaresolverr_request_duration histogram
+flaresolverr_request_duration_bucket{domain="nowsecure.nl",le="0.0"} 0.0
+flaresolverr_request_duration_bucket{domain="nowsecure.nl",le="10.0"} 1.0
+flaresolverr_request_duration_bucket{domain="nowsecure.nl",le="25.0"} 1.0
+flaresolverr_request_duration_bucket{domain="nowsecure.nl",le="50.0"} 1.0
+flaresolverr_request_duration_bucket{domain="nowsecure.nl",le="+Inf"} 1.0
+flaresolverr_request_duration_count{domain="nowsecure.nl"} 1.0
+flaresolverr_request_duration_sum{domain="nowsecure.nl"} 5.858
+# HELP flaresolverr_request_duration_created Request duration in seconds
+# TYPE flaresolverr_request_duration_created gauge
+flaresolverr_request_duration_created{domain="nowsecure.nl"} 1.6901416571570296e+09
+```
+
 ## Captcha Solvers
 
 > **Warning**

requirements.txt

@@ -2,9 +2,10 @@ bottle==0.12.25
 waitress==2.1.2
 selenium==4.10.0
 func-timeout==4.3.5
+prometheus-client==0.17.1
 # required by undetected_chromedriver
 requests==2.31.0
-certifi==2023.5.7
+certifi==2023.7.22
 websockets==11.0.3
 # only required for linux
 xvfbwrapper==0.2.9

src/bottle_plugins/prometheus_plugin.py

@@ -0,0 +1,53 @@
+import logging
+import os
+import urllib.parse
+
+from dtos import V1ResponseBase
+from metrics import start_metrics_http_server, REQUEST_COUNTER, REQUEST_DURATION
+
+PROMETHEUS_ENABLED = os.environ.get('PROMETHEUS_ENABLED', 'false').lower() == 'true'
+PROMETHEUS_PORT = int(os.environ.get('PROMETHEUS_PORT', 8192))
+
+
+def setup():
+    if PROMETHEUS_ENABLED:
+        start_metrics_http_server(PROMETHEUS_PORT)
+
+
+def prometheus_plugin(callback):
+    """
+    Bottle plugin to expose Prometheus metrics
+    http://bottlepy.org/docs/dev/plugindev.html
+    """
+    def wrapper(*args, **kwargs):
+        actual_response = callback(*args, **kwargs)
+
+        if PROMETHEUS_ENABLED:
+            try:
+                export_metrics(actual_response)
+            except Exception as e:
+                logging.warning("Error exporting metrics: " + str(e))
+
+        return actual_response
+
+    def export_metrics(actual_response):
+        res = V1ResponseBase(actual_response)
+
+        domain = "unknown"
+        if res.solution and res.solution.url:
+            parsed_url = urllib.parse.urlparse(res.solution.url)
+            domain = parsed_url.hostname
+
+        run_time = (res.endTimestamp - res.startTimestamp) / 1000
+        REQUEST_DURATION.labels(domain=domain).observe(run_time)
+
+        result = "unknown"
+        if res.message == "Challenge solved!":
+            result = "solved"
+        elif res.message == "Challenge not detected!":
+            result = "not_detected"
+        elif res.message.startswith("Error"):
+            result = "error"
+        REQUEST_COUNTER.labels(domain=domain, result=result).inc()
+
+    return wrapper

src/flaresolverr.py

@@ -8,6 +8,7 @@ from bottle import run, response, Bottle, request, ServerAdapter
 
 from bottle_plugins.error_plugin import error_plugin
 from bottle_plugins.logger_plugin import logger_plugin
+from bottle_plugins import prometheus_plugin
 from dtos import V1RequestBase
 import flaresolverr_service
 import utils
@@ -24,10 +25,6 @@ class JSONErrorBottle(Bottle):
 
 app = JSONErrorBottle()
 
-# plugin order is important
-app.install(logger_plugin)
-app.install(error_plugin)
-
 
 @app.route('/')
 def index():
@@ -101,6 +98,13 @@ if __name__ == "__main__":
     # test browser installation
     flaresolverr_service.test_browser_installation()
 
+    # start bootle plugins
+    # plugin order is important
+    app.install(logger_plugin)
+    app.install(error_plugin)
+    prometheus_plugin.setup()
+    app.install(prometheus_plugin.prometheus_plugin)
+
     # start webserver
     # default server 'wsgiref' does not support concurrent requests
     # https://github.com/FlareSolverr/FlareSolverr/issues/680

src/metrics.py

@@ -0,0 +1,32 @@
+import logging
+
+from prometheus_client import Counter, Histogram, start_http_server
+import time
+
+REQUEST_COUNTER = Counter(
+    name='flaresolverr_request',
+    documentation='Total requests with result',
+    labelnames=['domain', 'result']
+)
+REQUEST_DURATION = Histogram(
+    name='flaresolverr_request_duration',
+    documentation='Request duration in seconds',
+    labelnames=['domain'],
+    buckets=[0, 10, 25, 50]
+)
+
+
+def serve(port):
+    start_http_server(port=port)
+    while True:
+        time.sleep(600)
+
+
+def start_metrics_http_server(prometheus_port: int):
+    logging.info(f"Serving Prometheus exporter on http://0.0.0.0:{prometheus_port}/metrics")
+    from threading import Thread
+    Thread(
+        target=serve,
+        kwargs=dict(port=prometheus_port),
+        daemon=True,
+    ).start()