setup scrapper

dealwatch/cli.py

@@ -2,20 +2,52 @@ import argparse
 
 import yaml
 
+from prometheus_client import start_http_server
+
 from dealwatch.scrape_target import ScrapeTarget
 
 def main():
-    parser = argparse.ArgumentParser("An utility to scrape e-commerce target price fluctuations")
+    parser = argparse.ArgumentParser("An utility to scrape e-commerce product price and expose them as prometheus metrics")
     parser.add_argument(
         '-c', '--config',
         help='The configuration file. (default: %(default)s)',
         type=str,
         default='dealwatch.yml',
     )
+    parser.add_argument(
+        '--user-agent',
+        help='The user-agent to spoof. (default: %(default)s)',
+        type=str,
+        default='Mozilla/5.0 (X11; Linux x86_64; rv:106.0) Gecko/20100101 Firefox/106.0',
+    )
+    parser.add_argument(
+        '-p', '--listen-port',
+        help='The listen port for the http server. (default: %(default)s)',
+        type=int,
+        default=8000,
+    )
+    parser.add_argument(
+        '-a', '--listen-address',
+        help='The listen address for the http server. (default: %(default)s)',
+        type=str,
+        default='0.0.0.0',
+    )
 
     args = parser.parse_args()
-    products = parse_config(args.config)
-    print(products)
+    scrape_targets = parse_config(args.config)
+
+    # setup the headers for each scrape targets
+    for scrape_target in scrape_targets:
+        scrape_target.headers = {
+            'Accept': '*/*',
+            'User-Agent': args.user_agent,
+        }
+
+    # start the http server to server the prometheus metrics
+    start_http_server(args.listen_port, args.listen_address)
+
+    for scrape_target in scrape_targets:
+        print(scrape_target.query_target())
 
 def parse_config(config_filename):
     result = []

dealwatch/scrape_target.py

@@ -1,9 +1,36 @@
 import re
 
+import httpx
+import parsel
+
 class ScrapeTarget:
     def __init__(self, product_name, target_name, url, selector, regex=None):
         self.product_name = product_name
         self.target_name = target_name
         self.url = url
-        self.selector = selector
+        self.selector = selector+'::text'
         self.regex = re.compile(regex if regex else r'[0-9]+(\.[0-9]{2})?')
+        self.headers = {}
+
+    def query_target(self):
+        print('Query product %s, target %s' % (self.product_name, self.target_name))
+        # some sites get suspicious if we talk to them in HTTP/1.1
+        # we use httpx to have HTTP2 support and circumvent that issue
+        query_response = httpx.get(
+            url=self.url,
+            headers=self.headers,
+            follow_redirects=True,
+        ).text
+        selector = parsel.Selector(text=query_response)
+
+        # Match the selector
+        selector_match = selector.css(self.selector).get()
+        if selector_match:
+            # Match the regex
+            regex_match = self.regex.search(selector_match)
+            if regex_match:
+                str_result = regex_match.group(0)
+                # Convert the reult to float
+                float_result = float(str_result)
+                return float_result
+        return None

setup.cfg

@@ -11,7 +11,7 @@ setup_requires =
   setuptools_scm
 install_requires=
   PyYAML~=6.0
-  requests~=2.28.1
+  httpx~=0.23.0
   parsel~=1.6.0
   prometheus-client~=0.15.0