swann: add ee-scrape-data, for putting allowance data into prometheus

ops/nixos/swann/default.nix

@@ -513,5 +513,29 @@ in {
       -format.new=true
   '';
 
+  systemd.services.ee-scrape-data = let
+    scriptFile = ./ee-scrape-data.py;
+    python = pkgs.python3.withPackages (pm: with pm; [
+      requests
+      beautifulsoup4
+      html5lib
+    ]);
+  in {
+    enable = true;
+    serviceConfig = {
+      Type = "oneshot";
+      ExecStart = "${python}/bin/python ${scriptFile} /run/prometheus-textfile-exports/ee-scrape-data.prom";
+    };
+  };
+  systemd.timers.ee-scrape-data = {
+    enable = true;
+    wantedBy = [ "multi-user.target" ];
+    timerConfig = {
+      OnBootSec = "2m";
+      OnUnitInactiveSec = "1m";
+      RandomizedDelaySec = "20";
+    };
+  };
+
   system.stateVersion = "21.03";
 }

ops/nixos/swann/ee-scrape-data.py

@@ -0,0 +1,97 @@
+import re
+import sys
+import textwrap
+
+import bs4
+import requests
+
+
+BYTE_SUFFIXES = {
+    "": 1,
+    "B": 1,
+    "kB": 1024,
+    "MB": 1024 * 1024,
+    "GB": 1024 * 1024 * 1024,
+    "TB": 1024 * 1024 * 1024 * 1024,
+}
+
+TIME_SUFFIXES = {
+    "Days": 60 * 60 * 24,
+    "Day": 60 * 60 * 24,
+    "Hrs": 60 * 60,
+    "Hr": 60 * 60,
+    "Mins": 60,
+    "Min": 60,
+}
+
+
+def uniec(n):
+    m = re.match(r"^([0-9]+(?:[.][0-9]+)?)([a-zA-Z]*)$", n)
+    if not m:
+        raise ValueError(f"invalid suffixed-bytes {n}")
+    val, suffix = m.groups()
+    val = float(val)
+    if suffix not in BYTE_SUFFIXES:
+        raise ValueError(f"unknown suffix {suffix} from {n}")
+    return val * BYTE_SUFFIXES[suffix]
+
+
+def untime(n):
+    remaining = n
+    x = 0
+    while remaining and (m := re.match(r"^([0-9]+) ([a-zA-Z]+)(?: (.*)|$)", remaining)):
+        val, suffix, remaining = m.groups()
+        val = float(val)
+        if suffix not in TIME_SUFFIXES:
+            raise ValueError(f"unknown suffix {suffix} from {n}")
+        x += val * TIME_SUFFIXES[suffix]
+    return x
+
+
+def scrape_data():
+    resp = requests.get("http://add-on.ee.co.uk/mbbstatus")
+    resp.raise_for_status()
+
+    soup = bs4.BeautifulSoup(resp.text, "html5lib")
+
+    data = {}
+
+    account_number_el = soup.select("p.account__details > span")[1]
+    data["account_number"] = account_number_el.get_text().strip().replace(" ", "")
+
+    allowance_left_el = soup.select("span.allowance__left")[0]
+    allowance_left_str, allowance_total_str = list(allowance_left_el.stripped_strings)
+    data["allowance_left"] = uniec(allowance_left_str)
+    if allowance_total_str.startswith("left of "):
+        allowance_total_str = allowance_total_str[len("left of ") :]
+    data["allowance_total"] = uniec(allowance_total_str)
+
+    timespan_str = " ".join(soup.select(".allowance__timespan")[0].stripped_strings)
+    if timespan_str.startswith("Lasts for "):
+        timespan_str = timespan_str[len("Lasts for ") :]
+    data["time_remaining"] = untime(timespan_str)
+
+    return textwrap.dedent(
+        f"""
+        ee_allowance_left{{account_number="{data['account_number']}"}} {data['allowance_left']}
+        ee_allowance_total{{account_number="{data['account_number']}"}} {data['allowance_total']}
+        ee_time_remaining{{account_number="{data['account_number']}"}} {data['time_remaining']}
+    """
+    ).strip()
+
+
+def main(args):
+    if len(args) > 2:
+        print(f"{args[0]} (output path)", file=sys.stderr)
+        sys.exit(1)
+
+    data = scrape_data()
+    if len(args) == 1:
+        print(data)
+    else:
+        with open(args[1], "w") as f:
+            f.write(data)
+
+
+if __name__ == "__main__":
+    main(sys.argv)