Add week 7 materials

2026-10-21 23:03:28 +03:00
parent 4bb38fb0a8
commit a987b82834
22 changed files with 1265 additions and 0 deletions
@@ -0,0 +1,67 @@
+"""Discover instances, save one address, and compare cached/fresh requests."""
+import argparse
+import json
+from pathlib import Path
+import sys
+import time
+from urllib.request import urlopen
+
+BASE = "http://consul:8500"
+CACHE = Path("/work/consul-address.json")
+
+
+def get(url):
+    with urlopen(url, timeout=2) as response:
+        return json.load(response)
+
+
+def discover():
+    rows = get(BASE + "/v1/health/service/orders?passing=true")
+    return sorted([{"id": r["Service"]["ID"], "address": r["Service"]["Address"],
+                    "port": r["Service"]["Port"]} for r in rows], key=lambda r: r["id"])
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("action", choices=["list", "save", "cached", "fresh", "wait"])
+    parser.add_argument("--ids", default="app-a,app-b", help="Expected passing IDs for wait")
+    args = parser.parse_args()
+    if args.action == "wait":
+        expected = sorted(args.ids.split(","))
+        deadline = time.monotonic() + 30
+        while time.monotonic() < deadline:
+            try:
+                rows = discover()
+                if [r["id"] for r in rows] == expected:
+                    print(json.dumps(rows, indent=2))
+                    return
+            except OSError:
+                pass
+            time.sleep(0.5)
+        raise RuntimeError("Passing instances did not reach " + str(expected))
+    if args.action == "list":
+        print(json.dumps(discover(), indent=2))
+        return
+    if args.action == "cached":
+        endpoint = json.loads(CACHE.read_text())
+    else:
+        rows = discover()
+        if not rows:
+            raise RuntimeError("No passing instances")
+        endpoint = rows[0]
+    if args.action == "save":
+        CACHE.parent.mkdir(parents=True, exist_ok=True)
+        CACHE.write_text(json.dumps(endpoint), encoding="utf-8")
+        print("SAVED", endpoint)
+        return
+    url = f"http://{endpoint['address']}:{endpoint['port']}/"
+    print(("CACHED" if args.action == "cached" else "FRESH"), endpoint["id"], url, flush=True)
+    print(json.dumps(get(url), indent=2))
+
+
+if __name__ == "__main__":
+    try:
+        main()
+    except (OSError, ValueError, RuntimeError) as error:
+        print("REQUEST FAILED:", error, file=sys.stderr)
+        sys.exit(1)