plugin/builder: use requests python package

Use the requests python package, which is more convenient to use,
and also supports sessions, where global options, like TLS certs
can be set.
Adapt the container and the spec file to install and require
the python package.

plugins/builder/osbuild.py

@@ -20,8 +20,8 @@ import enum
 import json
 import sys
 import time
+import requests
 import urllib.parse
-import urllib.request
 
 from string import Template
 from typing import Dict, List
@@ -161,37 +161,34 @@ class ComposeStatus:
 class Client:
     def __init__(self, url):
         self.url = url
+        self.http = requests.Session()
 
     def compose_create(self, nvr: NVR, distro: str, images: List[ImageRequest], kojidata: ComposeRequest.Koji):
         url = urllib.parse.urljoin(self.url, f"/compose")
-        req = urllib.request.Request(url)
         cro = ComposeRequest(nvr, distro, images, kojidata)
-        dat = json.dumps(cro.as_dict())
-        raw = dat.encode('utf-8')
-        req = urllib.request.Request(url, raw)
-        req.add_header('Content-Type', 'application/json')
-        req.add_header('Content-Length', len(raw))
 
-        try:
-            with urllib.request.urlopen(req, raw) as res:
-                payload = res.read().decode('utf-8')
-        except urllib.error.HTTPError as e:
-            body = e.read().decode('utf-8').strip()
+        res = self.http.post(url, json=cro.as_dict())
+
+        if res.status_code != 201:
+            body = res.content.strip()
             msg = f"Failed to create the compose request: {body}"
             raise koji.GenericError(msg) from None
 
-        ps = json.loads(payload)
+        ps = res.json()
         compose_id, koji_build_id = ps["id"], ps["koji_build_id"]
         return compose_id, koji_build_id
 
     def compose_status(self, compose_id: str):
         url = urllib.parse.urljoin(self.url, f"/compose/{compose_id}")
-        req = urllib.request.Request(url)
-        with urllib.request.urlopen(req) as res:
-            data = res.read().decode('utf-8')
-        js = json.loads(data)
 
-        return ComposeStatus.from_dict(js)
+        res = self.http.get(url)
+
+        if res.status_code != 200:
+            body = res.content.strip()
+            msg = f"Failed to get the compose status: {body}"
+            raise koji.GenericError(msg) from None
+
+        return ComposeStatus.from_dict(res.json())
 
     def wait_for_compose(self, compose_id: str, *, sleep_time=2):
         while True: