Add service_ports module (#52)

changes/52.feature

@@ -0,0 +1 @@
+Add `service_ports` module to place the common routines for parsing service ports declarations

src/ai/backend/common/service_ports.py

@@ -0,0 +1,52 @@
+import re
+from typing import (
+    Sequence, List, Set, Any
+)
+
+from .types import ServicePort, ServicePortProtocols
+
+__all__ = (
+    'parse_service_ports'
+)
+
+_rx_service_ports = re.compile(
+    r'^(?P<name>[\w-]+):(?P<proto>\w+):(?P<ports>\[\d+(?:,\d+)*\]|\d+)(?:,|$)')
+
+
+def parse_service_ports(s: str, exception: Any) -> Sequence[ServicePort]:
+    items: List[ServicePort] = []
+    used_ports: Set[int] = set()
+    while True:
+        match = _rx_service_ports.search(s)
+        if match:
+            s = s[len(match.group(0)):]
+            name = match.group('name')
+            if not name:
+                raise exception('Service port name must be not empty.')
+            protocol = match.group('proto')
+            if protocol == 'pty':
+                # unsupported, skip
+                continue
+            if protocol not in ('tcp', 'http', 'preopen'):
+                raise exception(f'Unsupported service port protocol: {protocol}')
+            ports = tuple(map(int, match.group('ports').strip('[]').split(',')))
+            for p in ports:
+                if p in used_ports:
+                    raise exception(f'The port {p} is already used by another service port.')
+                if p >= 65535:
+                    raise exception(f'The service port number {p} must be smaller than 65535.')
+                if p in (2000, 2001, 2002, 2003, 2200, 7681):
+                    raise exception('The service ports 2000 to 2003, 2200 and 7681 '
+                                       'are reserved for internal use.')
+                used_ports.add(p)
+            items.append({
+                'name': name,
+                'protocol': ServicePortProtocols(protocol),
+                'container_ports': ports,
+                'host_ports': (None,) * len(ports),
+            })
+        else:
+            break
+        if not s:
+            break
+    return items