Implement container attach

Signed-off-by: Jhon Honce <jhonce@redhat.com>

contrib/python/podman/libs/__init__.py

@@ -1,4 +1,5 @@
 """Support files for podman API implementation."""
+import collections
 import datetime
 import functools
 
@@ -12,12 +13,11 @@ __all__ = [
 
 
 def cached_property(fn):
-    """Cache return to save future expense."""
+    """Decorate property to cache return value."""
     return property(functools.lru_cache(maxsize=8)(fn))
 
 
-# Cannot subclass collections.UserDict, breaks varlink
-class Config(dict):
+class Config(collections.UserDict):
     """Silently ignore None values, only take key once."""
 
     def __init__(self, **kwargs):

contrib/python/podman/libs/_containers_attach.py

@@ -0,0 +1,111 @@
+"""Exported method Container.attach()."""
+
+import fcntl
+import os
+import select
+import signal
+import socket
+import struct
+import sys
+import termios
+import tty
+
+CONMON_BUFSZ = 8192
+
+
+class Mixin:
+    """Publish attach() for inclusion in Container class."""
+
+    def attach(self, eot=4, stdin=None, stdout=None):
+        """Attach to container's PID1 stdin and stdout.
+
+        stderr is ignored.
+        """
+        if stdin is None:
+            stdin = sys.stdin.fileno()
+
+        if stdout is None:
+            stdout = sys.stdout.fileno()
+
+        with self._client() as podman:
+            attach = podman.GetAttachSockets(self._id)
+
+        # This is the UDS where all the IO goes
+        io_socket = attach['sockets']['io_socket']
+        assert len(io_socket) <= 107,\
+            'Path length for sockets too long. {} > 107'.format(
+                len(io_socket)
+            )
+
+        # This is the control socket where resizing events are sent to conmon
+        ctl_socket = attach['sockets']['control_socket']
+
+        def resize_handler(signum, frame):
+            """Send the new window size to conmon.
+
+            The method arguments are not used.
+            """
+            packed = fcntl.ioctl(stdout, termios.TIOCGWINSZ,
+                                 struct.pack('HHHH', 0, 0, 0, 0))
+            rows, cols, _, _ = struct.unpack('HHHH', packed)
+
+            with open(ctl_socket, 'w') as skt:
+                # send conmon window resize message
+                skt.write('1 {} {}\n'.format(rows, cols))
+
+        def log_handler(signum, frame):
+            """Send command to reopen log to conmon.
+
+            The method arguments are not used.
+            """
+            with open(ctl_socket, 'w') as skt:
+                # send conmon reopen log message
+                skt.write('2\n')
+
+        try:
+            # save off the old settings for terminal
+            original_attr = termios.tcgetattr(stdout)
+            tty.setraw(stdin)
+
+            # initialize containers window size
+            resize_handler(None, sys._getframe(0))
+
+            # catch any resizing events and send the resize info
+            # to the control fifo "socket"
+            signal.signal(signal.SIGWINCH, resize_handler)
+        except termios.error:
+            original_attr = None
+
+        try:
+            # Prepare socket for communicating with conmon/container
+            with socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET) as skt:
+                skt.connect(io_socket)
+                skt.sendall(b'\n')
+
+                sources = [skt, stdin]
+                while sources:
+                    readable, _, _ = select.select(sources, [], [])
+                    for r in readable:
+                        if r is skt:
+                            data = r.recv(CONMON_BUFSZ)
+                            if not data:
+                                sources.remove(skt)
+
+                            # Remove source marker when writing
+                            os.write(stdout, data[1:])
+                        elif r is stdin:
+                            data = os.read(stdin, CONMON_BUFSZ)
+                            if not data:
+                                sources.remove(stdin)
+
+                            skt.sendall(data)
+
+                            if eot in data:
+                                sources.clear()
+                                break
+                        else:
+                            raise ValueError('Unknown source in select')
+        finally:
+            if original_attr:
+                termios.tcsetattr(stdout, termios.TCSADRAIN, original_attr)
+                signal.signal(signal.SIGWINCH, signal.SIG_DFL)

contrib/python/podman/libs/containers.py

@@ -6,8 +6,10 @@ import json
 import signal
 import time
 
+from ._containers_attach import Mixin as AttachMixin
 
-class Container(collections.UserDict):
+
+class Container(collections.UserDict, AttachMixin):
     """Model for a container."""
 
     def __init__(self, client, id, data):
@@ -46,12 +48,6 @@ class Container(collections.UserDict):
         with self._client() as podman:
             return self._refresh(podman)
 
-    def attach(self, detach_key=None, no_stdin=False, sig_proxy=True):
-        """Attach to running container."""
-        with self._client() as podman:
-            # TODO: streaming and port magic occur, need arguments
-            podman.AttachToContainer()
-
     def processes(self):
         """Show processes running in container."""
         with self._client() as podman: