[5137] Added kea-shell.py

src/bin/shell/kea-shell.py

@@ -0,0 +1,81 @@
+#!/usr/bin/python
+
+# First, let's import the right kea_connector.
+# We have two versions: one for python 2.x and another for python 3.x.
+# Sadly, there's no unified way to handle http connections. The recommended
+# way is to use Requests (http://docs.python-requests.org/en/master/), but
+# that's a stand alone package that requires separate installation. One of
+# the design requirements was to not require any additional packages, so
+# the code uses standard libraries available in python. Hence two versions.
+import sys
+import signal
+import argparse
+
+if (sys.version_info[0] == 2):
+    # This is Python 2.x
+    import kea_connector2 as kea_connector
+else:
+    if (sys.version_info[0] == 3):
+        # This is Python 3.x
+        import kea_connector3 as kea_connector
+    else:
+        # This is... have no idea what it is.
+        raise SystemExit("Unknown python version:" + str(sys.version_info[0]))
+
+from kea_conn import CARequest, CAResponse
+
+# Second step: Need to parse command line parameters. We will use argparse for
+# that purpose. It does great job with having default values, taking care of
+# the help and sanity checking input parameters.
+
+parser = argparse.ArgumentParser(description='Connects to Kea Control Agent.')
+parser.add_argument('--host', type=str, nargs=1, default='127.0.0.1',
+                    help='hostname of the CA to connect to')
+parser.add_argument('--port', type=int, nargs=1, default=8000,
+                    help='TCP port of the CA to connect to')
+parser.add_argument('--timeout', type=int, nargs=1, default='10',
+                    help='Timeout (in seconds) when attempting to connect to CA')
+parser.add_argument('command', type=str, nargs="?", default='list-commands',
+                    help='command to be executed. If not specified, "list-commands" is used')
+cmd_args = parser.parse_args()
+
+# Ok, now time to put the parameters parsed into the structure to be used by the
+# connection.
+params = CARequest()
+params.command = cmd_args.command
+params.http_host = cmd_args.host[0]
+params.http_port = cmd_args.port[0]
+params.timeout = cmd_args.timeout
+
+params.generateBody()
+params.generateHeaders()
+
+conn = kea_connector.KeaConnector()
+
+def timeout_handler(signum, frame):
+    print ("Connection timeout")
+    sys.exit(1)
+
+# Load command processor
+# @todo - command specific processing will be added as part of future work
+# (either #5138 or #5139, whichever is implemented first)
+
+# Read parameters from stdin (they're optional for some commands)
+for line in sys.stdin:
+    params.params += line
+
+# Set the timeout timer. If the connection takes too long,
+# it will send a signal to us.
+signal.signal(signal.SIGALRM, timeout_handler)
+signal.alarm(params.timeout)
+
+# Ok, everything is ready. Let's send the command and get a response.
+try:
+    resp = conn.sendCA(params)
+except Exception as e:
+    print("Failed to run: " + str(e))
+    sys.exit(1)
+
+resp.printResp()
+
+sys.exit(0)