dcos node log

cli/dcoscli/node/main.py

@@ -3,19 +3,24 @@
 Usage:
     dcos node --info
     dcos node [--json]
+    dcos node log [--follow --lines=N --master --slave=<slave-id>]
 
 Options:
-    -h, --help    Show this screen
-    --info        Show a short description of this subcommand
-    --json        Print json-formatted nodes
-    --version     Show version
+    -h, --help            Show this screen
+    --info                Show a short description of this subcommand
+    --json                Print json-formatted nodes
+    --follow              Output data as the file grows
+    --lines=N             Output the last N lines [default: 10]
+    --master              Output the leading master's Mesos log
+    --slave=<slave-id>    Output this slave's Mesos log
+    --version             Show version
 """
 
 import dcoscli
 import docopt
 from dcos import cmds, emitting, errors, mesos, util
 from dcos.errors import DCOSException
-from dcoscli import tables
+from dcoscli import log, tables
 
 logger = util.get_logger(__name__)
 emitter = emitting.FlatEmitter()
@@ -51,6 +56,11 @@ def _cmds():
             arg_keys=[],
             function=_info),
 
+        cmds.Command(
+            hierarchy=['node', 'log'],
+            arg_keys=['--follow', '--lines', '--master', '--slave'],
+            function=_log),
+
         cmds.Command(
             hierarchy=['node'],
             arg_keys=['--json'],
@@ -90,3 +100,51 @@ def _list(json_):
             emitter.publish(output)
         else:
             emitter.publish(errors.DefaultError('No slaves found.'))
+
+
+def _log(follow, lines, master, slave):
+    """ Prints the contents of master and slave logs.
+
+    :param follow: same as unix tail's -f
+    :type follow: bool
+    :param lines: number of lines to print
+    :type lines: int
+    :param master: whether to print the master log
+    :type master: bool
+    :param slave: the slave ID to print
+    :type slave: str | None
+    :returns: process return code
+    :rtype: int
+    """
+
+    if not (master or slave):
+        raise DCOSException('You must choose one of --master or --slave.')
+
+    lines = util.parse_int(lines)
+
+    mesos_files = _mesos_files(master, slave)
+
+    log.log_files(mesos_files, follow, lines)
+
+    return 0
+
+
+def _mesos_files(master, slave_id):
+    """Returns the MesosFile objects to log
+
+    :param master: whether to include the master log file
+    :type master: bool
+    :param slave_id: the ID of a slave.  used to include a slave's log
+                     file
+    :type slave_id: str | None
+    :returns: MesosFile objects
+    :rtype: [MesosFile]
+    """
+
+    files = []
+    if master:
+        files.append(mesos.MesosFile('/master/log'))
+    if slave_id:
+        slave = mesos.get_master().slave(slave_id)
+        files.append(mesos.MesosFile('/slave/log', slave=slave))
+    return files