baseimage-tutorial-framework/lib/tfw/builtins/process_managing_event_handler.py

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import logging
from xmlrpc.client import Fault as SupervisorFault
from tfw.config import TFWENV
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from tfw.networking import Scope
from tfw.components import ProcessManager, LogManager
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LOG = logging.getLogger(__name__)
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class ProcessManagingEventHandler(ProcessManager, LogManager):
keys = ['processmanager']
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"""
Event handler that can manage processes managed by supervisor.
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This EventHandler accepts messages that have a data['command'] key specifying
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a command to be executed.
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Every message must contain a data['process_name'] field with the name of the
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process to manage. This is the name specified in supervisor config files like so:
[program:someprogram]
Commands available: start, stop, restart, readlog
(the names are as self-documenting as it gets)
"""
def __init__(self, log_tail=0):
ProcessManager.__init__(self, TFWENV.SUPERVISOR_HTTP_URI)
LogManager.__init__(self, TFWENV.SUPERVISOR_HTTP_URI)
self.log_tail = log_tail
self.commands = {
'start': self.start_process,
'stop': self.stop_process,
'restart': self.restart_process
}
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def handle_event(self, message, server_connector):
try:
data = message['data']
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try:
self.commands[data['command']](data['process_name'])
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except SupervisorFault as fault:
message['data']['error'] = fault.faultString
finally:
message['data']['stdout'] = self.read_stdout(
data['process_name'],
self.log_tail
)
message['data']['stderr'] = self.read_stderr(
data['process_name'],
self.log_tail
)
server_connector.send_message(message, scope=Scope.WEBSOCKET)
except KeyError:
LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)