This allows plugins to add controls to nodes that already have some
controls set by other plugin. Previously only the last plugin that
sets the controls in the node would have its controls visible. That
was because of NodeControls' Merge function that actually weren't
merging data from two inputs, but rather returning data that was newer
and discarding the older one.
Plugins are queried for reports two times in a second. That's often
enough to get the shortcut reports. The reports are sent together with
the response.
Thanks to that, plugins can react to requests from controls they
exposed.
To make it work, plugins registry modifies each plugin's report by
prepending the plugin ID to the control name the plugin has exposed
before sending it to the app. Then the registry installs the control
request handler for this faked control name, which forwards the
request to the correct plugin.
This adds a new API endpoint to plugins next to "/report" - a
"/control" entry. The body of the request is the JSON-encoded
xfer.Request instance.
We will want to put plugin id in a control id, which is sent to an app
and then to GUI. When we get a control request from GUI, we will want
to extract the plugin ID from the control name. To do it unambiguously
we need some separator made of chars that are not allowed in a plugin
name. This is to avoid the situation when there are two plugins:
"Plugin" and "PluginFoo". "Plugin" exposes a control named
"FooControl" and "PluginFoo" exposes a control named "Control". Faking
the control names which will be sent to the app would result in two
"PluginFooControl".
One possible option for plugin ID and control name separator would be
"/", but that won't work, since the request sent from GUI to the app
to <probe>/<node>/<control> would actually be
<probe>/<node>/<plugin>/<control> and as such wouldn't match the URL
template in RegisterControlRoutes().
* It sends unexpected TCP RSTs (causing connection reset by peer errors in the python plugin)
Exception happened during processing of request from
Traceback (most recent call last):
File "/usr/lib/python2.7/SocketServer.py", line 295, in _handle_request_noblock
self.process_request(request, client_address)
File "/usr/lib/python2.7/SocketServer.py", line 321, in process_request
self.finish_request(request, client_address)
File "./http-requests.py", line 145, in finish_request
self.RequestHandlerClass(request, '-', self)
File "/usr/lib/python2.7/SocketServer.py", line 658, in __init__
self.handle()
File "/usr/lib/python2.7/BaseHTTPServer.py", line 349, in handle
self.handle_one_request()
File "/usr/lib/python2.7/BaseHTTPServer.py", line 312, in handle_one_request
self.raw_requestline = self.rfile.readline(65537)
File "/usr/lib/python2.7/socket.py", line 480, in readline
data = self._sock.recv(self._rbufsize)
error: [Errno 104] Connection reset by peer
* It doesn't reuse connections
Squash of:
* Include plugins in the report
* show plugin list in the UI
* moving metric and metadata templates into the probe reports
* update js for prime -> priority
* added retry to plugin handshake
* added iowait plugin
* review feedback
* plugin documentation
