first try to define plugin api

1 files changed, 164 insertions, 0 deletions

diff --git a/tasker/plugins.py b/tasker/plugins.py
new file mode 100644
index 0000000..9d5caf9
--- /dev/null
+++ b/tasker/plugins.py
@@ -0,0 +1,164 @@
+from configuration import Config
+import imp
+import os
+import subprocess
+
+class DummyPlugin(object):
+    def __init__(self):
+        self._diagnosed = False #diagnoistics has not been run yet
+        self._state = "init" #we have no internal state yet
+        pass
+
+    #workaround, so we can use special plugins not composed of python objects
+    #like shell scripts or arbitrary binaries
+    def get_plugin(self):
+        return self
+
+    def call(self, step):
+        """call one step from plugin"""
+        return getattr(self, step)()
+
+    def info(self):
+        """Returns tuple (Plugin name, Plugin version, Plugin author)"""
+        return ("Dummy plugin", "0.0.1", "Martin Sivak <msivak@redhat.com>")
+
+    #list of all actions provided
+    def actions(self):
+        """Returns list of available actions"""
+        return set(["init", "backup", "diagnose", "describe", "fix", "restore", "destroy"])
+
+    #investigate internal state and tell us next action to perform in auto-mode
+    def nextstep(self):
+        """Returns next step needed for automated mode"""
+        return state
+
+    #iterate protocol allows us to use loops
+    def __iter__(self):
+        return self
+
+    def next(self):
+        s = self.nextstep()
+        if s==None:
+            raise StopIteration()
+
+    #default (mandatory) plugin actions
+    def init(self):
+        self._state = "backup"
+        return True
+
+    def destroy(self):
+        self._state = None
+        return True
+
+    def backup(self):
+        self._state = "diagnose"
+        return True
+
+    def restore(self):
+        self._state = "destroy"
+        return True
+
+    def diagnose(self):
+        self._diagnosed = True
+        self._state = "describe"
+        return self._diagnosed
+
+    def fix(self):
+        if not self._diagnosed:
+            self._state = "diagnose"
+            return False
+
+        self._state = "destroy"
+        return True
+
+    def describe(self):
+        self._state = "fix"
+        return ""
+
+class BinPlugin(DummyPlugin):
+    def __init__(self, bin):
+        DummyPlugin.__init__(self)
+        self._binpath = bin
+    
+    def init(self):
+        self._state = "backup"
+        return True
+
+    def destroy(self):
+        self._state = None
+        return True
+
+    def backup(self):
+        self._state = "diagnose"
+        return True
+
+    def restore(self):
+        self._state = "destroy"
+        return True
+
+    def diagnose(self):
+        self._diagnosed = True
+        self._state = "describe"
+        return self._diagnosed
+
+    def fix(self):
+        if not self._diagnosed:
+            self._state = "diagnose"
+            return False
+
+        self._state = "destroy"
+        return True
+
+    def describe(self):
+        self._state = "fix"
+        return ""
+
+class PluginSystem(object):
+    """Encapsulate all plugin detection and import stuff"""
+
+    def __init__(self, config = Config):
+        self._path = Config.plugin.path
+        self._plugins = {}
+
+        #create list of potential modules in the path
+        importlist = set()
+        for f in os.listdir(self._path):
+            if os.path.isdir(f) and os.path.isfile(os.path.join(self._path, "__init__.py")):
+                importlist.add(f)
+            elif os.path.isfile(f) and (f[-3:]==".so" or f[-3:]==".py"):
+                importlist.add(f[:-3])
+            elif os.path.isfile(f) and (f[-4:]==".pyc" or f[-4:]==".pyo"):
+                importlist.add(f[:-4])
+            elif os.path.isfile(f) and f[-7:]==".plugin":
+                self._plugins[f[:-4]] = BinPlugin(os.path.join(self._path, f))
+
+        #try to import the modules as FirstAidKit.plugins.modulename
+        for m in importlist:
+            if m in Config.plugin.disabled:
+                continue
+
+            imp.acquire_lock()
+            try:
+                moduleinfo = imp.find_module(m, self._path)
+                module = imp.load_module("."join(["FirstAidKit", "plugins", m]), *moduleinfo)
+            finally:
+                imp.release_lock()
+
+            self._plugins[m] = module
+
+    def list(self):
+        """Return the list of imported plugins"""
+        return self._plugins.keys()
+
+    def autorun(self, plugin):
+        """Perform automated run of plugin"""
+        p = self._plugins[plugin].get_plugin() #get instance of plugin
+        for step in p: #autorun all the needed steps
+            print "Running step %s in plugin %s ..." % (plugin, step,)
+            res = getattr(p, step)()
+            print "Result is:", res
+
+    def getplugin(self, plugin):
+        """Get instance of plugin, so we can call the steps manually"""
+        return self._plugins[plugin].get_plugin()
+