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authorValerii Ponomarov <vponomar@redhat.com>2019-03-07 20:30:44 +0530
committervponomar <vponomar@redhat.com>2019-03-18 11:34:37 +0000
commit32b611b2a6498b1de307142e335e09d1e0ec082c (patch)
treeaaf600ab6e6adabab7c3facbf30ae6f056731969 /openshift-storage-libs/openshiftstoragelibs/podcmd.py
parent0fcdb081517c5904969b89b20326d21b361e448e (diff)
Reorder lib files removing redundant dir layer
Move all the files of 'cns-libs/cnslibs/common' dir to the 'openshift-storage-libs/openshiftstoragelibs', because 'common' is the only dir there, which doesn't really makes sense. And "cns" is old project name, so, replace it with "openshift-storage-libs". Also, fix all the imports of these libs. Change-Id: Ife00a73554e73b21b214b15016b0c8dbbf423446
Diffstat (limited to 'openshift-storage-libs/openshiftstoragelibs/podcmd.py')
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1 files changed, 141 insertions, 0 deletions
diff --git a/openshift-storage-libs/openshiftstoragelibs/podcmd.py b/openshift-storage-libs/openshiftstoragelibs/podcmd.py
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+"""Convenience wrappers for running commands within a pod
+
+The goal of this module is to support running glusto commands in pods
+without a lot of boilerplate and hassle. The basic idea is that we
+have our own run() function that can be addressed to a pod using the
+Pod object (namedtuple). This run function will work like a normal
+g.run() when not using the Pod object.
+
+Example:
+ >>> run("my-host.local", ["parted", "/dev/sda", "p"])
+ 0, "<...stdout...>", "<...stderr...>"
+
+ >>> run(Pod("my-host.local", "my-pod-426ln"),
+ ... ["pvs"])
+ 0, "<...stdout...>", "<...stderr...>"
+
+In addition, if there's a need to to use some higher level functions
+that directly call into glusto run we can monkey-patch the glusto object
+using the GlustoPod context manager. GlustoPod can also be used as a
+decorator.
+
+Imagine a function that direcly calls g.run:
+ >>> def get_magic_number(host, ticket):
+ ... s, out, _ = g.run(host, ['magicall', '--ticket', ticket])
+ ... if s != 0:
+ ... return None
+ ... return out.strip()
+
+If you want to have this operate within a pod you can use the GlustoPod
+manager to enable the pod-aware run method and pass it a Pod object
+as the first argument. Example:
+ >>> def check_magic_number(ticket):
+ ... with GlustoPod():
+ ... m = get_magic_number(Pod('myhost', 'mypod'), ticket)
+ ... return m > 42
+
+Similarly it can be used as a context manager:
+ >>> @GlustoPod()
+ ... def funky(x):
+ ... m = get_magic_number(Pod('myhost', 'mypod'), ticket)
+ ... return m > 42
+
+Because the custom run fuction only runs commands in pods when passed
+a Pod object it is fairly safe to enable the monkey-patch over the
+lifetime of a function that addresses both hosts and pods.
+"""
+
+from collections import namedtuple
+from functools import partial, wraps
+import types
+
+from glusto.core import Glusto as g
+
+from openshiftstoragelibs import openshift_ops
+
+# Define a namedtuple that allows us to address pods instead of just
+# hosts,
+Pod = namedtuple('Pod', 'node podname')
+
+
+def run(target, command, log_level=None, orig_run=g.run):
+ """Function that runs a command on a host or in a pod via a host.
+ Wraps glusto's run function.
+
+ Args:
+ target (str|Pod): If target is str object and
+ it equals to 'auto_get_gluster_endpoint', then
+ Gluster endpoint gets autocalculated to be any of
+ Gluster PODs or nodes depending on the deployment type of
+ a Gluster cluster.
+ If it is str object with other value, then it is considered to be
+ an endpoint for command.
+ If 'target' is of the 'Pod' type,
+ then command will run on the specified POD.
+ command (str|list): Command to run.
+ log_level (str|None): log level to be passed on to glusto's
+ run method
+ orig_run (function): The default implementation of the
+ run method. Will be used when target is not a pod.
+
+ Returns:
+ A tuple of the command's return code, stdout, and stderr.
+ """
+ # NOTE: orig_run captures the glusto run method at function
+ # definition time in order to capture the method before
+ # any additional monkeypatching by other code
+
+ if target == 'auto_get_gluster_endpoint':
+ ocp_client_node = list(g.config['ocp_servers']['client'].keys())[0]
+ gluster_pods = openshift_ops.get_ocp_gluster_pod_names(ocp_client_node)
+ if gluster_pods:
+ target = Pod(ocp_client_node, gluster_pods[0])
+ else:
+ target = list(g.config.get("gluster_servers", {}).keys())[0]
+
+ if isinstance(target, Pod):
+ prefix = ['oc', 'rsh', target.podname]
+ if isinstance(command, types.StringTypes):
+ cmd = ' '.join(prefix + [command])
+ else:
+ cmd = prefix + command
+
+ # unpack the tuple to make sure our return value exactly matches
+ # our docstring
+ return g.run(target.node, cmd, log_level=log_level)
+ else:
+ return orig_run(target, command, log_level=log_level)
+
+
+class GlustoPod(object):
+ """A context manager / decorator that monkeypatches the
+ glusto object to support running commands in pods.
+ """
+
+ def __init__(self, glusto_obj=None):
+ self.runfunc = None
+ self._g = glusto_obj or g
+
+ def __enter__(self):
+ """Patch glusto to use the wrapped run method.
+ """
+ self.runfunc = self._g.run
+ # we "capture" the prior glusto run method here in order to
+ # stack on top of any previous monkeypatches if they exist
+ self._g.run = partial(run, orig_run=self.runfunc)
+
+ def __exit__(self, etype, value, tb):
+ """Restore the orginal run method.
+ """
+ self._g.run = self.runfunc
+ self.runfunc = None
+
+ def __call__(self, func):
+ """Allow GlustoPod to be used as a decorator.
+ """
+ @wraps(func)
+ def wrapper(*args, **kwargs):
+ with self:
+ result = func(*args, **kwargs)
+ return result
+ return wrapper