#
return '/usr/sbin/haproxy -f frontend.cfg -f local.cfg', {}
def signaled(self, js, process=None):
#
# - this pod can be switched to draining mode when being signaled
# - the configuration file will be re-written using an alternate template
# - the pod must then be restarted for the change to take effect
# - the input YAML payload should be a comma separated list of urls, for instance :
#
# urls:
# - 127.345.24.100:9000
# - 138.12.123.56:9000
#
urls = js['urls'].split(',')
logger.info('rendering draining.cfg (%s)' % js['urls'])
env = Environment(
loader=FileSystemLoader(join(dirname(__file__), 'templates')))
mappings = \
{
'default': self.hints['namespace'],
'listeners': {'listener-%d' % index: endpoint for index, endpoint in enumerate(urls)}
}
template = env.get_template('draining.cfg')
with open('%s/frontend.cfg' % self.cwd, 'w') as f:
f.write(template.render(mappings))
Pod().boot(Strategy, model=Model)
if __name__ == '__main__':
class Strategy(Piped):
cwd = '/opt/flask'
checks = 5
check_every = 1
metrics = True
def sanity_check(self, pid):
#
# - Randomly decide to be stressed
# - Curl to the Flask in subprocess to check number of threaded requests running.
#
@retry(timeout=30.0, pause=0)
def _self_curl():
reply = get('http://localhost:9000/threads')
code = reply.status_code
assert code == 200 or code == 201, 'Self curling failed'
return merge({'stressed': choice(['Very', 'Nope'])},
json.loads(reply.text))
return _self_curl()
def configure(self, _):
return 'python -u webserver.py', {}
Pod().boot(Strategy)
#
# - you can override the default settings, for instance here to tell ochopod what configure()
# returns should actually be treated as a shell command
#
shell = True
#
# - you can also pipe the sub-process stderr/out and include them in the pod log
#
pipe_subprocess = True
def configure(self, _):
#
# - simply return what you wish to run (a simple shell statement in our case)
# - deriving from Piped means the SDK will use popen() to fork an ancillary process
# - you can also set optional environment variables on that process (presently $LAPSE)
# - note that whatever value you pass will be turned into a string (e.g you can use numbers)
#
return "sleep $LAPSE && echo 'hello world' && exit 0", {'LAPSE': 5}
#
# - that's it, just boot the SDK with your process strategy
# - the local=1 means we force everything to be looked up on localhost
# - if you run this script locally you should see 'hello world' printed on stdout after 5 seconds
# - since we exit with 0 the pod will automatically be finalized (e.g shutdown gracefully)
# - simply type CTRL-C to exit
#
Pod().boot(Strategy, local=1)