Python scripts used in ActiveState webinar "Advanced Scaling Techniques with PaaS"

autoscale-on-cpu.py

from stackato.interfaces import StackatoInterface
from bs4 import BeautifulSoup
import requests
import yaml

CREDENTIALS = yaml.load(open('credentials.yml'))

APP_NAME = 'your-app-name'
NEW_RELIC_USER_ID = 'your-user-id'
NEW_RELIC_APPLICATION_ID = 'your-app-id'

# scaling threshold
CPU_THRESHOLD = 80.5

# flags
DEBUG = False
VERBOSE = True

# max instance
MAX_INSTANCES = 3

def get_newrelic_threshold_value(user, appid, name='CPU'):
    headers = {'x-api-key': CREDENTIALS['token']}
    url = 'https://api.newrelic.com/api/v1/accounts/' + user + '/applications/' + appid + '/threshold_values.xml'

    if DEBUG:
        print url
        print headers

    r = requests.get(url, headers=headers)

    # read from the response body as xml data
    soup = BeautifulSoup(r.text, 'xml')
   
    # return the value of the specified threshold_value's name from the response
    return soup.find_all(attrs={'name': name})[0]['metric_value']

if __name__ == "__main__":

    # convert to float, since the CPU threshold value is returned as a string
    metric_value = float(get_newrelic_threshold_value(NEW_RELIC_USER_ID,NEW_RELIC_APPLICATION_ID))

    if VERBOSE:
        print "metric_value is " + str(metric_value)
        print "CPU_THRESHOLD is " + str(CPU_THRESHOLD)

    if metric_value < CPU_THRESHOLD:
        if VERBOSE:
            print "metric_value < CPU_THRESHOLD"
        print('application running normally. no new instances spawned.')
    else:
        if VERBOSE:
	        print "metric_value => CPU_THRESHOLD"

        sti = StackatoInterface(CREDENTIALS['target'], CREDENTIALS['username'], CREDENTIALS['password'])

        if sti.login():
            app = sti.get_app(APP_NAME)
            print APP_NAME + " currently running " + str(app['runningInstances']) + " instances."

            if app['instances'] < MAX_INSTANCES:

                # increase the number of instances
            	app['instances'] += 1
                # making a PUT request to the application
                if sti.put_app(APP_NAME, app):
                    print('added one more instance to this application.')

            else:
                print('reached max instances.')

credentials.yml

target: https://api.stackato-xxxx.local/
username: your-stackato-username
password: your-stackato-password
token: your-newrelic-api-key

requirements.txt

requests
PyYAML
beautifulsoup4
python-stackato

simple_newrelic.py

import requests
import yaml

CREDENTIALS = yaml.load(open('credentials.yml'))

APP_NAME = 'your-app-name'
NEW_RELIC_USER_ID = 'your-user-id'
NEW_RELIC_APPLICATION_ID = 'your-app-id'

headers = {'x-api-key': CREDENTIALS['token']}

url = 'https://api.newrelic.com/api/v1/accounts/' + NEW_RELIC_USER_ID + '/applications/' + NEW_RELIC_APPLICATION_ID + '/threshold_values.xml'

print requests.get(url, headers=headers).text

simple_stackato.py

from stackato.interfaces import StackatoInterface
import yaml
import json

CREDENTIALS = yaml.load(open('credentials.yml'))

sti = StackatoInterface(CREDENTIALS['target'], CREDENTIALS['username'], CREDENTIALS['password'])

if sti.login():
  print json.dumps(sti.get_apps())