autoscale.py

import requests
import base64
import json

from apscheduler.schedulers.blocking import BlockingScheduler

from config import APP, KEY, PROCESS


#############
### tasks ###
#############

# Generate Base64 encoded API Key
BASEKEY = base64.b64encode(":" + KEY)
# Create headers for API call
HEADERS = {
    "Accept": "application/vnd.heroku+json; version=3",
    "Authorization": BASEKEY
}


def scale(size):
    payload = {'quantity': size}
    json_payload = json.dumps(payload)
    url = "https://api.heroku.com/apps/" + APP + "/formation/" + PROCESS
    try:
        result = requests.patch(url, headers=HEADERS, data=json_payload)
    except:
        return None
    if result.status_code == 200:
        return "Success!"
    else:
        return "Failure"


def get_current_dyno_quantity():
    url = "https://api.heroku.com/apps/" + APP + "/formation"
    try:
        result = requests.get(url, headers=HEADERS)
        for formation in json.loads(result.text):
            current_quantity = formation["quantity"]
            return current_quantity
    except:
        return None


#################
### scheduler ###
#################

sched = BlockingScheduler()


@sched.scheduled_job('cron', hour=7)
def scale_out_to_three():
    print 'Scaling out ...'
    print scale(3)


@sched.scheduled_job('cron', hour=22)
def scale_in_to_two():
    print 'Scaling in ...'
    print scale(2)


@sched.scheduled_job('cron', hour=3)
def scale_in_to_one():
    print 'Scaling in ...'
    print scale(1)


@sched.scheduled_job('interval', minutes=3)
def fail_safe():
    print "pinging ..."
    r = requests.get('https://APPNAME.herokuapp.com/')
    current_number_of_dynos = get_current_dyno_quantity()
    if r.status_code == 200 and r.elapsed.microseconds / 1000 < 5000:
        print "... success!"
    if r.status_code < 200 or r.status_code > 299:
        if current_number_of_dynos < 3:
            print 'Scaling out ...'
            print scale(3)
    if r.elapsed.microseconds / 1000 > 5000:
        if current_number_of_dynos < 3:
            print 'Scaling out ...'
            print scale(3)

sched.start()

config.py

APP = "<add your app name>"
KEY = "<add your API key>"
PROCESS = "web"