Where are you?

After a discussion with co-workers (and numerous plane flights from Seattle, WA to Iowa for weddings), they remarked that they never knew which weekends I’d be in Iowa. So the result was this website!

Powered by AWS Route 53, Static Website Hosting via AWS S3, and dynamic updates via AWS Lambda which periodically check my Google Calendar to update the site accordingly based on the presence of an event (in Iowa) or not (not in Iowa). It also comes with a convenient API (for no good reason): http://isderbyiniowa.com/api/ The cool thing with this simple website is there are no backend servers maintained by me since it is all hosted via S3!

Architecture

The key thing to note is the power behind the site is Lambda, triggered by an hourly CloudWatch event. Everything else is standard work to set up a static website in S3.

The bucket contents is pretty basic:

- isderbyiniowa.com/
  - api/
    - no.html
    - yes.html
  - no.html
  - yes.html

The trick to making this work is pointing the index and error pages in the S3 Static Website Hosting configuration to yes.html or no.html, instead of what most people set it to: index.html. Hitting the api subpage will also give you the correct JSON since the files within it mimic the yes.html and no.html structure. It doesn’t vend HTML though :)

This is the magic to this site - so now we need to find a way to dynamically change it…

Making Static Actually Dynamic

When the lambda function is invoked, it contacts the Google Calendar API. It then looks to see, on a specific calendar I have, if there is an event going on. An event going on means that it will know I am in Iowa - I only put an event on this calendar when I actually am in Iowa. Based on what it determined, it then contacts AWS’s S3 API and updates the WebsiteConfiguration map accordingly:

• In Iowa? yes.html
• Not in Iowa? no.html

WARNING: Python code written in under 2 hours ahead!

from __future__ import print_function

import boto3
from datetime import datetime, timedelta
import json
import logging
import urllib
import urllib2

logger = logging.getLogger()
logger.setLevel(logging.INFO)

# Settings
# Google
calendarId = "FILL_ME_IN"
apiKey = "FILL_ME_IN"
# AWS
s3Bucket = "FILL_ME_IN"


def lambda_handler(event, context):
    logger.info('got event: {}'.format(event))

    # Timing stuff
    if event["time"]:
        now = datetime.strptime(event["time"], "%Y-%m-%dT%H:%M:%SZ")
        timeZoneOffset = "00:00"
    else:
        datetime.utcnow()
        timeZoneOffset = "07:00"
    tomorrowNow = now + timedelta(days=1)
    timeMin = "{0}T00:00:00-{1}".format(now.date(), timeZoneOffset)
    timeMax = "{0}T00:00:00-{1}".format(tomorrowNow.date(), timeZoneOffset)

    response = getEvents(timeMin, timeMax)

    location = None
    if "items" in response and len(response["items"]) > 0:
        firstEvent = response["items"][0]
        if "location" in response:
            logger.error("In Iowa, at {0}".format(firstEvent["location"]))
            location = firstEvent["location"]

        inIowa = True
    else:
        inIowa = False

    updateInIowa(inIowa)

    return {"result": {
            "inIowa": inIowa,
            "location": location,
            }}


def getEvents(timeMin, timeMax):
    logger.info("Grabbing events from {0} to {1}".format(timeMin, timeMax))

    url = "https://www.googleapis.com/calendar/v3/calendars/{0}/events?timeMax={1}&timeMin={2}&key={3}".format(
            urllib.quote(calendarId),
            urllib.quote(timeMax),
            urllib.quote(timeMin),
            urllib.quote(apiKey))

    data = urllib2.urlopen(url)
    response = data.read()
    logger.info(response)

    return json.loads(response)

def updateInIowa(yesNo):
    if yesNo == True:
        update = "yes.html"
    elif yesNo == False:
        update = "no.html"
    else:
        logger.error("Unknown value: {0}".format(yesNo))

    logger.info("Updating website to {0}".format(update))

    client = boto3.client('s3', region_name='us-east-1')
    response = client.put_bucket_website(
            Bucket=s3Bucket,
            WebsiteConfiguration={
                'ErrorDocument': {
                    'Key': update
                },
                'IndexDocument': {
                    'Suffix': update
                },
            }
        )
    logging.info("AWS S3 CLI Response: {0}".format(response))

Where To Go From Here

Currently, the bucket is not being fronted by CloudFront. If the website got really popular, I would front it with a CloudFront distribution to cut down on costs. With it getting very few hits (usually when I send it out to continue to joke), it costs fractions of a penny to operate today.

Ending Thoughts

For my safety, the people visiting the website only know that I’m in Iowa or not, but not the exact location. That would get weird, fast…

So…am I in Iowa?

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