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| Bluemix: Bring Your Own Community |
Because IBM Bluemix is based on Cloud Foundry, I am using the Cloud Foundry-related tools (mainly "cf") to interact with Bluemix. A first challenge is that a Python runtime is not built into Bluemix/Cloud Foundry and I have to tell it to prepare the runtime for me. It is called "Bring Your Own Community". When you click that icon, some helpful description comes up, pointing you to how to get started.
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| Bluemix: Get started with own buildpacks |
The trick is use some scripting to package framework and runtime support and it is called buildpack. For Python there are several buildpacks available and I am going to use this one. It is specified whenever pushing the application from my local machine to Bluemix:
cf push weatherFN -b https://github.com/ephoning/heroku-buildpack-python.git
As a starter, I downloaded a sample Python-based Web application that is deployable to Bluemix/Cloud Foundry. It comes with 5 files, one of them a small "hello.py", the actual application. The other files are:
- runtime.txt - it specifies the Python version
- requirements.txt to list the dependencies on other Python modules
- Procfile - tells the runtime what and how to start
- README.md with some basic introductions
2014/06/27 11:20 EDNY 271120Z 22007KT 180V240 CAVOK 24/06 Q1017
However, it would require decoding (for untrained people like myself). So I looked further and I found OpenWeatherMap. They offer the weather data in various formats, including JSON. The data for Friedrichshafen can easily be fetched like this and look like in this sample:
{"coord":{"lon":9.48,"lat":47.65},"sys":{"message":0.0037,"country":"DE","sunrise":1403839575,"sunset":1403897051}, "weather":[{"id":800,"main":"Clear","description":"Sky is Clear","icon":"01d"}], "base":"cmc stations","main":{"temp":297.46,"humidity":41,"pressure":1010.562,"temp_min":297.15,"temp_max":297.95}, "wind":{"speed":1,"gust":4,"deg":61}, "clouds":{"all":0},"dt":1403869524,"id":2924585,"name":"Friedrichshafen","cod":200}
Python has a built-in JSON module and it is easy to load and dump the data:
wdata = json.load(urllib.urlopen(url))
print json.dumps(wdata, indent=2)
A single field can be accessed using array notation (description of current weather condition):
wdata["weather"][0]["description"]
After some local testing I pushed the code to Bluemix as shown earlier. My Web app is called "weatherFN" as in "weather in Friedrichshafen". When the index page is requested the app redirects to the weather for Friedrichshafen:
http://weatherfn.mybluemix.net/weather/Friedrichshafen
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| Weather in Friedrichshafen |
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| Weather in London |
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| Weather in Recife |
Weather looks nice, I learned more about IBM Bluemix and how to use Python today. Now it is almost time for the weekend.
Last but not least, here is the entire Python code that I used:
import os
from flask import Flask,redirect
import urllib
import json
BASE_URL = "http://api.openweathermap.org/data/2.5/weather?q="
app = Flask(__name__)
@app.route('/')
def index():
return redirect('/weather/Friedrichshafen')
@app.route('/weather/<city>')
def weather(city):
url = "%s/%s" % (BASE_URL, city)
wdata = json.load(urllib.urlopen(url))
print json.dumps(wdata, indent=2)
page='<title>current weather for '+wdata["name"]+'</title>'
page +='<h1>Current weather for '+wdata["name"]+' ('+wdata["sys"]["country"]+')</h1>'
page += '<br/>Min Temp. '+str(wdata["main"]["temp_min"]-273.15)+'<br/>'
page += '<br/>Max Temp. '+str(wdata["main"]["temp_max"]-273.15)+'<br/>'
page += '<br/>Current Temp. '+str(wdata["main"]["temp"]-273.15)+'<br/>'
page += '<br/>Weather: '+wdata["weather"][0]["description"]+'<br/>'
return page
port = os.getenv('VCAP_APP_PORT', '5000')
if __name__ == "__main__":
app.run(host='0.0.0.0', port=int(port)) There are follow-up articles to this one describing how I enabled a custom domain for my Bluemix application and how I added a Cloudant / couchDB to my Python application on Bluemix.
