Getting Started with Python on Bluemix

To get started, we'll take you through a sample Python Flask app, help you set up a development environment, deploy to Bluemix and add a Cloudant database.

Prerequisites

You'll need the following:

1. Clone the sample app

Now you're ready to start working with the app. Clone the repo and change to the directory where the sample app is located.

git clone https://github.com/IBM-Bluemix/get-started-python
cd get-started-python

Peruse the files in the get-started-python directory to familiarize yourself with the contents.

2. Run the app locally

Install the dependencies listed in the requirements.txt External link icon file to be able to run the app locally.

You can optionally use a virtual environment External link icon to avoid having these dependencies clash with those of other Python projects or your operating system.

pip install -r requirements.txt

Run the app.

python hello.py

View your app at: http://localhost:8000

3. Prepare the app for deployment

To deploy to {{site.data.keyword.Bluemix_notm}}, it can be helpful to set up a manifest.yml file. One is provided for you with the sample. Take a moment to look at it.

The manifest.yml includes basic information about your app, such as the name, how much memory to allocate for each instance and the route. In this manifest.yml random-route: true generates a random route for your app to prevent your route from colliding with others. You can replace random-route: true with host: myChosenHostName, supplying a host name of your choice. Learn more...

applications:
- name: GetStartedPython
  random-route: true
  memory: 128M

4. Deploy the app

You can use the Cloud Foundry CLI to deploy apps.

Choose your API endpoint

cf api <API-endpoint>

Replace the API-endpoint in the command with an API endpoint from the following list.

URL	Region
https://api.ng.bluemix.net	US South
https://api.eu-gb.bluemix.net	United Kingdom
https://api.au-syd.bluemix.net	Sydney

cf login

From within the get-started-python directory push your app to {{site.data.keyword.Bluemix_notm}}

cf push

This can take a minute. If there is an error in the deployment process you can use the command cf logs <Your-App-Name> --recent to troubleshoot.

When deployment completes you should see a message indicating that your app is running. View your app at the URL listed in the output of the push command. You can also issue the

cf apps

command to view your apps status and see the URL.

5. Add a database

Next, we'll add a NoSQL database to this application and set up the application so that it can run locally and on {{site.data.keyword.Bluemix_notm}}.

Log in to {{site.data.keyword.Bluemix_notm}} in your Browser. Browse to the Dashboard. Select your application by clicking on its name in the Name column.
Click on Connections then Connect new.
In the Data & Analytics section, select Cloudant NoSQL DB and Create the service.
Select Restage when prompted. {{site.data.keyword.Bluemix_notm}} will restart your application and provide the database credentials to your application using the VCAP_SERVICES environment variable. This environment variable is only available to the application when it is running on {{site.data.keyword.Bluemix_notm}}.

Environment variables enable you to separate deployment settings from your source code. For example, instead of hardcoding a database password, you can store this in an environment variable which you reference in your source code. Learn more...

6. Use the database

We're now going to update your local code to point to this database. We'll create a json file that will store the credentials for the services the application will use. This file will get used ONLY when the application is running locally. When running in {{site.data.keyword.Bluemix_notm}}, the credentials will be read from the VCAP_SERVICES environment variable.

Create a file called vcap-local.json in the get-started-python directory with the following content:

{
  "services": {
    "cloudantNoSQLDB": [
      {
        "credentials": {
          "username":"CLOUDANT_DATABASE_USERNAME",
          "password":"CLOUDANT_DATABASE_PASSWORD",
          "host":"CLOUDANT_DATABASE_HOST"
        },
        "label": "cloudantNoSQLDB"
      }
    ]
  }
}

Back in the {{site.data.keyword.Bluemix_notm}} UI, select your App -> Connections -> Cloudant -> View Credentials
Copy and paste the username, password, and host from the credentials to the same fields of the vcap-local.json file replacing CLOUDANT_DATABASE_USERNAME, CLOUDANT_DATABASE_PASSWORD, and CLOUDANT_DATABASE_URL.
Run your application locally.

python hello.py

View your app at: http://localhost:8000. Any names you enter into the app will now get added to the database.

Make any changes you want and re-deploy to {{site.data.keyword.Bluemix_notm}}!

cf push

View your app at the URL listed in the output of the push command, for example, myUrl.mybluemix.net.

sebschrader / get-started-python