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Now that we've got our app working,

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you might think we've reached the end of today's lessons,

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but there's just one final thing I want to talk to you about.

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And that is the environment. Not the environment as a whole,

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but more precisely environment variables.

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Now what our environment variables anyways?

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If you go into your PyCharm project

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and you go into this tab where it says "Terminal", here

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if you type in env (set on Windows) and hit "Enter",

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you can see a whole bunch of variables.

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So you've got a key and a value

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and in between there is just a single equal (=) sign.

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So these are the different variables that are set in the environment in which

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your code is run.

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These variables have values which are strings

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which can be used in our applications or our code.

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Now inside Python

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anywhere you can also type env and you can see some slightly different

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environment variables which are relative to the Python anywhere environment.

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What exactly all these environment variables used for? Well,

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there's two major use cases. One is for convenience.

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Normally when you deploy a large application,

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the process is quite complicated. And once you've done it,

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you kind of don't want to mess around with the code base and update the code

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files like your main.py for example. Instead,

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you could have these environment variables, which you can change. For example,

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if you had an application that was sending you emails out to your clients,

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then your client base emails might change day to day.

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So certain variables that are being used in your code base could be set as

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environment variables

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and you can modify those variables without having to touch the code.

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A second reason might be for security.

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So when you're developing software,

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you might be uploading your code based somewhere, for example

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to store it online or to a service like PythonAnywhere.

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And it's usually not a good idea to have things like your authentication keys or

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your API keys to be stored in the same place as the rest of your code.

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That's where environment variables come in.

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So environment variables essentially allow us to separate out where we store

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our keys, our secret stuff,

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and various other variables away from where our code base is located.

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In our case,

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it doesn't really matter because we haven't got a paid account anywhere in here.

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It doesn't really matter if somebody steals our auth token or our API key,

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because none of those are linked to our payment details. Now, however,

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if we were to upgrade our accounts on open weather map's API

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or on Twilio's API,

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then we definitely want to keep these two things secret; auth token and the API

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key.

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Instead of having it located in the same place where we've got our code base

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which means you might accidentally upload it somewhere on the internet where

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other people can see it, instead,

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we can store these two things as environment variables.

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We can create an environment variable by simply typing export

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and then the name of the variable which I'll call OWM

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_API_KEY. And then it's really important that we have no spaces,

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but just a single equal sign.

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And then we're going to store everything that's in between the quotation marks.

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So I'm going to copy that from over here,

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and I'm going to paste that in here. Once I've exported that

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and then if I hit "env" again, you'll see

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now in this updated environment

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you can see that environment variable go in right there.

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And now we can tap into that environment variable in any of the code that we run

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from this particular environment. To do that we have to use this os module that

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we've already got.

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So I'm going to delete everything that's currently stored in the API key.

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And instead, I'm going to tap into os.environ,

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and then I'm going to use a method called get to get the value of a particular

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environment variable.

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The name is everything that's before the equal sign.

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So let's go ahead and paste it in here. And now when I run this code,

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so using python3 and then the name of the file,

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you can see that it successfully runs queuing our message into Twilio.

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Now go ahead and do the same thing with the auth token.

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You want to save this as an environment

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variable code auth_token in all caps,

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similar to what we've got here.

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And you want to store this value in the environment variable.

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Pause the video and give that a go. All right.

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So we're going to follow the exact same thing that we did before. We use the

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export keyword and then we type in the name of the environment variable

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which is going to be AUTH_TOKEN. And then really importantly,

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we just have an equal sign, no spaces,

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and we're going to store this value without the double-quotes

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and we're going to put it in here. Now in our environment variables,

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you can see we've got our open weather map API key.

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And if we scroll up a bit more, you can see our auth token as well.

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So now we can replace this string with our os.environ.get

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and then we pass in the name of the key which is AUTH_TOKEN.

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And now let's run our code again with python3 main.py.

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And you can see it's still works as before.

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But now if somebody comes across this particular code base on the internet,

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they won't be able to use our Twilio account or our open weather map account

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because both of these keys are now hidden. Let's go ahead and hit save.

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So now we're going to do the same thing,

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but at the point where we run our code from our task scheduler.

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So go ahead and right-click on this snake and then open the link in a new tab so

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that we can go to our tasks section.

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And here we're going to edit our command. Instead of just running Python main

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.py, we're going to export those two environment variables.

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This is why we've got two screens open up so we can actually copy the actual

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values. The first value is going to be our open weather map

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API key. So I'm going to copy that. And then here,

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I'm going to write export and then paste in that first key. Now,

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afterward, I'm going to use a semi-colon to denote a new line

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and then I'm going to export the next key. Scrolling up,

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we can see our auth token right here so we're going to copy that as well

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and we're going to export that as the other environment variable.

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And then finally, we're going to cap it off with a semicolon.

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So now you should have your export OWM_API_KEY

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and then your exporting your auth token as well. And then finally,

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on the last line, we're running our python3 main.py.

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Now let's change this to run at the current time.

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So it's going to be UTC time which happens to be 10 o'clock

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and then instead of 46, it's now 48

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so I'm going to change that to 49. And then I'm gonna hit the tick.

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And now we're going to wait to see if it actually works

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even though we've taken out the API keys from our main.py

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because we're exporting it in our command.

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Let's see if we still get the notification message.

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There you have it. It's still working as before.

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But now this is invisible to people

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if they happen to access our main.py.

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Now don't worry. The service of Python anywhere are pretty secure.

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Nobody's really going to hack into your account

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just to look into your main.py.

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The bigger problem is when you upload your own code to places like Git

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Hub or a BitBucket,

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basically places that are essentially a Dropbox for code.

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And when you have it on there, because your code could be public,

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that's where the problem happens.

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If people look at your code file and they see that you've got API keys in there,

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then they might steal them. So whenever you're uploading your code publicly,

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always be careful that you strip it of all of the API keys and instead use

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environment variables like we have here to pull it from the environment.

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All that's left to do for you is to update your latitude and longitude to your

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actual local latitude and longitude instead of the rainy place that we're

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testing. And you've now completed the rain alert application.

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Now I've showed you quite a few different APIs,

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but there's a whole world of APIs for you to explore.

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And if you have the patience to read their documentation and understand how to

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work with their APIs, then you now know how to work with their endpoints,

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how to pass parameters and also how to authenticate yourself with their servers.

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So here's a list of fun APIs that you can use to build applications with.

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I've shown you how you can make a rain alert and send yourself SMS messages,

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or how to get the location of the ISS or the sunrise and sunset times,

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but there's a whole bunch of other APIs for you to explore. For example,

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things like the open movie database API,

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which contains a whole bunch of movie related data,

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or looking up songs and artists using the Spotify API and a whole lot more.

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So I'll leave you to explore that.

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And if you come up with something innovative and interesting,

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be sure to share it with the rest of us in the Q&A below this lesson so that

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we can all check it out and admire your hard work.