Welcome to Cloud Coffee Break Episode One!
This episode is available on YouTube, here.
Slides for this episode are available here.
Our free eBook, What is Serverless?, that I mention, is available here.
This README consists of further description of the prerequisites necessary for the "Serverless Hello World" app I talk about in the video, along with details of creating and deploying the Hello World app.
In the video I mention three prerequisites for creating the "Serverless Hello World" app:
- Suitable credentials to an AWS account.
- Install AWS CLI, configure with your credentials
- Install AWS SAM CLI
Here I'll go through these in a little more detail.
"Serverless Hello World" uses Amazon Web Services (AWS). In order to deploy the app you therefore need access to an AWS Account.
If you already have access to AWS you can skip this step, otherwise you'll need to create your own AWS account. Three points worth knowing before you do this:
- You'll need to provide a payment method (typically a credit card).
- Low throughput use, including what I cover in "Serverless Hello World", will be covered by the AWS Free Tier, but you'll be responsible for any charges beyond this tier.
- You'll need a "root user" email address that has not been used for any other AWS account. Since I use Google for email, I often use the same basic email address but with a
+sign in the username part to differentiate, which works fine for AWS signup.
The actual process for creating an account is to go to aws.amazon.com, hit the "Create an account" button, and follow the guide. The official instructions from AWS are also available here.
Once you know which AWS account you're going to use you'll need to have credentials for accessing AWS from the command line. There are a variety of ways of doing this, however if you're a beginner I recommend the following:
- Create an IAM User for your account
- Assign it AdministratorAccess privileges (assuming this is not a production account!)
- Create programmatic access keys for the user
There's a guide to doing this provided by the folks at Serverless Stack here.
First make sure you have an Access Key ID and a Secret Access Key to go with it - e.g. from the final step above.
A lot of what I do in the series uses the AWS Command Line Interface - a tool you can use from your terminal to access the vast array of AWS products. If you don't already have the AWS CLI installed (try running aws to see if you do) then you'll need to install it.
Installing the AWS CLI has got somewhat complicated over the years, especially since right now AWS have two supported major versions - AWS CLI Version 1 and, yep, you guessed it, AWS CLI Version 2. I recommend you use V2 if this is your first time using the AWS CLI.
If you're using a Mac by far the easiest way to install the AWS CLI is to use Homebrew, as follows:
% brew install awscli
If you're using something other than a Mac, or you don't use Homebrew, then you can install the AWS CLI either as a python pip package (named awscli), or a system application. Further instructions are available on the AWS website here.
Once the AWS CLI is installed, you should be able to run it from a terminal using the aws command.
The first thing you'll need to do is configure it with keys. Again, if this is your first time using AWS I recommend you run the aws configure command and follow the prompts, however there are many other more complicated ways of performing this task.
When running aws configure you'll also be asked to specify a Default region name and Default output format . Typically I start with us-east-1 and json, but you have may want to pick a region nearer to your location - just make sure you use the same region when using the AWS Web Console.
The documentation for using aws configure is available here.
A good way to test your AWS configuration is to run a simple command. aws s3 ls is a good short one (which will successfully return nothing in a new account!), otherwise aws sts get-caller-identity will give you some more details about your connection.
And finally, we can install the AWS SAM CLI - a tool which layers on top of the AWS CLI to provide various goodies.
SAM CLI uses Docker for some of its features, and this is mentioned in the docs, but for the Hello World app Docker is not unnecessary, and can be ignored.
Again, if you're on a Mac the easiest way to install SAM is via homebrew, as follows:
% brew tap aws/tap
% brew install aws-sam-cli
Otherwise the documentation available here.
If SAM is successfully installed you should be able to see something like the following
% sam --version
SAM CLI, version 1.0.0
First of all, create a new directory and switch to it, e.g.:
% mkdir hello-world
% cd hello-world
Next, in this directory, create a new file named template.yaml, the contents of which are provided here.
Build and Deploy this app as follows:
% sam deploy --guided
The --guided form is useful for beginners since it will walk you through capturing some configuration, which it then saves to a local file. You can use the default answers (just hit enter) apart from the question HelloWorldFunction may not have authorization defined, Is this okay? - to which you must explicitly hit y, and enter. For subsequent deployments of the same app, just run sam deploy .
If SAM ran successfully then your application is now deployed! To call it, you need to know the URL. You can get that by visiting the API Gateway section of the AWS Web Console at https://console.aws.amazon.com/apigateway - if you don't see your API make sure that the region selector (top right of the page next to "support" is set to the same region as your AWS CLI configuration.) Click on your API and you should be able to see "Invoke URL". If you click on that you should be able to see "Hello World!" output to your browser. Congratulations!
Since this application is available to the public internet you probably want to tear it down when you're done with it. To do so, run the following, changing the stack-name if you used something else in the deployment step:
% aws cloudformation delete-stack --stack-name sam-app