116 lines
3.2 KiB
Markdown
116 lines
3.2 KiB
Markdown
|
---
|
||
|
|
categories:
|
||
|
|
- DevOps
|
||
|
|
- Backend
|
||
|
|
tags: [AWS]
|
||
|
|
---
|
||
|
|
|
||
|
|
# AWS SAM
|
||
|
|
|
||
|
|
SAM stands for **serverless application model**. It is a framework developed by AWS to simplify the process of building, deploying and managing serverless applications. It provides a concise syntax for defining the components of a serverless application, such as [Lambda functions](/DevOps/AWS/AWS_Lambda/Lambda_programming_model.md), [API gateway](/DevOps/AWS/AWS_API_Gateway.md) and database tables.
|
||
|
|
|
||
|
|
The SAM infrastructure is defined in a YAML file which is then deployed to AWS. SAM syntax gets transformed into CloudFormation during the deployment process. (CloudFormation is a broader and more robust AWS tool for large, highly scaleable infrastructures).
|
||
|
|
|
||
|
|
## Key features of SAM
|
||
|
|
|
||
|
|
- Single deployment configuration
|
||
|
|
- Integration with development tools
|
||
|
|
- Local testing and debugging
|
||
|
|
- Built on AWS CloudFormation
|
||
|
|
|
||
|
|
## Main technologies required
|
||
|
|
|
||
|
|
### Docker
|
||
|
|
|
||
|
|
Whilst SAM can be used to create a deployable file for AWS it can also be run as a container for local development with Docker.
|
||
|
|
|
||
|
|
### AWS CLI
|
||
|
|
|
||
|
|
This is installed using Python and allows you to interact directly with AWS via the command-line.
|
||
|
|
|
||
|
|
### AWS SAM CLI
|
||
|
|
|
||
|
|
See [https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/install-sam-cli.html](https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/install-sam-cli.html)
|
||
|
|
|
||
|
|
## Setting up credentials for the AWS CLI
|
||
|
|
|
||
|
|
```
|
||
|
|
aws configure
|
||
|
|
AWS Access Key ID [None]: AK*******
|
||
|
|
AWS Secret Access Key [None]: ukp******
|
||
|
|
Default region name [None]:
|
||
|
|
Default output format [None]:
|
||
|
|
```
|
||
|
|
|
||
|
|
This information can be found in the Security Credentials section of the given [IAM](/DevOps/AWS/AWS_User_management_and_roles.md#iam) user:
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
## Starting a SAM project
|
||
|
|
|
||
|
|
First create a directory for your project which will serve as the repository:
|
||
|
|
|
||
|
|
```sh
|
||
|
|
mkdir aws-sam-learning
|
||
|
|
cd aws-sam-learning
|
||
|
|
```
|
||
|
|
|
||
|
|
Then we can use the `sam` cli to bootstrap the project:
|
||
|
|
|
||
|
|
```sh
|
||
|
|
sam init --runtime nodejs16.x
|
||
|
|
```
|
||
|
|
|
||
|
|
We can just click through and accept the basic HelloWorld Lambda.
|
||
|
|
|
||
|
|
This will create the Lambda as well as an API Gateway trigger URL.
|
||
|
|
|
||
|
|
### `template.yaml`
|
||
|
|
|
||
|
|
This is autogenerated and details the main constituents of the project. There are lots of fields but the most important are the following:
|
||
|
|
|
||
|
|
```yaml
|
||
|
|
HelloWorldFunction:
|
||
|
|
Type: AWS::Serverless::Function
|
||
|
|
Properties:
|
||
|
|
CodeUri: hello-world/
|
||
|
|
Handler: app.lambdaHandler
|
||
|
|
Runtime: nodejs16.x
|
||
|
|
Architectures:
|
||
|
|
- x86_64
|
||
|
|
Events:
|
||
|
|
HelloWorld:
|
||
|
|
Type: Api
|
||
|
|
Properties:
|
||
|
|
Path: /hello
|
||
|
|
Method: get
|
||
|
|
```
|
||
|
|
|
||
|
|
This details the location of the [handler function](/DevOps/AWS/AWS_Lambda/Lambda_handler_function.md) which is contained at the path `hello-world/app.js`:
|
||
|
|
|
||
|
|
```js
|
||
|
|
exports.lambdaHandler = async (event, context) => {
|
||
|
|
try {
|
||
|
|
// const ret = await axios(url);
|
||
|
|
response = {
|
||
|
|
statusCode: 200,
|
||
|
|
body: JSON.stringify({
|
||
|
|
message: "hello world",
|
||
|
|
// location: ret.data.trim()
|
||
|
|
}),
|
||
|
|
};
|
||
|
|
} catch (err) {
|
||
|
|
console.log(err);
|
||
|
|
return err;
|
||
|
|
}
|
||
|
|
|
||
|
|
return response;
|
||
|
|
};
|
||
|
|
```
|
||
|
|
|
||
|
|
It also lists the `get` event that we can use to call API Gateway and trigger the Lambda.
|
||
|
|
|
||
|
|
The full template is below:
|
||
|
|
|
||
|
|
|