Tag Archives: guide

Move Selection to Single Line – Visual Code

Hi everyone,

A quick post on how to merge a multiline block into a single line using Visual Studio Code:

-- From this
CREATE TABLE posts
(
    post_id INT IDENTITY(1,1) PRIMARY KEY,
    title VARCHAR(100),
    description VARCHAR(MAX),
    user_id VARCHAR(255) NOT NULL,
    created DATETIME NOT NULL,
    updated DATETIME NOT NULL,
    version INT NOT NULL,
    up_votes INT NOT NULL,
    down_votes INT NOT NULL,
    updated DATETIME NOT NULL
);

-- To this
CREATE TABLE posts ( post_id INT IDENTITY(1,1) PRIMARY KEY, title VARCHAR(100), description VARCHAR(MAX), user_id VARCHAR(255) NOT NULL, created DATETIME NOT NULL, updated DATETIME NOT NULL, version INT NOT NULL, up_votes INT NOT NULL, down_votes INT NOT NULL, updated DATETIME NOT NULL )

Simply highlight your code block, press F1, and then type “join lines”. Pressing enter will join everything. If you’re on a mac you can also use ctrl+j.

Advertisements

Overriding Global Variables – AWS SAM Local

Hi everyone,

Today I’ve added local overrides to the global variables in my template.yml file. This was pretty finicky – a lot of conflicting suggestions out there unfortunately. These are the settings that ended up working for me.

local-env-var-overrides.json:

{
    "Parameters": {
        "RDS_HOSTNAME_TEST": "192.168.0.31"
    }
}

template.yaml

Globals:
  Function:
    Environment:
      Variables:        
        RDS_HOSTNAME_TEST:
          Type: String
          Default: 'DEFAULT'

aws sam local command:

sam local start-api --env-vars "local-env-var-overrides.json"

create.js

exports.createTrapHandler = async (event, context, callback) => {

	try {

        console.log("RDS_HOSTNAME_TEST: " + process.env.RDS_HOSTNAME_TEST)
        // Outputs: 192.168.0.31

This link ended up being pretty useful: https://www.npmjs.com/package/aws-sam-local

Cognito Auth with AWS SAM

Hi everyone,

I’ve spent today implementing Cognito with AWS SAM and it took quite a while to work out what needed to be done – unfortunately there’s a lot of conflicting doco out there. Posting a sample template just in case it’s able to help anyone else out.

The first thing to do is to explicitly define you rest API. By default AWS SAM will generate one with a default logical id of ServerlessRestApi. You’ll need to override this:

Resources:
  # See links for more info
  # Referencing cognito authorizer: https://github.com/awslabs/serverless-application-model/issues/512#issuecomment-411284092
  # Logical id is auto generated: https://github.com/awslabs/serverless-application-model/blob/master/docs/internals/generated_resources.rst#api
  # Sample template.yml: https://github.com/awslabs/serverless-application-model/blob/release/v1.8.0/examples/2016-10-31/api_cognito_auth/template.yaml
  MyCustomApi:
    Type: "AWS::Serverless::Api"
    Properties:
      StageName: Prod
      Auth: # We will eventually define other auth options here such as Usage Plans/Api Keys, AWS_IAM, and Resource Policies
        DefaultAuthorizer: MyCustomCognitoAuthorizer
        Authorizers:
          MyCustomCognitoAuthorizer:
            UserPoolArn: !GetAtt MyCustomCognitoUserPool.Arn # Can be a string, or array
            # Identity: # Optional
              # Header: ... # Optional; Default: Authorization
              # ValidationExpression: ...  # Optional; ensures the request header matches a pattern before checking in with the Authorizer endpoint; is there a default we can set for Cognito User Pools Auth?

You’ll also need to create a user pool and client:

# Creating a cognito user pool - https://github.com/awslabs/serverless-application-model/blob/master/examples/2016-10-31/api_cognito_auth/template.yaml
  MyCustomCognitoUserPool:
    Type: AWS::Cognito::UserPool
    Properties:
      UserPoolName: !Ref CognitoUserPoolName
      # LambdaConfig:
        # PreSignUp: !GetAtt PreSignupLambdaFunction.Arn
      Policies:
        PasswordPolicy:
          MinimumLength: 8
      UsernameAttributes:
        - email
      Schema:
        - AttributeDataType: String
          Name: email
          Required: false

  MyCustomCognitoUserPoolClient:
    Type: AWS::Cognito::UserPoolClient
    Properties:
      UserPoolId: !Ref MyCustomCognitoUserPool
      ClientName: !Ref CognitoUserPoolClientName
      GenerateSecret: false

You then add the api id and the auth attribute to each of your function properties. If you’ve used the default authorizer property when defining the associated api you can override it by using authorizer: none.

GetBreedFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: breed.getBreedHandler
      Policies: arn:aws:iam::aws:policy/AmazonDynamoDBFullAccess
      Runtime: nodejs8.10
      Environment:
        Variables:
          TABLE_CAT_BREED: !Ref CatBreedTable
      Events:
        GetEvent:
          Type: Api
          Properties:
            Path: /breed/{breedId}
            Method: get
            RestApiId: !Ref MyCustomCustomApi
            Auth:
              Authorizer: NONE

Hopefully that’s able to help you out. If you run into any trouble I found the following link pretty useful: https://github.com/awslabs/serverless-application-model/blob/release/v1.8.0/examples/2016-10-31/api_cognito_auth/template.yaml

AWS SAM Cheat Sheet/Quick Reference

Hi everyone,

This will just be a living cheat sheet or quick reference for using AWS SAM with nodejs. I’ll add to it as I find things that are useful or I might need again.

General AWS SAM Info:

Description Example More
Validate template sam validate
Start AWS Sam Locally https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-quick-start.html
Access config variable in Lambda const CAT_BREED_TABLE = process.env.CAT_BREED_TABLE; https://stackoverflow.com/a/48491845/522859
Dynamically reference another resource in template.yml CAT_BREED_TABLE: !Ref DynamoDbCatBreedTable https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-ref.html

Dynamo DB Local Info:

Description Example More
Create table aws dynamodb create-table –table-name CatBreeds –attribute-definitions AttributeName=CatBreedId,AttributeType=S –key-schema AttributeName=CatBreedId,KeyType=HASH –provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5
–endpoint-url http://192.168.0.31:8000
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Tools.CLI.html
List Tables aws dynamodb list-tables –endpoint-url http://192.168.0.31:8000 https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Tools.CLI.html
List All Rows in Table aws dynamodb scan –table-name PestinatorTable –endpoint-url http://192.168.0.31:8000 https://stackoverflow.com/a/52236600/522859

Node.js Info:

Description Example More
Run tests npm test

Parsing DynamoDB Items – AWS Lambda with Node.js

Hi everyone,

A quick post on how to parse DynamoDB items into something more readable when using lambda with Node.js:

Original:

console.log(data["Item"]);

{
    CatBreedId: { S: '17acbc81-2b4a-462b-be87-bcc49580b1ae'},
    Name: { S: 'Cat #1'}
}

Parsed:

console.log(AWS.DynamoDB.Converter.unmarshall(data["Item"]));

{
    "CatBreedId": "17acbc81-2b4a-462b-be87-bcc49580b1ae",
    "Name": "Cat #1"
}

Official doco is here: https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/DynamoDB/Converter.html

Thanks to the following stackoverflow post for the info: https://stackoverflow.com/a/44536616/522859

Update Wireless Info on Raspberry Pi

Hi everyone,

Just a quick post on how to configure wireless info on a raspberry pi. To start with, open the config file:

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

You can then add any number of connections to the file with varying priorities:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=AU

network={
        ssid="Mobile Network"
        psk="YOUR_PASSWORD"
        key_mgmt=WPA-PSK
        priority=2
}

network={
        ssid="Home Network"
        psk="YOUR_PASSWORD"
        key_mgmt=WPA-PSK
        priority=10
}

Then save the file. Your raspberry pi will now connect to the network with the highest priority first (home network), when that’s not available it will use the network with the lower priority (mobile network).

The official doco is actually pretty good for this use case if you need more info: https://www.raspberrypi.org/documentation/configuration/wireless/wireless-cli.md