simple-dynamodb-go-code

Overview

Code to try out accessing DynamoDB from Go

Quickstart

Common

• Install go dependencies and tools with make install_tools
• Generate mock files with make generate
• Check the tests pass with make test

Local DB

• Follow the steps below to setup a local profile
• Set the following environment variables (these match the values as in the notes below)

export LOCAL_DYNAMO_REGION=am-morpork
export LOCAL_DYNAMO_ENDPOINT_URL=http://localhost:7001
export DESCRIBE_TABLE_NAME=permissions

• Now run the make command

make run_dynamoconnect

This should pick up the created DB and print out some information about it

AWS DynamoDB

• Using, ideally, a clean shell use awsume to assume the correct role
• Set the environment variables

export DESCRIBE_TABLE_NAME=<name of DynamoDB table>

• Run the make target

make run_dynamoconnect

• This should connect to AWS and retrieve information about the table

Notes

Setting up Go code

• Initial module setup

go mod init github.com/fionahiklas/simple-dynamodb-go-code

• Adding AWS config package (used a similar command for all the dependencies)

go get -u github.com/aws/aws-sdk-go-v2/config

Setting up Local DynamoDB instance

• Installed the AWS command line tools using brew install awscli
• Creating a new AWS profile

aws configure --profile dynamodblocal

AWS Access Key ID [None]: 12345
AWS Secret Access Key [None]: 12345 
Default region name [None]: am-morpork
Default output format [None]: json

• Use the awsume command (I installed this using brew install awsume) to switch to this profile

. awsume dynamodblocal

• Start the local DynamoDB container

docker run -d -p 7001:8000 amazon/dynamodb-local

• Check that the DB is available

aws dynamodb list-tables --endpoint-url http://localhost:7001

• This should give output like this

{
    "TableNames": []
}

Creating a local table

• Run the following command

aws dynamodb create-table \
 --table-name permissions \
 --attribute-definitions \
   AttributeName=userId,AttributeType=S \
   AttributeName=resourceId,AttributeType=S \
 --key-schema \
   AttributeName=userId,KeyType=HASH \
   AttributeName=resourceId,KeyType=RANGE \
 --billing-mode PAY_PER_REQUEST \
 --endpoint-url http://localhost:7001

• You should be able to verify the table exists with the following command

aws dynamodb describe-table --table-name permissions --endpoint-url http://localhost:7001/

References

AWS

• Post about the question Is there a way to specify endpoint-url in AWS config
• Open issue about allowing endpoint config
• Using the endpoint resolver
• Using endpoint resolver with fallback
• Using custom HTTP client