Setup:

• git clone git@github.com:aburkut/eth-blocks.git
• cd eth-blocks
• nvm use 14.17
• npm install

Environment variables:

For reference look at .env-example file

• ETHERSCAN_API_KEY=xx - API_KEY value for Etherscan https://etherscan.io/
• ETHERSCAN_NETWORK=xxx - network (homestead, ropsten, etc.) for Etherscan
• BLOCK_START=xxx - the value indicates from which block number to start from for initial run
• BLOCKS_DDB_TABLE=blocks - AWS Dynamodb table name where blocks will be stored
• TRANSACTIONS_DDB_TABLE=transactions - AWS Dynamodb table name where transactions will be stored
• AWS_ACCESS_KEY_ID=xxx - AWS access key id
• AWS_SECRET_ACCESS_KEY=xxx - AWS secret access key
• AWS_REGION=us-east-1 - AWS region
• STATE_BUCKET=eth-blocks-state - AWS S3 bucket
• BLOCKS_STATE_FILE=blocks-state.txt - AWS S3 state file to store state file with current processed block number
• SMART_CONTRACT_NETWORK=ropsten - network where smart contract will be deployed
• SMART_CONTRACT_ADDRESS=xxx - smart contract address
• PRIVATE_KEY=xxx - private key to iteract with smart contract

NPM scripts:

• npm run build - compile TS files and install deps for dist folder
• npm run start:dev:puller - runs puller service (for local development)
• npm run start:dev:calc - runs calc service (for local development)
• npm run deploy:contract - deploy smart contract to specific network
• npm test - runs tests
• npm run lint - runs eslint checks
• npm run lint:fix - runs eslint checks and fixes problems

Architecture:

• Serverless architecture (cheap, scalable, no efforts to manage)
• Two AWS scheduled Lambda functions - puller and calc. The first one is responsible for pulling blocks and transactions from Etherscan API into database, runs on schedule every 1 minute. The second one calculates total number of blocks and ETH spent for gas gee for a day and puts the data into Solidity smart contract. Runs on schedule once a day at 00:10.
• S3 bucket to store the latest processed block number for puller lambda
• Database - AWS Dynamodb tables to store blocks and transactions

Directory structure

• contracts - contains Solidity smart contract
• src - contains source code of Node.js AWS Lambda functions and script to deploy smart contract
• terraform - contains terraform templates to provision AWS resources required by the application
• test - contains tests

Deploy smart contract:

• export SMART_CONTRACT_NETWORK=xxx - put network of your choise
• export PRIVATE_KEY=xxx - put your private key
• npm run deploy:contract outputs smart contract address

Terraform

To provision AWS resources need to run the following steps:

• npm run build to compile TS files and create dist folder that will be deployed as AWS lambda function by terraform
• cd terraform
• export AWS_ACCESS_KEY_ID=xxx & export AWS_SECRET_ACCESS_KEY=xxx to give terraform access to AWS cloud
• terraform init to download providers and modules
• terraform plan to see which AWS resources will be created
• terraform apply to provision infrastructure

Technical details:

The lambda functions a built on the top on Nest.js framework and Typescript.