Simple GraphQL API for blocks from Bitcoin's blockchain

• Built with Apollo and REST Data Sources
• Uses Blockchain.com Explorer API

Hosted example: https://blocks-graphql-api.herokuapp.com/

Screen Shot 2020年12月02日 at 23 55 48

• For caching in this project optimal setup would be Cache Aside strategy with LRU policy
• Caching can be implemented at two levels in Apollo - GraphQL level and Data Fetching level
  • In this project GraphQL resources caching is used (as described in documentation)
  • Also, caching together with requests deduplication is implemented in Data Sources itself (as described in this post)
  • Cache population on start is not implemented for the simplicity reason
• For production setup I would have a separate instance with Redis or Memcached
  • To implement a single cache layer for multiple web server node instances
• For development setup I just used a simple built-in caching instruments from Apollo

• Now used simple winston console logger
• In a real-world environment logs should be written into files and rotated

• Build and run scripts are not fully production-ready, they are not properly optimized
• Lots of things like proper validation are simplified
• No logging implemented at the moment
• It's still pretty naive implementation of blockchain-like API

Query examples:

{
 blocks(date: "2020年11月29日", offset: 0, limit: 10) {
 total
 blocks {
 height
 hash
 time 
 }
 }
 
 block(hash: "0000000000000000000ca70f82b7fa348ddb5d00ed9526ed40a7ccf85e5b18e4") {
 hash
 ver
 fee
 prev_block
 mrkl_root
 time
 bits
 block_index
 height
 weight
 main_chain
 n_tx
 nonce
 size
 }
 
 transactions(hash: "0000000000000000000ca70f82b7fa348ddb5d00ed9526ed40a7ccf85e5b18e4", offset: 0, limit: 10) {
 total
 transactions {
 fee
 hash
 inputs {
 index
 prev_out {
 addr
 value
 }
 }
 lock_time
 out {
 addr
 value
 }
 size
 time
 tx_index
 weight
 }
 }
}