NEAR Lake Framework

NEAR Lake Framework is a small library companion to NEAR Lake. It allows you to build your own indexer that subscribes to the stream of blocks from the NEAR Lake data source and create your own logic to process the NEAR Protocol data.

Example

```norun fn main() -> anyhow::Result<()> { nearlakeframework::LakeBuilder::default() .testnet() .startblockheight(112205773) .build()? .run(handleblock)?; Ok(()) }

// The handler function to take the Block // and print the block height async fn handleblock( block: nearlakeprimitives::block::Block, ) -> anyhow::Result<()> { eprintln!( "Block #{}", block.blockheight(), );

Ok(())

} ```

Pass the context to the function

```no_run

[derive(nearlakeframework::LakeContext)]

struct MyContext { my_field: String }

fn main() -> anyhow::Result<()> {

let context = MyContext {
    my_field: "My value".to_string(),
};

near_lake_framework::LakeBuilder::default()
    .testnet()
    .start_block_height(112205773)
    .build()?
    .run_with_context(handle_block, &context)?;

Ok(())

}

// The handler function to take the Block // and print the block height async fn handleblock( block: nearlakeprimitives::block::Block, context: &MyContext, ) -> anyhow::Result<()> { eprintln!( "Block #{} / {}", block.blockheight(), context.my_field, );

Ok(())

} ```

Parent Transaction for the Receipt Context

It is an old problem that the NEAR Protocol doesn't provide the parent transaction hash in the receipt. This is a problem for the indexer that needs to know the parent transaction hash to build the transaction tree. We've got you covered with the lake-parent-transaction-cache crate that provides a cache for the parent transaction hashes.

```norun use nearlakeframework::nearlakeprimitives; use nearlakeprimitives::CryptoHash; use lakeparenttransactioncache::{ParentTransactionCache, ParentTransactionCacheBuilder}; use nearlakeprimitives::actions::ActionMetaDataExt;

fn main() -> anyhow::Result<()> { let parenttransactioncachectx = ParentTransactionCacheBuilder::default() .build()?; // Lake Framework start boilerplate nearlakeframework::LakeBuilder::default() .mainnet() .startblockheight(88444526) .build()? // developer-defined async function that handles each block .runwithcontext(printfunctioncalltxhash, &parenttransactioncachectx)?; Ok(()) }

async fn printfunctioncalltxhash( mut block: nearlakeprimitives::block::Block, ctx: &ParentTransactionCache, ) -> anyhow::Result<()> { // Cache has been updated before this function is called. let blockheight = block.blockheight(); let actions: Vec<( &nearlakeprimitives::actions::FunctionCall, Option, )> = block .actions() .filtermap(|action| action.asfunctioncall()) .map(|action| { ( action, ctx.getparenttransactionhash(&action.receipt_id()), ) }) .collect();

if !actions.is_empty() {
    // Here's the usage of the context.
    println!("Block #{:?}\n{:#?}", block_height, actions);
}

Ok(())

} ```

Tutorials:

More examples

You might want to have a look at the always up-to-date examples in examples folder.

Other examples that we try to keep up-to-date but we might fail sometimes:

How to use

AWS S3 Credentials

In order to be able to get objects from the AWS S3 bucket you need to provide the AWS credentials.

Passing credentials to the config builder

```rust use nearlakeframework::LakeBuilder;

fn main() {

let credentials = awscredentialtypes::Credentials::new( "AKIAIOSFODNN7EXAMPLE", "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY", None, None, "customcredentials", ); let s3config = awssdks3::Config::builder() .credentials_provider(credentials) .build();

let lake = LakeBuilder::default() .s3config(s3config) .s3bucketname("near-lake-data-custom") .s3regionname("eu-central-1") .startblockheight(1) .build() .expect("Failed to build LakeConfig");

}

```

You should never hardcode your credentials, it is insecure. Use the described method to pass the credentials you read from CLI arguments

File-based AWS credentials

AWS default profile configuration with aws configure looks similar to the following:

~/.aws/credentials text [default] aws_access_key_id=AKIAIOSFODNN7EXAMPLE aws_secret_access_key=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY

AWS docs: Configuration and credential file settings

Environmental variables

Alternatively, you can provide your AWS credentials via environment variables with constant names:

text $ export AWS_ACCESS_KEY_ID=AKIAIOSFODNN7EXAMPLE $ AWS_SECRET_ACCESS_KEY=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY $ AWS_DEFAULT_REGION=eu-central-1

Dependencies

Add the following dependencies to your Cargo.toml

```toml ... [dependencies] futures = "0.3.5" itertools = "0.10.3" tokio = { version = "1.1", features = ["sync", "time", "macros", "rt-multi-thread"] } tokio-stream = { version = "0.1" }

NEAR Lake Framework

near-lake-framework = "0.8.0" ```

Custom S3 storage

In case you want to run your own near-lake instance and store data in some S3 compatible storage (Minio or Localstack as example) You can owerride default S3 API endpoint by using s3_endpoint option

bash $ mkdir -p /data/near-lake-custom && minio server /data

``` use nearlakeframework::LakeBuilder;

#[tokio::main]

async fn main() {

let awsconfig = awsconfig::fromenv().load().await; let mut s3conf = awssdks3::config::Builder::from(&awsconfig) .endpointurl("http://0.0.0.0:9000") .build();

let lake = LakeBuilder::default() .s3config(s3conf) .s3bucketname("near-lake-data-custom") .s3regionname("eu-central-1") .startblockheight(1) .build() .expect("Failed to build LakeConfig");

}

```

Configuration

Everything should be configured before the start of your indexer application via LakeConfigBuilder struct.

Available parameters:

Cost estimates (Updated Mar 10, 2022 with more precise calculations)

TL;DR approximately $20 per month (for AWS S3 access, paid directly to AWS) for the reading of fresh blocks

Historical indexing

| Blocks | GET | LIST | Subtotal GET | Subtotal LIST | Total $ | |---|---|---|---|---|---| | 1000 | 5000 | 4 | 0.00215 | 0.0000216 | $0.00 | | 86,400 | 432000 | 345.6 | 0.18576 | 0.00186624 | $0.19 | | 2,592,000 | 12960000 | 10368 | 5.5728 | 0.0559872 | $5.63 | | 77,021,059 | 385105295 | 308084.236 | 165.5952769 | 1.663654874 | $167.26 |

Note: ~77m of blocks is the number of blocks on the moment I was calculating.

84,400 blocks is approximate number of blocks per day (1 block per second * 60 seconds * 60 minutes * 24 hours)

2,592,000 blocks is approximate number of blocks per months (86,400 blocks per day * 30 days)

Tip of the network indexing

| Blocks | GET | LIST | Subtotal GET | Subtotal LIST | Total $ | |---|---|---|---|---|---| | 1000 | 5000 | 1000 | 0.00215 | 0.0054 | $0.01 | | 86,400 | 432000 | 86,400 | 0.18576 | 0.46656 | $0.65 | | 2,592,000 | 12960000 | 2,592,000 | 5.5728 | 13.9968 | $19.57 | | 77,021,059 | 385105295 | 77,021,059 | 165.5952769 | 415.9137186 | $581.51 |

Explanation:

Assuming NEAR Protocol produces accurately 1 block per second (which is really not, the average block production time is 1.3s). A full day consists of 86400 seconds, that's the max number of blocks that can be produced.

According to the Amazon S3 prices list requests are charged for $0.0054 per 1000 requests and get is charged for $0.00043 per 1000 requests.

Calculations (assuming we are following the tip of the network all the time):

text 86400 blocks per day * 5 requests for each block / 1000 requests * $0.0004 per 1k requests = $0.19 * 30 days = $5.7 Note: 5 requests for each block means we have 4 shards (1 file for common block data and 4 separate files for each shard)

And a number of list requests we need to perform for 30 days:

```text 86400 blocks per day / 1000 requests * $0.005 per 1k list requests = $0.47 * 30 days = $14.1

$5.7 + $14.1 = $19.8 ```

The price depends on the number of shards

Future plans

We use Milestones with clearly defined acceptance criteria: