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

fn main() -> anyhow::Result<()> {
    near_lake_framework::LakeBuilder::default()
        .testnet()
        .start_block_height(112205773)
        .build()?
        .run(handle_block)?;
    Ok(())
}

// The handler function to take the `Block`
// and print the block height
async fn handle_block(
    block: near_lake_primitives::block::Block,
) -> anyhow::Result<()> {
    eprintln!(
        "Block #{}",
        block.block_height(),
    );
#    Ok(())
}

Pass the context to the function

#[derive(near_lake_framework::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 handle_block(
    block: near_lake_primitives::block::Block,
    context: &MyContext,
) -> anyhow::Result<()> {
    eprintln!(
        "Block #{} / {}",
        block.block_height(),
        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.

use near_lake_framework::near_lake_primitives;
use near_lake_primitives::CryptoHash;
use near_lake_parent_transaction_cache::{ParentTransactionCache, ParentTransactionCacheBuilder};
use near_lake_primitives::actions::ActionMetaDataExt;

fn main() -> anyhow::Result<()> {
    let parent_transaction_cache_ctx = ParentTransactionCacheBuilder::default()
        .build()?;
    // Lake Framework start boilerplate
    near_lake_framework::LakeBuilder::default()
        .mainnet()
        .start_block_height(88444526)
        .build()?
        // developer-defined async function that handles each block
        .run_with_context(print_function_call_tx_hash, &parent_transaction_cache_ctx)?;
    Ok(())
}

async fn print_function_call_tx_hash(
    mut block: near_lake_primitives::block::Block,
    ctx: &ParentTransactionCache,
) -> anyhow::Result<()> {
    // Cache has been updated before this function is called.
    let block_height = block.block_height();
    let actions: Vec<(
        &near_lake_primitives::actions::FunctionCall,
        Option<CryptoHash>,
    )> = block
        .actions()
        .filter_map(|action| action.as_function_call())
        .map(|action| {
            (
                action,
                ctx.get_parent_transaction_hash(&action.receipt_id()),
            )
        })
        .collect();

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

    Ok(())
}

Tutorials:

• https://youtu.be/GsF7I93K-EQ
• Migrating to NEAR Lake Framework from NEAR Indexer Framework

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:

• https://github.com/near-examples/near-lake-raw-printer simple example of a data printer built on top of NEAR Lake Framework

• https://github.com/near-examples/near-lake-accounts-watcher another simple example of the indexer built on top of NEAR Lake Framework for a tutorial purpose

• https://github.com/near-examples/indexer-tx-watcher-example-lake an example of the indexer built on top of NEAR Lake Framework that watches for transactions related to specified account(s)

• https://github.com/octopus-network/octopus-near-indexer-s3 a community-made project that uses NEAR Lake Framework

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

use near_lake_framework::LakeBuilder;

# fn main() {
let credentials = aws_credential_types::Credentials::new(
    "AKIAIOSFODNN7EXAMPLE",
    "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY",
    None,
    None,
    "custom_credentials",
);
let s3_config = aws_sdk_s3::Config::builder()
    .credentials_provider(credentials)
    .build();

let lake = LakeBuilder::default()
    .s3_config(s3_config)
    .s3_bucket_name("near-lake-data-custom")
    .s3_region_name("eu-central-1")
    .start_block_height(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

[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:

$ 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

...
[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

• run minio

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

• pass custom aws_sdk_s3::config::Config to the [LakeBuilder]

use near_lake_framework::LakeBuilder;

# #[tokio::main]
# async fn main() -> anyhow::Result<()> {
    let aws_config = aws_config::from_env().load().await;
    let s3_config = aws_sdk_s3::config::Builder::from(&aws_types::SdkConfig::from(aws_config))
        .endpoint_url("http://0.0.0.0:9000")
        .build();

    LakeBuilder::default()
        .s3_bucket_name("near-lake-custom")
        .s3_region_name("eu-central-1")
        .start_block_height(0)
        .s3_config(s3_config)
        .build()
        .expect("Failed to build Lake");

#    Ok(())
# }

Configuration

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

Available parameters:

• start_block_height(value: u64) - block height to start the stream from
• optional s3_bucket_name(value: impl Into<String>) - provide the AWS S3 bucket name (you need to provide it if you use custom S3-compatible service, otherwise you can use [LakeConfigBuilder::mainnet] and [LakeConfigBuilder::testnet])
• optional LakeConfigBuilder::s3_region_name(value: impl Into<String>) - provide the AWS S3 region name (if you need to set a custom one)
• optional LakeConfigBuilder::s3_config(value: aws_sdk_s3::config::Config - provide custom AWS SDK S3 Config

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

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

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):

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:

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:

• MVP
• 0.8 High-level update
• 1.0