ERA file support

[philknows]

Problem description

As Ethereum moves towards a world where historical information over 1 year is purged on nodes that don't really need it, support has been gaining around ERA files .e2s to store and redistribute execution, but also beacon chain history and state. We should be able to support integrating this data structure format in Lodestar.

Solution description

The solution is not as straight forward, but we can work towards how we can approach supporting these files.

• How do we integrate them?
• If we can parse them, what do we do with them?
• If we can generate .e2s files, when do we create them and how does that affect our database?

As of today, no specification has been proposed about how to integrate an endpoint for supporting this feature.

Additional context

Implementation of e2store files by Nimbus: https://github.com/status-im/nimbus-eth2/blob/stable/docs/e2store.md
EthResearch Post: https://ethresear.ch/t/era-archival-files-for-block-and-consensus-data/13526
Ultralight (Portal Network) integration: ethereumjs/ultralight#613

[philknows]

Requirements (do we want to do these?):

• Tool to create an .era file
• Being able to configure the BN to point to a dir with the era files and use them for historical state type tasks.
• There are multiple points in the BN to regenerate the data files: Once every period after the period finalizes. Or after X months (after the block data availability period is over during prune).