eth-tailz

Purely functional stream processing of Ethereum transaction Event Logs for nayms/contracts-v3, implemented in Scala with ZIO and web3j.

Build native image

Application can be built as a native binary executable, that does not require the JVM runtime. Run the following to produce the native binary:

sbt nativeImage

Native image descriptors are produced by running the app with an agent:

sbt nativeImageRunAgent

Executable binary eth-tailz will be available inside the target folder.

Run it by giving it a contract address and a block number from which to start streaming. For example, you can run:

./target/eth-tailz --forever --polling-interval 12 --chunk-size 10000 0x39e2f550fef9ee15b459d16bD4B243b04b1f60e5 17088059

Metals MCP server

This project ships with a .mcp.json that points Claude Code at a Metals MCP server on http://localhost:37765/mcp. Start it from the project root with:

metals-mcp --workspace . --client claude --port 37765

Then run /mcp in Claude Code to confirm the metals server connects. See Scala with Claude Code for more background.

Workaround GraalVM issues

Current version of this code works with Graal VM Java 21.

Sbt native image plugin uses Coursier to detect java. Make sure to have Graal VM installed via Coursier.

Make sure to set GRAAL_HOME environment variable pointing to a GraalVM installation folder.

You might also get the following error:

[error] Failed to automatically install native-image. To fix this problem, install native-image manually and start sbt with the environment variable 'NATIVE_IMAGE_INSTALLED=true'

In that case make sure to have NATIVE_IMAGE_INSTALLED environment variable set to true.