Deploying Your Precompile

We made it! Everything works in our Ginkgo tests, and now we want to spin up a local network with the Hello World precompile activated.

Start the server in a terminal in a new tab using avalanche-network-runner. Please check out this link for more information on Avalanche Network Runner, how to download it, and how to use it. The server will be in "listening" mode waiting for API calls.

We will start the server from the Subnet-EVM directory so that we can use a relative file path to the genesis JSON file:

cd $GOPATH/src/github.com/ava-labs/subnet-evm

Then run ANR:

avalanche-network-runner server \
--log-level debug \
--port=":8080" \
--grpc-gateway-port=":8081"

Since we already compiled AvalancheGo and Subnet-EVM/Precompile-EVM in a previous step, we should have the AvalancheGo and Subnet-EVM binaries ready to go.

We can now set the following paths. AVALANCHEGO_EXEC_PATH points to the latest AvalancheGo binary we have just built. AVALANCHEGO_PLUGIN_PATH points to the plugins path which should have the Subnet-EVM binary we have just built:

export AVALANCHEGO_EXEC_PATH="${GOPATH}/src/github.com/ava-labs/avalanchego/build/avalanchego"
export AVALANCHEGO_PLUGIN_PATH="${GOPATH}/src/github.com/ava-labs/avalanchego/build/plugins"

The following command will "issue requests" to the server we just spun up. We can use avalanche-network-runner to spin up some nodes that run the latest version of Subnet-EVM:

  avalanche-network-runner control start \
  --log-level debug \
  --endpoint="0.0.0.0:8080" \
  --number-of-nodes=5 \
  --avalanchego-path ${AVALANCHEGO_EXEC_PATH} \
  --plugin-dir ${AVALANCHEGO_PLUGIN_PATH} \
  --blockchain-specs '[{"vm_name": "subnetevm", "genesis": "./tests/precompile/genesis/hello_world.json"}]'

We can look at the server terminal tab and see it booting up the local network. If the network startup is successful then you should see something like this:

[blockchain RPC for "srEXiWaHuhNyGwPUi444Tu47ZEDwxTWrbQiuD7FmgSAQ6X7Dy"] "http://127.0.0.1:9650/ext/bc/2jDWMrF9yKK8gZfJaaaSfACKeMasiNgHmuZip5mWxUfhKaYoEU"
[blockchain RPC for "srEXiWaHuhNyGwPUi444Tu47ZEDwxTWrbQiuD7FmgSAQ6X7Dy"] "http://127.0.0.1:9652/ext/bc/2jDWMrF9yKK8gZfJaaaSfACKeMasiNgHmuZip5mWxUfhKaYoEU"
[blockchain RPC for "srEXiWaHuhNyGwPUi444Tu47ZEDwxTWrbQiuD7FmgSAQ6X7Dy"] "http://127.0.0.1:9654/ext/bc/2jDWMrF9yKK8gZfJaaaSfACKeMasiNgHmuZip5mWxUfhKaYoEU"
[blockchain RPC for "srEXiWaHuhNyGwPUi444Tu47ZEDwxTWrbQiuD7FmgSAQ6X7Dy"] "http://127.0.0.1:9656/ext/bc/2jDWMrF9yKK8gZfJaaaSfACKeMasiNgHmuZip5mWxUfhKaYoEU"
[blockchain RPC for "srEXiWaHuhNyGwPUi444Tu47ZEDwxTWrbQiuD7FmgSAQ6X7Dy"] "http://127.0.0.1:9658/ext/bc/2jDWMrF9yKK8gZfJaaaSfACKeMasiNgHmuZip5mWxUfhKaYoEU"

This shows the extension to the API server on AvalancheGo that's specific to the Subnet-EVM Blockchain instance. To interact with it, you will want to append the /rpc extension, which will supply the standard Ethereum API calls.

For example, you can use the RPC URL: http://127.0.0.1:9650/ext/bc/2jDWMrF9yKK8gZfJaaaSfACKeMasiNgHmuZip5mWxUfhKaYoEU/rpc

Maintenance

You should always keep your fork up to date with the latest changes in the official Subnet-EVM repo. If you have forked the Subnet-EVM repo, there could be conflicts and you may need to manually resolve them.

If you used Precompile-EVM, you can update your repo by bumping Subnet-EVM versions in go.mod and version.sh

Conclusion

We have now created a stateful precompile from scratch with the precompile generation tool. We hope you had fun and learned a little more about the Subnet-EVM. Now that you have created a simple stateful precompile, we urge you to create one of your own.

If you have an idea for a stateful precompile that may be useful to the community, feel free to create a fork of Subnet-EVM and create a pull request.