Developers' guide

NOTE: These instructions are for people who want to contribute Go source code changes. If you just want to run ethereum, use the normal Installation Instructions

This document is the entry point for developers of the Go implementation of Ethereum. Developers here refer to the hands-on: who are interested in build, develop, debug, submit a bug report or pull request or contribute code to go-ethereum.

Building and Testing

Go Environment

We assume that you have go v1.8 installed, and GOPATH is set.

Note:You must have your working copy under $GOPATH/src/github.com/ethereum/go-ethereum.

Since go does not use relative path for import, working in any other directory will have no effect, since the import paths will be appended to $GOPATH/src, and if the lib does not exist, the version at master HEAD will be downloaded.

Most likely you will be working from your fork of go-ethereum, let’s say from github.com/nirname/go-ethereum. Clone or move your fork into the right place:

git clone git@github.com:nirname/go-ethereum.git $GOPATH/src/github.com/ethereum/go-ethereum

Managing Vendored Dependencies

All other dependencies are tracked in the vendor/ directory. We use govendor to manage them.

If you want to add a new dependency, run govendor fetch <import-path>, then commit the result.

If you want to update all dependencies to their latest upstream version, run govendor fetch +v.

You can also use govendor to run certain commands on all go-ethereum packages, excluding vendored code. Example: to recreate all generated code, run govendor generate +l.

Building Executables

Switch to the go-ethereum repository root directory.

You can build all code using the go tool, placing the resulting binary in $GOPATH/bin.

go install -v ./...

go-ethereum exectuables can be built individually. To build just geth, use:

go install -v ./cmd/geth

Read about cross compilation of go-ethereum here.

Git flow

To make life easier try git flow it sets this all up and streamlines your work flow.

Testing

Testing one library:

go test -v -cpu 4 ./eth

Using options -cpu (number of cores allowed) and -v (logging even if no error) is recommended.

Testing only some methods:

go test -v -cpu 4 ./eth -run TestMethod

Note: here all tests with prefix TestMethod will be run, so if you got TestMethod, TestMethod1, then both!

Running benchmarks, eg.:

go test -v -cpu 4 -bench . -run BenchmarkJoin

for more see go test flags

Metrics and monitoring

geth can do node behaviour monitoring, aggregation and show performance metric charts. Read about metrics and monitoring

Getting Stack Traces

If geth is started with the --pprof option, a debugging HTTP server is made available on port 6060. You can bring up http://localhost:6060/debug/pprof to see the heap, running routines etc. By clicking full goroutine stack dump (clicking http://localhost:6060/debug/pprof/goroutine?debug=2) you can generate trace that is useful for debugging.

Note that if you run multiple instances of geth, this port will only work for the first instance that was launched. If you want to generate stacktraces for these other instances, you need to start them up choosing an alternative pprof port. Make sure you are redirecting stderr to a logfile.

geth -port=30300 -verbosity 5 --pprof --pprofport 6060 2>> /tmp/00.glog
geth -port=30301 -verbosity 5 --pprof --pprofport 6061 2>> /tmp/01.glog
geth -port=30302 -verbosity 5 --pprof --pprofport 6062 2>> /tmp/02.glog

Alternatively if you want to kill the clients (in case they hang or stalled syncing, etc) but have the stacktrace too, you can use the -QUIT signal with kill:

killall -QUIT geth

This will dump stack traces for each instance to their respective log file.

Contributing

Thank you for considering to help out with the source code! We welcome contributions from anyone on the internet, and are grateful for even the smallest of fixes!

GitHub is used to track issues and contribute code, suggestions, feature requests or documentation.

If you’d like to contribute to go-ethereum, please fork, fix, commit and send a pull request (PR) for the maintainers to review and merge into the main code base. If you wish to submit more complex changes though, please check up with the core devs first on our gitter channel to ensure those changes are in line with the general philosophy of the project and/or get some early feedback which can make both your efforts much lighter as well as our review and merge procedures quick and simple.

PRs need to be based on and opened against the master branch (unless by explicit agreement, you contribute to a complex feature branch).

Your PR will be reviewed according to the Code Review Guidelines.

We encourage a PR early approach, meaning you create the PR the earliest even without the fix/feature. This will let core devs and other volunteers know you picked up an issue. These early PRs should indicate ‘in progress’ status.

Dev Tutorials (mostly outdated)