Go-ethereum: Documentation on testnet and genesis might be broken

[lethalman]

System information

Geth
Version: 1.7.2-unstable
Git Commit: 41b77455296526c249abdf812e17f449e7f362e4
Architecture: amd64
Protocol Versions: [63 62]
Network Id: 1
Go Version: go1.9.1
Operating System: linux
GOPATH=
GOROOT=/usr/local/go

Expected behaviour

Launching the command here to initialize the genesis block should not fail: http://www.ethdocs.org/en/latest/network/test-networks.html#launching-geth

build/bin/geth --identity "testnode" --datadir "$HOME/.etest" --nodiscover --maxpeers 0 --networkid 1999 init genesis.json

Actual behaviour

It fails with:

Fatal: invalid genesis file: json: cannot unmarshal hex string of odd length into Go struct field Genesis.extraData of type hexutil.Bytes

Then I empty the extraData field and I get this other output:

WARN [10-14|01:06:34] No etherbase set and no accounts found as default 
INFO [10-14|01:06:34] Allocated cache and file handles         database=/somewhere cache=16 handles=16
Fatal: Failed to write genesis block: genesis has no chain configuration

Steps to reproduce the behaviour

Create a genesis.json as per http://www.ethdocs.org/en/latest/network/test-networks.html#launching-geth :

{
    "nonce": "0x0000000000000042",     
    "timestamp": "0x0",
    "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "extraData": "0x0",     
    "gasLimit": "0x8000000",     
    "difficulty": "0x400",
    "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "coinbase": "0x3333333333333333333333333333333333333333",     
    "alloc": {}
}

Then run:

build/bin/geth --identity "testnode" --datadir "$HOME/.etest" --nodiscover --maxpeers 0 --networkid 1999 init genesis.json

Testing issue

I've noticed that the genesis_test.go calls geth init but doesn't check for the status code to be zero. This means the test passed even though it should have failed.

Code reference: https://github.com/ethereum/go-ethereum/blob/master/cmd/geth/genesis_test.go#L33

In fact the output of build/env.sh go test github.com/ethereum/go-ethereum/cmd/geth -run TestCustomGenesis -v is:

=== RUN   TestCustomGenesis
--- PASS: TestCustomGenesis (1.18s)
    test_cmd.go:231: (stderr) WARN [10-14|01:10:00] No etherbase set and no accounts found as default 
    test_cmd.go:231: (stderr) INFO [10-14|01:10:00] Allocated cache and file handles         database=/tmp/geth-test598189369/geth/chaindata cache=16 handles=16
    test_cmd.go:231: (stderr) Fatal: Failed to write genesis block: genesis has no chain configuration
[...]
PASS

Contributing

I'm willing to contribute. All I need to know is:

1. Should the documentation be fixed to have extraData empty
2. Should geth init ignore the fact that there's no config key in the genesis?

[chinmoy159]

try using the following text as the genesis.json

{
"nonce": "0x0000000000000042",
"timestamp": "0x0",
"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"extraData": "0x",
"gasLimit": "0x8000000",
"difficulty": "0x400",
"config": {},
"mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"coinbase": "0x3333333333333333333333333333333333333333", "alloc": { }

}

obviously, don't put the dashes !!

the extraData part can be either empty or set to "0x"
to eliminate the second error, I added the part :-
"config": {}
that's all,
try this, it should work

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.