Feat/chaincmd dumpgenesis

[meowsbits]

I have a hard time believing this doesn't already exist... although I could not find it anywhere. @soc1c where/how do you make the configs like https://github.com/etclabscore/mordor/blob/master/mgeth.json ?

If it in fact this command (or an equivalent) doesn't already exist, then we should make this PR to ETH.

• Write genesis JSON config to stdout.

Use:

$ ./build/bin/geth --classic dumpgenesis 2>/dev/null | jj config -p
{
  "chainId": 61,
  "homesteadBlock": 1150000,
  "eip7FBlock": null,
  "daoForkBlock": 1920000,
  "eip150Block": 2500000,
  "eip150Hash": "0xca12c63534f565899681965528d536c52cb05b7c48e269c2a6cb77ad864d878a",
  "eip155Block": 3000000,
  "eip158Block": 8772000,
  "eip160Block": 3000000,
  "byzantiumBlock": 8772000,
  "ecip1010PauseBlock": 3000000,
  "ecip1010Length": 2000000,
  "ecip1017EraRounds": 5000000,
  "disposalBlock": 5900000,
  "ethash": {},
  "trustedCheckpoint": null,
  "trustedCheckpointOracle": null
}

[tzdybal]

LGTM (except one typo)

[tzdybal]

Suggested change

	utils.Fatalf("could not encode defaulty genesis")
	utils.Fatalf("could not encode default genesis")

[meowsbits]

I made default into an adjective because there are more than one 'default' genes_es_ available... so 'could not encode default genesis' implies that it failed to encode the genesis, while in fact it failed with all/any of them...

EDIT
...so 'could not encode a default genesis' would be maybe a better way of saying this...

[tzdybal]

LGTM

[soc1c]

Jupp, @meowsbits, this was a unique feature for geth classic. I manually crafted the spec you linked above.

I'm supporting this PR but would also encourage to move forward with actual chain specs just like parity or classic geth do.

[meowsbits]

Made upstream, ethereum/go-ethereum#20191