Gas price cannot be set to 0 with miner.gasprice option set to 0

[XDitto0165]

System information

Geth
Version: 1.10.25-stable
Git Commit: 69568c5
Architecture: amd64
Go Version: go1.18.5
Operating System: linux

Expected behaviour

The geth was started with the option miner.gasprice set to 0:
geth --datadir /data2 --nodiscover --networkid 5291592 --netrestrict 10.32.80.0/27 --allow-insecure-unlock --unlock 0x879769d76BEad81e23aDBdd993Ca37872b0e6aa4 --mine --password /data/password.txt --http --http.addr="127.0.0.1" --http.api="eth,web3,net,admin,personal,miner" --http.corsdomain="*" --miner.gasprice 0 --port 30310 --http.port 8555
When run the following command to check gas price:

curl -X POST localhost:8555 -H "Content-Type: application/json" --data '
> {
> "jsonrpc": "2.0",
> "method": "eth_gasPrice",
> "params": [],
> "id": 1
> }
> '

It should return 0 gas price:

{"jsonrpc":"2.0","id":1,"result":"0x0"}

Actual behaviour

When run the following command to check gas price:

curl -X POST localhost:8555 -H "Content-Type: application/json" --data '
> {
> "jsonrpc": "2.0",
> "method": "eth_gasPrice",
> "params": [],
> "id": 1
> }
> '

It returns the default value of 1 trillion gas price

{"jsonrpc":"2.0","id":1,"result":"0x3b9aca00"}

[holiman]

I think eth_gasPrice returns the oracle gas price, as in the price in the latest blocks. So it only indirectly maps to miner.gasprice.

[fjl]

The gas price oracle will ignore transactions below the price configured by --gpo.ignoreprice, and the default value of that option is slightly above zero. You can try setting this to zero, but I'm not sure whether that will make it suggest a price of zero.

In general, the gas price oracle is not designed to work well in an environment where transactions can be submitted with zero fee.

[karalabe]

You cannot set the miner.gasPrice to 0, if you try, you'll see a warning in the logs:

WARN [12-01|11:51:18.506] Sanitizing invalid miner gas price       provided=0    updated=1,000,000,000

Geth explicitly does not allow this because accepting 0 priced transactions would mean that you also accept/pool them from the network and propagate them, which is essentially a very potent DoS vector (I can send arbitrary junk tx from arbitrary non-existing account since there's no cost).

[Inderdeep01]

Hey, I want to set up private network with zero gas price. Please help me with that.

[sirajongithub]

Hello, In the latest geth version 1.12, I am unable to set and use gas price as zero (--miner.gasprice 0). I was able to set and use gas price to 0 until geth version 1.10.15

If I have geth private blockchain network and I don't want to charge anything for any transaction I would set gas price to 0. Is this feature removed in geth version 1.12 ?

https://github.com/SirajChaudhary/setup-a-private-ethereum-blockchain-multinodes-network

[bradbrown-gtmn]

I also noticed that this seemed to stop working recently. I've used geth's private clique networks to test contract behavior as recently as 5 months ago using 0-gas transactions and I can no longer do this. What gives?

[rmlearney-digicatapult]

@GTMN-bradbrown we solved this by setting:

baseFeePerGas: 0x1 in genesis.json

and adding the following switch at startup time:

--gpo.ignoreprice 0

This sets a gas price of 2. While not zero, it's a decent workaround.