Is their any way to get current value of a0 parameter from node. The parameters are not found in configuration file. These are not passed as parameter when the node is started.
You can get the protocol parameters using cardano-cli:
$ cardano-cli query protocol-parameters --mary-era --mainnet
{
"poolDeposit": 500000000,
"protocolVersion": {
"minor": 0,
"major": 4
},
"minUTxOValue": 1000000,
"decentralisationParam": 0.12,
"maxTxSize": 16384,
"minPoolCost": 340000000,
"minFeeA": 44,
"maxBlockBodySize": 65536,
"minFeeB": 155381,
"eMax": 18,
"extraEntropy": {
"tag": "NeutralNonce"
},
"maxBlockHeaderSize": 1100,
"keyDeposit": 2000000,
"nOpt": 500,
"rho": 3.0e-3,
"tau": 0.2,
"a0": 0.3
}
a0 is the last key in the above output.