[Feature] minimum commission rate upgrade

[yun-yeo]

Summary of changes

This PR is still under consensus and need governance proposal to be reflected on chain.

What're Changed

• Add upgrade handler to make validators commission to bigger than minimum rate (= initially 5%)
• Implement ante handler to check whether MsgCreateValidator and MsgEditValidator's commission rate is bigger than minimum rate (= initially 5%)
• New parameter is introduced ante.MinimumCommissionEnforced.
• New ante store value is introduced MinimumCommission.
• New gRPC endpoint /terra/ante/v2/params introduced.
• New gRPC endpoint /terra/ante/v2/minimum_commission introduced.
• New cmd terrad query ante params introduced.
• New cmd terrad query ante minimum-commission introduced.
• New proposal /terra.ante.v2.MinimumCommissionUpdateProposal added
  • This proposal will check and update validator commissions, whose commission rate little than the given proposal value.
• New proposal creation cmd terrad tx gov submit-proposal minimum-commission-update

{
  ...
  "content": {
    "@type": "/terra.ante.v2.MinimumCommissionUpdateProposal",
    "title": "minimum commission update",
    "description": "minimum commission update desc",
    "minimum_commission": "0.030000000000000000"
  },
  ...
}

Default ante.Params

// Ante params default values
const (
	// DefaultMinimumCommissionEnforced minimum commission Enforced flag
	DefaultMinimumCommissionEnforced bool = true
)

Default ante.GenesisState

// Ante params default values
var (
	// Default minimum commission rate
	DefaultMinimumCommission sdk.Dec = sdk.NewDecWithPrec(10, 2) // 10%
)

[codecov-commenter]

Codecov Report

Merging #47 (c66baa0) into main (5a3cd66) will decrease coverage by 2.86%.
The diff coverage is 61.45%.

@@            Coverage Diff             @@
##             main      #47      +/-   ##
==========================================
- Coverage   73.70%   70.84%   -2.87%     
==========================================
  Files           7       17      +10     
  Lines         658      830     +172     
==========================================
+ Hits          485      588     +103     
- Misses        148      209      +61     
- Partials       25       33       +8     

Impacted Files	Coverage Δ
app/ante/proposal_handler.go	0.00% <0.00%> (ø)
app/ante/types/codec.go	0.00% <0.00%> (ø)
app/upgrade.go	0.00% <0.00%> (ø)
app/ante/types/proposal.go	14.28% <14.28%> (ø)
app/ante/types/params.go	41.17% <41.17%> (ø)
app/ante/types/genesis.go	75.00% <75.00%> (ø)
app/app.go	88.40% <75.75%> (-1.29%)	⬇️
app/ante/min_commission.go	89.47% <89.47%> (ø)
app/ante/ante.go	71.42% <100.00%> (+1.05%)	⬆️
app/ante/keeper/grpc_querier.go	100.00% <100.00%> (ø)
... and 2 more

[dylanschultzie]

Nice job, looks like you covered all the cases:

1. if val_commission < minimum, upgrade it
2. don't allow val to create at under minimum
3. don't allow val to edit to below minimum
4. DO allow to edit above minimum
5. DO allow to create above minimum

The only case I see missing is creating with the minimum commission.

[AutoStake-com]

Nice job, looks like you covered all the cases:

1. if val_commission < minimum, upgrade it
2. don't allow val to create at under minimum
3. don't allow val to edit to below minimum
4. DO allow to edit above minimum
5. DO allow to create above minimum

The only case I see missing is creating with the minimum commission.

Just seen this PR; nice!
Think these switch case statements will handle new validator creation messages
https://github.com/terra-money/core/pull/47/files#diff-e3bd85f729e3ebf3e9b2bb00eba3d579a0e53d80cc8a4750151279c9041ee81cR39

[JSHan94]

fmt.Sprintf("commission can't be lower than %s%%", minimumCommission.String()),

it shows 0.1%, % should be removed

[JSHan94]

10%, not 5%