refactor: Use config in gov keeper (#11093)

## Description

ref: https://github.com/cosmos/cosmos-sdk/pull/11034#discussion_r797461320



---

### Author Checklist

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please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

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your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

CHANGELOG.md

@@ -119,7 +119,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [\#10748](https://github.com/cosmos/cosmos-sdk/pull/10748) Move legacy `x/gov` api to `v1beta1` directory.
 * [\#10816](https://github.com/cosmos/cosmos-sdk/pull/10816) Reuse blocked addresses from the bank module. No need to pass them to distribution. 
 * [\#10852](https://github.com/cosmos/cosmos-sdk/pull/10852) Move `x/gov/types` to `x/gov/types/v1beta2`.
-* [\#10868](https://github.com/cosmos/cosmos-sdk/pull/10868), [\#10989](https://github.com/cosmos/cosmos-sdk/pull/10989) The Gov keeper accepts now 2 more mandatory arguments, the ServiceMsgRouter and a maximum proposal metadata length.
+* [\#10868](https://github.com/cosmos/cosmos-sdk/pull/10868), [\#10989](https://github.com/cosmos/cosmos-sdk/pull/10989), [\#11093](https://github.com/cosmos/cosmos-sdk/pull/11093) The Gov keeper accepts now 2 more mandatory arguments, the ServiceMsgRouter and a gov Config including the max metadata length.
 
 ### Client Breaking Changes
 

simapp/app.go

@@ -302,10 +302,14 @@ func NewSimApp(
 		AddRoute(paramproposal.RouterKey, params.NewParamChangeProposalHandler(app.ParamsKeeper)).
 		AddRoute(distrtypes.RouterKey, distr.NewCommunityPoolSpendProposalHandler(app.DistrKeeper)).
 		AddRoute(upgradetypes.RouterKey, upgrade.NewSoftwareUpgradeProposalHandler(app.UpgradeKeeper))
-	govMaxMetadataLen := uint64(10000)
+	govConfig := govtypes.DefaultConfig()
+	/*
+		Example of setting gov params:
+		govConfig.MaxMetadataLen = 10000
+	*/
 	govKeeper := govkeeper.NewKeeper(
 		appCodec, keys[govtypes.StoreKey], app.GetSubspace(govtypes.ModuleName), app.AccountKeeper, app.BankKeeper,
-		&stakingKeeper, govRouter, app.msgSvcRouter, govMaxMetadataLen,
+		&stakingKeeper, govRouter, app.msgSvcRouter, govConfig,
 	)
 
 	app.GovKeeper = *govKeeper.SetHooks(

x/gov/keeper/keeper.go

@@ -42,8 +42,7 @@ type Keeper struct {
 	// Msg server router
 	router *middleware.MsgServiceRouter
 
-	// maxMetadataLen defines the maximum proposal metadata length.
-	maxMetadataLen uint64
+	config types.Config
 }
 
 // NewKeeper returns a governance keeper. It handles:
@@ -57,7 +56,7 @@ func NewKeeper(
 	cdc codec.BinaryCodec, key storetypes.StoreKey, paramSpace types.ParamSubspace,
 	authKeeper types.AccountKeeper, bankKeeper types.BankKeeper, sk types.StakingKeeper,
 	legacyRouter v1beta1.Router, router *middleware.MsgServiceRouter,
-	maxMetadataLen uint64,
+	config types.Config,
 ) Keeper {
 
 	// ensure governance module account is set
@@ -70,16 +69,21 @@ func NewKeeper(
 	// could create invalid or non-deterministic behavior.
 	legacyRouter.Seal()
 
+	// If MaxMetadataLen not set by app developer, set to default value.
+	if config.MaxMetadataLen == 0 {
+		config.MaxMetadataLen = types.DefaultConfig().MaxMetadataLen
+	}
+
 	return Keeper{
-		storeKey:       key,
-		paramSpace:     paramSpace,
-		authKeeper:     authKeeper,
-		bankKeeper:     bankKeeper,
-		sk:             sk,
-		cdc:            cdc,
-		legacyRouter:   legacyRouter,
-		router:         router,
-		maxMetadataLen: maxMetadataLen,
+		storeKey:     key,
+		paramSpace:   paramSpace,
+		authKeeper:   authKeeper,
+		bankKeeper:   bankKeeper,
+		sk:           sk,
+		cdc:          cdc,
+		legacyRouter: legacyRouter,
+		router:       router,
+		config:       config,
 	}
 }
 

x/gov/keeper/proposal.go

@@ -12,7 +12,7 @@ import (
 
 // SubmitProposal create new proposal given an array of messages
 func (keeper Keeper) SubmitProposal(ctx sdk.Context, messages []sdk.Msg, metadata []byte) (v1beta2.Proposal, error) {
-	if metadata != nil && len(metadata) > int(keeper.maxMetadataLen) {
+	if metadata != nil && uint64(len(metadata)) > keeper.config.MaxMetadataLen {
 		return v1beta2.Proposal{}, types.ErrMetadataTooLong.Wrapf("got metadata with length %d", len(metadata))
 	}
 

x/gov/spec/02_state.md

@@ -36,6 +36,9 @@ the following `JSON` template:
 
 This makes it far easier for clients to support multiple networks.
 
+The metadata has a maximum length that is chosen by the app developer, and
+passed into the gov keeper as a config.
+
 ### Writing a module that uses governance
 
 There are many aspects of a chain, or of the individual modules that you may want to

x/gov/spec/03_messages.md

@@ -9,10 +9,12 @@ order: 3
 Proposals can be submitted by any account via a `MsgSubmitProposal`
 transaction.
 
-+++ https://github.com/cosmos/cosmos-sdk/blob/v0.40.0/proto/cosmos/gov/v1beta1/tx.proto#L24-L39
++++ https://github.com/cosmos/cosmos-sdk/blob/ab9545527d630fe38761aa61cc5c95eabd68e0e6/proto/cosmos/gov/v1beta2/tx.proto#L34-L44
 
-The `Content` of a `MsgSubmitProposal` message must have an appropriate router
-set in the governance module.
+All `sdk.Msgs` passed into the `messages` field of a `MsgSubmitProposal` message
+must be registered in the app's `MsgServiceRouter`. Each of these messages must
+have one signer, namely the gov module account. And finally, the metadata length
+must not be larger than the `maxMetadataLen` config passed into the gov keeper.
 
 **State modifications:**
 
@@ -21,7 +23,7 @@ set in the governance module.
 - Initialise `Proposal`'s attributes
 - Decrease balance of sender by `InitialDeposit`
 - If `MinDeposit` is reached:
-    - Push `proposalID` in `ProposalProcessingQueue`
+  - Push `proposalID` in `ProposalProcessingQueue`
 - Transfer `InitialDeposit` from the `Proposer` to the governance `ModuleAccount`
 
 A `MsgSubmitProposal` transaction can be handled according to the following
@@ -35,6 +37,8 @@ upon receiving txGovSubmitProposal from sender do
 
   if !correctlyFormatted(txGovSubmitProposal)
     // check if proposal is correctly formatted and the messages have routes to other modules. Includes fee payment.
+    // check if all messages' unique Signer is the gov acct.
+    // check if the metadata is not too long.
     throw
 
   initialDeposit = txGovSubmitProposal.InitialDeposit
@@ -51,9 +55,8 @@ upon receiving txGovSubmitProposal from sender do
   proposalID = generate new proposalID
   proposal = NewProposal()
 
-  proposal.Title = txGovSubmitProposal.Title
-  proposal.Description = txGovSubmitProposal.Description
-  proposal.Type = txGovSubmitProposal.Type
+  proposal.Messages = txGovSubmitProposal.Messages
+  proposal.Metadata = txGovSubmitProposal.Metadata
   proposal.TotalDeposit = initialDeposit
   proposal.SubmitTime = <CurrentTime>
   proposal.DepositEndTime = <CurrentTime>.Add(depositParam.MaxDepositPeriod)
@@ -83,7 +86,7 @@ Once a proposal is submitted, if
 - Add `deposit` of sender in `proposal.Deposits`
 - Increase `proposal.TotalDeposit` by sender's `deposit`
 - If `MinDeposit` is reached:
-    - Push `proposalID` in `ProposalProcessingQueueEnd`
+  - Push `proposalID` in `ProposalProcessingQueueEnd`
 - Transfer `Deposit` from the `proposer` to the governance `ModuleAccount`
 
 A `MsgDeposit` transaction has to go through a number of checks to be valid.

x/gov/types/config.go

@@ -0,0 +1,14 @@
+package types
+
+// Config is a config struct used for intialising the gov module to avoid using globals.
+type Config struct {
+	// MaxMetadataLen defines the maximum proposal metadata length.
+	MaxMetadataLen uint64
+}
+
+// DefaultConfig returns the default config for gov.
+func DefaultConfig() Config {
+	return Config{
+		MaxMetadataLen: 255,
+	}
+}