> For the complete documentation index, see [llms.txt](https://titanlabs.gitbook.io/titan-chain/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://titanlabs.gitbook.io/titan-chain/validator/about-titan-chain/developers/modules/core/upgrade.md). # Upgrade ## Abstract `x/upgrade` is an implementation of a Cosmos SDK module that facilitates smoothly upgrading a live Cosmos chain to a new (breaking) software version. It accomplishes this by providing a `PreBlocker` hook that prevents the blockchain state machine from proceeding once a pre-defined upgrade block height has been reached. The module does not prescribe anything regarding how governance decides to do an upgrade, but just the mechanism for coordinating the upgrade safely. Without software support for upgrades, upgrading a live chain is risky because all of the validators need to pause their state machines at exactly the same point in the process. If this is not done correctly, there can be state inconsistencies which are hard to recover from. * Concepts * State * Events * Client * CLI * REST * gRPC * Resources ## Concepts ### Plan The `x/upgrade` module defines a `Plan` type in which a live upgrade is scheduled to occur. A `Plan` can be scheduled at a specific block height. A `Plan` is created once a (frozen) release candidate along with an appropriate upgrade `Handler` (see below) is agreed upon, where the `Name` of a `Plan` corresponds to a specific `Handler`. Typically, a `Plan` is created through a governance proposal process, where if voted upon and passed, will be scheduled. The `Info` of a `Plan` may contain various metadata about the upgrade, typically application specific upgrade info to be included on-chain such as a git commit that validators could automatically upgrade to. ```go type Plan struct { Name string Height int64 Info string } ``` #### Sidecar Process If an operator running the application binary also runs a sidecar process to assist in the automatic download and upgrade of a binary, the `Info` allows this process to be seamless. This tool is [Cosmovisor](https://github.com/cosmos/cosmos-sdk/tree/main/tools/cosmovisor#readme). ### Handler The `x/upgrade` module facilitates upgrading from major version X to major version Y. To accomplish this, node operators must first upgrade their current binary to a new binary that has a corresponding `Handler` for the new version Y. It is assumed that this version has fully been tested and approved by the community at large. This `Handler` defines what state migrations need to occur before the new binary Y can successfully run the chain. Naturally, this `Handler` is application specific and not defined on a per-module basis. Registering a `Handler` is done via `Keeper#SetUpgradeHandler` in the application. ```go type UpgradeHandler func(Context, Plan, VersionMap) (VersionMap, error) ``` During each `EndBlock` execution, the `x/upgrade` module checks if there exists a `Plan` that should execute (is scheduled at that height). If so, the corresponding `Handler` is executed. If the `Plan` is expected to execute but no `Handler` is registered or if the binary was upgraded too early, the node will gracefully panic and exit. ### StoreLoader The `x/upgrade` module also facilitates store migrations as part of the upgrade. The `StoreLoader` sets the migrations that need to occur before the new binary can successfully run the chain. This `StoreLoader` is also application specific and not defined on a per-module basis. Registering this `StoreLoader` is done via `app#SetStoreLoader` in the application. ```go func UpgradeStoreLoader (upgradeHeight int64, storeUpgrades *store.StoreUpgrades) baseapp.StoreLoader ``` If there's a planned upgrade and the upgrade height is reached, the old binary writes `Plan` to the disk before panicking. This information is critical to ensure the `StoreUpgrades` happens smoothly at correct height and expected upgrade. It eliminiates the chances for the new binary to execute `StoreUpgrades` multiple times everytime on restart. Also if there are multiple upgrades planned on same height, the `Name` will ensure these `StoreUpgrades` takes place only in planned upgrade handler. ### Proposal Typically, a `Plan` is proposed and submitted through governance via a proposal containing a `MsgSoftwareUpgrade` message. This proposal prescribes to the standard governance process. If the proposal passes, the `Plan`, which targets a specific `Handler`, is persisted and scheduled. The upgrade can be delayed or hastened by updating the `Plan.Height` in a new proposal. ```protobuf https://github.com/cosmos/cosmos-sdk/blob/v0.47.0-rc1/proto/cosmos/upgrade/v1beta1/tx.proto#L29-L41 ``` #### Cancelling Upgrade Proposals Upgrade proposals can be cancelled. There exists a gov-enabled `MsgCancelUpgrade` message type, which can be embedded in a proposal, voted on and, if passed, will remove the scheduled upgrade `Plan`. Of course this requires that the upgrade was known to be a bad idea well before the upgrade itself, to allow time for a vote. ```protobuf https://github.com/cosmos/cosmos-sdk/blob/v0.47.0-rc1/proto/cosmos/upgrade/v1beta1/tx.proto#L48-L57 ``` If such a possibility is desired, the upgrade height is to be `2 * (VotingPeriod + DepositPeriod) + (SafetyDelta)` from the beginning of the upgrade proposal. The `SafetyDelta` is the time available from the success of an upgrade proposal and the realization it was a bad idea (due to external social consensus). A `MsgCancelUpgrade` proposal can also be made while the original `MsgSoftwareUpgrade` proposal is still being voted upon, as long as the `VotingPeriod` ends after the `MsgSoftwareUpgrade` proposal. ## State The internal state of the `x/upgrade` module is relatively minimal and simple. The state contains the currently active upgrade `Plan` (if one exists) by key `0x0` and if a `Plan` is marked as "done" by key `0x1`. The state contains the consensus versions of all app modules in the application. The versions are stored as big endian `uint64`, and can be accessed with prefix `0x2` appended by the corresponding module name of type `string`. The state maintains a `Protocol Version` which can be accessed by key `0x3`. * Plan: `0x0 -> Plan` * Done: `0x1 | byte(plan name) -> BigEndian(Block Height)` * ConsensusVersion: `0x2 | byte(module name) -> BigEndian(Module Consensus Version)` * ProtocolVersion: `0x3 -> BigEndian(Protocol Version)` The `x/upgrade` module contains no genesis state. ## Events The `x/upgrade` does not emit any events by itself. Any and all proposal related events are emitted through the `x/gov` module. ## Client ### CLI A user can query and interact with the `upgrade` module using the CLI. #### Query The `query` commands allow users to query `upgrade` state. ```bash simd query upgrade --help ``` **applied** The `applied` command allows users to query the block header for height at which a completed upgrade was applied. ```bash simd query upgrade applied [upgrade-name] [flags] ``` If upgrade-name was previously executed on the chain, this returns the header for the block at which it was applied. This helps a client determine which binary was valid over a given range of blocks, as well as more context to understand past migrations. Example: ```bash simd query upgrade applied "test-upgrade" ``` Example Output: ```bash "block_id": { "hash": "A769136351786B9034A5F196DC53F7E50FCEB53B48FA0786E1BFC45A0BB646B5", "parts": { "total": 1, "hash": "B13CBD23011C7480E6F11BE4594EE316548648E6A666B3575409F8F16EC6939E" } }, "block_size": "7213", "header": { "version": { "block": "11" }, "chain_id": "testnet-2", "height": "455200", "time": "2021-04-10T04:37:57.085493838Z", "last_block_id": { "hash": "0E8AD9309C2DC411DF98217AF59E044A0E1CCEAE7C0338417A70338DF50F4783", "parts": { "total": 1, "hash": "8FE572A48CD10BC2CBB02653CA04CA247A0F6830FF19DC972F64D339A355E77D" } }, "last_commit_hash": "DE890239416A19E6164C2076B837CC1D7F7822FC214F305616725F11D2533140", "data_hash": "E3B0C44298FC1C149AFBF4C8996FB92427AE41E4649B934CA495991B7852B855", "validators_hash": "A31047ADE54AE9072EE2A12FF260A8990BA4C39F903EAF5636B50D58DBA72582", "next_validators_hash": "A31047ADE54AE9072EE2A12FF260A8990BA4C39F903EAF5636B50D58DBA72582", "consensus_hash": "048091BC7DDC283F77BFBF91D73C44DA58C3DF8A9CBC867405D8B7F3DAADA22F", "app_hash": "28ECC486AFC332BA6CC976706DBDE87E7D32441375E3F10FD084CD4BAF0DA021", "last_results_hash": "E3B0C44298FC1C149AFBF4C8996FB92427AE41E4649B934CA495991B7852B855", "evidence_hash": "E3B0C44298FC1C149AFBF4C8996FB92427AE41E4649B934CA495991B7852B855", "proposer_address": "2ABC4854B1A1C5AA8403C4EA853A81ACA901CC76" }, "num_txs": "0" } ``` **module versions** The `module_versions` command gets a list of module names and their respective consensus versions. Following the command with a specific module name will return only that module's information. ```bash simd query upgrade module_versions [optional module_name] [flags] ``` Example: ```bash simd query upgrade module_versions ``` Example Output: ```bash module_versions: - name: auth version: "2" - name: authz version: "1" - name: bank version: "2" - name: crisis version: "1" - name: distribution version: "2" - name: evidence version: "1" - name: feegrant version: "1" - name: genutil version: "1" - name: gov version: "2" - name: ibc version: "2" - name: mint version: "1" - name: params version: "1" - name: slashing version: "2" - name: staking version: "2" - name: transfer version: "1" - name: upgrade version: "1" - name: vesting version: "1" ``` Example: ```bash regen query upgrade module_versions ibc ``` Example Output: ```bash module_versions: - name: ibc version: "2" ``` **plan** The `plan` command gets the currently scheduled upgrade plan, if one exists. ```bash regen query upgrade plan [flags] ``` Example: ```bash simd query upgrade plan ``` Example Output: ```bash height: "130" info: "" name: test-upgrade time: "0001-01-01T00:00:00Z" upgraded_client_state: null ``` #### Transactions The upgrade module supports the following transactions: * `software-proposal` - submits an upgrade proposal: ```bash simd tx upgrade software-upgrade v2 --title="Test Proposal" --summary="testing" --deposit="100000000stake" --upgrade-height 1000000 \ --upgrade-info '{ "binaries": { "linux/amd64":"https://example.com/simd.zip?checksum=sha256:aec070645fe53ee3b3763059376134f058cc337247c978add178b6ccdfb0019f" } }' --from cosmos1.. ``` * `cancel-software-upgrade` - cancels a previously submitted upgrade proposal: ```bash simd tx upgrade cancel-software-upgrade --title="Test Proposal" --summary="testing" --deposit="100000000stake" --from cosmos1.. ``` ### REST A user can query the `upgrade` module using REST endpoints. #### Applied Plan `AppliedPlan` queries a previously applied upgrade plan by its name. ```bash /cosmos/upgrade/v1beta1/applied_plan/{name} ``` Example: ```bash curl -X GET "http://localhost:1317/cosmos/upgrade/v1beta1/applied_plan/v2.0-upgrade" -H "accept: application/json" ``` Example Output: ```bash { "height": "30" } ``` #### Current Plan `CurrentPlan` queries the current upgrade plan. ```bash /cosmos/upgrade/v1beta1/current_plan ``` Example: ```bash curl -X GET "http://localhost:1317/cosmos/upgrade/v1beta1/current_plan" -H "accept: application/json" ``` Example Output: ```bash { "plan": "v2.1-upgrade" } ``` #### Module versions `ModuleVersions` queries the list of module versions from state. ```bash /cosmos/upgrade/v1beta1/module_versions ``` Example: ```bash curl -X GET "http://localhost:1317/cosmos/upgrade/v1beta1/module_versions" -H "accept: application/json" ``` Example Output: ```bash { "module_versions": [ { "name": "auth", "version": "2" }, { "name": "authz", "version": "1" }, { "name": "bank", "version": "2" }, { "name": "crisis", "version": "1" }, { "name": "distribution", "version": "2" }, { "name": "evidence", "version": "1" }, { "name": "feegrant", "version": "1" }, { "name": "genutil", "version": "1" }, { "name": "gov", "version": "2" }, { "name": "ibc", "version": "2" }, { "name": "mint", "version": "1" }, { "name": "params", "version": "1" }, { "name": "slashing", "version": "2" }, { "name": "staking", "version": "2" }, { "name": "transfer", "version": "1" }, { "name": "upgrade", "version": "1" }, { "name": "vesting", "version": "1" } ] } ``` ### gRPC A user can query the `upgrade` module using gRPC endpoints. #### Applied Plan `AppliedPlan` queries a previously applied upgrade plan by its name. ```bash cosmos.upgrade.v1beta1.Query/AppliedPlan ``` Example: ```bash grpcurl -plaintext \ -d '{"name":"v2.0-upgrade"}' \ localhost:9090 \ cosmos.upgrade.v1beta1.Query/AppliedPlan ``` Example Output: ```bash { "height": "30" } ``` #### Current Plan `CurrentPlan` queries the current upgrade plan. ```bash cosmos.upgrade.v1beta1.Query/CurrentPlan ``` Example: ```bash grpcurl -plaintext localhost:9090 cosmos.slashing.v1beta1.Query/CurrentPlan ``` Example Output: ```bash { "plan": "v2.1-upgrade" } ``` #### Module versions `ModuleVersions` queries the list of module versions from state. ```bash cosmos.upgrade.v1beta1.Query/ModuleVersions ``` Example: ```bash grpcurl -plaintext localhost:9090 cosmos.slashing.v1beta1.Query/ModuleVersions ``` Example Output: ```bash { "module_versions": [ { "name": "auth", "version": "2" }, { "name": "authz", "version": "1" }, { "name": "bank", "version": "2" }, { "name": "crisis", "version": "1" }, { "name": "distribution", "version": "2" }, { "name": "evidence", "version": "1" }, { "name": "feegrant", "version": "1" }, { "name": "genutil", "version": "1" }, { "name": "gov", "version": "2" }, { "name": "ibc", "version": "2" }, { "name": "mint", "version": "1" }, { "name": "params", "version": "1" }, { "name": "slashing", "version": "2" }, { "name": "staking", "version": "2" }, { "name": "transfer", "version": "1" }, { "name": "upgrade", "version": "1" }, { "name": "vesting", "version": "1" } ] } ``` ## Resources A list of (external) resources to learn more about the `x/upgrade` module. * [Cosmos Dev Series: Cosmos Blockchain Upgrade](https://medium.com/web3-surfers/cosmos-dev-series-cosmos-sdk-based-blockchain-upgrade-b5e99181554c) - 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