tendermint/UPGRADING.md

Upgrading Tendermint Core

This guide provides steps to be followed when you upgrade your applications to a newer version of Tendermint Core.

v0.33.0

This release is not compatible with previous blockchains due to commit becoming signatures only and fields in the header have been removed.

Config Changes

You will need to generate a new config if you have used a prior version of tendermint.

• Tags have been entirely renamed throughout the codebase to events and there keys are called compositeKeys.
• Evidence Params has been changed to include duration.
  • consensus_params.evidence.max_age_duration.
  • Renamed consensus_params.evidence.max_age to max_age_num_blocks.

Go API

• libs/common has been removed in favor of specific pkgs.
  • async
  • service
  • rand
  • net
  • strings
  • cmap
• removal of errors pkg

RPC Changes

• /validators is now paginated (default: 30 vals per page)
• /block_results response format updated see RPC docs for details
• Event suffix has been removed from the ID in event responses
• IDs are now integers not json-client-XYZ

v0.32.0

This release is compatible with previous blockchains, however the new ABCI Events mechanism may create some complexity for nodes wishing to continue operation with v0.32 from a previous version. There are some minor breaking changes to the RPC.

Config Changes

If you have db_backend set to leveldb in your config file, please change it to goleveldb or cleveldb.

RPC Changes

The default listen address for the RPC is now 127.0.0.1. If you want to expose it publicly, you have to explicitly configure it. Note exposing the RPC to the public internet may not be safe - endpoints which return a lot of data may enable resource exhaustion attacks on your node, causing the process to crash.

Any consumers of /block_results need to be mindful of the change in all field names from CamelCase to Snake case, eg. results.DeliverTx is now results.deliver_tx. This is a fix, but it's breaking.

ABCI Changes

ABCI responses which previously had a Tags field now have an Events field instead. The original Tags field was simply a list of key-value pairs, where each key effectively represented some attribute of an event occuring in the blockchain, like sender, receiver, or amount. However, it was difficult to represent the occurence of multiple events (for instance, multiple transfers) in a single list. The new Events field contains a list of Event, where each Event is itself a list of key-value pairs, allowing for more natural expression of multiple events in eg. a single DeliverTx or EndBlock. Note each Event also includes a Type, which is meant to categorize the event.

For transaction indexing, the index key is prefixed with the event type: {eventType}.{attributeKey}. If the same event type and attribute key appear multiple times, the values are appended in a list.

To make queries, include the event type as a prefix. For instance if you previously queried for recipient = 'XYZ', and after the upgrade you name your event transfer, the new query would be for transfer.recipient = 'XYZ'.

Note that transactions indexed on a node before upgrading to v0.32 will still be indexed using the old scheme. For instance, if a node upgraded at height 100, transactions before 100 would be queried with recipient = 'XYZ' and transactions after 100 would be queried with transfer.recipient = 'XYZ'. While this presents additional complexity to clients, it avoids the need to reindex. Of course, you can reset the node and sync from scratch to re-index entirely using the new scheme.

We illustrate further with a more complete example.

Prior to the update, suppose your ResponseDeliverTx look like:

abci.ResponseDeliverTx{
  Tags: []kv.Pair{
    {Key: []byte("sender"), Value: []byte("foo")},
    {Key: []byte("recipient"), Value: []byte("bar")},
    {Key: []byte("amount"), Value: []byte("35")},
  }
}

The following queries would match this transaction:

query.MustParse("tm.event = 'Tx' AND sender = 'foo'")
query.MustParse("tm.event = 'Tx' AND recipient = 'bar'")
query.MustParse("tm.event = 'Tx' AND sender = 'foo' AND recipient = 'bar'")

Following the upgrade, your ResponseDeliverTx would look something like: the following Events:

abci.ResponseDeliverTx{
  Events: []abci.Event{
    {
      Type: "transfer",
      Attributes: kv.Pairs{
        {Key: []byte("sender"), Value: []byte("foo")},
        {Key: []byte("recipient"), Value: []byte("bar")},
        {Key: []byte("amount"), Value: []byte("35")},
      },
    }
}

Now the following queries would match this transaction:

query.MustParse("tm.event = 'Tx' AND transfer.sender = 'foo'")
query.MustParse("tm.event = 'Tx' AND transfer.recipient = 'bar'")
query.MustParse("tm.event = 'Tx' AND transfer.sender = 'foo' AND transfer.recipient = 'bar'")

For further documentation on Events, see the docs.

Go Applications

The ABCI Application interface changed slightly so the CheckTx and DeliverTx methods now take Request structs. The contents of these structs are just the raw tx bytes, which were previously passed in as the argument.

v0.31.6

There are no breaking changes in this release except Go API of p2p and mempool packages. Hovewer, if you're using cleveldb, you'll need to change the compilation tag:

Use cleveldb tag instead of gcc to compile Tendermint with CLevelDB or use make build_c / make install_c (full instructions can be found at https://tendermint.com/docs/introduction/install.html#compile-with-cleveldb-support)

v0.31.0

This release contains a breaking change to the behaviour of the pubsub system. It also contains some minor breaking changes in the Go API and ABCI. There are no changes to the block or p2p protocols, so v0.31.0 should work fine with blockchains created from the v0.30 series.

RPC

The pubsub no longer blocks on publishing. This may cause some WebSocket (WS) clients to stop working as expected. If your WS client is not consuming events fast enough, Tendermint can terminate the subscription. In this case, the WS client will receive an error with description:

{
  "jsonrpc": "2.0",
  "id": "{ID}#event",
  "error": {
    "code": -32000,
    "msg": "Server error",
    "data": "subscription was cancelled (reason: client is not pulling messages fast enough)" // or "subscription was cancelled (reason: Tendermint exited)"
  }
}

Additionally, there are now limits on the number of subscribers and
subscriptions that can be active at once. See the new
`rpc.max_subscription_clients` and `rpc.max_subscriptions_per_client` values to
configure this.

Applications

Simple rename of ConsensusParams.BlockSize to ConsensusParams.Block.

The ConsensusParams.Block.TimeIotaMS field was also removed. It's configured in the ConsensusParsm in genesis.

Go API

See the CHANGELOG. These are relatively straight forward.

v0.30.0

This release contains a breaking change to both the block and p2p protocols, however it may be compatible with blockchains created with v0.29.0 depending on the chain history. If your blockchain has not included any pieces of evidence, or no piece of evidence has been included in more than one block, and if your application has never returned multiple updates for the same validator in a single block, then v0.30.0 will work fine with blockchains created with v0.29.0.

The p2p protocol change is to fix the proposer selection algorithm again. Note that proposer selection is purely a p2p concern right now since the algorithm is only relevant during real time consensus. This change is thus compatible with v0.29.0, but all nodes must be upgraded to avoid disagreements on the proposer.

Applications

Applications must ensure they do not return duplicates in ResponseEndBlock.ValidatorUpdates. A pubkey must only appear once per set of updates. Duplicates will cause irrecoverable failure. If you have a very good reason why we shouldn't do this, please open an issue.

v0.29.0

This release contains some breaking changes to the block and p2p protocols, and will not be compatible with any previous versions of the software, primarily due to changes in how various data structures are hashed.

Any implementations of Tendermint blockchain verification, including lite clients, will need to be updated. For specific details:

• Merkle tree
• ConsensusParams

There was also a small change to field ordering in the vote struct. Any implementations of an out-of-process validator (like a Key-Management Server) will need to be updated. For specific details:

• Vote

Finally, the proposer selection algorithm continues to evolve. See the work-in-progress specification.

For everything else, please see the CHANGELOG.

v0.28.0

This release breaks the format for the priv_validator.json file and the protocol used for the external validator process. It is compatible with v0.27.0 blockchains (neither the BlockProtocol nor the P2PProtocol have changed).

Please read carefully for details about upgrading.

Note: Backup your config/priv_validator.json before proceeding.

priv_validator.json

The config/priv_validator.json is now two files: config/priv_validator_key.json and data/priv_validator_state.json. The former contains the key material, the later contains the details on the last message signed.

When running v0.28.0 for the first time, it will back up any pre-existing priv_validator.json file and proceed to split it into the two new files. Upgrading should happen automatically without problem.

To upgrade manually, use the provided privValUpgrade.go script, with exact paths for the old priv_validator.json and the locations for the two new files. It's recomended to use the default paths, of config/priv_validator_key.json and data/priv_validator_state.json, respectively:

go run scripts/privValUpgrade.go <old-path> <new-key-path> <new-state-path>

External validator signers

The Unix and TCP implementations of the remote signing validator have been consolidated into a single implementation. Thus in both cases, the external process is expected to dial Tendermint. This is different from how Unix sockets used to work, where Tendermint dialed the external process.

The PubKeyMsg was also split into separate Request and Response types for consistency with other messages.

Note that the TCP sockets don't yet use a persistent key, so while they're encrypted, they can't yet be properly authenticated. See #3105. Note the Unix socket has neither encryption nor authentication, but will add a shared-secret in #3099.

v0.27.0

This release contains some breaking changes to the block and p2p protocols, but does not change any core data structures, so it should be compatible with existing blockchains from the v0.26 series that only used Ed25519 validator keys. Blockchains using Secp256k1 for validators will not be compatible. This is due to the fact that we now enforce which key types validators can use as a consensus param. The default is Ed25519, and Secp256k1 must be activated explicitly.

It is recommended to upgrade all nodes at once to avoid incompatibilities at the peer layer - namely, the heartbeat consensus message has been removed (only relevant if create_empty_blocks=false or create_empty_blocks_interval > 0), and the proposer selection algorithm has changed. Since proposer information is never included in the blockchain, this change only affects the peer layer.

Go API Changes

libs/db

The ReverseIterator API has changed the meaning of start and end. Before, iteration was from start to end, where start > end. Now, iteration is from end to start, where start < end. The iterator also excludes end. This change allows a simplified and more intuitive logic, aligning the semantic meaning of start and end in the Iterator and ReverseIterator.

Applications

This release enforces a new consensus parameter, the ValidatorParams.PubKeyTypes. Applications must ensure that they only return validator updates with the allowed PubKeyTypes. If a validator update includes a pubkey type that is not included in the ConsensusParams.Validator.PubKeyTypes, block execution will fail and the consensus will halt.

By default, only Ed25519 pubkeys may be used for validators. Enabling Secp256k1 requires explicit modification of the ConsensusParams. Please update your application accordingly (ie. restrict validators to only be able to use Ed25519 keys, or explicitly add additional key types to the genesis file).

v0.26.0

This release contains a lot of changes to core data types and protocols. It is not compatible to the old versions and there is no straight forward way to update old data to be compatible with the new version.

To reset the state do:

$ tendermint unsafe_reset_all

Here we summarize some other notable changes to be mindful of.

Config Changes

All timeouts must be changed from integers to strings with their duration, for instance flush_throttle_timeout = 100 would be changed to flush_throttle_timeout = "100ms" and timeout_propose = 3000 would be changed to timeout_propose = "3s".

RPC Changes

The default behaviour of /abci_query has been changed to not return a proof, and the name of the parameter that controls this has been changed from trusted to prove. To get proofs with your queries, ensure you set prove=true.

Various version fields like amino_version, p2p_version, consensus_version, and rpc_version have been removed from the node_info.other and are consolidated under the tendermint semantic version (ie. node_info.version) and the new block and p2p protocol versions under node_info.protocol_version.

ABCI Changes

Field numbers were bumped in the Header and ResponseInfo messages to make room for new version fields. It should be straight forward to recompile the protobuf file for these changes.

Proofs

The ResponseQuery.Proof field is now structured as a []ProofOp to support generalized Merkle tree constructions where the leaves of one Merkle tree are the root of another. If you don't need this functionality, and you used to return <proof bytes> here, you should instead return a single ProofOp with just the Data field set:

[]ProofOp{
    ProofOp{
        Data: <proof bytes>,
    }
}

For more information, see:

• ADR-026
• Relevant ABCI documentation
• Description of keys

Go API Changes

crypto/merkle

The merkle.Hasher interface was removed. Functions which used to take Hasher now simply take []byte. This means that any objects being Merklized should be serialized before they are passed in.

node

The node.RunForever function was removed. Signal handling and running forever should instead be explicitly configured by the caller. See how we do it here.

Other

All hashes, except for public key addresses, are now 32-bytes.

v0.25.0

This release has minimal impact.

If you use GasWanted in ABCI and want to enforce it, set the MaxGas in the genesis file (default is no max).

v0.24.0

New 0.24.0 release contains a lot of changes to the state and types. It's not compatible to the old versions and there is no straight forward way to update old data to be compatible with the new version.

To reset the state do:

$ tendermint unsafe_reset_all

Here we summarize some other notable changes to be mindful of.

Config changes

p2p.max_num_peers was removed in favor of p2p.max_num_inbound_peers and p2p.max_num_outbound_peers.

# Maximum number of inbound peers
max_num_inbound_peers = 40

# Maximum number of outbound peers to connect to, excluding persistent peers
max_num_outbound_peers = 10

As you can see, the default ratio of inbound/outbound peers is 4/1. The reason is we want it to be easier for new nodes to connect to the network. You can tweak these parameters to alter the network topology.

RPC Changes

The result of /commit used to contain header and commit fields at the top level. These are now contained under the signed_header field.

ABCI Changes

The header has been upgraded and contains new fields, but none of the existing fields were changed, except their order.

The Validator type was split into two, one containing an Address and one containing a PubKey. When processing RequestBeginBlock, use the Validator type, which contains just the Address. When returning ResponseEndBlock, use the ValidatorUpdate type, which contains just the PubKey.

Validator Set Updates

Validator set updates returned in ResponseEndBlock for height H used to take effect immediately at height H+1. Now they will be delayed one block, to take effect at height H+2. Note this means that the change will be seen by the ABCI app in the RequestBeginBlock.LastCommitInfo at block H+3. Apps were already required to maintain a map from validator addresses to pubkeys since v0.23 (when pubkeys were removed from RequestBeginBlock), but now they may need to track multiple validator sets at once to accomodate this delay.

Block Size

The ConsensusParams.BlockSize.MaxTxs was removed in favour of ConsensusParams.BlockSize.MaxBytes, which is now enforced. This means blocks are limitted only by byte-size, not by number of transactions.