What’s new in the v2.0 Alpha

A word about the Alpha release

The Alpha release of Hyperledger Fabric v2.0 allows users to try out two exciting new features — the new Fabric chaincode lifecycle and FabToken. The Alpha release is being offered to provide users a preview of new capabilities and is not meant to be used in production. Additionally there is no upgrade support to the v2.0 Alpha release, and no intended upgrade support from the the Alpha release to future versions of v2.x.

Fabric chaincode lifecycle

The Fabric 2.0 Alpha introduces decentralized governance for chaincode, with a new process for installing a chaincode on your peers and starting it on a channel. The new Fabric chaincode lifecycle allows multiple organizations to come to agreement on the parameters of a chaincode, such as the chaincode endorsement policy, before it can be used to interact with the ledger. The new model offers several improvements over the previous lifecycle:

  • Multiple organizations must agree to the parameters of a chaincode: In the release 1.x versions of Fabric, one organization had the ability to set parameters of a chaincode (for instance the endorsement policy) for all other channel members. The new Fabric chaincode lifecycle is more flexible since it supports both centralized trust models (such as that of the previous lifecycle model) as well as decentralized models requiring a sufficient number of organizations to agree on an endorsement policy before it goes into effect.
  • Safer chaincode upgrade process: In the previous chaincode lifecycle, the upgrade transaction could be issued by a single organization, creating a risk for a channel member that had not yet installed the new chaincode. The new model allows for a chaincode to be upgraded only after a sufficient number of organizations have approved the upgrade.
  • Easier endorsement policy updates: Fabric lifecycle allows you to change an endorsement policy without having to repackage or reinstall the chaincode. Users can also take advantage of a new default policy that requires endorsement from a majority of members on the channel. This policy is updated automatically when organizations are added or removed from the channel.
  • Inspectable chaincode packages: The Fabric lifecycle packages chaincode in easily readable tar files. This makes it easier to inspect the chaincode package and coordinate installation across multiple organizations.
  • Start multiple chaincodes on a channel using one package: The previous lifecycle defined each chaincode on the channel using a name and version that was specified when the chaincode package was installed. You can now use a single chaincode package and deploy it multiple times with different names on the same or different channel.

Using the new chaincode lifecycle

Use the following tutorials to get started with the new chaincode lifecycle:

Restrictions and limitations

The new Fabric chaincode lifecycle in the v2.0 Alpha release is not yet feature complete. Specifically, be aware of the following limitations in the Alpha release:

  • CouchDB indexes are not yet supported
  • Chaincodes defined with the new lifecycle are not yet discoverable via service discovery

These limitations will be resolved after the Alpha release.

FabToken

The Fabric 2.0 Alpha also provides users the ability to easily represent assets as tokens on Fabric channels. FabToken is a token management system that uses an Unspent Transaction Output (UTXO) model to issue, transfer, and redeem tokens using the identity and membership infrastructure provided by Hyperledger Fabric.

  • token/FabToken: This operations guide provides a detailed overview of how to use tokens on a Fabric network. The guide also includes an example on how to create and transfer tokens using the token CLI.

Alpine images

Starting with v2.0, Hyperledger Fabric Docker images will use Alpine Linux, a security-oriented, lightweight Linux distribution. This means that Docker images are now much smaller, providing faster download and startup times, as well as taking up less disk space on host systems. Alpine Linux is designed from the ground up with security in mind, and the minimalist nature of the Alpine distribution greatly reduces the risk of security vulnerabilities.

Raft ordering service

Introduced in v1.4.1, Raft is a crash fault tolerant (CFT) ordering service based on an implementation of Raft protocol in etcd. Raft follows a “leader and follower” model, where a leader node is elected (per channel) and its decisions are replicated to the followers. Raft ordering services should be easier to set up and manage than Kafka-based ordering services, and their design allows organizations spread out across the world to contribute nodes to a decentralized ordering service.

Release notes

The release notes provide more details for users moving to the new release, along with a link to the full release change log.