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amqp_witness_plugin: sign blocks as non-producer and publish over AMQP #9122
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spoonincode
commented
May 21, 2020
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| std::unique_ptr<reliable_amqp_publisher> rqueue; | ||
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| struct amqp_witness_msg { |
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I really didn't want to do it because the message is so simple.... but it's probably best practice to version any struct sent
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You could always encode future extensions in the first byte, replacing is_sig_digest.
heifner
reviewed
May 21, 2020
heifner
reviewed
May 21, 2020
3 tasks
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What does it exactly do ? |
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Simply put, allows a fully validating node to sign the action merkle root of a block it fully validated and then publish that signature over AMQP for other components to consume and act upon. See #9379 for a version that places the signatures on chain instead. This is a small building block in a larger system. |
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Change Description
A witness is, conceptually, a node that signs a block attesting that the entire contents of the block are valid. A producer is a witness. This plugin extends the concept to a non-producing node. When the plugin is activated irreversible blocks are signed and those signatures are published to an AMQP exchange.
An AMQP server and existing exchange must be specified. The plugin is able to use any existing signature provider: a soft key specified in the config, keosd, or a Secure Enclave key. Blocks older than a specified age will not be signed -- useful for sync or replay.
Either the block’s signature digest or simply its action merkle root is reported in the message and what is signed. I believe this is appropriate to identify the block for both applications considered. A stateful application, like a light validator, will know the block signature digest it is seeking witness signatures for. A stateless application, like an application that is only inspecting action receipts, only wishes to know that the action receipt merkle proof for a block satisfies a merkle root that a witness has signed.
This plugin communicates to the AMQP server via the reliable_amqp_publisher for increased publishing reliability.
Consensus Changes
API Changes
Documentation Additions
Yes big time; a new plugin and the start of more AMQP support throughout nodeos.