* Init should take a list of peers
This commit adds `--peers` option to `ipfs-cluster-service init`
`ipfs-cluster-service init --peers <multiaddress,multiaddress>`
- Adds and writes the given peers to the peerstore file
- For raft config section, adds the peer IDs to the `init_peerset`
- For crdt config section, add the peer IDs to the `trusted_peers`
Specifying "*" as part of "trusted_peers" in the configuration will
result in trusting all peers.
This is useful for private clusters where we don't want to list every
peer ID in the config.
TrustedPeers are specified in the configuration. Additional peers
can be added at runtime with Trust/Distrust functions.
Unfortunately we cannot use consensus.PeerAdd as a way to trust a peer as
cluster.PeerAdd+Join can be called by any peer and this calls
consensus.PeerAdd.
The result is consensus.PeerAdd doing a lot in Raft while consensus.Trust does
nothing, while in CRDTs consensus.Trust does something but consensus.PeerAdd
does nothing. But this is more or less consistent.
This adds a new "crdt" consensus component using go-ds-crdt.
This implies several refactors to fully make cluster consensus-component
independent:
* Delete mapstate and fully adopt dsstate (after people have migrated).
* Return errors from state methods rather than ignoring them.
* Add a new "datastore" modules so that we can configure datastores in the
main configuration like other components.
* Let the consensus components fully define the "state.State". Thus, they do
not receive the state, they receive the storage where we put the state (a
go-datastore).
* Allow to customize how the monitor component obtains Peers() (the current
peerset), including avoiding using the current peerset. At the moment the
crdt consensus uses the monitoring component to define the current peerset.
Therefore the monitor component cannot rely on the consensus component to
produce a peerset.
* Re-factor/re-implementation of "ipfs-cluster-service state"
operations. Includes the dissapearance of the "migrate" one.
The CRDT consensus component defines creates a crdt-datastore (with ipfs-lite)
and uses it to intitialize a dssate. Thus the crdt-store is elegantly
wrapped. Any modifications to the state get automatically replicated to other
peers. We store all the CRDT DAG blocks in the local datastore.
The consensus components only expose a ReadOnly state, as any modifications to
the shared state should happen through them.
DHT and PubSub facilities must now be created outside of Cluster and passed in
so they can be re-used by different components.
