IPFS Cluster Peerset Management

IPFS Cluster Dec 15, 2019

Adding and removing peers from the Cluster might be a simpler or  trickier operation depending on the “consensus” component used by the  cluster (the consensus component is in charge on managing the peerset).

Listing peers

$ ipfs-cluster-ctl peers ls

The peers ls command will produce the list of peers in the cluster will all their information. It is the equivalent of calling ipfs-cluster-ctl id on every cluster peer and building a list with the results, but for it  to work it needs to contact all the current peers of the cluster,  meaning it can be a slow operation. Instead, if you just want a list of  the peer IDs in the cluster you can see it wit hthe id command (the text output only shows the number of peers):

$ ipfs-cluster-ctl --enc=json id

Adding new peers

Adding new peers to a cluster works exactly as described in the Bootstrapping the Cluster section. The works-for-all method is to use the ipfs-cluster-service daemon --bootstrap flag.

Removing peers

CRDT mode

In CRDT-mode, peers can be simply stopped. Other peers may consider  them part of the peerset until their last metric expires. Thus, reducing  the metric ttls will speed this up.

Raft mode

In Raft-mode, peers can be stopped, but then they will not be  available to participate in cluster operations and will still be  considered part of the peerset. This is perfectly fine if the peer will  be re-started on the future and the majority of cluster peers will still  be online. Otherwise, the departing peer needs to be manually removed  with:

$ ipfs-cluster-ctl peers rm <pid>
Raft peers can only be removed when the Raft cluster has at least 50% of its members online.

This can be called from the peer shutting down (self-removal) or from  any other peer. In any case, it will cause the peer to shut itself down  when it realizes it has been removed.

Alternatively, the leave_on_shutdown configuration option can be set to true. With this option, a peer shutting down cleanly will try to remove itself from the Raft peerset in the process. Peers which have been removed from the Raft peerset automatically clean their state and will need to bootstrap again to it to re-join it.

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Vaibhav Saini

Co-Founder TowardsBlockchain, Dappkit, SimpleAsWater | YC SUS 19 | IITD | Blockchain | AI | Speaker | Writer

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