Host Labels

wasmCloud hosts are associated with a set of label key-value pairs. Labels are used to distinguish hosts in auctions and schedule workloads with wadm.

Built-in Labels

All hosts include the following auto-generated labels:

• hostcore.arch (e.g. aarch64)
• hostcore.os (e.g. linux)
• hostcore.osfamily (e.g. unix)

Providing Labels at Start Time

Users can supply an arbitrary number of additional labels using host config values.

For example when starting a host via wash, use the -l/--label switch:

console

wash up -l foo=bar

Dynamically Adjusting Labels

Since labels are used for auctions and scheduling workloads, it's useful to be able to dynamically adjust a host's label at runtime. For example, consider a label like cordon, which might be used to indicate that a host should not be eligible for any new workloads. Hosts respond to requests to put/delete labels via the control interface over wasmbus.ctl.v1.{lattice}.label.[put|del].{host-id}.

You can use the wash label command to add labels easily:

shell

wash label <host-id> key=value cloud=aws region=us-east-1

Additionally, you can add the --delete flag to delete a set of labels

shell

wash label <host-id> key=value cloud=aws region=us-east-1 --delete