Module cartridge.rpc

get_candidates (role_name[, opts])

List candidates suitable for performing a remote call. Candidates are deduced from a local config and membership, which may differ from replica to replica (e.g. during patch_clusterwide ). It may produce invalid candidates.

Parameters:

• role_name: (string)
• opts:
  • leader_only: (optional boolean) Filter instances which are leaders now.(default: false)
  • healthy_only: (optional boolean) The member is considered healthy ifit reports either ConfiguringRoles or RolesConfigured stateand its SWIM status is either alive or suspect (added in v1.1.0-11, default: true)
  • labels: (optional table) Filter instances that have the specified labels. Adding labels is possible via theedit_topology method or via graphqlExample: rpc.get_candidates(„role“, { labels = {[„msk“] = „dc“} })

Returns:

({string,…}) URIs

call (role_name, fn_name[, args[, opts]])

Perform a remote procedure call. Find a suitable healthy instance with an enabled role and perform a [ net.box conn:call ]( https://tarantool.io/en/doc/latest/reference/reference_lua/net_box/#net-box-call) on it. rpc.call() can only be used for functions defined in role return table unlike net.box conn:call() , which is used for global functions as well.

Parameters:

• role_name: (string)
• fn_name: (string)
• args: (table) (optional)
• opts:
  • prefer_local: (optional boolean) Don’t perform a remote call if possible. When the role is enabledlocally and current instance is healthy the remote netbox call issubstituted with a local Lua function call. When the option isdisabled it never tries to perform call locally and always usesnetbox connection, even to connect self.(default: true)
  • leader_only: (optional boolean) Perform a call only on the replica set leaders.(default: false)
  • uri: (optional string) Force a call to be performed on this particular uri.Disregards member status and opts.prefer_local .Conflicts with opts.leader_only = true .(added in v1.2.0-63)
  • labels: (optional table) Filter instances that have the specified labels. Adding labels is possible via theedit_topology method or via graphql.Example: rpc.call(„role“, „func“, {}, { labels = { [„msk“] = „dc“ } })
  • remote_only: (deprecated) Use prefer_local instead.
  • timeout: passed to net.box conn:call options.
  • buffer: passed to net.box conn:call options.
  • on_push: passed to net.box conn:call options.
  • on_push_ctx: passed to net.box conn:call options.
  • is_async: passed to net.box conn:call options.

Returns:

conn:call() result

Or

(nil)

(table) Error description

Usage:

-- myrole.lua
return {
    role_name = 'myrole',
    add = function(a, b) return a + b end,
}

-- call it as follows:
cartridge.rpc_call('myrole', 'add', {2, 2}) -- returns 4

get_connection (role_name[, opts])

Connect to an instance with an enabled role. Candidates to connect are deduced from a local config and membership, which may differ from replica to replica (e.g. during patch_clusterwide ). It may produce invalid candidates.

Parameters:

• role_name: (string)
• opts:
  • prefer_local: (optional boolean)
  • leader_only: (optional boolean)
  • labels: (optional table)

Returns:

net.box connection

Or

(nil)

(table) Error description