Fly.RPC (Fly RPC v0.2.0) View Source

Provides an RPC interface for executing an MFA on a node within a region.

Configuration

Assumes each node is running the Fly.RPC server in its supervision tree and exports FLY_REGION environment variable to identify the fly region.

To run code on a specific region call rpc_region/4. A node found within the given region will be chosen at random. Raises if no nodes exist on the given region.

The special :primary region may be passed to run the rpc against the region identified by the PRIMARY_REGION environment variable.

Examples

> rpc_region("hkg", String, :upcase, ["fly"])
"FLY"

> rpc_region(Fly.primary_region(), String, :upcase, ["fly"])
"FLY"

> rpc_region(:primary, String, :upcase, ["fly"])
"FLY"

Server

The GenServer's responsibility is just to monitor other nodes as they enter and leave the cluster. It maintains a list of nodes and the Fly.io region where they are deployed in an ETS table that other processes can use to find and initiate their own RPC calls to.

Link to this section Summary

Types

region()

tab()

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

handle_continue(atom, state)

Callback implementation for GenServer.handle_continue/2.

init(opts)

Callback implementation for GenServer.init/1.

is_rpc_supported?(node)

Executes a function on the remote node to determine if the RPC API support is available.

region(node)

Asks a node what Fly region it's running in.

region_nodes(tab \\ :fly_regions, region)

Returns the Elixir OTP nodes registered the region. Reads from a local cache.

rpc(node, module, func, args, timeout \\ 5000)

Executes the function on the remote node and waits for the response.

rpc_region(region, module, func, args, opts \\ [])

Executes the MFA on an available node in the desired region.

start_link(opts)

Link to this section Types

region()

Specs

region() :: String.t() | :primary

tab()

Specs

tab() :: atom() | reference()

Link to this section Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

See Supervisor.

handle_continue(atom, state)

Callback implementation for GenServer.handle_continue/2.

init(opts)

Callback implementation for GenServer.init/1.

is_rpc_supported?(node)

Specs

is_rpc_supported?(node()) :: boolean()

Executes a function on the remote node to determine if the RPC API support is available.

Support may not exist on the remote node in a "first roll out" scenario.

region(node)

Specs

region(node()) :: {:ok, any()} | :error

Asks a node what Fly region it's running in.

Returns :error if RPC is not supported on remote node.

region_nodes(tab \\ :fly_regions, region)

Returns the Elixir OTP nodes registered the region. Reads from a local cache.

rpc(node, module, func, args, timeout \\ 5000)

Specs

rpc(node(), module(), func :: atom(), args :: [any()], non_neg_integer()) ::
  any()

Executes the function on the remote node and waits for the response.

Exits after timeout milliseconds.

rpc_region(region, module, func, args, opts \\ [])

Specs

rpc_region(region(), module(), func :: atom(), [any()], keyword()) :: any()

Executes the MFA on an available node in the desired region.

If the region is the "primary" region or the "local" region then execute the function immediately. Supports the string name of the region or :primary for the current configured primary region.

Otherwise find an available node and select one at random to execute the function.

Raises ArgumentError when no available nodes.

Example

> RPC.rpc_region("hkg", Kernel, :+, [1, 2])
3

> RPC.rpc_region(:primary, Kernel, :+, [1, 2])
3