nerves_hub v0.7.4 NervesHub.ConsoleChannel

Wraps IEx.Server setting this process as the group_leader. This allows tunneling the io_request's over the channel socket.

The remote console ability is disabled by default and requires the remote_iex key to be enabled in the config:

config :nerves_hub, remote_iex: true

Once connected, IO requests on the device will be pushed up the socket for the following events:

get_line - IO is requesting the next line from user input. Typically just iex () >
put_chars - Display the sepcified characters from the IEx Server for user review
- This requires an immediate reply of :ok and then IEx will send a :get_line request to await the user input. NervesHubWeb handles immediately replies :ok to these events (see below)
init_attempt - Pushed asynchronously after attempting to init an IEx Server. Payload has a success key with a boolean value to specify whether the server process was started successfully or not

The following events are supported from the socket:

iex_terminate - Kill any running IEx server in the channel
init - The console channel starts without a linked IEx Server by default. This must be called before sending I/O back and forth. Only one IEx Server is initialized for this channel. If IEx Server has already been initialized and is in a good state, then calling init will continue to use the linked session and have no effect.
io_reply - Send the reply characters to the IO. Requires specific keys in payload
- kind - event that you're replying to. Either get_line or put_chars
- data - characters to be put into the IO. put_chars requires this to be ok or error
phx_close or phx_error - This will cause the channel to attempt rejoining every 5 seconds. You can change the rejoin timing in the config

config :nerves_hub, rejoin_after: 3_000

For more info, see The Erlang I/O Protocol

Link to this section Summary

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

init(opts)

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

start_link(opts)

Link to this section Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

See Supervisor.

init(opts)

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

init_arg is the argument term (second argument) passed to start_link/3.

Returning {:ok, state} will cause start_link/3 to return {:ok, pid} and the process to enter its loop.

Returning {:ok, state, timeout} is similar to {:ok, state} except handle_info(:timeout, state) will be called after timeout milliseconds if no messages are received within the timeout.

Returning {:ok, state, :hibernate} is similar to {:ok, state} except the process is hibernated before entering the loop. See c:handle_call/3 for more information on hibernation.

Returning {:ok, state, {:continue, continue}} is similar to {:ok, state} except that immediately after entering the loop the c:handle_continue/2 callback will be invoked with the value continue as first argument.

Returning :ignore will cause start_link/3 to return :ignore and the process will exit normally without entering the loop or calling c:terminate/2. If used when part of a supervision tree the parent supervisor will not fail to start nor immediately try to restart the GenServer. The remainder of the supervision tree will be started and so the GenServer should not be required by other processes. It can be started later with Supervisor.restart_child/2 as the child specification is saved in the parent supervisor. The main use cases for this are:

The GenServer is disabled by configuration but might be enabled later.
An error occurred and it will be handled by a different mechanism than the Supervisor. Likely this approach involves calling Supervisor.restart_child/2 after a delay to attempt a restart.

Returning {:stop, reason} will cause start_link/3 to return {:error, reason} and the process to exit with reason reason without entering the loop or calling c:terminate/2.

Callback implementation for GenServer.init/1.