74 lines
1.9 KiB
Elixir
74 lines
1.9 KiB
Elixir
defmodule HAHandler.DRBD.Watcher do
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# TODO: add support for SSH public keys authentication.
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use GenServer
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require Logger
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def start_link(opts) do
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GenServer.start_link(__MODULE__, opts)
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end
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defp connect(hostname, password) do
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case :inet.gethostbyname(to_charlist(hostname), :inet6) do
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{:ok, {:hostent, _name, _aliases, _addrtype, _length, [addr]}} ->
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SSHEx.connect(
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ip: addr,
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user: 'root',
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password: password,
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silently_accept_hosts: true
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)
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err ->
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err
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end
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end
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@impl true
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def init(opts) do
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state = %{
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backend: nil,
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last_reconnect: nil,
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hostname: Keyword.get(opts, :hostname),
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password: Keyword.get(opts, :password),
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}
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# This action will be processed once the GenServer is fully
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# started/operational. This process handle connection failures by itself,
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# as we don't want to crash loop into supervisor logic (which is only there
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# to handle unexpected failure).
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send self(), :reconnect
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{:ok, state}
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end
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@impl true
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def handle_info(:reconnect, state = %{hostname: hostname, password: password}) do
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case connect(hostname, password) do
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{:ok, pid} ->
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{:noreply, %{state | backend: pid}}
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{:error, err} ->
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# Nothing to do, as the next request will trigger the reconnect logic
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# (see :execute call).
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{:noreply, state}
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end
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end
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@impl true
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def handle_call({:execute, cmd}, _from, %{backend: backend} = state) do
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case SSHEx.run(backend, cmd) do
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{:ok, _output, _status} = reply->
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{:reply, reply, state}
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{:error, :closed} = reply ->
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# Asynchroneously tries to reopen the connection to the backend.
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send self(), :reconnect
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{:reply, reply, state}
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{:error, _err} = reply ->
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# Do not take action on unknown error.
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{:reply, reply, state}
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end
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end
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end
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