92 lines
3.2 KiB
Elixir
92 lines
3.2 KiB
Elixir
defmodule HAHandler.DRBD do
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require Logger
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@supervisor HAHandler.DRBD.Supervisor
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# There might be >1 resources configured in DRBD!
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@default_resource_id "1"
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# We don't support DRBD 9 for the time being, as /proc/drbd does not have a
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# stable API.
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@supported_drbd_major_version "8"
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# Parsing of /proc/drbd, assuming DRBD 8. Splitting the regexes helps humans
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# wrapping their head around what's going on. And yes, it's fragile: we need
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# drbd 9 to get a JSON interface to `drbdadm status`.
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@drbd_proc_cmd "cat /proc/drbd"
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@block_regex ~r/(?<version_block>(.|\n)*)\n(?<resource_block>\n\s(.|\n)*)/
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@version_regex ~r/version: (?<full>(?<major>\d+)\.(?<intermediate>\d+)\.(?<minor>\d))/
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@resource_split_regex ~r{(\n\s(\d+)\:\s)}
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@id_extraction_regex ~r/\n\s(?<id>\d+)\:\s/
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@data_extraction_regex ~r/cs:(?<cs>(\w|\/)+)\sro:(?<ro>(\w|\/)+)\sds:(?<ds>(\w|\/)+)\s/
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# Empty state, when backend is not queryable for some reason.
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@empty_state %{
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hostname: "unknown",
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version: "",
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mode: "",
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status: "unknown",
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data: ""
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}
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def get_instances() do
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watchers = Supervisor.which_children(@supervisor)
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for {hostname, pid, _type, _modules} <- watchers do
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{hostname, pid}
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end
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end
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def get_stats() do
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get_instances()
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|> Enum.map(fn instance -> get_state(instance) end)
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end
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def get_state({hostname, pid}) do
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empty_reply = %{@empty_state | hostname: hostname}
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case GenServer.call(pid, {:execute, @drbd_proc_cmd}) do
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{:ok, raw, 0} ->
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case Regex.named_captures(@block_regex, raw) do
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%{"version_block" => version_block, "resource_block" => resource_block} ->
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version = Regex.named_captures(@version_regex, version_block)
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if Map.get(version, "major") != @supported_drbd_major_version do
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{:error, "unsupported DRBD version #{inspect(version)}"}
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else
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resources = Regex.split( @resource_split_regex, resource_block,
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[include_captures: true, trim: true])
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|> Enum.chunk_every(2)
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|> Enum.map(fn [raw_id, raw_data] ->
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%{}
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|> Map.merge(Regex.named_captures(@id_extraction_regex, raw_id))
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|> Map.merge(Regex.named_captures(@data_extraction_regex, raw_data))
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end)
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default_resource = resources
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|> Enum.filter(fn r -> r["id"] == @default_resource_id end)
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|> Enum.at(0)
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processed_reply = %{
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version: Map.get(version, "full"),
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mode: Map.get(default_resource, "ro"),
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status: Map.get(default_resource, "ds"),
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data: resources
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}
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Map.merge(empty_reply, processed_reply)
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end
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_ ->
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Logger.warning("Failed to query DRBD backend: could not parse /proc/drbd.")
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end
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{:ok, _, posix_err} ->
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Logger.warning("Failed to query DRBD backend: POSIX #{inspect(posix_err)}.")
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empty_reply
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{:error, err} ->
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Logger.warning("Failed to query DRBD backend: #{inspect(err)}.")
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empty_reply
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end
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end
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end
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