/
watch.ex
222 lines (182 loc) · 6.67 KB
/
watch.ex
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defmodule K8s.Client.Runner.Stream.Watch do
@moduledoc """
Watches a `K8s.Client.list/3` operation and returns an Elixir [`Stream`](https://hexdocs.pm/elixir/Stream.html) of events.
"""
alias K8s.Client.Runner.Base
require Logger
import K8s.Sys.Logger, only: [log_prefix: 1]
@time_before_retry 5
@type t :: %__MODULE__{
conn: K8s.Conn.t(),
operation: K8s.Operation.t(),
resource_version: binary(),
http_opts: keyword(),
remainder: binary()
}
defstruct [:conn, :operation, :resource_version, :http_opts, remainder: ""]
@doc """
Watches resources and returns an Elixir Stream of events emmitted by kubernetes.
### Example
iex> {:ok,conn} = K8s.Conn.from_file("~/.kube/config", [context: "docker-desktop"])
...> op = K8s.Client.list("v1", "Namespace")
...> K8s.Client.Runner.Watch.Stream.stream(conn, op, []) |> Stream.map(&IO.inspect/1) |> Stream.run()
"""
@spec stream(K8s.Conn.t(), K8s.Operation.t(), keyword()) ::
{:ok, Enumerable.t()} | K8s.Client.Provider.error_t()
def stream(conn, operation, http_opts) do
http_opts =
http_opts
|> Keyword.put_new(:params, [])
|> put_in([:params, :allowWatchBookmarks], true)
|> put_in([:params, :watch], 1)
do_resource(conn, struct!(operation, verb: :list), http_opts, nil)
end
@spec do_resource(
K8s.Conn.t(),
K8s.Operation.t(),
keyword(),
nil | binary(),
retries :: non_neg_integer()
) ::
{:ok, Enumerable.t()} | K8s.Client.Provider.error_t()
defp do_resource(conn, operation, http_opts, resource_version, retries \\ 0)
defp do_resource(conn, operation, http_opts, nil, retries) do
with {:ok, resource_version} <- get_resource_version(conn, operation) do
do_resource(conn, operation, http_opts, resource_version, retries)
end
end
defp do_resource(conn, operation, http_opts, resource_version, retries) do
with http_opts <- put_in(http_opts, [:params, :resourceVersion], resource_version),
{:ok, stream} <- Base.stream(conn, operation, http_opts) do
stream =
stream
|> K8s.Client.HTTPStream.transform_to_lines()
|> K8s.Client.HTTPStream.decode_json_objects()
|> Stream.reject(&(&1 == {:status, 200}))
|> Stream.filter(&(&1 == :done || elem(&1, 0) in [:status, :object, :error]))
|> Stream.transform(
%__MODULE__{
conn: conn,
operation: operation,
http_opts: http_opts,
resource_version: resource_version
},
&reduce/2
)
{:ok, stream}
else
error when retries > 0 ->
Logger.warning(
log_prefix(
"Error when starting stream. Waiting #{@time_before_retry}s before retrying. #{retries} retries left."
),
library: :k8s,
error: error
)
Process.sleep(@time_before_retry * 1_000)
do_resource(conn, operation, http_opts, resource_version, retries - 1)
error ->
Logger.warning(log_prefix("Error when starting stream."), library: :k8s, error: error)
error
end
end
@spec reduce(K8s.Client.Provider.http_chunk_t(), t() | :halt) ::
{:halt, nil} | {Enumerable.t(), t()}
defp reduce(_, :halt), do: {:halt, nil}
defp reduce(:done, state) do
Logger.debug(
log_prefix("Watcher terminated the request. Starting a new watch request."),
library: :k8s
)
{:ok, stream} =
do_resource(state.conn, state.operation, state.http_opts, state.resource_version, 5)
{stream, state}
end
defp reduce({:error, reason}, state) do
Logger.warning(
log_prefix(
"Error #{inspect(reason)} received from the watcher. Waiting #{@time_before_retry} before restarting the watcher"
),
library: :k8s
)
Process.sleep(@time_before_retry * 1_000)
{:ok, stream} =
do_resource(state.conn, state.operation, state.http_opts, state.resource_version, 5)
{stream, state}
end
defp reduce({:status, 410}, state) do
Logger.warning(
log_prefix("410 Gone received from watcher - resetting the resource version"),
library: :k8s
)
{:ok, stream} = do_resource(state.conn, state.operation, state.http_opts, nil)
{stream, :halt}
end
defp reduce({:status, status}, _state) do
Logger.warning(
log_prefix("Erronous async status #{status} received from watcher - aborting the watch"),
library: :k8s
)
{:halt, nil}
end
defp reduce({:object, object}, state) do
process_object(object, state)
end
@spec process_object(map(), t()) :: {Enumerable.t(), t()}
defp process_object(
%{"type" => "ERROR", "object" => %{"message" => message, "code" => 410} = object},
state
) do
Logger.debug(
log_prefix("#{message} - resetting the resource version"),
library: :k8s,
object: object
)
new_state = struct!(state, resource_version: nil)
{[], new_state}
end
defp process_object(%{"type" => "BOOKMARK", "object" => object}, state) do
Logger.debug(
log_prefix("Bookmark received"),
library: :k8s,
object: object
)
{[], struct!(state, resource_version: object["metadata"]["resourceVersion"])}
end
defp process_object(
%{"object" => %{"metadata" => %{"resourceVersion" => resource_version}}},
%{resource_version: resource_version} = state
) do
# resource version already obeserved.
{[], state}
end
defp process_object(%{"object" => %{"kind" => _} = object} = new_event, state) do
# Emit new event
new_state = struct!(state, resource_version: object["metadata"]["resourceVersion"])
{[new_event], new_state}
end
defp process_object(%{"object" => %{"message" => message} = object}, state) do
# Objects with only the "message" field but no "kind" are cosidered errors.
Logger.error(
log_prefix(
"Erronous event received from watcher: #{message} - resetting the resource version"
),
library: :k8s,
object: object
)
new_state = struct!(state, resource_version: nil)
{[], new_state}
end
@spec get_resource_version(K8s.Conn.t(), K8s.Operation.t()) :: {:ok, binary} | Base.error_t()
defp get_resource_version(%K8s.Conn{} = conn, %K8s.Operation{} = operation) do
with {:ok, payload} <- Base.run(conn, operation) do
rv = parse_resource_version(payload)
{:ok, rv}
end
end
@resource_version_json_path ~w(metadata resourceVersion)
@spec parse_resource_version(any) :: binary
defp parse_resource_version(%{} = payload),
do: get_in(payload, @resource_version_json_path) || "0"
defp parse_resource_version(_), do: "0"
end