# `Tesla.Middleware.Fuse`
[🔗](https://github.com/elixir-tesla/tesla/blob/v1.17.0/lib/tesla/middleware/fuse.ex#L2)

Circuit Breaker middleware using [fuse](https://github.com/jlouis/fuse).

Remember to add `{:fuse, "~> 2.4"}` to dependencies (and `:fuse` to applications in `mix.exs`)
Also, you need to recompile tesla after adding `:fuse` dependency:

```
mix deps.clean tesla
mix deps.compile tesla
```

## Examples

```elixir
defmodule MyClient do
  def client do
    Tesla.client([
      {Tesla.Middleware.Fuse,
        opts: {{:standard, 2, 10_000}, {:reset, 60_000}},
        keep_original_error: true,
        should_melt: fn
          {:ok, %{status: status}} when status in [428, 500, 504] -> true
          {:ok, _} -> false
          {:error, _} -> true
        end,
        mode: :sync}
    ])
  end
end
```

## Options

- `:name` - fuse name (defaults to module name)
- `:opts` - fuse options (see fuse docs for reference)
- `:keep_original_error` - boolean to indicate if, in case of melting (based on `should_melt`), it should return the upstream's error or the fixed one `{:error, unavailable}`.
It's false by default, but it will be true in `2.0.0` version
- `:should_melt` - function to determine if response should melt the fuse
- `:mode` - how to query the fuse, which has two values:
  - `:sync` - queries are serialized through the `:fuse_server` process (the default)
  - `:async_dirty` - queries check the fuse state directly, but may not account for recent melts or resets

## SASL logger

fuse library uses [SASL (System Architecture Support Libraries)](http://erlang.org/doc/man/sasl_app.html).

You can disable its logger output using:

```elixir
config :sasl, sasl_error_logger: :false
```

Read more at [jlouis/fuse#32](https://github.com/jlouis/fuse/issues/32) and [jlouis/fuse#19](https://github.com/jlouis/fuse/issues/19).

---

*Consult [api-reference.md](api-reference.md) for complete listing*