# `Arangox.GunClient`
[🔗](https://github.com/ArangoDB-Community/arangox/blob/v0.8.0/lib/arangox/client/gun.ex#L2)

An HTTP client implementation of the [`:gun`](https://ninenines.eu/docs/en/gun/2.1/guide "documentation") library. Requires [`:gun`](https://hex.pm/packages/gun "hex.pm") to be added
as a dependency.

Speaks HTTP/1.1 and HTTP/2 over TCP, TLS (Transport Layer Security) and unix
domain sockets. The driver sets no `protocols` option, so `:gun`'s own
defaults apply: HTTP/1.1 on cleartext, and on TLS an ALPN
(Application-Layer Protocol Negotiation) offer of both protocols with
HTTP/2 preferred. `client_opts: %{protocols: [:http2]}` asserts HTTP/2 on
cleartext by prior knowledge, or pins TLS to it.

The request-body size bound documented on `Arangox.MintClient` does not
apply here: `:gun` queues a request body and honours `WINDOW_UPDATE`
itself, so this client carries a body of any size under HTTP/2.

The merged header list is delivered to `:gun` as given — order kept,
duplicates kept, names as written. Response headers come back as the
parsed list on `Arangox.Response` — names lowercased, order and repeats
as received.

The per-request socket write bounds documented on `Arangox.MintClient`
deliberately do not apply here: `:gun` writes from its own process, so a
caller can never block inside a socket send, and every caller wait is
bounded by the request deadline. The socket still carries the same
teardown hygiene as the other clients — a bounded driver queue and an
abort on close — protecting `:gun`'s process rather than the caller.

`Arangox.MintClient` is the default and the one the documentation assumes.
This client is supported for applications already using it.

Conforms to the `Arangox.Client` error contract: every failure is an
`Arangox.Error` carrying a `:reason` atom, and neither `connect/2` nor
`request/3` raises or exits.

### Options

`:client_opts` is a map, merged over the options below. Gun takes its
transport options under `:tcp_opts` and `:tls_opts`; `:ssl_opts` given to
`Arangox.start_link/1` reaches the latter.

[__Hex.pm__](https://hex.pm/packages/gun)

[__Documentation__](https://ninenines.eu/docs/en/gun/2.1/guide)

---

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