Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/g-andrade/backwater

Intercluster RPC for Erlang and Elixir
https://github.com/g-andrade/backwater

distribution-independent elixir erlang intercluster rpc

Last synced: 2 months ago
JSON representation

Intercluster RPC for Erlang and Elixir

Awesome Lists containing this project

README 

        
# backwater



**This library is not under continuous maintenance; if you'd like to perform

maintenance yourself, feel free to open an issue requesting access.**



[![](https://img.shields.io/hexpm/v/backwater.svg?style=flat)](https://hex.pm/packages/backwater)

[![](https://github.com/g-andrade/backwater/actions/workflows/ci.yml/badge.svg)](https://github.com/g-andrade/backwater/actions/workflows/ci.yml)

[![Erlang Versions](https://img.shields.io/badge/Supported%20Erlang%2FOTP-22%20to%2026-blue)](https://www.erlang.org)



### Backwater - Intercluster RPC for Erlang and Elixir



`backwater` allows you to call remote modules without depending on the

Erlang distribution protocol.



It's targeted at scenarios where nodes in one datacenter need to call

nodes in another datacenter, over unsecure or unstable networks.



#### Usage



Run `make shell` to bring up a shell. We're going to expose the

`string` module and call it remotely.



##### 1. Generate a secret



``` erlang

Secret = crypto:strong_rand_bytes(32).

```



##### 2. Start the server



``` erlang

backwater:start_clear_server(Secret, [string]).

% {ok, _ServerPid}

```



##### 3. Execute a remote call



``` erlang

backwater:call({"127.0.0.1", Secret}, string, to_upper, ["hello"]).

% {ok, "HELLO"}

```



#### Details



`backwater` is built on top of

[cowboy](https://github.com/ninenines/cowboy) and

[hackney](https://github.com/benoitc/hackney).



##### Requirements



  - Erlang/OTP 22 or higher

  - rebar3



##### Documentation



Documentation is hosted on [HexDocs](https://hexdocs.pm/backwater/).



##### Authentication and integrity



All requests and responses are authenticated and signed using a modified

version of [HTTP

signatures](https://tools.ietf.org/id/draft-cavage-http-signatures-07.txt);

nevertheless, it's **strongly** recommended to use HTTPS, as HTTP

signatures offer no protection against replay attacks - besides risking

exposure of sensitive data.



##### Exceptions



By default, remote exceptions are returned as errors on the caller's

side. This behaviour can be tweaked using the

`rethrow_remote_exceptions` flag in `:call/5` options.



Remote stack traces are returned by default. Because they are

computationally expensive to generate, this behaviour can be can be

changed using the `return_exception_stacktraces` flag in

`:start_clear_server` / `:start_tls_server` backwater options.



##### Serialisation



The [external term format](http://erlang.org/doc/apps/erts/erl_ext_dist)

is used for all function arguments and return values.



Because trust is assumed unless declared otherwise (like in regular

Erlang clusters), unsafe terms are decoded by default.



For function arguments, this behaviour can be tweaked through the

`decode_unsafe_terms` setting in backwater options when running

`:start_clear_server` or `:start_tls_server`.



For return values, this behaviour can be tweaked through the

`decode_unsafe_terms` setting in `:call/5` options.



##### Compression



By default, both serialised function arguments and serialised return

values larger than 300 bytes are subject to attempted compression using

gzip. The actual compression result is only used if it is indeed smaller

than the original payload.



For function arguments, this threshold can be tweaked through the

`compression_threshold` setting in `:call/5` options.



For return values, this threshold can be tweaked through the

`compression_threshold` setting in backwater options when running

`:start_clear_server` or `:start_tls_server`.



##### Payload limits



By default, both serialised function arguments and serialised return

values larger than 8 MiB are rejected (independently of whether they're

transmitted in compressed form or not.)



For function arguments, this limit (in bytes) can be adjusted using the

`max_encoded_args_size` setting in backwater options when running

`:start_clear_server` or `:start_tls_server`.



For return values, this limit (in bytes) can be adjusted using the

`max_encoded_result_size` setting in `:call/5` options.



##### Timeouts and ports



The default listen port for HTTP is 8080; for HTTPS, it's 8443. This can

be adjusted on server using the `http` options, and on clients by

specifying it in `Endpoint`.



The client enforces a default connection timeout of 8s, and a receive

timeout of 5s. Either can be adjusted using either `connect_timeout` or

`recv_timeout`, respectively, in `:call/5` options.



The server enforces a default receive timeout of 5s. This can be

adjusted using the `recv_timeout` setting in backwater options, when

running `:start_clear_server` or `:start_tls_server`.



##### On using alternative HTTP clients



For now, the best way to achieve this is to build requests using the

`backwater_request` module and interpret responses using the

`backwater_response` module.



#### License



MIT License



Copyright (c) 2017-2022 Guilherme Andrade



Permission is hereby granted, free of charge, to any person obtaining a

copy of this software and associated documentation files (the

"Software"), to deal in the Software without restriction, including

without limitation the rights to use, copy, modify, merge, publish,

distribute, sublicense, and/or sell copies of the Software, and to

permit persons to whom the Software is furnished to do so, subject to

the following conditions:



The above copyright notice and this permission notice shall be included

in all copies or substantial portions of the Software.



THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY

CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,

TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.