README.md

katipo

An HTTP/HTTP2 client library for Erlang built around libcurl-multi and libevent.

Status

Usage

{ok, _} = application:ensure_all_started(katipo).
Pool = api_server,
{ok, _} = katipo_pool:start(Pool, 2, [{pipelining, multiplex}]).
Url = <<"https://example.com">>.
ReqHeaders = [{<<"User-Agent">>, <<"katipo">>}].
Opts = #{headers => ReqHeaders,
         body => <<"0d5cb3c25b0c5678d5297efa448e1938">>,
         connecttimeout_ms => 5000,
         proxy => <<"http://127.0.0.1:9000">>,
         ssl_verifyhost => false,
         ssl_verifypeer => false},
{ok, #{status := 200,
       headers := RespHeaders,
       cookiejar := CookieJar,
       body := RespBody}} = katipo:post(Pool, Url, Opts).

Or passing the entire request as a map

{ok, _} = application:ensure_all_started(katipo).
Pool = api_server,
{ok, _} = katipo_pool:start(Pool, 2, [{pipelining, multiplex}]).
ReqHeaders = [{<<"User-Agent">>, <<"katipo">>}].
Req = #{url => <<"https://example.com">>.
        method => post,
        headers => ReqHeaders,
        body => <<"0d5cb3c25b0c5678d5297efa448e1938">>,
        connecttimeout_ms => 5000,
        proxy => <<"http://127.0.0.1:9000">>,
        ssl_verifyhost => false,
        ssl_verifypeer => false},
{ok, #{status := 200,
       headers := RespHeaders,
       cookiejar := CookieJar,
       body := RespBody}} = katipo:req(Pool, Req).

Why

We wanted a compatible and high-performance HTTP client so took advantage of the 15+ years of development that has gone into libcurl. To allow large numbers of simultaneous connections libevent is used along with the libcurl-multi interface.

Documentation

API

-type method() :: get | post | put | head | options.
katipo_pool:start(Name :: atom(), size :: pos_integer(), PoolOptions :: proplist()).
katipo_pool:stop(Name :: atom()).

katipo:req(Pool :: atom(), Req :: map()).
katipo:Method(Pool :: atom(), URL :: binary()).
katipo:Method(Pool :: atom(), URL :: binary(), ReqOptions :: map()).

Application Config

Option	Values	Default	Notes
mod_metrics	folsom | exometer | noop	noop	see erlang-metrics

Request options

Option	Type	Default	Notes
headers	[{binary(), iodata()}]	[]
cookiejar	opaque (returned in response)	[]
body	iodata()	<<>>
connecttimeout_ms	pos_integer()	30000	docs
followlocation	boolean()	false	docs
ssl_verifyhost	boolean()	true	docs
ssl_verifypeer	boolean()	true	docs
capath	binary()	undefined
cacert	binary()	undefined
timeout_ms	pos_integer()	30000
maxredirs	non_neg_integer()	9
proxy	binary()	undefined	docs
return_metrics	boolean()	false
tcp_fastopen	boolean()	false	docs curl >= 7.49.0
interface	binary()	undefined	docs
unix_socket_path	binary()	undefined	docs curl >= 7.40.0
lock_data_ssl_session	boolean()	false	docs curl >= 7.23.0
doh_url	binary()	undefined	docs curl >= 7.62.0
http_version	curl_http_version_none curl_http_version_1_0 curl_http_version_1_1 curl_http_version_2_0 curl_http_version_2tls curl_http_version_2_prior_knowledge	curl_http_version_none	docs curl >= 7.62.0
sslcert	binary()	undefined	docs
sslkey	binary()	undefined	docs
sslkey_blob	binary() (DER format)	undefined	docs curl >= 7.71.0
keypasswd	binary()	undefined	docs
http_auth	basic digest ntlm negotiate	undefined	docs
userpwd	binary()	undefined	docs

Responses

{ok, #{status := pos_integer(),
       headers := headers(),
       cookiejar := cookiejar(),
       body := body(),
       metrics => proplist()}}

{error, #{code := atom(), message := binary()}}

Pool Options

Option	Type	Default	Note
pipelining	nothing http1 multiplex	nothing	HTTP pipelining CURLMOPT_PIPELINING
max_pipeline_length	non_neg_integer()	100
max_total_connections	non_neg_integer()	0 (no limit)	docs

Metrics

• ok
• error
• status.XXX
• total_time
• curl_time
• namelookup_time
• connect_time
• appconnect_time
• pretransfer_time
• redirect_time
• starttransfer_time

System dependencies

• libevent-dev
• libcurl4-openssl-dev
• make
• curl
• libssl-dev
• gcc

Testing

The official Erlang Docker image has everything needed to build and test Katipo

TODO

• A more structured way to ifdef features based on curl version