Using IEx with a remote API with HTTPoison, it can be handy to show int he console the request and response you get back with hackney.
You can do this by entering the following in iex:
:hackney_trace.enable(:max, :io)
You can also add this to .iex.exs file so it’ll always be added to your iex sessions by default so you don’t need to always retype it when needed.
This will give you an output like this:
iex(1)> HTTPoison.get("https://jsonplaceholder.typicode.com/todos/1")
[hackney trace 80 <0.208.0> 2020:01:10 11:59:45 4110] request
Content: [{module,hackney},
{line,311},
{method,get},
{url,{hackney_url,hackney_ssl,https,
<<"jsonplaceholder.typicode.com">>,
<<"/todos/1">>,<<"/todos/1">>,<<>>,<<>>,
"jsonplaceholder.typicode.com",443,<<>>,<<>>}},
{headers,[]},
{body,<<>>},
{options,[]}]
[hackney trace 60 <0.208.0> 2020:01:10 11:59:45 4110] request without proxy
Content: [{module,hackney},{line,683}]
[hackney trace 60 <0.208.0> 2020:01:10 11:59:45 4110] connect
Content: [{module,hackney_connect},
{line,35},
{transport,hackney_ssl},
{host,"jsonplaceholder.typicode.com"},
{port,443},
{dynamic,true}]
[hackney trace 80 <0.208.0> 2020:01:10 11:59:45 4111] no socket in the pool
Content: [{module,hackney_connect},{line,230},{pool,default}]
[hackney trace 80 <0.208.0> 2020:01:10 11:59:45 4481] new connection
Content: [{module,hackney_connect},{line,279}]
[hackney trace 40 <0.208.0> 2020:01:10 11:59:45 4481] perform request
Content: [{module,hackney_request},
{line,102},
{header_data,[<<"GET /todos/1 HTTP/1.1\r\n">>,
[[<<"Host">>,": ",
<<"jsonplaceholder.typicode.com">>,"\r\n"],
[<<"User-Agent">>,": ",<<"hackney/1.15.2">>,
"\r\n"],
"\r\n"]]},
{perform_all,true},
{expect,false}]
[hackney trace 80 <0.208.0> 2020:01:10 11:59:45 4530] got response
Content: [{module,hackney},
{line,379},
{response,
{ok,200,
[{<<"Date">>,<<"Fri, 10 Jan 2020 12:00:32 GMT">>},
{<<"Content-Type">>,
<<"application/json; charset=utf-8">>},
{<<"Content-Length">>,<<"83">>},
{<<"Connection">>,<<"keep-alive">>},
{<<"Set-Cookie">>,
<<"__cfduid=d57cd6aa517712b71a7bdc8b947d36ad31578657632; expires=Sun, 09-Feb-20 12:00:32 GMT; path=/; domain=.typicode.com; HttpOnly; SameSite=Lax">>},
{<<"X-Powered-By">>,<<"Express">>},
{<<"Vary">>,<<"Origin, Accept-Encoding">>},
{<<"Access-Control-Allow-Credentials">>,<<"true">>},
{<<"Cache-Control">>,<<"max-age=14400">>},
{<<"Pragma">>,<<"no-cache">>},
{<<"Expires">>,<<"-1">>},
{<<"X-Content-Type-Options">>,<<"nosniff">>},
{<<"Etag">>,<<"W/\"53-hfEnumeNh6YirfjyjaujcOPPT+s\"">>},
{<<"Via">>,<<"1.1 vegur">>},
{<<"CF-Cache-Status">>,<<"HIT">>},
{<<"Age">>,<<"6237">>},
{<<"Accept-Ranges">>,<<"bytes">>},
{<<"Expect-CT">>,
<<"max-age=604800, report-uri=\"https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct\"">>},
{<<"Server">>,<<"cloudflare">>},
{<<"CF-RAY">>,<<"552e7dbadb66df30-MEL">>}],
{client,
{1578,657585,110420},
{metrics_ng,metrics_dummy},
hackney_ssl,"jsonplaceholder.typicode.com",443,
<<"jsonplaceholder.typicode.com">>,[],
{sslsocket,
{gen_tcp,#Port<0.27>,tls_connection,undefined},
[<0.257.0>,<0.256.0>]},
{default,#Ref<0.437769858.2554068993.81094>,
{"jsonplaceholder.typicode.com",443,hackney_ssl},
<0.234.0>,hackney_ssl},
#Ref<0.437769858.2554068993.81094>,true,hackney_pool,
5000,false,5,false,5,nil,nil,
{hparser,response,4096,10,0,on_body,
<<"{\n \"userId\": 1,\n \"id\": 1,\n \"title\": \"delectus aut autem\",\n \"completed\": false\n}">>,
{1,1},
<<>>,[],83,<<>>,<<"keep-alive">>,
<<"application/json; charset=utf-8">>,<<>>,
waiting},
{20,
{dict,20,16,16,8,80,48,
{[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],
[]},
{{[[<<"content-length">>,
{2,<<"Content-Length">>,<<"83">>}],
[<<"accept-ranges">>,
{16,<<"Accept-Ranges">>,<<"bytes">>}]],
[],
[[<<"date">>,
{0,<<"Date">>,
<<"Fri, 10 Jan 2020 12:00:32 GMT">>}],
[<<"x-content-type-options">>,
{11,<<"X-Content-Type-Options">>,
<<"nosniff">>}],
[<<"cf-cache-status">>,
{14,<<"CF-Cache-Status">>,<<"HIT">>}],
[<<"expect-ct">>,
{17,<<"Expect-CT">>,
<<"max-age=604800, report-uri=\"https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct\"">>}],
[<<"cf-ray">>,
{19,<<"CF-RAY">>,
<<"552e7dbadb66df30-MEL">>}]],
[[<<"expires">>,{10,<<"Expires">>,<<"-1">>}]],
[],
[[<<"etag">>,
{12,<<"Etag">>,
<<"W/\"53-hfEnumeNh6YirfjyjaujcOPPT+s\"">>}],
[<<"server">>,
{18,<<"Server">>,<<"cloudflare">>}]],
[[<<"vary">>,
{6,<<"Vary">>,
<<"Origin, Accept-Encoding">>}]],
[[<<"cache-control">>,
{8,<<"Cache-Control">>,
<<"max-age=14400">>}]],
[],
[[<<"x-powered-by">>,
{5,<<"X-Powered-By">>,<<"Express">>}]],
[[<<"content-type">>,
{1,<<"Content-Type">>,
<<"application/json; charset=utf-8">>}],
[<<"pragma">>,
{9,<<"Pragma">>,<<"no-cache">>}],
[<<"age">>,{15,<<"Age">>,<<"6237">>}]],
[[<<"access-control-allow-credentials">>,
{7,<<"Access-Control-Allow-Credentials">>,
<<"true">>}]],
[[<<"connection">>,
{3,<<"Connection">>,<<"keep-alive">>}]],
[[<<"set-cookie">>,
{4,<<"Set-Cookie">>,
<<"__cfduid=d57cd6aa517712b71a7bdc8b947d36ad31578657632; expires=Sun, 09-Feb-20 12:00:32 GMT; path=/; domain=.typicode.com; HttpOnly; SameSite=Lax">>}],
[<<"via">>,{13,<<"Via">>,<<"1.1 vegur">>}]],
[],[]}}}},
connected,waiting,nil,normal,false,false,false,
undefined,false,fun hackney_request:send/2,waiting,
nil,4096,<<>>,[],
{1,1},
83,nil,nil,<<"GET">>,<<"/todos/1">>,nil}}},
{client,
{client,
{1578,657585,110420},
{metrics_ng,metrics_dummy},
hackney_ssl,"jsonplaceholder.typicode.com",443,
<<"jsonplaceholder.typicode.com">>,[],
{sslsocket,
{gen_tcp,#Port<0.27>,tls_connection,undefined},
[<0.257.0>,<0.256.0>]},
{default,#Ref<0.437769858.2554068993.81094>,
{"jsonplaceholder.typicode.com",443,hackney_ssl},
<0.234.0>,hackney_ssl},
#Ref<0.437769858.2554068993.81094>,true,hackney_pool,
5000,false,5,false,5,nil,nil,nil,
{0,
{dict,0,16,16,8,80,48,
{[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]},
{{[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],
[]}}}},
connected,start,nil,normal,false,false,false,undefined,
false,nil,waiting,nil,4096,<<>>,[],undefined,nil,nil,nil,
nil,undefined,nil}}]
{:ok,
%HTTPoison.Response{
body: "{\n \"userId\": 1,\n \"id\": 1,\n \"title\": \"delectus aut autem\",\n \"completed\": false\n}",
headers: [
{"Date", "Fri, 10 Jan 2020 12:00:32 GMT"},
{"Content-Type", "application/json; charset=utf-8"},
{"Content-Length", "83"},
{"Connection", "keep-alive"},
{"Set-Cookie",
"__cfduid=d57cd6aa517712b71a7bdc8b947d36ad31578657632; expires=Sun, 09-Feb-20 12:00:32 GMT; path=/; domain=.typicode.com; HttpOnly; SameSite=Lax"},
{"X-Powered-By", "Express"},
{"Vary", "Origin, Accept-Encoding"},
{"Access-Control-Allow-Credentials", "true"},
{"Cache-Control", "max-age=14400"},
{"Pragma", "no-cache"},
{"Expires", "-1"},
{"X-Content-Type-Options", "nosniff"},
{"Etag", "W/\"53-hfEnumeNh6YirfjyjaujcOPPT+s\""},
{"Via", "1.1 vegur"},
{"CF-Cache-Status", "HIT"},
{"Age", "6237"},
{"Accept-Ranges", "bytes"},
{"Expect-CT",
"max-age=604800, report-uri=\"https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct\""},
{"Server", "cloudflare"},
{"CF-RAY", "552e7dbadb66df30-MEL"}
],
request: %HTTPoison.Request{
body: "",
headers: [],
method: :get,
options: [],
params: %{},
url: "https://jsonplaceholder.typicode.com/todos/1"
},
request_url: "https://jsonplaceholder.typicode.com/todos/1",
status_code: 200
}}