How can I get TLS working with Erlang 21? - ssl

Question

I have the following problem:
Elixir
[centos#ip-172-172-3-49 helix]$ env MIX_ENV=prod mix release
Could not find Hex, which is needed to build dependency :plug_cowboy
Shall I install Hex? (if running non-interactively, use "mix local.hex --force") [Yn] Y
18:12:32.462 [info] ['TLS', 32, 'client', 58, 32, 73, 110, 32, 115, 116, 97, 116, 101, 32, 'hello', 32, 'received SERVER ALERT: Fatal - Handshake Failure', 10]
** (Mix) httpc request failed with: {:failed_connect, [{:to_address, {'repo.hex.pm', 443}}, {:inet6, [:inet6], :enetunreach}, {:inet, [:inet], {:tls_alert, 'handshake failure'}}]}
Could not install Hex because Mix could not download metadata at https://repo.hex.pm/installs/hex-1.x.csv.
I guess the root cause is this with Erlang
Erlang/OTP 21 [erts-10.2.1] [source] [64-bit] [smp:36:36] [ds:36:36:10] [async-threads:1] [hipe]
1> ssl:start().
ok
2> Sock = fun() -> {ok, S} = gen_tcp:connect("google.com", 443, []), S end.
#Fun<erl_eval.20.128620087>
3> ssl:connect(Sock(), []).
=INFO REPORT==== 28-Dec-2018::18:10:30.019612 ===
TLS client: In state hello received SERVER ALERT: Fatal - Handshake Failure
{error,{tls_alert,"handshake failure"}}
Is there a workaround for this yet? Os is Centos 7.
Update1
On MacOS it works:
Erlang/OTP 21 [erts-10.2] [source] [64-bit] [smp:6:6] [ds:6:6:10] [async-threads:1] [hipe] [dtrace]
Eshell V10.2 (abort with ^G)
1> ssl:start().
ok
2> Sock = fun() -> {ok, S} = gen_tcp:connect("google.com", 443, []), S end.
#Fun<erl_eval.20.128620087>
3> ssl:connect(Sock(), []).
{ok,{sslsocket,{gen_tcp,#Port<0.6>,tls_connection,undefined},
[<0.100.0>,<0.99.0>]}}
4>

Answer 1

It turns out that the Erlang RPM I was using does not support the new SSL in Erlang properly.
https://github.com/rabbitmq/erlang-rpm/releases/download/v21.2.1/erlang-21.2.1-1.el7.centos.x86_64.rpm
Using a different version from Erlang Solutions works fine:
https://packages.erlang-solutions.com/erlang/esl-erlang/FLAVOUR_1_general/esl-erlang_21.2-1~centos~7_amd64.rpm

Answer 2

ssl:connect/2 is described here: http://erlang.org/doc/man/ssl.html#connect-2.
Connecting is as easy as:
ssl:start().
ssl:connect("www.google.com", 443, []).