The Problem

I am following the Getting Started Guide at https://hexdocs.pm/ecto/getting-started.html, trying to set up in a docker container. The steps in the guide work on my physical machine, but when I follow them for the container, I get the following error when I run mix ecto.create at the appropriate step:

04:48:05.579 [error] GenServer #PID<0.177.0> terminating
** (RuntimeError) Connect raised a FunctionClauseError error. The exception details are hidden, as
they may contain sensitive data such as database credentials.

    (postgrex) lib/postgrex/messages.ex:371: Postgrex.Messages.decode_auth_type/1
    (postgrex) lib/postgrex/messages.ex:64: Postgrex.Messages.parse/3
    (postgrex) lib/postgrex/protocol.ex:2004: Postgrex.Protocol.msg_decode/1
    (postgrex) lib/postgrex/protocol.ex:1978: Postgrex.Protocol.msg_recv/3
    (postgrex) lib/postgrex/protocol.ex:589: Postgrex.Protocol.auth_recv/3
    (postgrex) lib/postgrex/protocol.ex:504: Postgrex.Protocol.handshake/2
    (db_connection) lib/db_connection/connection.ex:135: DBConnection.Connection.connect/2
    (connection) lib/connection.ex:622: Connection.enter_connect/5
Last message: nil
** (Mix) The database for Friends.Repo couldn't be created: an exception was raised:
    ** (RuntimeError) Connect raised a FunctionClauseError error. The exception details are hidden, as
they may contain sensitive data such as database credentials.

        (postgrex) lib/postgrex/messages.ex:371: Postgrex.Messages.decode_auth_type/1
        (postgrex) lib/postgrex/messages.ex:64: Postgrex.Messages.parse/3
        (postgrex) lib/postgrex/protocol.ex:2004: Postgrex.Protocol.msg_decode/1
        (postgrex) lib/postgrex/protocol.ex:1978: Postgrex.Protocol.msg_recv/3
        (postgrex) lib/postgrex/protocol.ex:589: Postgrex.Protocol.auth_recv/3
        (postgrex) lib/postgrex/protocol.ex:504: Postgrex.Protocol.handshake/2
        (db_connection) lib/db_connection/connection.ex:135: DBConnection.Connection.connect/2
        (connection) lib/connection.ex:622: Connection.enter_connect/5

The Situation/Configuration

I have set up Postgres in my docker container so that the postgres user has a password, and I have used that password in the config/config.exs file. I know the password works, as I can use psql with it. The config file mentioned looks like this:

use Mix.Config

config :friends, Friends.Repo,
  adapter: Ecto.Adapters.Postgres,
  database: "friends_repo",
  username: "postgres",
  password: "<password>",
  hostname: "localhost"


config :friends, ecto_repos: [Friends.Repo]

Now, since there is always a request for the pg_hba.conf file in similar situations, I provide that below. (As this is a development machine, I am less concered about security than I am about getting something working in the first place.)

local   all             postgres                                md5
# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     peer
# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     peer
host    replication     all             127.0.0.1/32            md5
host    replication     all             ::1/128                 md5

Finally, the following are the versions of related applications and tools.

Postgres

                                                    version
-----------------------------------------------------------------------------------------------------------------------------
     PostgreSQL 10.5 (Ubuntu 10.5-0ubuntu0.18.04) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 7.3.0-16ubuntu3) 7.3.0, 64-bit

Elixir

Erlang/OTP 21 [erts-10.0.5] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe]

Elixir 1.7.2 (compiled with Erlang/OTP 20)

Running Command: mix deps.update

Resolving Hex dependencies...
Dependency resolution completed:
Unchanged:
  connection 1.0.4
  db_connection 1.1.3
  decimal 1.5.0
  ecto 2.2.10
  poolboy 1.5.1
  postgrex 0.13.5

Final Notes

I’ve read similar topics and problems on this forum, on github, and other places found from Google, but the answers I found did not help. Thus, my hope is that someone here can provide some direction and help get things working.

Thank you in advance.