How to connect elixir phoenix api with docker container?

Phoenix Forum Questions / Help
, , ,
1

I have a application that was running on windows communicating with posgres via postgres mappig localhost8080 to 5432 on postgres container
altought now I need to run everything on linux container, and I cant get to connect my api with postgres even if they were working before, so my question is
How can I do them to communicate with each other? How can I put them in the same network and organize commucation?
I need the elixir app to have all ports exposed to test tcp connections, so a simple intern redirect thing wouldnt work
my docker compose file

version: '3.9'

services:
  elixir_app:
    build:
      context: .
      dockerfile: Dockerfile
    deploy:
      resources:
        limits:
          memory: 25GB
          cpus: "12"
        reservations:
          memory: "0"
          cpus: "0"
    stdin_open: true
    tty: true
  postis:
    image: postgres
    container_name: postis
    environment:
      POSTGRES_PASSWORD: 12345
      POSTGRES_USER: pedri
    ports:
      - "5432:5432"
    volumes:
      - postgres_data:C:\Users\henri\Documents

volumes:
  postgres_data:

config

config :testespay, Testespay.Repo,
  log: false,
  database: "teste10",
  user: "pedri",
  password: "12345",
  hostname: "localhost",
  port: 5432

when I try to run this app container, I get the error

14:17:33.153 [error] Failure while translating Erlang's logger event
** (MatchError) no match of right hand side value: %{label: {:gen_statem, :terminate}, name: #PID<0.507.0>, reason: {:error, %KeyError{key: :username, term: [pool_index: 8, types: Postgrex.DefaultTypes, pool: DBConnection.ConnectionPool, repo: Testespay.Repo, telemetry_prefix: [:testespay, :repo], otp_app: :testespay, timeout: 15000, pool_size: 10, log: false, database: "teste10", user: "pedri", password: "12345", hostname: "localhost", port: 5431, show_sensitive_data_on_connection_error: true], message: nil}, [{Keyword, :fetch!, 2, [file: ~c"lib/keyword.ex", line: 602]}, {Postgrex.Protocol, :startup, 2, [file: ~c"lib/postgrex/protocol.ex", line: 833]}, {Postgrex.Protocol, :handshake, 3, [file: ~c"lib/postgrex/protocol.ex", line: 729]}, {Postgrex.Protocol, :connect_endpoints, 6, [file: ~c"lib/postgrex/protocol.ex", line: 209]}, {DBConnection.Connection, :handle_event, 4, [file: ~c"lib/db_connection/connection.ex", line: 74]}, {:gen_statem, :loop_state_callback, 11, [file: ~c"gen_statem.erl", line: 1397]}, {:proc_lib, :init_p_do_apply, 3, [file: ~c"proc_lib.erl", line: 241]}]}, log: [], state: Postgrex.Protocol, queue: [internal: {:connect, :init}], modules: [DBConnection.Connection], client_info: :undefined, callback_mode: :handle_event_function, postponed: [], timeouts: {0, []}, state_enter: false}
    (logger 1.17.0) lib/logger/translator.ex:306: Logger.Translator.report_gen_statem_terminate/2
    (logger 1.17.0) lib/logger/utils.ex:47: Logger.Utils.translate/5
    (logger 1.17.0) lib/logger/utils.ex:25: Logger.Utils.translator/2
    (kernel 9.2.2) logger_backend.erl:101: :logger_backend.do_apply_filters/4
    (kernel 9.2.2) logger_backend.erl:86: :logger_backend.apply_filters/4
    (kernel 9.2.2) logger_backend.erl:32: :logger_backend.log_allowed/3
    (stdlib 5.2.1) gen_statem.erl:2591: :gen_statem.terminate/7
    (stdlib 5.2.1) proc_lib.erl:241: :proc_lib.init_p_do_apply/3

14:17:33.150 [error] Failure while translating Erlang's logger event
** (MatchError) no match of right hand side value: %{label: {:gen_statem, :terminate}, name: #PID<0.509.0>, reason: {:error, %KeyError{key: :username, term: [pool_index: 2, types: Postgrex.DefaultTypes, pool: DBConnection.ConnectionPool, repo: Testespay.Repo, telemetry_prefix: [:testespay, :repo], otp_app: :testespay, timeout: 15000, pool_size: 10, log: false, database: "teste10", user: "pedri", password: "12345", hostname: "localhost", port: 5431, show_sensitive_data_on_connection_error: true], message: nil}, [{Keyword, :fetch!, 2, [file: ~c"lib/keyword.ex", line: 602]}, {Postgrex.Protocol, :startup, 2, [file: ~c"lib/postgrex/protocol.ex", line: 833]}, {Postgrex.Protocol, :handshake, 3, [file: ~c"lib/postgrex/protocol.ex", line: 729]}, {Postgrex.Protocol, :connect_endpoints, 6, [file: ~c"lib/postgrex/protocol.ex", line: 209]}, {DBConnection.Connection, :handle_event, 4, [file: ~c"lib/db_connection/connection.ex", line: 74]}, {:gen_statem, :loop_state_callback, 11, [file: ~c"gen_statem.erl", line: 1397]}, {:proc_lib, :init_p_do_apply, 3, [file: ~c"proc_lib.erl", line: 241]}]}, log: [], state: Postgrex.Protocol, queue: [internal: {:connect, :init}], modules: [DBConnection.Connection], client_info: :undefined, callback_mode: :handle_event_function, postponed: [], timeouts: {0, []}, state_enter: false}
    (logger 1.17.0) lib/logger/translator.ex:306: Logger.Translator.report_gen_statem_terminate/2
    (logger 1.17.0) lib/logger/utils.ex:47: Logger.Utils.translate/5
    (logger 1.17.0) lib/logger/utils.ex:25: Logger.Utils.translator/2
    (kernel 9.2.2) logger_backend.erl:101: :logger_backend.do_apply_filters/4
    (kernel 9.2.2) logger_backend.erl:86: :logger_backend.apply_filters/4
    (kernel 9.2.2) logger_backend.erl:32: :logger_backend.log_allowed/3
    (stdlib 5.2.1) gen_statem.erl:2591: :gen_statem.terminate/7
    (stdlib 5.2.1) proc_lib.erl:241: :proc_lib.init_p_do_apply/3

the network info around
1-> the network container
2-> postgres container

"Networks": {
			"host": {
				"IPAMConfig": null,
				"Links": null,
				"Aliases": null,
				"MacAddress": "",
				"DriverOpts": null,
				"NetworkID": "1ea463e456351180d5d16950cc6c451dc7a64e9a030901f04c141f9f49808176",
				"EndpointID": "41f016f6a0ac589e0dfa29f0e0c371fe055797edf2e24e7f013430406a1930c4",
				"Gateway": "",
				"IPAddress": "",
				"IPPrefixLen": 0,
				"IPv6Gateway": "",
				"GlobalIPv6Address": "",
				"GlobalIPv6PrefixLen": 0,
				"DNSNames": null
			}

"Networks": {
			"fpay_default": {
				"IPAMConfig": null,
				"Links": null,
				"Aliases": [
					"postiscompose",
					"postiscompose"
				],
				"MacAddress": "02:42:ac:12:00:02",
				"DriverOpts": null,
				"NetworkID": "7b5a170b04b96013cf9f2ddc635cd64af162dc58bef6c078a2e3b6a52e468083",
				"EndpointID": "0fe7f9fbc7aa503bd4e8fc64cd8241f688b3873765a82cc7a8e0c73520657ca1",
				"Gateway": "172.18.0.1",
				"IPAddress": "172.18.0.2",

so I tried running the app with a docker alone postgres (only with images and not compose anymore)
this is the network result
container app

"Networks": {
			"bridge": {
				"IPAMConfig": null,
				"Links": null,
				"Aliases": null,
				"MacAddress": "02:42:ac:11:00:03",
				"DriverOpts": null,
				"NetworkID": "a7f2086d19490cea6832395ef97ccb4b05f31bea753bcc4cefbaa4c10ca36b3a",
				"EndpointID": "b684a7e8e50f3a302f08fca7db7ad9a69bbff62f1aaedb3d18a5c8785f392f49",
				"Gateway": "172.17.0.1",
				"IPAddress": "172.17.0.3",
				"IPPrefixLen": 16,
				"IPv6Gateway": "",
				"GlobalIPv6Address": "",
				"GlobalIPv6PrefixLen": 0,
				"DNSNames": null
			}

postgres

"Networks": {
			"bridge": {
				"IPAMConfig": null,
				"Links": null,
				"Aliases": null,
				"MacAddress": "02:42:ac:11:00:02",
				"DriverOpts": null,
				"NetworkID": "a7f2086d19490cea6832395ef97ccb4b05f31bea753bcc4cefbaa4c10ca36b3a",
				"EndpointID": "67c5e450a0b3cadf645b1c458bbc72f8e6325b6e3bec340d1b5b5905d9368313",
				"Gateway": "172.17.0.1",
				"IPAddress": "172.17.0.2",
				"IPPrefixLen": 16,
				"IPv6Gateway": "",
				"GlobalIPv6Address": "",
				"GlobalIPv6PrefixLen": 0,

I mapped postgres to 5431:5432 on host, and modified my config arquive to connect to localhost:5432

with this second configuration (2 stadalone containers instead of compose)
Im abble to connect to db, but I got timeout, apparently the connections doesnt close itselt, bcs I never had this error when runnig this application before

[error] Postgrex.Protocol (#PID<0.463.0>) timed out because it was handshaking for longer than 15000ms
[error] Postgrex.Protocol (#PID<0.463.0>) failed to connect: ** (DBConnection.ConnectionError) tcp recv (idle): closed
[error] Postgrex.Protocol (#PID<0.464.0>) timed out because it was handshaking for longer than 15000ms
[error] Postgrex.Protocol (#PID<0.464.0>) failed to connect: ** (DBConnection.ConnectionError) tcp recv (idle): closed
[error] Postgrex.Protocol (#PID<0.462.0>) timed out because it was handshaking for longer than 15000ms
[error] Postgrex.Protocol (#PID<0.462.0>) failed to connect: ** (DBConnection.ConnectionError) tcp recv (idle): closed
[error] Postgrex.Protocol (#PID<0.469.0>) timed out because it was handshaking for longer than 15000ms
[error] Postgrex.Protocol (#PID<0.469.0>) failed to connect: ** (DBConnection.ConnectionError) tcp recv (idle): closed
[error] Postgrex.Protocol (#PID<0.470.0>) timed out because it was handshaking for longer than 15000ms
2

no idea why my application on containers were giving me those weird debug messages, but I ran the app on a normal WSL2 ubuntu and could check the error

: connection refused - :econnrefused
[error] Postgrex.Protocol (#PID<0.467.0>) failed to connect: ** (DBConnection.ConnectionError) tcp connect (localhost:5432): connection refused - :econnrefused

the network mapping was corretly defined (postgres running on localhost ports and mapped) but my config.ex connection port (5431) was being override by connection port on dev.ex (5432)

3

That’s how Elixir’s config works though. Check the bottom of your config.exs?

4

You need to use postis as your hostname not localhost.

1 Like
5

You need to use postis as your hostname not localhost.

Not with their current config.

Using the ports mapping 5432:5432 will expose the service at port 5432 on the host, so localhost is correct in that case.

If the ports mapping was just 5432, then you would be correct.

@henriquesati Are you using the Dockerfile that comes with Phoenix? Because if you are, then your settings are probably being loaded from prod.exs (among others) since IIRC the default Dockerfile builds a production-ready container. So the config would loaded in this order: config.exs → prod.exs → runtime.exs (the later files overwrite any settings in the earlier files).

IMO, these DB/repo settings should be in runtime.exs 100% of the time anyway. But that’s a whole other can of worms.

1 Like
6

Sure but… WSL2. I heard stories about Docker not always doing what it’s supposed to do in this environment. I’d still stick to the host names inside the docker-compose.yml file.

1 Like
7

on my config file? why?

8

exactly, i’m trying to make base level config to deploy in any ec2 with docker compose, this without any dependency using or being build by wsl2, only contaieners
problem is the dev-env needs the app to connect to the postgres when I compose (what its not happening)