krakend connection refused 500

Question

I have this krakend.json:

{
    "$schema": "https://www.krakend.io/schema/v2.4/krakend.json",
    "version": 3,
    "port": 8080,
    "host": ["http://localhost:8080"],
    "endpoints": [
        {
          "@comment": "Bla bla",
          "endpoint": "/app/{identification}",
          "backend": [
            {
              "host": ["http://localhost:4802"],
              "url_pattern": "/app/{identification}"
            }
          ]
        }
    ]
}

my docker-compose.yml:

version: "3"
services:
  krakend_ce:
    # The :watch image restarts the service automatically when the configuration files change.
    # Do not use this image in production, it's meant to speed up your testing and development.
    image: devopsfaith/krakend:watch
    volumes:
      - .:/etc/krakend
    ports:
      - "1234:1234"
      - "8080:8080"
      - "8090:8090"
    command: ["run", "-d", "-c", "/etc/krakend/krakend.json"]
    depends_on:
      - myservice
  myservice:
    image: myservice:latest
    volumes:
      - ./config/application.yaml:/usr/application/config/application.yaml:ro
      - ./logs:/usr/application/logs
    ports:
      - "4802:4802"

Those containers:

docker ps
CONTAINER ID   IMAGE                       COMMAND                  CREATED          STATUS          PORTS                                                                                                                             NAMES
a8b301aed1c3   devopsfaith/krakend:watch   "/entrypoint.sh run …"   2 minutes ago    Up 6 seconds    0.0.0.0:1234->1234/tcp, :::1234->1234/tcp, 0.0.0.0:8080->8080/tcp, :::8080->8080/tcp, 0.0.0.0:8090->8090/tcp, :::8090->8090/tcp   myservice_krakend_ce_1
a1cd2e890510   myservice:latest         "java -Djava.securit…"   28 minutes ago   Up 28 minutes   0.0.0.0:4802->4802/tcp, :::4802->4802/tcp                                                                                         myservice_1

The log:

 docker logs -f a8b301aed1c3
Watching changes on files /etc/krakend/
Ignoring saves to file out.json
[00] Starting service
[00] Parsing configuration file: /etc/krakend/krakend.json
[00] 2023/09/20 12:29:45 KRAKEND INFO: Starting KrakenD v2.4.3
[00] 2023/09/20 12:29:45 KRAKEND DEBUG: [SERVICE: Gin] Debug enabled
[00] 2023/09/20 12:29:45 KRAKEND INFO: Starting the KrakenD instance
[00] 2023/09/20 12:29:45 KRAKEND DEBUG: [ENDPOINT: /app/:identification] Building the proxy pipe
[00] 2023/09/20 12:29:45 KRAKEND DEBUG: [BACKEND: /app/{{.identification}}] Building the backend pipe
[00] 2023/09/20 12:29:45 KRAKEND DEBUG: [ENDPOINT: /app/:identification] Building the http handler
[00] 2023/09/20 12:29:45 KRAKEND DEBUG: [ENDPOINT: /app/:identification][JWTSigner] Signer disabled
[00] 2023/09/20 12:29:45 KRAKEND INFO: [ENDPOINT: /app/:identification][JWTValidator] Validator disabled for this endpoint
[00] 2023/09/20 12:29:45 KRAKEND INFO: [SERVICE: Gin] Listening on port: 8080
[00] [GIN] 2023/09/20 - 12:30:07 | 200 |     122.211µs |      172.18.0.1 | GET      "/__health"
[00] [GIN] 2023/09/20 - 12:30:08 | 200 |      28.809µs |      172.18.0.1 | GET      "/__health"
[00] [GIN] 2023/09/20 - 12:30:09 | 200 |      53.791µs |      172.18.0.1 | GET      "/__health"
[00] 2023/09/20 12:30:16 KRAKEND ERROR: [ENDPOINT: /app/:identification] Get "http://localhost:4802/app/110033323312176": dial tcp 127.0.0.1:4802: connect: connection refused
[00] [GIN] 2023/09/20 - 12:30:16 | 500 |     703.485µs |      172.18.0.1 | GET      "/app/110033323312176"
[00] Error #01: Get "http://localhost:4802/app/110033323312176": dial tcp 127.0.0.1:4802: connect: connection refused
[00] 2023/09/20 12:30:16 KRAKEND ERROR: [ENDPOINT: /app/:identification] Get "http://localhost:4802/app/110033323312176": dial tcp 127.0.0.1:4802: connect: connection refused
[00] [GIN] 2023/09/20 - 12:30:16 | 500 |      541.71µs |      172.18.0.1 | GET      "/app/110033323312176"
[00] Error #01: Get "http://localhost:4802/app/110033323312176": dial tcp 127.0.0.1:4802: connect: connection refused
Watching changes on files /etc/krakend/
Ignoring saves to file out.json
[00] Starting service
[00] Parsing configuration file: /etc/krakend/krakend.json
[00] 2023/09/20 12:31:59 KRAKEND INFO: Starting KrakenD v2.4.3
[00] 2023/09/20 12:31:59 KRAKEND DEBUG: [SERVICE: Gin] Debug enabled
[00] 2023/09/20 12:31:59 KRAKEND INFO: Starting the KrakenD instance
[00] 2023/09/20 12:31:59 KRAKEND DEBUG: [ENDPOINT: /app/:identification] Building the proxy pipe
[00] 2023/09/20 12:31:59 KRAKEND DEBUG: [BACKEND: /app/{{.identification}}] Building the backend pipe
[00] 2023/09/20 12:31:59 KRAKEND DEBUG: [ENDPOINT: /app/:identification] Building the http handler
[00] 2023/09/20 12:31:59 KRAKEND DEBUG: [ENDPOINT: /app/:identification][JWTSigner] Signer disabled
[00] 2023/09/20 12:31:59 KRAKEND INFO: [ENDPOINT: /app/:identification][JWTValidator] Validator disabled for this endpoint
[00] 2023/09/20 12:31:59 KRAKEND INFO: [SERVICE: Gin] Listening on port: 8080
[00] 2023/09/20 12:33:15 KRAKEND ERROR: [ENDPOINT: /app/:identification] Get "http://localhost:4802/app/110033323312176": dial tcp 127.0.0.1:4802: connect: connection refused
[00] [GIN] 2023/09/20 - 12:33:15 | 500 |    1.070179ms |      172.18.0.1 | GET      "/app/110033323312176"
[00] Error #01: Get "http://localhost:4802/app/110033323312176": dial tcp 127.0.0.1:4802: connect: connection refused
[00] 2023/09/20 12:33:52 KRAKEND ERROR: [ENDPOINT: /app/:identification] Get "http://localhost:4802/app/110033323312176": dial tcp 127.0.0.1:4802: connect: connection refused
[00] [GIN] 2023/09/20 - 12:33:52 | 500 |     530.808µs |      172.18.0.1 | GET      "/app/110033323312176"
[00] Error #01: Get "http://localhost:4802/app/110033323312176": dial tcp 127.0.0.1:4802: connect: connection refused

I called: http://localhost:8080/app/110033323312176 and i got an error.

Answer 1

You are making KrakenD connect to http://localhost:4802.

This port does not exist in the KrakenD container, but in your application container. You should change the configuration to:

 "host": ["http://myservice:4802"],