C#•17mo ago

Local machine refuses to connect to an ASP.NET Core Web API container

Hello

I need to find out how to access my Docker container via the host machine. My connection is refused, no matter the tool I use (browser,

curl

curl

wget

wget

wget

wget, javascript's

fetch

fetch

). I've been looking for a solution since yesterday, but no success at all.
I've been trying to instantiate two containers within a same docker network, which is basically an ASP.NET Core Web API and a PostgreSQL server.

I have 0 Docker knowledge at all. I was using Rider's feature for instantiating containers and it worked properly. However, I decided to use a

docker-compose.yml

docker-compose.yml

file instead, because I was editing the same environment variables in both containers (such as PostgreSQL credentials and a default user seed data). I've deleted the IDE configuration before I actually start to build the

docker-compose.yml

docker-compose.yml

file as follows:

version: '3.8'

services:
  webapi:
    image: trsaints-frontend-api
    build:
      context: .
      dockerfile: Dockerfile
    environment:
      - JWT_SINGING_KEY=${JWT_SINGING_KEY}
      - JWT_ISSUER=${JWT_ISSUER}
      - JWT_AUDIENCE=${JWT_AUDIENCE}
      - DB_HOST=db
      - DB_PORT=5432
      - DB_NAME=${DB_NAME}
      - DB_USER=${DB_USER}
      - DB_PASSWORD=${DB_PASSWORD}
      - ALLOWED_HOSTS=${ALLOWED_HOSTS}
      - ALLOWED_CORS_DOMAINS=${ALLOWED_CORS_DOMAINS}
      - ADMIN_USERNAME=${ADMIN_USERNAME}
      - ADMIN_PASSWORD=${ADMIN_PASSWORD}
      - ASPNETCORE_URLS=http://localhost:8080
    ports:
      - "8082:8080"
      - "8081:8081"
    depends_on:
      - db
    networks:
      - trsaints-network

  db:
    image: postgres:alpine3.20
    environment:
      - POSTGRES_DB=${DB_NAME}
      - POSTGRES_USER=${DB_USER}
      - POSTGRES_PASSWORD=${DB_PASSWORD}
    ports:
      - "5433:5432"
    volumes:
      - postgres_data:/var/lib/postgresql/data
    networks:
      - trsaints-network

volumes:
  postgres_data:

networks:
  trsaints-network:

version: '3.8'

services:
  webapi:
    image: trsaints-frontend-api
    build:
      context: .
      dockerfile: Dockerfile
    environment:
      - JWT_SINGING_KEY=${JWT_SINGING_KEY}
      - JWT_ISSUER=${JWT_ISSUER}
      - JWT_AUDIENCE=${JWT_AUDIENCE}
      - DB_HOST=db
      - DB_PORT=5432
      - DB_NAME=${DB_NAME}
      - DB_USER=${DB_USER}
      - DB_PASSWORD=${DB_PASSWORD}
      - ALLOWED_HOSTS=${ALLOWED_HOSTS}
      - ALLOWED_CORS_DOMAINS=${ALLOWED_CORS_DOMAINS}
      - ADMIN_USERNAME=${ADMIN_USERNAME}
      - ADMIN_PASSWORD=${ADMIN_PASSWORD}
      - ASPNETCORE_URLS=http://localhost:8080
    ports:
      - "8082:8080"
      - "8081:8081"
    depends_on:
      - db
    networks:
      - trsaints-network

  db:
    image: postgres:alpine3.20
    environment:
      - POSTGRES_DB=${DB_NAME}
      - POSTGRES_USER=${DB_USER}
      - POSTGRES_PASSWORD=${DB_PASSWORD}
    ports:
      - "5433:5432"
    volumes:
      - postgres_data:/var/lib/postgresql/data
    networks:
      - trsaints-network

volumes:
  postgres_data:

networks:
  trsaints-network:

version: '3.8'

services:
  webapi:
    image: trsaints-frontend-api
    build:
      context: .
      dockerfile: Dockerfile
    environment:
      - JWT_SINGING_KEY=${JWT_SINGING_KEY}
      - JWT_ISSUER=${JWT_ISSUER}
      - JWT_AUDIENCE=${JWT_AUDIENCE}
      - DB_HOST=db
      - DB_PORT=5432
      - DB_NAME=${DB_NAME}
      - DB_USER=${DB_USER}
      - DB_PASSWORD=${DB_PASSWORD}
      - ALLOWED_HOSTS=${ALLOWED_HOSTS}
      - ALLOWED_CORS_DOMAINS=${ALLOWED_CORS_DOMAINS}
      - ADMIN_USERNAME=${ADMIN_USERNAME}
      - ADMIN_PASSWORD=${ADMIN_PASSWORD}
      - ASPNETCORE_URLS=http://localhost:8080
    ports:
      - "8082:8080"
      - "8081:8081"
    depends_on:
      - db
    networks:
      - trsaints-network

  db:
    image: postgres:alpine3.20
    environment:
      - POSTGRES_DB=${DB_NAME}
      - POSTGRES_USER=${DB_USER}
      - POSTGRES_PASSWORD=${DB_PASSWORD}
    ports:
      - "5433:5432"
    volumes:
      - postgres_data:/var/lib/postgresql/data
    networks:
      - trsaints-network

volumes:
  postgres_data:

networks:
  trsaints-network:

version: '3.8'

services:
  webapi:
    image: trsaints-frontend-api
    build:
      context: .
      dockerfile: Dockerfile
    environment:
      - JWT_SINGING_KEY=${JWT_SINGING_KEY}
      - JWT_ISSUER=${JWT_ISSUER}
      - JWT_AUDIENCE=${JWT_AUDIENCE}
      - DB_HOST=db
      - DB_PORT=5432
      - DB_NAME=${DB_NAME}
      - DB_USER=${DB_USER}
      - DB_PASSWORD=${DB_PASSWORD}
      - ALLOWED_HOSTS=${ALLOWED_HOSTS}
      - ALLOWED_CORS_DOMAINS=${ALLOWED_CORS_DOMAINS}
      - ADMIN_USERNAME=${ADMIN_USERNAME}
      - ADMIN_PASSWORD=${ADMIN_PASSWORD}
      - ASPNETCORE_URLS=http://localhost:8080
    ports:
      - "8082:8080"
      - "8081:8081"
    depends_on:
      - db
    networks:
      - trsaints-network

  db:
    image: postgres:alpine3.20
    environment:
      - POSTGRES_DB=${DB_NAME}
      - POSTGRES_USER=${DB_USER}
      - POSTGRES_PASSWORD=${DB_PASSWORD}
    ports:
      - "5433:5432"
    volumes:
      - postgres_data:/var/lib/postgresql/data
    networks:
      - trsaints-network

volumes:
  postgres_data:

networks:
  trsaints-network:

Both containers run properly, I just can't connect to the api container externally.

Thiago R.OP•8/17/24, 5:13 PM

Source Code

this is the API source code: https://github.com/trsaints/trsaints-frontend-api

The api container's http port is mapping to 8082 becaues I have an apache server running on the host's 8080 port. But that shouldn't be an issue at all, as far as I know.

What I've tried until then

Also, I've tried the following suggestions from forum posts with related issues:

Checking `iptables` rules to assure the container address is not being blocked by the host's firewall:`sudo iptables -L -v -n | grep 808`:

    0     0 ACCEPT     6    --  !br-233688ab8a57 br-233688ab8a57  0.0.0.0/0            172.18.0.3           tcp dpt:8080
    0     0 ACCEPT     6    --  !br-233688ab8a57 br-233688ab8a57  0.0.0.0/0            172.18.0.3           tcp dpt:8081

    0     0 ACCEPT     6    --  !br-233688ab8a57 br-233688ab8a57  0.0.0.0/0            172.18.0.3           tcp dpt:8080
    0     0 ACCEPT     6    --  !br-233688ab8a57 br-233688ab8a57  0.0.0.0/0            172.18.0.3           tcp dpt:8081

Disabling `ufw` temporarily
Setting `ASPNETCORE_URLS` to `http://+:8080/`
Adding `Kestrel:EndPoints:Http:Url=http://+:8080` to `docker-compose.yml`
Delete the container's and its images to clear any previous data

None of the options above had any effect.

blueberriesiftheywerecats•8/17/24, 5:15 PM

try changing

ASPNETCORE_URLS=http://localhost:8080
to
ASPNETCORE_URLS=http://+:8080

Bblueberriesiftheywerecats try changing - ASPNETCORE_URLS=http://localhost:8080 to - ASPNETCO...

Thiago R.OP•8/17/24, 5:23 PM

no effect ;/

blueberriesiftheywerecats•8/17/24, 5:24 PM

try adding
Kestrel:EndPoints:Http:Url=http://+:8080

Thiago R.OP•8/17/24, 5:29 PM

in the docker-compose file? no effect at all

TThiago R.# Source Code this is the API source code: <https://github.com/trsaints/trsaint...

Thiago R.OP•8/17/24, 5:34 PM

Docker networking

docker network inspectdocker network inspect for that

docker-compose

docker-compose

network is as follows. I just removed the MacAddressMacAddress parts for security reasons:

[
    {
        "Name": "trsaints-frontend-api_trsaints-network",
        "Id": "233688ab8a5770f3d111211532b94c44d1aba571082730ce255a2d28907fb62a",
        "Created": "2024-08-17T11:13:17.240077754-03:00",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": [
                {
                    "Subnet": "172.18.0.0/16",
                    "Gateway": "172.18.0.1"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "6c88858fcf034d3884d06e6938c1e4a58502611f0f477d95d28e070cd90cacdc": {
                "Name": "trsaints-frontend-api-webapi-1",
                "EndpointID": "eb2bdfd7b767d1db6d85d6d4181953edd24d5a3f41a53dae69b92e6193c40f52",
                "MacAddress": "[Removed from post for security reasons]",
                "IPv4Address": "172.18.0.3/16",
                "IPv6Address": ""
            },
            "6ddd6e368a0abd3671753083dc67aaed0be6f543c963c51b6d63c4cc01c3d6de": {
                "Name": "trsaints-frontend-api-db-1",
                "EndpointID": "6bbb83ee9689601cd27a40eb4e315832405d9ffbb0bc136364da9c1da5298482",
                "MacAddress": "[Removed from post for security reasons]",
                "IPv4Address": "172.18.0.2/16",
                "IPv6Address": ""
            }
        },
        "Options": {},
        "Labels": {
            "com.docker.compose.network": "trsaints-network",
            "com.docker.compose.project": "trsaints-frontend-api",
            "com.docker.compose.version": "2.29.1"
        }
    }
]

[
    {
        "Name": "trsaints-frontend-api_trsaints-network",
        "Id": "233688ab8a5770f3d111211532b94c44d1aba571082730ce255a2d28907fb62a",
        "Created": "2024-08-17T11:13:17.240077754-03:00",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": [
                {
                    "Subnet": "172.18.0.0/16",
                    "Gateway": "172.18.0.1"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "6c88858fcf034d3884d06e6938c1e4a58502611f0f477d95d28e070cd90cacdc": {
                "Name": "trsaints-frontend-api-webapi-1",
                "EndpointID": "eb2bdfd7b767d1db6d85d6d4181953edd24d5a3f41a53dae69b92e6193c40f52",
                "MacAddress": "[Removed from post for security reasons]",
                "IPv4Address": "172.18.0.3/16",
                "IPv6Address": ""
            },
            "6ddd6e368a0abd3671753083dc67aaed0be6f543c963c51b6d63c4cc01c3d6de": {
                "Name": "trsaints-frontend-api-db-1",
                "EndpointID": "6bbb83ee9689601cd27a40eb4e315832405d9ffbb0bc136364da9c1da5298482",
                "MacAddress": "[Removed from post for security reasons]",
                "IPv4Address": "172.18.0.2/16",
                "IPv6Address": ""
            }
        },
        "Options": {},
        "Labels": {
            "com.docker.compose.network": "trsaints-network",
            "com.docker.compose.project": "trsaints-frontend-api",
            "com.docker.compose.version": "2.29.1"
        }
    }
]

Thiago R.OP•8/17/24, 5:36 PM

As the output suggests, the container's address is 172.18.0.3172.18.0.3, but any tool that attempts to connect externally just gets refused and fails

Thiago R.OP•8/17/24, 5:38 PM

curl http://172.18.0.3:8082               
telnet 172.18.0.3 8082

curl: (7) Failed to connect to 172.18.0.3 port 8082 after 0 ms: Couldn't connect to server
Trying 172.18.0.3...
telnet: Unable to connect to remote host: Connection refused

curl http://172.18.0.3:8082               
telnet 172.18.0.3 8082

curl: (7) Failed to connect to 172.18.0.3 port 8082 after 0 ms: Couldn't connect to server
Trying 172.18.0.3...
telnet: Unable to connect to remote host: Connection refused

Thiago R.OP•8/17/24, 5:43 PM

Actually, I've tried to run busyboxbusybox and appropriateappropriate images for fetching data inside the network, but looks like the response is the same:

docker run --rm --network trsaints-frontend-api_trsaints-network appropriate/curl http://172.18.0.3:8080/swagger

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0

docker run --rm --network trsaints-frontend-api_trsaints-network appropriate/curl http://172.18.0.3:8080/swagger

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0

Sossenbinder•8/17/24, 6:19 PM

So you can confirm with the docker logs that the server is running?

Thiago R.OP•8/17/24, 6:28 PM

so, it was actually an IDE thing. Running the containers using the IDE's UI would actually set the environment to development and enable Swagger, for example

Thiago R.OP•8/17/24, 6:28 PM

I found out that the environment was set to ProductionProduction after some debugging

Thiago R.OP•8/17/24, 6:28 PM

I had to explicitly add an ASPNETCORE_ENVIRONMENTASPNETCORE_ENVIRONMENT to the

docker-compose.yml

docker-compose.yml

file

Thiago R.OP•8/17/24, 6:33 PM

thank you all for checking the post, btw

Local machine refuses to connect to an ASP.NET Core Web API container

Source Code

What I've tried until then

Docker networking

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What I've tried until then

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