Entity Framework and Docker Container

Question

First of all, I'm sorry for my English.

I am developing an ASP.NET Core Web API, and I am working with a friend. To work together comfortably I wanted to set up a Docker with our API, and a database running. And I have problem with Entity Framework.

Here is the problem, the name of the container for Postgres is postgres_image, so the connection string to connect to it from the api is:

"Host=postgres_image;Port=5432;Database=grdedb;Username=postgres;Password=postgres"

And it is working. But when I want to create an Entity Framework migration to the database located in the Docker container, it doesn't work; I have to change the host to localhost.

But when I change it the migration works and after that it is the API which stops.

Thank you very much for your help

My docker compose file

version: '3.4'

networks:
  grdeapi-dev:
    driver: bridge

services:
  grdeapi:
    image: grdeapi
    build:
      context: .
      dockerfile: ./Dockerfile
    ports:
      - 5101:5101
    networks:
      - grdeapi-dev
  postgres_image:
    image: postgres:latest
    ports:
      - 5432:5432
    restart: always
    volumes: 
      - db_volume:/var/lib/postgresql/data
    environment:
      POSTGRES_USER: "postgres"
      POSTGRES_PASSWORD: "postgres"
      POSTGRES_DB: "grdedb"
    networks:
      - grdeapi-dev
volumes: 
  db_volume:

My connection string

"Host=postgres_image;Port=5432;Database=grdedb;Username=postgres;Password=postgres"

And the error I get from the entity framework

Failed to connect to 212.95.74.75:5432

Entity framework works when I change the host to localhost, but then my dotnet api can't connect to my database.

I run the database migration on my local terminal. When I try to install ef on the docker container, it doesn't works so I couldn't do it from the docker terminal. — madebyfik
– madebyfik, Commented Dec 22, 2022 at 11:22

CodeCaster · Accepted Answer · 2022-12-22 11:27:48Z

1

Have a config for running in Docker, and one for running in development.

In the former (name it appsettings.Development.Docker.json for example) configure your connection string with the Docker hostname ("postgres_image"), and locally (when running from Visual Studio or when running migrations against said database server) just use "localhost". Name the latter appsettings.Development.json.

Then adjust your DOTNET_ENVIRONMENT accordingly:

services:
  grdeapi:
    DOTNET_ENVIRONMENT: "Development.Docker"

answered Dec 22, 2022 at 11:27

CodeCaster

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2 Comments

madebyfik Over a year ago

I did it but it still execute the connection string from appsettings.Development.json instead of appsettings.Development.Docker.json when I run ef database update

CodeCaster Over a year ago

If so, then you've configured them the wrong way around. "Development" is for your development PC, "Development.Docker" is for inside Docker.

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