This question already has answers here:
From inside of a Docker container, how do I connect to the localhost of the machine?
(40 answers)
Closed 3 months ago.
Hi everyone i was working in a django project with docker. and i have a problem to connect
docker container with postgres database, one the the way to connect is network_mode: host but i want to connect using custom network.
version: '3.3'
services:
web:
restart: always
container_name: main
command:
- /bin/bash
- -c
- |
python manage.py makemigrations accounts
python manage.py migrate
python manage.py runserver
image: main
build: .
volumes:
- .:/main
ports:
- "8000:8000"
extra_hosts:
- "dbhost:172.17.0.1"
networks:
- backend
networks:
backend:
volumes:
static:
If you are on Docker Desktop with WSL2 you can use host.docker.internal other than that you need to get the Gateway Ip from here: docker network inspect bridge it might be 172.17.0.1. Also to do this you don't want to use a specific network in your compose file but use the default one.
Related
I am building a Flask application in Python. I'm using SQLAlchemy to connect to PostgreSQL.
In the flask application, I'm using this to connect SQLAlchemy to PostgreSQL
engine = create_engine('postgresql://postgres:[mypassword]#db:5432/employee-manager-db')
And this is my docker-compose.yml
version: '3.8'
services:
backend:
build:
context: .
dockerfile: Dockerfile
ports:
- 8000:8000
volumes:
- .:/app
links:
- db:db
depends_on:
- pgadmin
db:
image: postgres:14.5
restart: always
volumes:
- .dbdata:/var/lib/postgresql
hostname: postgres
environment:
POSTGRES_PASSWORD: [mypassword]
POSTGRES_DB: employee-manager-db
pgadmin:
image: 'dpage/pgadmin4'
restart: always
environment:
PGADMIN_DEFAULT_EMAIL: [myemail]
PGADMIN_DEFAULT_PASSWORD: [mypassword]
ports:
- "5050:80"
depends_on:
- db
I can do "docker build -t employee-manager ." to build the image. However, when I do "docker run -p 5000:5000 employee-manager" to run the image, I get an error saying
conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
psycopg2.OperationalError: could not translate host name "db" to address: Try again
Does anybody know how to fix this? Thank you so much for your help
Your containers are on different networks and that is why they don't see each other.
When you run docker-compose up, docker-compose creates a separate network and puts all the services defined inside docker-compose.yml on that network. You can see that with docker network ls.
When you run a container with docker run, it is attached to the default bridge network, which is isolated from other networks.
There are several ways to fix this, but this one will serve you in many other scenarios:
Run docker container ls and identify the name or ID of the db container that was started with docker-compose
Then run your container with:
# ID_or_name from the previous point
docker run -p 5000:5000 --network container:<ID_or_name> employee-manager
This attached the new container to the same network as your database container.
Other ways include creating a network manually and defining that network as default in the docker-compose.yml. Then you can use docker run --network <network_name> ... to attach other containers to that network.
docker run doesn't read any of the information in the docker-compose.yml file, and it doesn't see things like the Docker network that Compose automatically creates.
In your case you already have the service fully-defined in the docker-compose.yml file, so you can use Compose commands to build and restart it
docker-compose build
docker-compose up -d # will delete and recreate changed containers
(If the name of the image is important to you – maybe you're pushing to a registry – you can specify image: alongside build:. links: are obsolete and you should remove them. I'd also avoid replacing the image's content with volumes:, since this misses any setup or modification that's done in the Dockerfile and it means you're running untested code if you ever deploy the image without the mount.)
I'm trying to containerize my application. I use mongodb and 2 more micro services.
As you can see in the docker compose file below, I have some problems.
My requirements:
main_image needs to connect to MongoDB.
gui_image needs to connect to MongoDB.
gui_image needs to show its GUI on port 8080 (Can use another port as well)
gui_image has to read and write to a file inside my computer.
MongoDB has to access a volume inside my computer.
main_image needs access to the internet.
Here is my questions:
1- Does exposing ports in docker file and docker-compose the same thing?
2- How do I mount a volume to mongodb as best practice?
3- How to accomplish the requirements above with the diagram below in docker-compose?
Here is my docker-compose file:
version: "3"
services:
mongo:
image: mongo:latest
ports:
- 27017:27017
main_image:
build:
context: .
dockerfile: .\my_project\dockerfile
depends_on:
- mongo
gui_image:
build:
context: .
dockerfile: .\my_gui\dockerfile
ports:
- 8080:8080
- 27017:27017
depends_on:
- mongo
Here is my dockerfile under my_gui directory:
FROM continuumio/miniconda3
WORKDIR /app
COPY . .
RUN pip install dash
EXPOSE 8080
EXPOSE 27017
ENTRYPOINT [ "python","gui_script.py"]
And lastly, here is my dockerfile under my_project directory:
FROM continuumio/miniconda3
WORKDIR /app
COPY . .
EXPOSE 27017
ENTRYPOINT [ "python","main_script.py"]
1.The EXPOSE instruction in Dockerfile informs Docker that the container listens on the specified network ports at runtime(like when using docker run -p command).
However using ports in compose is a dynamic way of specifying these ports. So images like nginx or apache which are always supposed to run on port 80 inside the container will use EXPOSE in Dockerfile itself.
While an image which has dynamic port which may be controlled using an environment variable will then use expose in docker run or compose file.
some_webapi:
environment:
- ASPNETCORE_URLS=http://*:80
build:
context: .
dockerfile: ./Dockerfile
2.As documented on the docker hub page for mongo image (https://hub.docker.com/_/mongo/) you can use
volumes:
- '/path/to/your/pc/folder:/path/inside/docker'
3.And for the last question you might wanna use Networking in Compose.
By default Compose sets up a single network for your app. Each container for a service joins the default network and is both reachable by other containers on that network, and discoverable by them at a hostname identical to the container name.
Services can join networks like this
gui_image:
build:
context: .
dockerfile: .\my_gui\dockerfile
ports:
- 8080:8080
- 27017:27017
depends_on:
- mongo
networks:
- gui
And also you have to define all the networks used by services in global scope of compose file
version: '3'
services:
networks:
gui:
After that containers will be able to see each other even by their container_name which you can define in services
mongo:
image: mongo:latest
ports:
- 27017:27017
container_name: gui_mogno
then you will be able to connect to mongo with a connection string like this mongodb://gui_mogno:27017/
You can get more information about networking here
I would like to access my Postgres database (docker container) from PhpStorm.
docker-compose.yml
# Run docker-compose build
# Run docker-compose up
# Live long and prosper
version: '3.1'
services:
apache:
build: .docker/apache
container_name: sf-apache
ports:
- 82:80
volumes:
- .docker/config/vhosts:/etc/apache2/sites-enabled
- ${SYMFONY_APP}:/home/wwwroot/sf3
depends_on:
- php
postgres:
container_name: postgres
restart: always
image: 'postgres:12.6'
ports:
- "5432:5432"
environment:
- "POSTGRES_USER=${PGSQL_ADMIN_USER}"
- "POSTGRES_PASSWORD=${PGSQL_ADMIN_PASSWORD}"
volumes:
- ./API/var/postgres:/var/lib/postgresql/data
- .docker/postgresql/init-database.sh:/docker-entrypoint-initdb.d/init-database.sh
My PhpStorm config :
I can access to my database via docker exec -it postgres bash
If php storm is on the same host then you need to use localhost. If both phpstorm and pg is part of the same compose file , then you would use the service name since both would be in the same virtual network
I found the solution.
I have a Postgres local and a Postgres with docker. My Postgres local get the upper hand on my docker Postgres. I have killed the service and put the container service name on it.
Works perfectly.
Thanks for you help,
I am currently trying to use Docker for my new Django/Postgres project. I am working on a Mac and usually use Postico to quickly connect to my database.
I used to connect like here:
I used the official Docker documentation to setup docker-compose. I now have the issue, that I can't connect via Postico to the postgres db. It seems to me that the problem comes from the ports not being exposed.
version: '3'
services:
db:
image: postgres
web:
build: .
command: python3 manage.py runserver 0.0.0.0:8000
volumes:
- .:/code
ports:
- "8000:8000"
depends_on:
- db
Just map the port to the host machine, add this to the db service in your Compose file:
ports:
- "5432:5432"
Also make sure to set the postgres password variable in the compose file like this
environment:
POSTGRES_PASSWORD: example
The default user is postgres, you can change it with the POSTGRES_USER variable.
You can read about the usage of the image with all options here: https://hub.docker.com/_/postgres/
By default Compose sets up a single network for your app.
Each container can be accessed by the name of the service in the compose file.
In your case you don't have to expose the port to the host machine for your web app to have access to it. You can simply use db as the hostname for postgres (and 5432 for the port) from any other service running on the same compose.
Actually a very similar example is provided in the docker compose documentation:
https://docs.docker.com/compose/networking/
I'm stuck on a very strange docker problem that I've not encountered before. What I want to do is to use docker-compose to make my application available from the internet. It's currently running on a instance on DigitalOcean and I'm currently working with the following docker-compose.yml:
version: '2.2'
services:
mongodb:
image: mongo:3.4
volumes:
- ./mongo:/data/db
ports:
- "27017"
mongoadmin: # web UI for mongo
image: mongo-express
ports:
- "8081:8081"
links:
- "mongodb:mongo"
environment:
- ME_CONFIG_OPTIONS_EDITORTHEME=ambiance
- ME_CONFIG_BASICAUTH_USERNAME=user
- ME_CONFIG_BASICAUTH_PASSWORD=pass
app:
image: project/name:0.0.1
volumes:
- ./project:/usr/src/app
working_dir: /usr/src/app
links:
- "mongodb:mongodb"
environment:
- NODE_ENV=production
command: ["npm", "start"]
ports:
- "3000:3000"
Mongoadmin connects properly and is able to connect to the database, while the database itself cannot be connected to from outside the host.
The problem is that the app won't connect to the right address. It is a express server using mongoose to connect to the database. Before connecting I'm logging the url it will connect to. In my config.js I've listed mongodb://mongodb/project, but this is resolved to localhost thus resulting in MongoError: failed to connect to server [localhost:27017] on first connect. The name of the container is resolved, but not to the proper address.
I've tried to connect to the IP (in the 172.18.0.0 range) that docker addressed to the container, but that also resolved to localhost. I've looked into /etc/hosts but this does not show anything related to this. Furthermore, I'm baffled because the mongo-express container is able to connect.
I've tried changing the name of the container, thinking it might be block for some reason due to previous runs or something like that, but this did not resolve the issue
I've tried both explicit links and implicit using dockers internal DNS resolve, but both did not work.
When binding port 27017 to localhost it is able to connect, but because of security and easy configuration via environment variables, I rather have the mongodb instance not bound to localhost.
I've also tried to run this on my local machine and that works as expected, being that both mongoadmin and app are able to connect to the mongodb container. My localmachine runs Docker version 1.12.6, build 78d1802, while the VPS runs on Docker version 17.06.2-ce, build cec0b72, thus a newer version.
Could this be a newly introduced bug? Or am I missing something else? Any help would be appreciated.
Your docker-compose file seems not have linked the app and mongodb container.
You have this:
app:
image: project/name:0.0.1
volumes:
- ./project:/usr/src/app
working_dir: /usr/src/app
environment:
- NODE_ENV=production
command: ["npm", "start"]
ports:
- "3000:3000"
While I think it should be this:
app:
image: project/name:0.0.1
volumes:
- ./project:/usr/src/app
working_dir: /usr/src/app
links:
- "mongodb:mongodb"
environment:
- NODE_ENV=production
command: ["npm", "start"]
ports:
- "3000:3000"