I have a problem about network in docker. In the docker-compose.yml includes 2 instance below
webserver (frontend + backend)
database
But i tried to bridge network and default but not working at all.The backend cannot connect to database show error "connection refuse". then i tried to docker exec -t .. into webserver and then ping to database it show "timeout".
I cannot connect database with ip address (i got a database ip address from docker exec and then hostname -i) but i connected success using "localhost"
this my docker-compose.yml
version: '3.8'
services:
postgres_server:
container_name: postgres14-4_container
image: postgres:14.4
command: postgres -c 'max_connections=200'
restart: always
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=postgres
ports:
- '5222:5432'
volumes:
- db:/var/lib/postgresql14/data
networks:
- web_network
webserver:
container_name: frontend_backend_container
image: webserver
ports:
- '9090:80'
- '8081:8081'
env_file:
- backend_env
depends_on:
- postgres_server
restart: always
networks:
- web_network
volumes:
db:
driver: local
networks:
web_network:
driver: bridge
To configure remote connections to postgres, you have to adjust pg_hba.conf. For example add:
# Remote access
host all all 0.0.0.0/0 trust
where is your backend_env file?
I guess you have there the host + port to connect to the db.
You don't need to define anything special (like the bridge).
The webserver container should be able to access the postgres_server via postgres_server:5432 (not localhost and not 5222).
Related
I need to resolve a container name to the IP Address from the docker host.
The reason for this is, i need a container to run on the host network, but it must be also able to resolve the container "backend" which it connects also to. (The container must be send & receive multicast packets)
docker-compose.yml
version: "3"
services:
database:
image: mongo
container_name: database
hostname: database
ports:
- "27017:27017"
backend:
image: "project/backend:latest"
container_name: backend
hostname: backend
environment:
- NODE_ENV=production
- DATABASE_HOST=database
- UUID=5025f846-7587-11ed-9ca7-8b992b5e7dd3
ports:
- "8080:8080"
depends_on:
- database
tty: true
frontend:
image: "project/frontend:latest"
container_name: frontend
hostname: frontend
ports:
- "80:80"
- "443:443"
depends_on:
- backend
environment:
- BACKEND_HOST=backend
connector:
image: "project/connector:latest"
container_name: connector
hostname: connector
ports:
- "1900:1900/udp"
#expose:
# - "1900/udp"
environment:
- NODE_ENV=production
- BACKEND_HOST=backend
- STARTUP_DELAY=1500
depends_on:
- backend
network_mode: host
tty: true
How can i resolve the hostname "backend" via docker from the docker host?
dig backend #127.0.0.11 & dig backend #172.17.0.1 did not work.
A test with a docker ubuntu image & socat proves, that i can receive ssdp multicast packets:
docker run --net host -it --rm ubuntu
socat UDP4-RECVFROM:1900,ip-add-membership=239.255.255.250:0.0.0.0,fork -
The only problem i now have is the DNS/Container name resolution from the host (network).
TL;DR
The container "connector" must be on the host network,but also be able to resolve the container name "backend" to the docker internal IP Address.
NOTE: Perhaps this is better suited on superuser or similar?
I have a unique situation where I need to be able to access a container over a custom local domain (example.test), which I've added to my /etc/hosts file which points to 127.0.0.1. The library I'm using for OIDC uses this domain for redirecting the browser and if it is an internal docker hostname, obviously the browser will not resolve.
I've tried pointing it to example.test, but it says it cannot connect. I've also tried looking up the private ip of the docker network, and that just times out.
Add the network_mode: host to the service definition of the calling application in the docker-compose.yml file. This allows calls to localhost to be routed to the server's localhost and not the container's localhost.
E.g.
docker-compose.yml
version: '3.7'
services:
mongodb:
image: mongo:latest
restart: always
logging:
driver: local
environment:
MONGO_INITDB_ROOT_USERNAME: ${DB_ADMIN_USERNAME}
MONGO_INITDB_ROOT_PASSWORD: ${DB_ADMIN_PASSWORD}
ports:
- 27017:27017
volumes:
- mongodb_data:/data/db
callingapp:
image: <some-img>
restart: always
logging:
driver: local
env_file:
- callingApp.env
ports:
- ${CALLING_APP_PORT}:${CALLING_APP_PORT}
depends_on:
- mongodb
network_mode: host // << Add this line
app:
image: <another-img>
restart: always
logging:
driver: local
depends_on:
- mongodb
env_file:
- app.env
ports:
- ${APP_PORT}:${APP_PORT}
volumes:
mongodb_data:
Server 1->10.0.0.47
Server 2->10.0.1.202
All ports between these two servers are open as they are in same VPN in aws
version: '3.3'
networks:
net:
external: true
services:
backend:
image: test/test-backend:prod
ports:
- "8000:8000"
depends_on:
- discovery
ERROR:Connection refused
Note When i try to change the composer like below
connection with mongo established but unable to access the service on port 8000
networks:
net:
external: true
services:
backend:
image: test/test-backend:prod
expose:
- "27017:27017"
ports:
- "8000:8000"
depends_on:
- discovery
The Expose instruction does not change anything, it's for documentation only. You can read more about it in the Dockerfile reference.
If the 2 Server are in the same Docker network, you could change the mongoDB port to 8000 in its installation configuration. Then, you don't need to specify a port etc. in the docker-compose configuration.
If you want to access the mongoDB service from outside, you have to change the docker-compose configuration to:
ports:
- "8000:27017"
I have 3 containers with my bot, server and db. after docker-compose up, server and db are working. telegram bot does get-request and takes this error:
Get "http://localhost:8080/user/": dial tcp 127.0.0.1:8080: connect: connection refused
docker-compose.yml
version: "3"
services:
db:
image: postgres
container_name: todo_postgres
restart: always
ports:
- "5432:5432"
environment:
# TODO: Change it to environment variables
POSTGRES_USER: user
POSTGRES_DB: somedb
POSTGRES_PASSWORD: pass
server:
depends_on:
- db
build: .
restart: always
ports:
- 8080:8080
environment:
DB_NAME: somedb
DB_USERNAME: user
DB_PASSWORD: pass
bot:
depends_on:
- server
build:
./src/telegram_bot
environment:
BOT_TOKEN: TOKEN
restart: always
links:
- server
When using compose, try using the containers hostname.. in the case your bot should try to connect to
server:8080
Compose will handle the name resolution to the IP you need
What you try is to access localhost within your container (service) bot.
Maybe this answer will help you to solve the problem. It sound similar to your problem.
But I want to provide you another solution to your problem:
In case it's not needed to access the containers form outside (from your host), one appraoch would be making use of the expose functionality and a docker network.
See docs.docker.com: network.
The expose functionality allows to access your other containers within your network
See docs.docker.com: expose
Expose ports without publishing them to the host machine - they’ll only be accessible to linked services. Only the internal port can be specified.
Example
What is this example doing?
A couple of steps that are not mandatory
Set a static ip within your docker container
These Steps are not needed and can be omitted. However, I like to do this, since you have now a better control over the network. You can access the containers by their hostname (which is the container name or service name) as well.
The steps that are needed are the following:
This exposes port 8080, but do not publish it.
expose:
- 8080
The network which allows static ip configuration
networks:
vpcbr:
driver: bridge
ipam:
config:
- subnet: 10.5.0.0/16
A complete file could look similar to this:
version: "3.8"
services:
first-service:
image: <your-image>
networks:
vpcbr:
ipv4_address: 10.5.0.2
expose:
- 8080
second-service:
image: <your-image>
networks:
vpcbr:
ipv4_address: 10.5.0.3
depends_on:
- first-service
networks:
vpcbr:
driver: bridge
ipam:
config:
- subnet: 10.5.0.0/16
Your bot container is up before your server & db containers.
When you use depends_on it's not accually waiting them to finish setup themeselves.
You should try some tricky algorithem for waiting the other container finish setup.
I remmember that when I used Nginx proxy I used something called wait-for-it.sh
I have a setup where I build 2 dockers with docker-compose.
1 container is a web application. I can access it with port 8080. Another container is ElasticSearch; it's accessible with port 9200.
This is the content of my docker-compose.yml file:
version: '3'
services:
serverapplication:
build: "serverapplication"
entrypoint:
- bash
- -x
- init.sh
command: ["jdbcUrl=${jdbcUrl} dbUser=${dbUser} dbUserPassword=${dbUserPassword}"]
ports:
- "8080:8080"
- "8443:8443"
- "8787:8787"
elasticsearch:
build: "elasticsearch"
environment:
- discovery.type=single-node
ports:
- "9200:9200"
- "9300:9300"
When I browse to http://localhost:8080/serverapplication I can see my server application.
When I browse to http://localhost:9200/ I can see the default page of ElasticSearch.
But when I try to access ElasticSearch from inside the serverapplication, I get a "connection refused". It seems that the 9200 port is unreachable at localhost for the server application.
How can I fix this?
It's never safe to use localhost, since localhost means something else for your host system, for elasticsearch and for your server application. You're only able to access the containers from your host's localhost because you're mapping container ports onto your host's ports.
put them in the same network
give the containers a name
access elasticsearch through its containername, which Docker automatically resolves to the current IP of your elasticsearch container.
Code:
version: '3'
services:
serverapplication:
container_name: serverapplication
build: "serverapplication"
entrypoint:
- bash
- -x
- init.sh
command: ["jdbcUrl=${jdbcUrl} dbUser=${dbUser} dbUserPassword=${dbUserPassword}"]
ports:
- "8080:8080"
- "8443:8443"
- "8787:8787"
networks:
- my-network
elasticsearch:
container_name: elasticsearch
build: "elasticsearch"
environment:
- discovery.type=single-node
ports:
- "9200:9200"
- "9300:9300"
networks:
- my-network
networks:
my-network:
driver: bridge
Your server application must use the host name elasticsearch to access elasticsearch service i.e., http://elasticsearch:9200
Your serverapplication and elasticsearch are running in different containers. The localhost of serverapplication is different from localhost of elasticsearch.
docker-compose sets up a network between the containers such that they can be accessed with their service names. So from your serverapplication, you must use the name 'elasticsearch' to connect to it.