I made two 2 containers, one for the RethinkDB and one for a nodejs app.
I want to connect my nodejs app to this RethinkDB but everytime I try get an error
Error:{"message":"Failed to connect to localhost:58015\nFull error:\n{\"code\":\"ECONNREFUSED\"
But I can connect the same nodejs app running without Docker to the RethinkDB, with the open port (58015).
My Docker compose config look like this
# Rethink DB
rethink:
build: docker/rethinkdb
container_name: rethink
ports:
- 58080:8080
- 58015:28015
- 59015:29015
# NodeJS
nodejs:
build: docker/nodejs
container_name: nodejs
ports:
- 53000:3000
- 55000:5000
depends_on:
- rethink
To connect my app to the db I set the host and port inside a JS config file
database: {
servers: [
{
host: process.env.DB_PORT_28015_TCP_ADDR || 'localhost',
port: process.env.DB_PORT_28015_TCP_PORT || 28015
}
],
name: 'atlas'
},
I tried with RethinkDB port (28015) and with my open port (58015) without success.
I tried to link this two containers with links, network_mode, without success too.
Every solutions I tried don't work.
I think my Rethink container is not ready when the nodejs app try to connect. I really don't understand the problem, if this not this.
The nodejs app is running with pm2
How can I made this app connect to my db ?
For you config, you should use
# Rethink DB
rethink:
build: docker/rethinkdb
container_name: rethink
ports:
- 58080:8080
- 58015:28015
- 59015:29015
# NodeJS
nodejs:
build: docker/nodejs
container_name: nodejs
ports:
- 53000:3000
- 55000:5000
links:
- rethink
depends_on:
- rethink
and in JS code
database: {
servers: [
{
host: process.env.DB_PORT_28015_TCP_ADDR || 'rethink',
port: process.env.DB_PORT_28015_TCP_PORT || 28015
}
],
name: 'atlas'
},
As far as I know, one Docker container will not see the other unless specifically linked and using the same net:
docker run \
--name ${NEWAPP} \
--restart=always \
--env MYAPPPAR=${PROJ} \
-v /var/log/docker/node/logs:/usr/src/app/log \
--link myapp_rethink_1:myapp_rethink_1 \
--net myapp_default \
-p ${PORT}:9000 \
-d ${NEWAPP}
So you need both --net and --link:
--link format is sourcecontainername:containeraliasname
--net so that containers can find each other with internal DNS / containername. You can check network with 'docker network ls'
When using newer versions of docker-compose, your services will be configured to run on the same network.
The top level service name in your 'docker-compose.yml' will become the host that needs to be specified, when connecting to RethinkDB from your app:
# docker-compose.yml
version: '3.2'
Services:
web:
build: .
links: db
...
db:
image: rethinkDB
...
Using the example above, you can connect to RethinkDB by using the host named 'db', within the app configuration file:
module.exports = {
rethinkdb: {
host: 'db',
port: 28015
}
};
Related
Good morning guys.
I'm having a problem connecting a nodejs application, in a container, to another container that contains a redis server. On my local machine I can connect the application to this redis container without any problem. However, when trying to upload this application in a container, a timeout error is returned.
I'm new to docker and I don't understand why I can connect to this docker container in the application running locally on my machine but that same connection doesn't work when I upload the application in a container.
I tried using docker-compose, but from what I understand it will upload in another container to the redis server, instead of using the redis container that is already in docker.
To connect to redis I'm using the following code:
createClient({
socket: {
host: process.env.REDIS_HOST,
port: Number(process.env.REDIS_PORT)
}
});
Where REDIS_HOST is the address of my container running on the server and REDIS_PORT is the port where this container is running on my server.
To run redis on docker I used the following guide: https://redis.io/docs/stack/get-started/install/docker/
I apologize if my problem was not very clear, I'm still studying docker.
You mentioned you are using Docker Compose. Here's an example showing how to start Redis in a container, and make your Node application wait for that container then use an environment variable in your Node application to specify the name of the host to connect to Redis on. In this example it connects to the container running Redis that I've called "redis":
version: "3.9"
services:
redis:
container_name: redis_kaboom
image: "redislabs/redismod"
ports:
- 6379:6379
volumes:
- ./redisdata:/data
entrypoint:
redis-server
--loadmodule /usr/lib/redis/modules/rejson.so
--appendonly yes
deploy:
replicas: 1
restart_policy:
condition: on-failure
node:
container_name: node_kaboom
build: .
volumes:
- .:/app
- /app/node_modules
command: sh -c "npm run load && npm run dev"
depends_on:
- redis
ports:
- 8080:8080
environment:
- REDIS_HOST=redis
So in your Node code you'd then use the value of process.env.REDIS_HOST to connect to the right Redis host. Here, I'm not using a password or a non-standard port, you could also supply those as environment variables that match the configuration of the Redis container in Docker Compose too if you needed to.
Disclosure: I work for Redis.
I know this is a common error, but I literally spent the entire day trying to get past this error, trying everything I could find online. But I cant find anything that works for me.
I am very new to Docker and using it for my NodeJS + Express + Postgresql + Redis application.
Here is what I have for my docker-compose file:
version: "3.8"
services:
db:
image: postgres:14.1-alpine
restart: always
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=admin
ports:
- "5432:5432"
volumes:
- db:/var/lib/postgresql/data
- ./db/init.sql:/docker-entrypoint-initdb.d/create_tables.sql
cache:
image: redis:6.2-alpine
restart: always
ports:
- "6379:6379"
command: redis-server --save 20 1 --loglevel warning
volumes:
- cache:/data
api:
container_name: api
build:
context: .
# target: production
# image: api
depends_on:
- db
- cache
ports:
- 3000:3000
environment:
NODE_ENV: production
DB_HOST: db
DB_PORT: 5432
DB_USER: postgres
DB_PASSWORD: admin
DB_NAME: postgres
REDIS_HOST: cache
REDIS_PORT: 6379
links:
- db
- cache
volumes:
- ./:/src
volumes:
db:
driver: local
cache:
driver: local
Here is my app.js upper part:
const express = require('express')
const app = express()
const cors = require('cors')
const redis = require('redis')
const client = redis.createClient({
host: 'cache',
port: 6379,
legacyMode: true // Also tried without this line, same behavior
})
client.connect()
client.on('connect', () => {
log('Redis connected')
})
app.use(cors())
app.use(express.json())
And my Dockerfile:
FROM node:16.15-alpine3.14
WORKDIR ./
COPY package.json ./
RUN npm install
COPY ./ ./
EXPOSE 3000 6379
CMD [ "npm", "run", "serve" ]
npm run serve is nodemon ./app.js.
I also already tried to prune the system and network.
What am I missing? Help!
There are two things to put in mind here,
First of All Docker Network:
Containers are exposed to your localhost system, so as a "Server" you can access each of them directly through the browser or the command-line, But
Taken for granted that you only can access the containers because they are exposed to a default network that is accessible by the root of the system - the docker user which you can inspect by the way.
The deployed containers are not exposed to each other by default, so you need to define a virtual network and expose them to it so they can talk to each other through the ports or the host name -- which will be the container_name
So you need to do two things:
Add a container name to the redis, in the compose file just like you did on the API
Create a network and bind all the services to it, one way of doing that will be:
version: "3.8"
Network:
my-network:
name: my-network
services:
....
cache:
container_name: cache
image: redis:6.2-alpine
restart: always
ports:
- "6379:6379"
command: redis-server --save 20 1 --loglevel warning
volumes:
- cache:/data
networks: # add it in all containers that communicate together
- my-network
Then and only then you can call redis container name as the host, since docker network will create a host name for the service by the container name,
When deploying the whole compose file later, the containers will be created and all will be joined to the network by default on startup and that will allow you API app to communicate with Redis container via the docker container name as the host name
Refer to these resources for more details:
Networking on Docker Compose
Docker Network Overview
A side Unrelated note:
I personally used redis from npm for some testing projects, but I found that ioredis was much better with TypeScript projects and more expected in its behavior
To Avoid any problems with Redis, make sure to create a password and use it to connect, sometimes redis randomly considers the client as a ReadOnly client and fails to find a read replica, adding the password solved it for me
Docker file for my node app
FROM node:latest
COPY . .
RUN npm install
EXPOSE 5000
CMD ["npm", "start"]
docker compose file -
version: '3'
services:
pern-todo-backend:
image: pern-todo-backend
ports:
- 5000:5000
command: bash -c 'while !</dev/tcp/db/5432; do sleep 1; done; npm start'
depends_on:
- db
environment:
- DATABASE_URL=postgres://postgres:*****#db:5432/pern
- PORT=5000
db:
image: postgres
ports:
- 5432:5432
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=****
- POSTGRES_DB=pern
when i try to hit the endpoint from postman -
{
"errno": -111,
"code": "ECONNREFUSED",
"syscall": "connect",
"address": "172.26.0.3",
"port": 5432
}
I tried updating my pg pool hostname as the name of my container also
const pool = new Pool({
user : 'postgres',
password : 'subh1994',
host : 'localhost',
port : 5432,
database : 'pern'
})
I'm new with Docker , please help . thanks
Can you check your container name of db service by docker ps
It can be different than service name (db), you can try replacing it in DATABASE_URL connection string.
But one weird thing is db is getting resolved to 172.26.0.3 if the db is correct container name then you can try checking logs by docker logs db to get details on what might be wrong.
On side note if you don't want datbase exposed to host you can skip the ports mapping in db service.
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.
https://docs.docker.com/compose/networking/
I am currently working on an angular app using Rest API (Express, Nodejs) and Postgresql. Everything worked well when hosted on my local machine. After testing, I moved the images to Ubuntu server so the app can be hosted on an external port. I am able to access the angular frontend using the https://serveripaddress:80 but when trying to login, the api is not connecting to Postgresql. I am getting an error message: ERR_CONNECTION_REFUSED. Here is my docker-compose file:
version: '3.0'
services:
db:
image: postgres:9.6-alpine
environment:
POSTGRES_DB: myDatabase
POSTGRES_PASSWORD: myPwd
POSTGRES_PORT: 5432
POSTGRES_HOST: db
ports:
- 5434:5432
restart: always
volumes:
- ./postgres-data:/var/lib/postgresql/data
backend: # name of the second service
image: myid/nodeapi
ports:
- 3000:3000
environment:
POSTGRES_DB: myDatabase
POSTGRES_PASSWORD: myPwd
POSTGRES_PORT: 5432
POSTGRES_HOST: db
depends_on:
- db
command: bash -c "sleep 20 && node server.js"
myapp-portal:
image: myId/angular-app
ports:
- "80:80"
depends_on:
- backend
volumes:
postgres-data:
The code to connect to database:
const { Client } = require('pg')
const client = new Client({
database: process.env.POSTGRES_DB,
user: 'postgres',
password: process.env.POSTGRES_PASSWORD,
host: process.env.POSTGRES_HOST,
port: process.env.POSTGRES_PORT
})
client.connect()
.then(
() => {
console.log("db connected");
})
and the docker-compose log for backend:
backend_1 | db connected
When I exec into the database docker container and connect to psql, I see that my database is created(used pg_dump manually) with all the tables and data. My guess is that node.js is connecting to the default Postgres database created at the time of the installation. I had the same issue on my local machine but I resolved it by creating a new server group in pgAdmin4 and creating a new db on port 5434. I prefer not to do this on server as it defeats the purpose of the concept of docker. Another thought is perhaps node.js is attempting to connect to the database even before it is up. That is the reason I added the line 'sleep 20' which worked on my local machine. Any thoughts on how I can fix this? TIA!
If you want to wait on the availability of a host and TCP port, you can use this script https://github.com/vishnubob/wait-for-it
In your docker file you can copy this file into container and change mode
RUN chmod +x wait-for-it.sh
Then in your docker compose run this script on service which you want to wait
entrypoint: bash -c "./wait-for-it.sh --timeout=0 service_name:service_port && node server.js"
Code first, it will be easier to explain what I'm after.
docker-compose.yml
version: '3.4'
services:
db:
user: '${UID}:${GID}'
image: postgres
container_name: postgres
ports:
- '5432:5432'
restart: always
environment:
POSTGRES_HOST: db
POSTGRES_USER: root
POSTGRES_PASSWORD: secret
POSTGRES_DATABASE: foo
PGDATA: /var/lib/postgresql/data/db
volumes:
- ./db/data:/var/lib/postgresql/data/db
- db-init.sh:/docker-entrypoint-initdb.d/:ro
cache:
image: redis:alpine
container_name: redis
sysctls:
net.core.somaxconn: '511'
ports:
- '6379:6379'
command: ['--requirepass "secret"']
api:
image: node:alpine
container_name: api
working_dir: /var/www/app
command: sh -c "npm start"
ports:
- '5000:5000'
volumes:
- node_modules:/var/www/app/node_modules
- .:/var/www/app
env_file: .env
depends_on:
- db
- cache
volumes:
node_modules:
postgres connection settings for node.js app:
export const {
POSTGRES_USER = 'root',
POSTGRES_PASSWORD = 'secret',
POSTGRES_HOST = 'db',
POSTGRES_PORT = 5432,
POSTGRES_DATABASE = 'foo',
} = process.env
issue:
When using service or container name (db or postgres) for the POSTGRES_HOST setting of node app:
I can successfully connect to, and query, the database.
I'm not able to run commands from host which affect the container. For example, seeding db won't work:
npx knex --esm seed:run
This makes sense, as the DNS resolution for db / postgres is taken care of by docker and those only have meaning on the network connecting the containers. Commands run from the host and targeting that container will fail as host doesn't know how to resolve the DNS here.
On the other hand, when using localhost for the POSTGRES_HOST setting of node app:
Queries to postgres from api will fail.
Commands run from the host, like npx knex --esm seed:run, will succeed.
Again, this makes perfect sense. Addressing container as localhost from host will work thanks to the port forwarding in docker-compose.yml. But in the context of the container, it refers to that very container: for api localhost means itself, and its trying to find a database on localhost:5432 or api:5432.
I want to have working inter-container network and also run commands from the host, addressing the said containers. I'm aware of two approaches to achieve that:
Use container / service name as POSTGRES_HOST, and run commands against the containers with:
docker exec -it <container_name> <command>
Assign static ips to the containers and use those instead of service / container names.
Do I have any other options here?
since you are exposing the database ports on the host machine you can do the following.
Use service or container name (db or postgres) for the POSTGRES_HOST, this way it will work for Docker containers.
when you run the seed command form the host, overwrite the POSTGRES_HOST. This can be done in this way
$ export POSTGRES_HOST=127.0.0.1
$ npx knex --esm seed:run
or in one step
$ POSTGRES_HOST=127.0.0.1 npx knex --esm seed:run