I can't figure out how to connect to my redis service from my app service. Using DDocker version 18.03.1-ce, build 9ee9f40ocker for Mac.
I've tried connecting the various ways I've found on similar questions:
const client = redis.createClient({ host: 'localhost', port: 6379});
const client = redis.createClient({ host: 'redis', port: 6379});
const client = redis.createClient('redis://redis:6379');
const client = redis.createClient('redis', 6379); // and reversed args
I always get some form of:
Error: Redis connection to localhost:6379 failed - connect ECONNREFUSED 127.0.0.1:6379
Error: Redis connection to redis:6379 failed - connect ECONNREFUSED 172.20.0.2:6379
Docker containers
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
0fd798d58561 app_app "pm2-runtime start e…" 2 seconds ago Up 7 seconds app
65d148e498f7 app_redis "docker-entrypoint.s…" About a minute ago Up 8 seconds 0.0.0.0:6379->6379/tcp redis
Redis works:
$ docker exec -it redis /bin/bash
root#65d148e498f7:/data# redis-cli ping
PONG
Redis Dockerfile (pretty simple)
FROM redis:4.0.9
COPY redis.conf /usr/local/etc/redis/redis.conf
CMD ["redis-server", "/usr/local/etc/redis/redis.conf"]
app Dockerfile
FROM node:10.3.0-slim
RUN mkdir -p /app
COPY src/* /app/
CMD ["pm2-runtime", "start", "/app/ecosystem.config.js"]
docker-compose.yml
version: "3"
services:
redis:
build: ./redis/
container_name: redis
restart: unless-stopped
ports:
- "6379:6379"
expose:
- "6379"
volumes:
- /var/run/docker.sock:/var/run/docker.sock
environment:
- 'API_PORT=6379'
- 'NODE_ENV=production'
app:
depends_on:
- redis
build: ./app/
container_name: app
restart: unless-stopped
volumes:
- /var/run/docker.sock:/var/run/docker.sock
- /app/node_modules
environment:
- 'NODE_ENV=production'
It looks like your redis image is configured to listen on 127.0.0.1 rather than all interfaces. This is not an issue with the default redis images, so either use the official image from docker hub, or correct your configuration to listen on 0.0.0.0.
You'll be able to verify this with netshoot:
docker run --rm --net container:app_redis nicolaka/netshoot netstat -ltn
In the redis conf, listening on all interface is done by commenting out the "bind" line in redis.conf.
Let me explain it in simple language. When you run docker-compose up it runs redis and app in separate containers. Now your app needs to connect/access the redis container (remember redis is not at your machines localhost, its inside a container and runs inside it at default port 6379). By default Docker will keep app container and redis container in same network and you can access a container by its service name (which in your case is redis and app) so in order to access redis from app container all you need is to use the default port 6379 and host will be the service name (in your case "redis").
For a node application running in a container get access to Redis (which was also running in a container) by
const redis = require("redis");
const client = redis.createClient(6379, "service-name-for-redis-container");
I solve this problem changing the redis host from 'localhost' to 'redis', exemple:
REDIS_HOST=redis
REDIS_PORT=6379
After the change my docker service started to comunicate with redis.
Original forum answer: https://forums.docker.com/t/connecting-redis-from-my-network-in-docker-net-core-application/92405
In my case the problem was that I was binding a different port on redis:
redis:
image: redis
ports:
- 49155:6379
And I was trying to connect to port 49155 but I needed to connect through port 6379 since the connection is from another service.
localhost from the app container's perspective won't be able to leave the app container. So the best bet is to use redis or the host's ip address.
If you want to reach redis from the app container, you'll need to link them or put them into the same network. Please add a network property to both services, using the same network name. Docker will then provide you with with valid dns lookups for the service names.
See the official docs at https://docs.docker.com/compose/compose-file/#networks (for the service: property) and https://docs.docker.com/compose/compose-file/#network-configuration-reference (for the top-level networks property).
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-compose up
Shows -
app_1 | Node server listening on port 3800 in 'development' mode
app_1 | node_redis: Warning: Redis server does not require a password, but a password was supplied.
app_1 | node_redis: Warning: Redis server does not require a password, but a password was supplied.
docker ps shows following -
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
9c3f8a951203 redis:latest "docker-entrypoint.s…" 6 minutes ago Up 6 minutes 6379/tcp mvc20_redis_1
b242b37adf15 mvc-nodejs "node app.js" 2 days ago Up 6 minutes 9005/tcp mvc20_app_1
docker-compose.yml contains following -
version: '2'
services:
app:
image: mvc-nodejs
redis:
image: redis:latest
command: ["redis-server", "--bind", "redis", "--port", "6379"]
Previously I used to access the application end points on http://localhost:3800.
But now it is not accessible. Is it because of the external port not being configured?
Earlier, before using docker-compose, I was specifying an external port while running a container like this -
docker run --name redis -p 6379:6379 redis
Do I need to do something similar?
Newbie here.
Update
Tried the port 9005 as well. Same result -
Could not get any response via Postman.
Try updating your app service and expose the internal port like this:
services:
app:
ports:
- 3800:3800
Where first 3800 is the port you're gonna access the app externally (host port), and the last 3800 is the port where your node app is listening to.
I have an existing node application that connects to redis at 127.0.0.1:6379. I am unable to change this.
I understand that with docker compose it connects the two services redis and node and allows them to connect using the redis hostname, however I can't change this.
How can I make it so that redis is accessible from the node application at the 127.0.0.1:6379 host and port?
Here's my docker-compose.yml file:
version: '3'
services:
redis:
image: redis
hostname: "127.0.0.1"
redis-cli:
image: redis
links:
- redis
command: redis-cli -h 127.0.0.1
Here's the output:
$ docker-compose run redis-cli
Starting install_redis_1 ... done
Could not connect to Redis at 127.0.0.1:6379: Connection refused
Could not connect to Redis at 127.0.0.1:6379: Connection refused
not connected>
You can use network_mode: host in both containers to make redis expose its 6379 on localhost, and make localhost available to redis-cli:
version: '3'
services:
redis:
image: redis
network_mode: host
redis-cli:
depends_on:
- redis
image: redis
network_mode: host
command: redis-cli -h 127.0.0.1 ping
And running it:
> docker-compose run redis-cli
Starting dockerredis_redis_1 ... done
PONG
I am trying to connect postgresdb service with nodejs web service using docker compose
My docker-compose.yml file
version: "3"
services:
web:
build: ./
ports:
- "40000:3000"
depends_on:
- postgres
postgres:
image: kartoza/postgis:9.6-2.4
restart: always
volumes:
- postgresdata:/data/db
environment:
- POSTGRES_PASS=password
- POSTGRES_DBNAME=sticki
- POSTGRES_USER=renga
- ALLOW_IP_RANGE=0.0.0.0/0
ports:
- "1000:5432"
volumes:
postgresdata:
So when i do docker-compose up in my root directory both services are running and i can access web service using localhost:40000 and postgres service using postico on localhost:1000
But in Node Web service i have written code to access postgres using Sequelize as
const sequelize = new Sequelize('sticki', 'renga', 'password', {
host: 'postgres',
dialect: 'postgres',
});
But I get the following error
SequelizeConnectionRefusedError: connect ECONNREFUSED 172.18.0.2:1000
Why does postgres Connection is made to 172.18.0.2 instead of localhost(0.0.0.0)? What i am doing wrong?
For your web container postgres is a DNS name defined in compose as a service. It fetches the postgres DNS IP address via docker internal DNS & network, that's why it's resolving to 172.18.0.2. If you go to web container & ping postgres, you will get the same IP.
As a fix, configure your node service to connect to host postgres on port 5432 since it's the container port. Port 1000 is the host machine port, if you want to use port 1000, configure node service to connect to your MACHINE_IP:1000.
PS - Localhost within a container means the container itself & nothing else.
Service name is taken from container_name - which is fixed. In your case you do not have that and name is created from folder where docker-compose.yml is + _ + service name + _1.
With this DNS name you can reach your service on the default network that docker-compose will create, from one service to reach the other.
Thanks