docker Error while trying to connect to mongodb - node.js

Question

I want to make simple restful API. I am using docker to do this. Here is my Dockerfile:
FROM mongo:3.2
EXPOSE 3000
RUN apt-get update; apt-get install curl -y
RUN curl -sL https://deb.nodesource.com/setup_6.x | bash -
RUN apt-get install -y nodejs
ADD . .
CMD node app.js
My docker-compose.yml looks like this:
version: '2'
services:
db:
build: ../images/mongodb
ports:
- "27017:27017"
- "3000:3000"
my app.js file looks like this:
var express = require('express')
var app = express()
var mongoose = require('mongoose');
mongoose.Promise = global.Promise;
mongoose.connect('mongodb://127.0.0.1:27017/sample');
app.get('/', function (req, res) {
res.send('Hello World!')
})
app.listen(3000, function () {
console.log('Example app listening on port 3000!')
})
When run docker-compose up --build, I am having and error:
db_1 | Example app listening on port 3000!
db_1 |
db_1 | events.js:160
db_1 | throw er; // Unhandled 'error' event
db_1 | ^
db_1 | MongoError: failed to connect to server [127.0.0.1:27017] on first connect [MongoError: connect ECONNREFUSED 127.0.0.1:27017]
db_1 | at Pool.<anonymous> (/node_modules/mongodb-core/lib/topologies/server.js:327:35)
db_1 | at emitOne (events.js:96:13)
db_1 | at Pool.emit (events.js:188:7)
db_1 | at Connection.<anonymous> (/node_modules/mongodb-core/lib/connection/pool.js:274:12)
db_1 | at Connection.g (events.js:291:16)
db_1 | at emitTwo (events.js:106:13)
db_1 | at Connection.emit (events.js:191:7)
db_1 | at Socket.<anonymous> (/node_modules/mongodb-core/lib/connection/connection.js:177:49)
db_1 | at Socket.g (events.js:291:16)
db_1 | at emitOne (events.js:96:13)
db_1 | at Socket.emit (events.js:188:7)
db_1 | at emitErrorNT (net.js:1281:8)
db_1 | at _combinedTickCallback (internal/process/next_tick.js:80:11)
db_1 | at process._tickCallback (internal/process/next_tick.js:104:9)
I have tried to go in docker machine with docker run -it mongo:3.2 /bin/bash
root#67062897d4f0:/# mongo
MongoDB shell version: 3.2.12
connecting to: test
2017-03-23T07:01:07.587+0000 W NETWORK [thread1] Failed to connect to 127.0.0.1:27017, in(checking socket for error after poll), reason: errno:111 Connection refused
2017-03-23T07:01:07.588+0000 E QUERY [thread1] Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed :
connect#src/mongo/shell/mongo.js:229:14
root#67062897d4f0:/# mongod
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] MongoDB starting : pid=29 port=27017 dbpath=/data/db 64-bit host=67062897d4f0
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] db version v3.2.12
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] git version: ef3e1bc78e997f0d9f22f45aeb1d8e3b6ac14a14
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] OpenSSL version: OpenSSL 1.0.1t 3 May 2016
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] allocator: tcmalloc
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] modules: none
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] build environment:
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] distmod: debian81
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] distarch: x86_64
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] target_arch: x86_64
2017-03-23T07:01:12.025+0000 I CONTROL [initandlisten] options: {}
2017-03-23T07:01:12.029+0000 I STORAGE [initandlisten] wiredtiger_open config: create,cache_size=8G,session_max=20000,eviction=(threads_max=4),config_base=false,statistics=(fast),log=(enabled=true,archive=true,path=journal,compressor=snappy),file_manager=(close_idle_time=100000),checkpoint=(wait=60,log_size=2GB),statistics_log=(wait=0),
2017-03-23T07:01:12.222+0000 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.
2017-03-23T07:01:12.222+0000 I CONTROL [initandlisten]
2017-03-23T07:01:12.223+0000 I CONTROL [initandlisten]
2017-03-23T07:01:12.223+0000 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2017-03-23T07:01:12.223+0000 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-03-23T07:01:12.223+0000 I CONTROL [initandlisten]
2017-03-23T07:01:12.228+0000 I FTDC [initandlisten] Initializing full-time diagnostic data capture with directory '/data/db/diagnostic.data'
2017-03-23T07:01:12.228+0000 I NETWORK [HostnameCanonicalizationWorker] Starting hostname canonicalization worker
2017-03-23T07:01:12.283+0000 I NETWORK [initandlisten] waiting for connections on port 27017
^C2017-03-23T07:01:13.447+0000 I CONTROL [signalProcessingThread] got signal 2 (Interrupt), will terminate after current cmd ends
2017-03-23T07:01:13.448+0000 I FTDC [signalProcessingThread] Shutting down full-time diagnostic data capture
2017-03-23T07:01:13.453+0000 I CONTROL [signalProcessingThread] now exiting
2017-03-23T07:01:13.453+0000 I NETWORK [signalProcessingThread] shutdown: going to close listening sockets...
2017-03-23T07:01:13.453+0000 I NETWORK [signalProcessingThread] closing listening socket: 5
2017-03-23T07:01:13.453+0000 I NETWORK [signalProcessingThread] closing listening socket: 6
2017-03-23T07:01:13.453+0000 I NETWORK [signalProcessingThread] removing socket file: /tmp/mongodb-27017.sock
2017-03-23T07:01:13.453+0000 I NETWORK [signalProcessingThread] shutdown: going to flush diaglog...
2017-03-23T07:01:13.453+0000 I NETWORK [signalProcessingThread] shutdown: going to close sockets...
2017-03-23T07:01:13.453+0000 I STORAGE [signalProcessingThread] WiredTigerKVEngine shutting down
2017-03-23T07:01:13.586+0000 I STORAGE [signalProcessingThread] shutdown: removing fs lock...
2017-03-23T07:01:13.586+0000 I CONTROL [signalProcessingThread] dbexit: rc: 0
Can someone please help me solve this ?

Answer 1

Amazing, I'm so glad I found this thread. I am going to add some keywords to it for other people.
If you get this error message, you could be running MongoDB on your local machine while trying to access it from inside a Docker container. The reason is that inside the Docker container, localhost or 127.0.0.1 refers to a different interface than your true local machine.
Error Output:
MongoError: failed to connect to server [127.0.0.1:27017] on first connect [MongoError: connect ECONNREFUSED 127.0.0.1:27017]
at Pool.<anonymous> (/app/node_modules/mongodb-core/lib/topologies/server.js:329:35)
at emitOne (events.js:96:13)
at Pool.emit (events.js:191:7)
at Connection.<anonymous> (/app/node_modules/mongodb-core/lib/connection/pool.js:280:12)
at Object.onceWrapper (events.js:293:19)
at emitTwo (events.js:106:13)
at Connection.emit (events.js:194:7)
at Socket.<anonymous> (/app/node_modules/mongodb-core/lib/connection/connection.js:187:49)
at Object.onceWrapper (events.js:293:19)
at emitOne (events.js:96:13)
at Socket.emit (events.js:191:7)
at emitErrorNT (net.js:1284:8)
at _combinedTickCallback (internal/process/next_tick.js:80:11)
at process._tickDomainCallback (internal/process/next_tick.js:128:9)
name: 'MongoError',
message: 'failed to connect to server [127.0.0.1:27017] on first connect [MongoError: connect ECONNREFUSED 127.0.0.1:27017]' }
Possible Fixes:
Enable remote connections from your MongoDB, and use your public IP to access it from inside the Docker Container.
Run MongoDB from inside the Container, and then you can refer to it with localhost.
Run another Docker Container, and enable remote connections on it. Investigate bind_ip in the MongoDB config file. Make sure you secure your database with auth credentials. Spend some time ensuring it is secure.
Remote connections are disabled by default in MongoDB, ie: going through a Docker container incorrectly.
Here is a helpful resource: https://hub.docker.com/_/mongo/

Answer 2

The issue I believe is that using CMD node app.js only starts node and not the database. Normally when creating this kind of simple app you use two containers. One for mongo one for node, as you aren't using a custom config for mongo or node you could just use images and map the code in your current folder to the /opt/ directory in the container, meaning all you need is a compose file and potentially don't need any Dockerfile's
Disclaimer obviously this isn't good enough for production, at some point you will probably want to use a Dockerfile for your app as it's best to start node as a user instead of root and put the files in a meaningful directory. But if all you want to do is use as a sandbox this should do.
Your docker compose would look like
version: "2"
services:
db:
image: mongo:3.2
ports:
- 27017
app:
image: node
links:
- db
volumes:
- '.:/opt/'
command: node /opt/app.js
ports:
- 3000:3000
If you want to go full in and specify a Dockerfile for each.
/docker-files/app/Dockerfile
# take from the latest node build
FROM node
# Make a directory /opt/app
RUN mkdir /opt/app
# Set work dir to /opt/app
WORKDIR /opt/app
# Do all your npm install etc....
CMD node app.js
/docker-files/db/Dockerfile
FROM mongo:3.2
# Do some fancy mongo stuff.
/docker-compose.yml
version: "2"
services:
db:
build:
context: docker-files/db
dockerfile: Dockerfile
ports:
- 27017
app:
build:
context: docker-files/app
dockerfile: Dockerfile
links:
- db
volumes:
- '.:/opt/app'
ports:
- 3000:3000

Answer 3

For docker-compose, you need to use a tag networks to link one container node with other. Look:
version: '2'
networks:
app-tier:
driver: bridge
services:
mongodb:
image: 'mongodb:latest'
networks:
- app-net
myapp:
image: 'YOUR_APPLICATION_IMAGE'
networks:
- app-net