I m not able to connect to mongo with a container docker - mongodb

Question

I m new to docker
so i followed up a tutorial here , part 6,7 and 8 in order to use and learn docker in a project.
The problem is that when i use docker-compose.yml to build images on my laptop,
my stack_server can connect to mongo.
But if i build images from docker hub and i pull and run them seperately on my laptop,my stack_server CAN't connect to mongo.
here is my docker-compose.yml :
client:
build: ./client
restart: always
ports:
- "80:80"
links:
- server
mongo:
image: mongo
command: --smallfiles
restart: always
ports:
- "27017:27017"
server:
build: ./server
restart: always
ports:
- "8080:8080"
links:
- mongo
However, my stack_client can connect to the stack_server.
and my commands to run my image (my images are public)
docker-run -i -t -p 27017:27017 mongo
docker-run -i -t -p 80:80 mik3fly4steri5k/stack_client
docker-run -i -t -p 8080:8080 mik3fly4steri5k/stack_server
and my error log
bryan#debian-dev7:~$ sudo docker run -i -t -p 8080:8080 mik3fly4steri5k/stack_server
[sudo] password for bryan:
Express server listening on 8080, in development mode
connection error: { Error: connect ECONNREFUSED 127.0.0.1:27017
at Object._errnoException (util.js:1021:11)
at _exceptionWithHostPort (util.js:1043:20)
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1175:14)
name: 'MongoError',
message: 'connect ECONNREFUSED 127.0.0.1:27017' }
here is my stack_server dockerfile
FROM node:latest
# Set in what directory commands will run
WORKDIR /home/app
# Put all our code inside that directory that lives in the container
ADD . /home/app
# Make sure NPM is not cached, remove everything first
RUN rm -rf /home/app/node_modules/npm \
&& rm -rf /home/app/node_modules
# Install dependencies
RUN npm install
# Tell Docker we are going to use this port
EXPOSE 8080
# The command to run our app when the container is run
CMD ["node", "app.js"]
First Solution but deprecated
docker-run -i -t -p 27017:27017 --name:mongo mongo
docker-run -i -t -p 80:80 mik3fly4steri5k/stack_client
docker-run -i -t -p 8080:8080 --link mongo:mongo mik3fly4steri5k/stack_server
I had to put a name on my mongo and to link it with the parameter --link when i run my stack_server
docker documentation
Warning: The --link flag is a deprecated legacy feature of Docker.
It may eventually be removed.
Unless you absolutely need to continue using it,
we recommend that you use user-defined networks to facilitate communication
between two containers instead of using --link.
One feature that user-defined networks do not support that you can do with
--link is sharing environmental variables between containers.
However, you can use other mechanisms such as volumes to share environment
variables between containers in a more controlled way.

Answer 1

Run your stack_server with below command
sudo docker run -i -t -p 8080:8080 --link mongo:mongo mik3fly4steri5k/stack_server
Note: --link flag is a deprecated

Answer 2

Your container is running. But is it healthy? I recommend that you implement Healthcheck
It’s actually would look pretty much the same:
(Docker-compose YAML)
healthcheck:
test: curl -sS http://127.0.0.1:8080 || echo 1
interval: 5s
timeout: 10s
retries: 3
Docker health checks is a cute little feature that allows attaching shell command to container and use it for checking if container’s content is alive enough.
I hope it can help you.
more info https://docs.docker.com/compose/compose-file/compose-file-v2/#healthcheck

Answer 3

To start MongoDB on a desire port you would have to do the followings:
client:
build: ./client
restart: always
ports:
- "80:80"
links:
- server
mongo:
image: mongo
command: mongod --port 27017
restart: always
ports:
- "27017:27017"
server:
build: ./server
restart: always
ports:
- "8080:8080"
links:
- mongo

Answer 4

Lets look at error
connection error: { Error: connect ECONNREFUSED 127.0.0.1:27017
Server trying to connect to localhost instead of mongo. You need to configure server to connect mongo to mongo:27017
mongo is alias created by docker for linking containers to each other.