CODEWITHSUNDEEP
containers
Sujit Singh
Sujit Singh

Reputation: 831

Why different instances of Docker image running on same port

I created a Asp.net application with Docker (windows) support. I created image (eshoplegacymvc:dev) of it and run it using command 

docker run eshoplegacymvc:dev

I ran above command multiple times, what I understand is that when we run it, website will be available.

Queries :

1) So if I run it 5 times, does it mean 5 instance of those websites are running?

2) If yes, then why port number of all is same? And how can I access those websites from local machine, I am not able to do that.

See below screenshot which shows all process running by using docker command

Docker ps

enter image description here

Upvotes: 0

Views: 1152

Answers (2)

Harsh Manvar
Harsh Manvar

Reputation: 30160

  1. Yes you are running 5 website instances
  2. you forget to setup port mapping

docker run -p 8888:80 eshoplegacymvc:dev using this command you can map ports

your website will be running on localhost:8888

for 5 container you can do it 5 time with -p 8777:80 with different ports 8888:80 ; 8999:80 which addressing to container port 80 and exposing it over 8777

Upvotes: 1

Sriram
Sriram

Reputation: 674

While running the docker command, you have not specified the port mapping. The ports 80/tcp shown is of container tcp port and not host port.

1) Yes, you are running 5 instance of websites. 2) To access website, you need to provide different port mapping for each container instance.

Example: 

docker run -p 8081:80 eshoplegacymvc:dev
docker run -p 8082:80 eshoplegacymvc:dev
docker run -p 8083:80 eshoplegacymvc:dev
docker run -p 8084:80 eshoplegacymvc:dev
docker run -p 8085:80 eshoplegacymvc:dev

In the above examples, tcp port 80 of the container binds to TCP port 8081/8082/8083/8084/8085 of the host machine.

You can access the site using http://localhost:8081/

For more information on port binding you can check docker docs

Upvotes: 2

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