docker run puts me into a node repl - node.js

Question

When I go to run docker run -p 8080:3000 --name cabinfeverInstance -t something/cabinfever I get put into a Node.js REPL, when I expect to see "Listening on port: 3000". Going to localhost:8000 results in a "didn’t send any data. ERR_EMPTY_RESPONSE". I have found no other instances of this occurring (maybe I am not searching Google for the correct words/tricky phrases). I did find this issue which seems somewhat related. Their solution was to "make the containerized app expect requests from the windows host machine IP (not container IP)", but I am not sure how to implement that. Also, their solution could also not be my solution.
What I have tried:
Clean/purging the data.
Running docker run -p 8080:3000/tcp -p 8080:3000/udp --name cabinfeverInstance -t something/cabinfever
Not specifying the specific port (8080).
Specifying 0.0.0.0.
Several additional ideas.
None have worked and I still get the wonderful Node REPL.
If anyone has any suggestions, I would appreciate them.
Here are the relevant files:
index.js
var express = require('express');
var app = express();
var port = 3000;
app.get('/', function(req,res) {
console.log(new Date().toLocaleString());
res.send(new Date().toLocaleString());
});
app.listen(port, () => {
console.log(`Listening at http://localhost: ${port}`);
});
package.json:
{
"name": "docnode",
"version": "1.0.0",
"description": "barebones node on docker",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "index.js"
},
"author": "my.email.address#gmail.com",
"license": "MIT",
"dependencies": {
"express": "^4.15.5"
}
}
docker-compose.yml:
version: "3"
services:
node:
build: .
command: node index.js
ports:
- "3000:3000"
Dockerfile:
FROM node:slim
LABEL author="my.email.address#gmail.com"
WORKDIR /app
# copy code, install npm dependencies
COPY index.js /app/index.js
COPY package.json /app/package.json
RUN npm install

Answer 1

You should specify the command to run in the Dockerfile, not the docker-compose.yml file:
CMD ["node", "index.js"]
When you docker run an image, the only options it considers are those on the docker run command line. docker run doesn't know about docker-compose.yml, so if you specify things like command: there it won't be honored. Since the CMD isn't in the Dockerfile and it isn't on the docker run command line (after the image name), you fall back to the base image's CMD, which in the case of node is to run the REPL.
With this change you don't need to override command: in the docker-compose.yml file and you can delete that line. Running
docker-compose up -d
will start the container(s) in the docker-compose.yml file with the options specified there (note, the ports: mapping and the docker run -p ports are slightly different).