Docker commit image starts node repl instead of serving a website-CodePudding

Goal is to NOT use a Dockerfile but to create a container, modify a container, then commit an image based off the container. It is for a course I am giving feedback on and I can NOT use a Dockerfile.

I have a folder, node-test-application with the following on an Ubuntu machine: package.json server.js

package.json

{
  "name": "docker_web_app",
  "version": "1.0.0",
  "description": "Node.js on Docker",
  "author": "First Last <[email protected]>",
  "main": "server.js",
  "scripts": {
    "start": "node server.js"
  },
  "dependencies": {
    "express": "^4.16.1"
  }
}

server.js

const express = require('express');
    
// Constants
const PORT = 8080;
const HOST = '0.0.0.0';
    
// App
const app = express();
app.get('/', (req, res) => {
  res.send('Hello World');
});
    
app.listen(PORT, HOST);
console.log(`Running on http://${HOST}:${PORT}`);

So this is the order of operations I'm following from within node-test-application: Run intermediate node container

docker run -d -t --name nodeint -p 3009:8080 node:16

copy files from

docker container cp . nodeint:/app

then I enter the container:

docker exec -it nodeint sh

Now inside the container, I cd into app directory:

cd app

My files are present: package.json server.js

I run npm install:

npm install

added 57 packages, and audited 58 packages in 3s

7 packages are looking for funding
  run `npm fund` for details

found 0 vulnerabilities
npm notice 
npm notice New minor version of npm available! 8.11.0 -> 8.12.1
npm notice Changelog: https://github.com/npm/cli/releases/tag/v8.12.1
npm notice Run npm install -g [email protected] to update!
npm notice

I run npm start:

npm start

> [email protected] start
> node server.js

Running on http://0.0.0.0:8080

I go to IPADDRESS:3009 And it's serving "Hello World" to the browser.

So now I ctrl c then ctrl d and I'm out of the container.

docker ps shows that the container is still running.

So I:

docker commit nodeint nodeapp:v1

and it returns the image ID

Now I expect to be able to run a container with the nodeapp:v1 image and have it serve me Hello World on the IPADDRESS:3010 port after I run the following command:

docker run -it --name nodeappcont -p 3010:8080 nodeapp:v1

but it gives me a node REPL:

Welcome to Node.js v16.15.1.
Type ".help" for more information.
>

And when I navigate to IPADDRESS:3010 I get nothing. Just site can't be reached.

When I run image history:

docker image history nodeapp:v1
IMAGE          CREATED         CREATED BY                                      SIZE      COMMENT
ebf532979d69   3 minutes ago   node                                            5.83MB    
b59df4e04d61   2 days ago      /bin/sh -c #(nop)  CMD ["node"]                 0B        
<missing>      2 days ago      /bin/sh -c #(nop)  ENTRYPOINT ["docker-entry…   0B        
<missing>      2 days ago      /bin/sh -c #(nop) COPY file:4d192565a7220e13…   388B      
<missing>      2 days ago      /bin/sh -c set -ex   && for key in     6A010…   7.6MB     
<missing>      2 days ago      /bin/sh -c #(nop)  ENV YARN_VERSION=1.22.19     0B        
<missing>      2 days ago      /bin/sh -c ARCH= && dpkgArch="$(dpkg --print…   95.3MB    
<missing>      2 days ago      /bin/sh -c #(nop)  ENV NODE_VERSION=16.15.1     0B        
<missing>      12 days ago     /bin/sh -c groupadd --gid 1000 node   && use…   334kB     
<missing>      12 days ago     /bin/sh -c set -ex;  apt-get update;  apt-ge…   510MB     
<missing>      12 days ago     /bin/sh -c apt-get update && apt-get install…   146MB     
<missing>      12 days ago     /bin/sh -c set -ex;  if ! command -v gpg > /…   17.5MB    
<missing>      12 days ago     /bin/sh -c set -eux;  apt-get update;  apt-g…   16.5MB    
<missing>      12 days ago     /bin/sh -c #(nop)  CMD ["bash"]                 0B        
<missing>      12 days ago     /bin/sh -c #(nop) ADD file:5c5cde050dbdbd5c7…   114MB

So how do I create an node image from a container with changes that will serve a node app? Remember, without using a Dockerfile.

CodePudding user response：

docker commit only saves the file system of the container. It doesn't save any running processes.

You can change the working directory and the start command, by using the --change/-c option on docker commit to apply Dockerfile statements from the command line. In your case, you could do

docker commit -c 'WORKDIR /app' -c 'CMD npm start' nodeint nodeapp:v1

Then you can run it with

docker run -it --name nodeappcont -p 3010:8080 nodeapp:v1

and npm start will run in the /app directory.