How can I copy files to a docker container when error happened:Nosuch container?

Question

I am new about docker, so ,if any wrong thoughts come from me ,please point out it.Thanks~

I aim at running a web server that was developed by me ,or a team I belong to,in the docker.

So, I thought out three steps:

Have a image ,copy the web files into it,and run the container.so,I do the step below:

1- get a docker image.

I try like this : docker pull centos, so that I can get a image based on centos.Here, I did not care about the version of centos,of course, it's version is 6.7 or ,just taged:latest.

Here,I check the image by docker images,and I can see it like this:

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
docker.io/centos    latest              d123f4e55e12        3 weeks ago         196.6 MB

So,I think this step successed.

2- try copying the files in local system to the container.

I stop at the path: /tornado,which had a folder named fordocker .The

fordocker contains the web-server files.

I try commonds like this(based on the guide):

docker cp fordocker/ d123f4e55e12:/web

But! Here comes the error:

Error response from daemon: No such container: d123f4e55e12

3- if I copy the files successfully,I could try like this:docker run -d centos xxx python web.py.

This step will come error?I don't know yet.

I searched a lot ,but do not explain the phenomenon.

It seemed that everyone,beside me ,use the commond would succes.

So,here comes the questions:

1- Is the method I thought out feasible? Must I create a images through profile?

2- Where comes the error if the method is feasible? Did the commond cp based on otherthings that I had not done?

3- What should I do if the method is not feasible?Create a image myself?

Have a good day~

Answer 1

You have docker images and docker container. That is different.

You pull or build images.

When you launch an image, it becomes a running container.

An image is not a running container, and so, you will not be able to copy a file inside an image.

I do not know if this what you want to do, but you may

1) launch an image

docker run ...

2) copy or modify a file

docker ps

shows your running container, and so you can

docker cp...

a file inside this running container

3) maybe save this modified image with

docker commit...

But usually, if you want to modify an image, you modify the Dockerfile, and so you can easily build a new image with such a command

docker build -t myuser/myimage:321 .

Notice the final dot, it means you use the Dockerfile that is local.

See for example a Dockerfile for Nginx

https://github.com/nginxinc/docker-nginx/blob/c8bfb9b5260d4ad308deac5343b73b027f684375/mainline/stretch/Dockerfile