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Packaging an app with Dockerfile

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Packaging the app: ✅ Pushing to DockerHub: ✅

See Error Pushing to Docker Hub below for how I troubleshot the issue!

What is my app?

A static webpage I had created for fun a few months ago. I knew it would come in handy!



What did I do?

  • Used demo static webpage for testing.
  • Created Dockerfile

💡 It should be Dockerfile, no extension. Dockerfile.Dockerfile is incorrect!

  • Used nginx Alpine as server and the following code:
FROM scratch as static-site
WORKDIR /app

COPY . . 

FROM nginx:1.16.0-alpine as server

COPY --from=static-site /app /usr/share/nginx/html

EXPOSE 80

CMD [ "nginx", "-g", "daemon off;"]

From Mwiza Kumwenda (see resources below).

I wondered if I should use "start" in the CMD [ "nginx", "-g", "daemon off;"] list/tuple, but it worked without it.

  • Exposed port 80
  • Created image;

Pushing the Image

Had to re-package it; Is there a way to push pre-existing packages?

Error Pushing to Docker Hub:

An image does not exist locally with the tag username/staticapptest

Also the same error for:

  • Image IDs that I know exist.


Yes, it is different than the image above, but it does exist.

  • New images created

It seems to ignore my attempts of the default tag(s) and latest.

Access is denied, despite being logged in on Docker in VS Code and Docker Desktop. Logging out and logging in doesn’t solve this.


Why?

The Fix

  • Creating the image as a container and then pushing it works

Steps Taken:

  1. Package app (above)
  2. Run the Image
  3. Take the Image ID and run within a container;
776442dod12   libtest:latest   "nginx -g 'daemon of…"   18 seconds ago   Up 13 seconds   0.0.0.0:80->80/tcp   hopeful_thompson
  1. Commit the container;
docker commit 776442dod12   <name>/libtest:<tag>
  1. 5 docker images reveals;
libtest            latest    776442dod12   25 hours ago     29.4MB
  1. Then I push it to my DockerHub;
docker push <name>/libtest:<tag>
The push refers to repository [docker.io/<name>/libtest]

And it works; Check it out publicly here.

What went wrong?

I had to make the image a container first. I thought the image would be enough.

Resources used:


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