Docker: COPY failed: file not found in build context (Dockerfile)

Question

I'd like to instruct Docker to COPY my certificates from the local /etc/ folder on my Ubuntu machine.

I get the error:

COPY failed: file not found in build context or excluded by .dockerignore: stat etc/.auth_keys/fullchain.pem: file does not exist

I have not excluded in .dockerignore

How can I do it?

Dockerfile:

FROM nginx:1.21.3-alpine

RUN rm /etc/nginx/conf.d/default.conf
RUN mkdir /etc/nginx/ssl
COPY nginx.conf /etc/nginx/conf.d
COPY ./etc/.auth_keys/fullchain.pem /etc/nginx/ssl/
COPY ./etc/.auth_keys/privkey.pem /etc/nginx/ssl/

WORKDIR /usr/src/app

I have also tried without the dot --> same error

COPY /etc/.auth_keys/fullchain.pem /etc/nginx/ssl/
COPY /etc/.auth_keys/privkey.pem /etc/nginx/ssl/

By placing the folder .auth_keys next to the Dockerfile --> works, but not desireable

COPY /.auth_keys/fullchain.pem /etc/nginx/ssl/
COPY /.auth_keys/privkey.pem /etc/nginx/ssl/

You can only `COPY` files that are located within your local source tree; you'll need to `cp` the files outside Docker space. [How to include files outside of Docker's build context?](https://stackoverflow.com/questions/27068596/how-to-include-files-outside-of-dockers-build-context) discusses this further, though it's impractical to pass the entire host filesystem as the build context. — David Maze, Nov 05 '21 at 11:40
For the particular case of private keys, you shouldn't `COPY` them into an image, though, since they can be very easily copied back out. The `docker run -v` option or Compose `volumes:` can [inject arbitrary host content into a container](https://docs.docker.com/storage/bind-mounts/) and isn't subject to `COPY`'s path restrictions. — David Maze, Nov 05 '21 at 11:42
Thanks, very useful and concise answer, May I please ask what a common solution is, to safety handle those keys in a production environment (by a separate script?) — Jaco, Nov 05 '21 at 11:43
In my case, I was just overworked and didn't realize that what I'm trying to copy doesn't exist on the host. `COPY filexyz /src/filexyz` Now, my current working directory on host didn't have any filexyz file so it failed. — Mujeeb Ishaque, Oct 03 '22 at 23:44

score 40 · Accepted Answer · answered Nov 05 '21 at 11:42

The docker context is the directory the Dockerfile is located in. If you want to build an image that is one of the restrictions you have to face.

In this documentation you can see how contexts can be switched, but to keep it simple just consider the same directory to be the context. Note; this also doesn't work with symbolic links.

So your observation was correct and you need to place the files you need to copy in the same directory.

Alternatively, if you don't need to copy them but still have them available at runtime you could opt for a mount. I can imagine this not working in your case because you likely need the files at startup of the container.

Bind-mounted files will be available at container startup (when the `ENTRYPOINT`/`CMD` runs) but not before (during `RUN` steps). For keys used to sign and encrypt TLS network traffic this is probably fine. — David Maze, Nov 05 '21 at 12:25

score 13 · Answer 2 · edited Aug 15 '22 at 20:41

It's also important to note that, as mentioned into the docs:

If you use STDIN or specify a URL pointing to a plain text file, the system places the contents into a file called Dockerfile, and any -f, --file option is ignored. In this scenario, there is no context.

That is, if you're running build like this:

docker build -t dh/myimage - < Dockerfile_test

Any COPY or ADD, having no context, will throw the error mentioned or another similar:

failed to compute cache key: "xyz" not found: not found

If you face this error and you're piping your Dockerfile, then I advise to use -f to target a custom Dockerfile.

docker build -t dh/myimage -f Dockerfile_test .

(. set the context to the current directory)

Here is a test you can do yourself :

In an empty directory, create a Dockerfile_test file, with this content

FROM nginx:1.21.3-alpine
COPY test_file /my_test_file

Then create a dummy file:

touch test_file

Run build piping the test Dockerfile, see how it fails because it has no context:

docker build -t dh/myimage - < Dockerfile_test
[..]
failed to compute cache key: "/test_file" not found: not found
[..]

Now run build with -f, see how the same Dockerfile works because it has context:

docker build -t dh/myimage -f Dockerfile_test .
[..]
 => [2/2] COPY test_file /my_test_file
 => exporting to image
[..]

I had this problem because I was building using STDIN thank you for the insight — Peter, Feb 22 '23 at 00:11

score 12 · Answer 3 · edited Aug 15 '22 at 20:40

@JustLudo's answer is correct, in this case. However, for those who have the correct files in the build directory and still seeing this issue; remove any trailing comments.

Coming from a C and javascript background, one may be forgiven for assuming that trailing comments are ignored (e.g. COPY my_file /etc/important/ # very important!), but they are not! The error message won't point this out, as of my version of docker (20.10.11).

For example, the above erroneous line will give an error:

COPY failed: file not found in build context or excluded by .dockerignore: stat etc/important/: file does not exist

... i.e. no mention that it is the trailing # important! that is tripping things up.

score 2 · Answer 4 · answered Apr 05 '23 at 09:09

Let me share my solution

Here is the outline of my project

├-app
 ├── Dockerfile
 ├── pom.xml
 ├── src

Now my docker command was to be fired from a directory outside of app and not inside app folder. So this is what worked for me

docker build -t $ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG -f app/Dockerfile app

Note the context which is generally specified as "." was now replaced with the "app" folder.

tema_skakun · Answer 5 · 2023-02-04T21:52:02.850

Check your docker-compos.yml, it might be changing the context directory.

I had a similar problem, with the only clarification: I was running Dockerfile with docker-compos.yml

This is what my Dockerfile looked like when I got the error:

FROM alpine:3.17.0
ARG DB_NAME \
    DB_USER \
    DB_PASS
RUN apk update && apk upgrade && apk add --no-cache \
    php \
    ...
EXPOSE 9000
COPY ./conf/www.conf /etc/php/7.3/fpm/pool.d   #<--- an error was here
COPY ./tools /var/www/                         #<--- and here
ENTRYPOINT ["sh", "/var/www/start.sh"]

This is part of my docker-compose.yml where I described my service.

wordpress:
container_name: wordpress
build:
  context: .          #<--- the problem was here
  dockerfile: requirements/wordpress/Dockerfile
  args:
    DB_NAME: ${DB_NAME}
    DB_USER: ${DB_USER}
    DB_PASS: ${DB_PASS}
ports:
  - "9000:9000"
depends_on:
  - mariadb
restart: unless-stopped
networks:
  - inception
volumes:
  - wp:/var/www/

My docker-compos.yml was changing the context directory. Then I wrote a new path in the Dockerfile and it all worked.

COPY ./requirements/wordpress/conf/www.conf /etc/php/7.3/fpm/pool.d
COPY ./requirements/wordpress/tools /var/www/

project structure

score 0 · Answer 6 · answered Feb 07 '23 at 20:41

0

FWIW this same error shows up when running gcloud builds submit if the files are included in .gitignore

answered Feb 07 '23 at 20:41

John Heyer

711
1
6
18

my man, thanks this was the issue for me lol – Barrufet Jul 15 '23 at 20:37

score 0 · Answer 7 · answered Feb 07 '23 at 20:48

0

Have you tried doing a simlink with ln -s to the /etc/certs/ folder in the docker build directory?

Alternatively you could have one image that has the certificates and in your image you just COPY FROM the docker image having the certs.

answered Feb 07 '23 at 20:48

domgom

283
2
9

score 0 · Answer 8 · answered Aug 09 '23 at 08:37

In my case was same error:

ERROR: Service 'php' failed to build: COPY failed: file not found in build context or excluded by .dockerignore: stat src/: file does not exist

I had: docker-compose.yml

version: '3'
services:
  php:
    build:
      context: .
      dockerfile: Dockerfile
    volumes:
      - ./src:/var/www/html
    ports:
      - 8080:80
    depends_on:
      - mysql
  mysql:
    image: mysql:latest
    environment:
      MYSQL_ROOT_PASSWORD: my_db_root_pass
      MYSQL_DATABASE: my_db
      MYSQL_USER: my_db_user
      MYSQL_PASSWORD: my_db_pass
    volumes:
      - mysql_data:/var/lib/mysql
volumes:
  mysql_data:

and Dockerfile

FROM php:7.4-apache
COPY src/ /var/www/html/

When I created a src folder and then added an index.php file to the src folder for example

<!DOCTYPE>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <title>Docker</title>
  </head>
  <body><p>Docker</p></body>
</html>

Everything worked

dudeNumber4 · Answer 9 · 2022-10-25T18:30:46.980

-1

I merely had quoted the source file while building a windows container, e.g.,
COPY "file with space.txt" c:/some_dir/new_name.txt
Docker doesn't like the quotes.

edited Oct 25 '22 at 18:30

answered Oct 25 '22 at 14:10

dudeNumber4

4,217
7
40
57

score -1 · Answer 10 · edited Feb 22 '23 at 13:02

I had the same error. I resolved it by adding this to my Docker build command:

docker build --no-cache -f ./example-folder/example-folder/Dockerfile

This repoints Docker to the home directory. Even if your Dockerfile seems to run (i.e. the system seems to locate it and starts running it), I found I needed to have the home directory pre-defined above, for any copying to happen.

Inside my Dockerfile, I had the file copying like this:

COPY ./example-folder/example-folder /home/example-folder/example-folder

Docker: COPY failed: file not found in build context (Dockerfile)

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