Docker: Ignore some files which are needed in build context - docker

I have a folder : /docker on my project root and it contains certain files like Apache configs which I need to copy to the correct folders during teh build.
Project-root
------docker folder
-----------apache.conf
Now
DOCKERFILE
In my dockerfile i have a copy command which copies the whole of root to the container.
`Issue`
I don't want the docker folder to be copied to the built image.
I added docker to the .dockerignore. But this leads to the problem that these files are not sent to the build context and then the build command fails.
WORKAROUND
Use the RUN command in the dockerfile to remove the docker folder instead of using .dockerignore
QUESTION
Is there any better solution?
DOCKER FILe:
FROM <baseimage>
WORKDIR /var/www/html/
COPY . /var/www/html/MYFOLDER
COPY ./docker/apache.conf /etc/httpd/conf/apache.conf
COPY ./docker/sites-enabled /etc/httpd/sites-enabled

Related

Clarify how docker command COPY behaves relative to docker build context

I want to copy the contents of a parent directory (relative to the position of the Dockerfile) into my image.
This is the folder structure:
app-root/
docker/
php81aws/
some-folder
Dockerfile
start-container
supervisord.conf
app_folders
app_files
I'm calling docker build as follows:
app-root#> docker build -t laravel -f docker/php81aws/Dockerfile .
Or from docker compose with:
services:
laravel:
build:
context: ./
dockerfile: docker/php81aws/Dockerfile
Therefore, the context should be in the app-root directory.
In the dockerfile, I'm using COPY like so:
COPY docker/php81aws/start-container /usr/local/bin/start-container
COPY docker/php81aws/supervisord.conf /etc/supervisor/conf.d/supervisord.conf
RUN chmod +x /usr/local/bin/start-container
COPY --chown=www:www . /var/www/
It always gives me this error:
failed to compute cache key: "/start-container" not found: not found
I tried to use COPY ./docker/php81aws/start-container and COPY start-container but the error is always the same. Of course copying the parent directory also fails.
You mention in a comment that your top-level app-root directory has a .dockerignore file that excludes the entire docker directory. While the Dockerfile will still be available, nothing else in that tree can be COPYed into the image, and if you COPY ./ ./ to copy the entire build context into the image, that directory won't be present.
Deleting this line from the .dockerignore file should fix your issue.
In general you want the .dockerignore file to include anything that's part of your host build-and-test environment, but should not by default be included in an image, possibly because the Dockerfile is going to rebuild it. In a Node context, for example, you almost always want to exclude the host's node_modules directory, or in a Java context often the Gradle build or Maven target directories. Anything you do want to include in the image needs to not be listed in .dockerignore.

docker cant find file in parent folder?

I have a problem where docker build can't find my files and I've tried many folder references but I cant get my head around the folder structure. No matter what its wrong.
This is my project (slimmed down) structure:
This is my docker file:
# pull official base image
FROM mcr.microsoft.com/dotnet/sdk:5.0 AS build-env
# set working directory
WORKDIR /app
# add app csprojfiles
COPY ./myapi.sln .
and this is the error:
failed to compute cache key: "/myapi.sln" not found: not found
I've tried COPY ../myapi.sln . and simply myapi.sln but its not found no matter what. Im running command docker build web.api/ from the parent myapi folder in command prompt.
Your path is wrong. By writing COPY ./myapi.sln . you assume that myapi.sln is in the same folder than the Dockerfile which is not the case.
Best practice is to put the Dockerfile at the root of your project so you can easily access all your files.
In anyway, you can't access a parent directory with absolute or relative path.
From the documentation:
The path must be inside the context of the build; you cannot COPY ../something/something, because the first step of a docker build is to send the context directory (and subdirectories) to the docker daemon.

Dockerfile in subdirectory causes Forbidden path outside the build context exception

I'm trying to put a dockerfile in a subdirectory of my main startup project AppMain. AppMain has a dependency project called AppDependency. When the dockerfile is in the root directory of AppMain, all works correctly, but when it's nested in a subdirectory of the AppMain, it fails with
4>Step 5/20 : COPY ["AppMain/AppMain.csproj", "AppMain/"]
4>COPY failed: stat /var/lib/docker/tmp/docker-builder453314675/AppMain/AppMain.csproj: no such file or directory
So that makes sense to me since it's nested in a subdirectory, so I simply added a "../" in front of the COPY commands but that results in the following context exception:
4>COPY failed: Forbidden path outside the build context: ../AppMain/AppMain.csproj ()
Alright so that makes sense as well because the docker documentation states that the context starts where the dockerfile is located, but this leads me to ask the real question.
If it cannot copy outside of the where the dockerfile is located and it works when its located in the root of AppMain, then why doesn't it fail when copying the AppReference project which obviously is above where the docker file is located and outside the context since it would have to go up one directory and then down to the AppReference project?
Is there a way to achieve having a dockerfile nested in a subdirectory?
The entire docker file is listed below.
FROM mcr.microsoft.com/dotnet/core/runtime:2.2-stretch-slim AS base
WORKDIR /app
FROM mcr.microsoft.com/dotnet/core/sdk:2.2-stretch AS build
WORKDIR /src
COPY ["AppMain/AppMain.csproj", "AppMain/"]
COPY ["AppReference/AppReference.csproj", "AppReference/"]
RUN dotnet restore "AppMain/AppMain.csproj"
COPY . .
WORKDIR "/src/AppMain"
RUN dotnet build "AppMain.csproj" -c Release -o /app
FROM build AS publish
RUN dotnet publish "AppMain.csproj" -c Release -o /app
FROM base AS final
WORKDIR /app
COPY --from=publish /app .
ENTRYPOINT ["dotnet", "AppMain.dll"]
When use docker build -t xxx . to build in the subdirectory, only the contents in . will submit to docker daemon for docker build. The things in parent folder will not be able to submit to docker engine to build.
So, you need to move the execution directory back to the parent folder with cd .., then use next to build, it will then send the . which now is the contents of parent folder to engine(But you need now specify dockerfile, like this)
docker build -t xxx -f ./YOUR_Subdirectory/Dockerfile .
It is really working.
What it is ?
SECURITY WARNING: You are building a Docker image from Windows against a non-Windows Docker host. All files and directories added to build context will have '-rwxr-xr-x' permissions. It is recommended to double check and reset permissions for sensitive files and directories.

Troubleshoot directory path error in COPY command in docker file

I am using COPY command in my docker file on top of ubuntu 16.04. I am getting error as no such file or directory eventhough the directory is present. In the below docker file I want to copy the directory "auth" present inside workspace directory to the docker image (at path /home/ubuntu) and then build the image.
FROM ubuntu:16.04
RUN apt-get update
COPY /home/ubuntu/authentication/workspace /home/ubuntu
WORKDIR /home/ubuntu/auth
a Dockerfile COPY command can only refer to files under the context - the current location of the Dockerfile, aka .
so you have a few options now:
if it is possible to copy the /home/ubuntu/authentication/workspace/ directory content to somewhere inside your project before the build (so now it will be included in your Dockerfile context and you can access it via COPY ./path/to/content /home/ubuntu) it can be great. but sometimes you dont want it.
instead of copying the directory, bind it to your container via a volume:
when you run the container, add a -v option:
docker run [....] -v /home/ubuntu/authentication/workspace:/home/ubuntu [...]
mind that a volume is designed so any change you made inside the container dir(/home/ubuntu) will affect the bound directory on your host side (/home/ubuntu/authentication/workspace) and vice versa.
i found a something over here: this guy is forcing the Dockerfile to accept his context- he is sitting inside the /home/ubuntu/authentication/workspace/ directory, and running there
docker build . -f /path/to/Dockerfile
so now inside his Dockerfile he can refer to /home/ubuntu/authentication/workspace as his context (.)

Docker: How to copy a file from one folder in a container to another?

I want to copy my compiled war file to tomcat deployment folder in a Docker container. As COPY and ADD deals with moving files from host to container, I tried
RUN mv /tmp/projects/myproject/target/myproject.war /usr/local/tomcat/webapps/
as a modification to the answer for this question. But I am getting the error
mv: cannot stat ΓÇÿ/tmp/projects/myproject/target/myproject.warΓÇÖ: No such file or directory
How can I copy from one folder to another in the same container?
You can create a multi-stage build:
https://docs.docker.com/develop/develop-images/multistage-build/
Build the .war file in the first stage and name the stage e.g. build, like that:
FROM my-fancy-sdk as build
RUN my-fancy-build #result is your myproject.war
Then in the second stage:
FROM my-fancy-sdk as build2
COPY --from=build /tmp/projects/myproject/target/myproject.war /usr/local/tomcat/webapps/
A better solution would be to use volumes to bind individual war files inside docker container as done here.
Why your command fails
The command you are running tries to access files which are out of context to for the dockerfile. When you build the image using docker build . the daemon sends context to the builder and only those files are accessible during the build. In docker build . the context is ., the current directory. Therefore, it will not be able to access /tmp/projects/myproject/target/myproject.war.
Copying from inside the container
Another option would be to copy while you are inside the container. First use volumes to mount the local folder inside the container and then go inside the container using docker exec -it <container_name> bash and then copy the required files.
Recommendation
But still, I highly recommend to use
docker run -v "/tmp/projects/myproject/target/myproject.war:/usr/local/tomcat/webapps/myproject.war" <image_name>

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