dockerfile COPY does not copy all the files - docker

I do
git clone https://github.com/openzipkin/zipkin.git
cd zipkin
The create a Dockerfile as below
FROM openjdk
RUN mkdir app
WORKDIR /app
COPY ./ .
ENTRYPOINT ["sleep", "1000000"]
then
docker build -t abc .
docker run abc
I then run docker exec -it CONTAINER_ID bash
pwd returns /app which is expected
but I ls and see that the files are not copied
only the directories and the xml file is copied into the /app directory
What is the reason? how to fix it?
Also I tried
FROM openjdk
RUN mkdir app
WORKDIR /app
COPY . /app
ENTRYPOINT ["sleep", "1000000"]

That repository contains a .dockerignore file which excludes everything except a set of things it selects.
That repository's docker directory also contains several build scripts for official images and you may find it easier to start your custom image FROM openzipkin/zipkin rather than trying to reinvent it.

Related

DNS resolution not working with Docker image

I have a Rust program that needs to do some DNS lookups. It works just fine with the following Dockerfile:
FROM rust:1.63.0-bullseye AS build
WORKDIR /app
COPY . .
RUN cargo build --release
EXPOSE 8080
ENTRYPOINT ["/app/target/release/router"]
I've tried to create a somewhat minimalistic image for the program like so:
FROM rust:1.63.0-bullseye AS build
WORKDIR /app
COPY . .
RUN cargo build --release
RUN mkdir -p /app/lib
RUN cp -LR $(ldd ./target/release/router | grep "=>" | cut -d ' ' -f 3) /app/lib
FROM scratch AS websocket-router-rust
WORKDIR /app
COPY --from=build /app/lib /app/lib
COPY --from=build /lib64/ld-linux-x86-64.so.2 /lib64/ld-linux-x86-64.so.2
COPY --from=build /app/target/release/router /app/router
ENV LD_LIBRARY_PATH=/app/lib
EXPOSE 8080
ENTRYPOINT ["/app/router"]
However, DNS lookups seem to fail when using the latter Dockerfile. Any ideas what files could be missing that should be copied from the build stage?
UPDATE: Got it working by running a file access tracer inside the Docker image while making a request to the server and then copying over all the files that were read with COPY --from... The Dockerfile got a bit messy, but it's less than 30MB now. The main problem was that ldd doesn't return libnss SOs, so those were missing from the image.
You can set the DNS addresses in /etc/docker/daemon.json file:
{
"dns": ["10.0.0.2", "8.8.8.8"]
}

Module Not found after attaching volume in docker

This is my dockerfile
FROM node:15
# sets the folder structure to /app directory
WORKDIR /app
# copy package.json to /app folder
COPY package.json .
RUN npm install
# Copy all files from current directory to current directory in docker(app)
COPY . ./
EXPOSE 3000
CMD ["node","index.js"]
I am using this command in my powershell to run the image in a container
docker run -v ${pwd}:/app -p 3000:3000 -d --name node-app node-app-image
${pwd}
returns the current directory.
But as soon as I hit enter, somehow node_modules isn't being installed in the container and I get "express not found" error in the log.
[![Docker log][1]][1]
I can't verify if node_modules isn't being installed because I can't get the container up to run the exec --it command.
I was following a freecodecamp tutorial and it seems to work in his pc and I've tried this command in command prompt too by replacing ${pwd} by %cd%.
This used to work fine before I added the volume flag in the command.
[1]: https://i.stack.imgur.com/4Fifu.png
Your problem was you build your image somewhere and then try to map another folder to it.
|_MyFolder/
|_ all-required-files
|_ all-required-folders
|_ Dockerfile
docker build -t node-app-image .
docker run -p 3000:3000 -d --name node-app node-app-image
Simplified Dockerfile
FROM node:15
# sets the folder structure to /app directory
WORKDIR /app
# Copy all files from current directory to current directory in docker(app)
COPY . ./
RUN npm install
EXPOSE 3000
CMD ["node","index.js"]

How to copy files into outside working directory

I want to copy the file to a folder location that is outside the working directory. I used the following lines in my docker file, but the files are not there when I look in the container.
WORKDIR /app
RUN cd ../opt/venv/lib/python3.7/site-packages/xxx/
COPY ./resources/abc.py .
When look a that /opt/venv/lib/python3.7/site-packages/xxx/ location the abc.py is not there
What is the issue with my approach? Appreciate your inputs.
You can't COPY a file from outside the build context. So if you are trying to COPY /opt/venv/lib/python3.7/site-packages/xxx/resources/abc.py into your docker image, and that is not in your build context, it will fail. Full stop.
Here's some annotated code.
# change to the /app directory in the container
WORKDIR /app
# run the command cd in the container. cd is a shell builtin, and after
# this command finishes you will still be inside the /app directory in
# your container.
RUN cd ../opt/venv/lib/python3.7/site-packages/xxx/
# Attempt to copy ./resources/abc.py from your host's build context
# (NOT /opt/venv/lib/python3.7/site-packages/xxx/) into the container.
COPY ./resources/abc.py .
The basic fix for this is to first copy abc.py into your build directory. Then you will be able to copy it into your docker container during your build like so:
WORKDIR /app
COPY abc.py .
# /app/abc.py now exists in your container
Note on cd
cd is a shell builtin that changes the working directory of the shell. When you execute it inside a script (or in this case a docker RUN) it only changes the working directory for that process, which ends when the script ends. After which your working directory will be the one you started in. So you cannot use it in the way you were intending. Much better explanation here.
Take this Dockerfile for example:
FROM alpine:latest
RUN cd /opt # cd to /opt
RUN pwd # check current directory, you're STILL in '/'
RUN cd /opt && \
pwd # works as expected because you're still in the same process that cd ran in.
# But once you exit this RUN command you will be back in '/'
# Use WORKDIR to set the working directory in a dockerfile
Here's the output of building that Dockerfile (removed noisy docker output):
$ docker build --no-cache .
Sending build context to Docker daemon 3.584kB
Step 1/4 : FROM alpine:latest
Step 2/4 : RUN cd /opt
Step 3/4 : RUN pwd
/
Step 4/4 : RUN cd /opt && pwd
/opt
From what I understand, you're trying to copy a file into a specific location (/opt/venv/lib/python3.7/site-packages/xxx/) in your Docker image that is outside the WORKDIR you defined in the Dockerfile for your image.
You can easily do this by specifying the absolute destination path in the COPY command:
WORKDIR /app
COPY ./resources/abc.py /opt/venv/lib/python3.7/site-packages/xxx/abc.py

Mount docker volume to host machine path

I need to access test result files in the host from the container. I know that I need to create a volume which maps between host and container, like below, but I get nothing written to the host.
docker run --rm -it -v <host_directory_path>:<container_path> imagename
Dockerfile:
FROM microsoft/dotnet:2.1-sdk AS builder
WORKDIR /app
COPY ./src/MyApplication.Program/MyApplication.Program.csproj ./src/MyApplication.Program/MyApplication.Program.csproj
COPY nuget.config ./
WORKDIR ./src/MyApplication.Program/
RUN dotnet restore
WORKDIR /app
COPY ./src ./src
WORKDIR ./src/MyApplication.Program/
RUN dotnet build MyApplication.Program.csproj -c Release
FROM builder as tester
WORKDIR /app
COPY ./test/MyApplication.UnitTests/MyApplication.UnitTests.csproj ./test/MyApplication.UnitTests/MyApplication.UnitTests.csproj
WORKDIR ./test/MyApplication.UnitTests/
RUN dotnet restore
WORKDIR /app
COPY ./test ./test
WORKDIR ./test/MyApplication.UnitTests/
RUN dotnet test /p:CollectCoverage=true /p:CoverletOutputFormat=cobertura
ENTRYPOINT ["dotnet", "reportgenerator", "-reports:coverage.cobertura.xml", "-targetdir:codecoveragereports", "-reportTypes:htmlInline"]
The command at the entry point is working correctly. It is writing the output to the MyApplication.UnitTests/codecoveragereports directory, but not to the host directory.
My docker run looks as follows:
docker run --rm -it -v /codecoveragereports:/app/test/MyApplication.UnitTests/codecoveragereports routethink.tests:latest
What could I be doing wrong?
Looks like a permission issue.
-v /codecoveragereports:/app/***/codecoveragereports is mounting a directory under the root / which is dangerous and you may not have the permission.
It's better to mount locally, like -v $PWD/codecoveragereports:/app/***/codecoveragereports, where $PWD is an environment variable equal to the current working directory.

will the commands in Dockerfile run as follows?

docker build Dockerfile .//running it correctly.
1.) I have mentioned in the comments each command will execute as written, Is that correct working of this Dockerfile?
2.)These commands will be used to make the image when I ran docker build, so
[ec2-user#ip-xx-xx-xx-xx ~]$cd /project/p1
[ec2-user#ip-xx-xx-xx-xx p1]$ls
Dockerfile a b c d
My Dockerfile consists of following commands.
Dockerfile
node 8.1.0 //puls the image from hub
RUN mkdir -p /etc/x/y //make directory in the host at path /etc/x/y
RUN mkdir /app //make directory in the host at path /app
COPY . /app //copy all the files that is
WORKDIR /app //cd /app; now the working directory will be /app for next commands i.e npm install.
RUN npm install
EXPOSE 3000 //what this will do?
Question 1: how to run docker build?
docker build Dockerfile . # am I running it correctly.
No, you run it with docker build . and docker will automatically look for the Dockerfile in the current directory. Or you use docker build -f Path_to_the_docker_file/DockerFile where you clearly specify the path to the DockerFile.
Question 2: Fixing errors and clarifying commands
There are few mistakes in the Dockerfile, check the edited comments:
# pulls the image from dockerhub : YES
# Needs to be preceeded with FROM
FROM node 8.1.0
# all directories are made inside the docker image
# make directory in the image at path /etc/x/y : YES
RUN mkdir -p /etc/x/y
# make directory in the image at path /app : YES
RUN mkdir /app
COPY . /app # copy all the files that is : YES
WORKDIR /app # cd /app; now the working directory will be /app for next commands i.e npm install. : YES
RUN npm install
EXPOSE 3000 # what this will do? => tells all docker instances of this image to listen on port 3000.

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