Problem
The $(pwd)/app directory locally contains many subdirectories and files. So does the directory in my Docker image /usr/local/app. When I run the following
docker run -it --rm -v $(pwd)/app:/usr/local/app my_image bash
the command is successful, but the /usr/local/app directory is now empty. It seems that I've mounted something to this location, but it's empty.
Is there something that I'm missing here that I should be aware of?
Context
This exact command used to succeed. The only recent change is that I uninstalled Docker Desktop in favor of just using the Docker Engine running on a local minikube instance. I'm using Docker version 20.10.22, build 3a2c30b63a on MacOS Ventura.
Related
I'm trying to mount a directory in /tmp to a directory in a container, namely /test. To do this, I've run:
docker run --rm -it -v /tmp/tmpl42ydir5/:/test alpine:latest ls /test
I expect to see a few files when I do this, but instead I see nothing at all.
I tried moving the folder into my home directory and running again:
docker run --rm -it -v /home/theolodus/tmpl42ydir5/:/test alpine:latest ls /test
at which point I see the expected output. This makes me thing I have mis-configured something and/or the permissions have bitten me. Have I missed a step in installing docker? I did it via sudo snap install docker, and then configured docker to let me run as non-root by adding myself to the docker group. Running as root doesn't help...
Host machine is Ubuntu 20.04, docker version is 19.03.11
When running docker as a snap...
all files that Docker uses, such as dockerfiles, to be in $HOME.
Ref: https://snapcraft.io/docker
The /tmp filesystem simply isn't accessible to the docker engine when it's running within the snap isolation. You can install docker directly on Ubuntu from the upstream Docker repositories for a more traditional behavior.
I am developing a Docker image. I started with a base image and was working inside it interactively, using bash. I installed a bunch of stuff, and the install (which included compiling a lot of code) took over 20 minutes, so to save my work, I used:
$ docker commit 0f08ac958391 myproject:wip
Now when I try to run the image:
$ docker run --rm -it myproject:wip
docker: Error response from daemon: cannot mount volume over existing file, file exists /var/lib/docker/overlay2/95aa9a9ea7cc0b1ba302adbd287e4d7059ee4fbe64183404df3bc65df332ee63/merged/run/host-services/ssh-auth.sock.
What is going on? How do I fix this?
Note about related/duplicate questions: while there are other questions about this error message, none of the answers directly explain why the error happens in this situation or what to do about it. In fact, most of the questions have no answers at all.
When I ran the base image, I included a mount for the SSH agent socket:
$ docker run --rm -it -v /run/host-services/ssh-auth.sock:/run/host-services/ssh-auth.sock myproject:dev /bin/bash
This bind mounts a file from the host (actually the Docker daemon VM) to a file in the Docker container. When I committed the running image, the image contained the file /run/host-services/ssh-auth.sock. The image also contained an empty volume reference to /run/host-services/ssh-auth.sock. This means that when I ran
$ docker run --rm -it myproject:wip
It was equivalent to running
$ docker run -v /run/host-services/ssh-auth.sock --rm -it myproject:wip
Unfortunately, what that command does is create an anonymous volume and mount it into the directory /run/host-services/ssh-auth.sock in the container. This works if the container has such a directory or even if it does not. What causes it to fail is if the target name is taken up by a file. Docker will not mount a volume over a file.
The solution is to explicitly provide a mapping from a host file to the target volume. Any host file will do, but in my case it is best to use the original. So this works:
docker run --rm -it -v /run/host-services/ssh-auth.sock:/run/host-services/ssh-auth.sock myproject:wip
I want to encrypt my Kubernetes file to integrate it with Travis CI and for that, I am installing Travis CI CLI via docker container. When the container runs and I mount my current working directory to /app It just creates an empty folder.
I have added the folder in shared folders as well in the Virtual Box but nothing seems to work. I am using Docker Toolbox on Windows 10 home.
docker run -it -v ${pwd}:/app ruby:2.3 sh
It creates the empty app folder along with the other folders in the container but does not mount the volumes.
I also tried using
docker run -it -v //c/complex:/app ruby:2.3 sh
as someone suggested to use the name you specify in the Virtual Box.
Docker run -it -v full path of current directory:/app ruby:2
Hi I have a windows machine and I installed a docker desktop on it and created a ubuntu container on it.
In docker settings I checked my C: Drive under shared drive option. and I created a folder under /opt named /mydata in this container
Now I run this command:
docker my_container_name run -v /Users/john/Documents/DOCKER_FOLDER:/opt/mydata
But I don't see the files under DOCKER_FOLDER to be in /opt/mydata folder.
Not sure what I a doing wrong.
the right command is:
docker my_container_name run -v c:/Users/john/Documents/DOCKER_FOLDER:/opt/mydata ls /opt/mydata
so you need to specify the volume letter and a command to run
I'm trying to learn Docker using Windows as the host OS to create a container using Rails image from Docker Hub.
I've created a Dockerfile with the content below and an empty Gemfile, however I'm still getting the error "Could not locate Gemfile".
Dockerfile
FROM rails:4.2.6
The commands I used are the following (not understanding what they actually do though):
ju.oliveira#br-54 MINGW64 /d/Juliano/ddoc
$ docker build -t ddoc .
Sending build context to Docker daemon 4.608 kB
Step 1 : FROM rails:4.2.6
---> 3fc52e59c752
Step 2 : MAINTAINER Juliano Nunes
---> Using cache
---> d3ab93260f0f
Successfully built d3ab93260f0f
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.
$ docker run --rm -v "$PWD":/usr/src/app -w /usr/src/app ruby:2.1 bundle install
Unable to find image 'ruby:2.1' locally
2.1: Pulling from library/ruby
fdd5d7827f33: Already exists
a3ed95caeb02: Pull complete
0f35d0fe50cc: Already exists
627b6479c8f7: Already exists
67c44324f4e3: Already exists
1429c50af3b7: Already exists
f4f9e6a0d68b: Pull complete
eada5eb51f5d: Pull complete
19aeb2fc6eae: Pull complete
Digest: sha256:efc655def76e69e7443aa0629846c2dd650a953298134a6f35ec32ecee444688
Status: Downloaded newer image for ruby:2.1
Could not locate Gemfile
So, my questions are:
Why it can't find the Gemfile if it's in the same directory as the Dockerfile?
What does the command docker run --rm -v "$PWD":/usr/src/app -w /usr/src/app ruby:2.1 bundle install do?
How do I set a folder in my host file system to be synced to the container (I'm trying to create a development environment for Rails projects using Docker on Windows)?
I don't know if this makes any difference, but I'm running this command from the bash executed via "Docker Quickstart Terminal" shortcut. I think all it does is run these commands in a default VM, though I could create a new one (but I don't know if I should do this).
Thank you and sorry for all these questions, but right know Docker seems very confusing for me.
You must mount HOST directory somewhere inside your HOME directory (e.g. c:/Users/john/*)
$PWD will give you a Unix-like path. If your shell is like Cygwin, it will look like /cygdrive/c/Users/... or something funny. However, Docker and VirtualBox is a Windows executable, so they expect a plain Windows path. However it seems Docker cannot accept a Windows path in the -v command line, so it is converted to /c/Users/.... The other people may be right; you may not be able to access a directory outside your home for some reason (but I wouldn't know why). To solve your problem, create a junction within your home that points to the path you want, then mount that path in your home.
>mklink /j \users\chloe\workspace\juliano \temp
Junction created for \users\chloe\workspace\juliano <<===>> \temp
>docker run -v /c/Users/Chloe/workspace/juliano:/app IMAGE-NAME ls
007.jpg
...
In your case that would be
mklink /j C:\Users\Juliano\project D:\Juliano\ddoc
docker run -v /c/Users/Juliano/project:/usr/src/app -w /usr/src/app ruby:2.1 bundle install
I don't know what --rm does. I assume -w sets the working directory. -v sets the volume mount and maps the host path to the container path. ruby:2.1 uses the Docker standard Ruby 2.1 image. bundle install run Bundler!