I am sorry for taking up your time.
I have a local docker setup and I want to copy files from my local host to my container.
But the thing is that I need a command that I can use WHILE i am inside the container.
To explain the situation further: I executed "docker exec -it CONTAINERNAME bash" to enter my container,
and now I am on /var/www/html
and I need to find a way to copy a file/folder from my local environment into that container.
Reason: I am currently writing a dockerfile which automates the process of setting things up. I need that very specific command because a Dockerfile RUN-command can only be executed while inside the container.
What I tried:
"docker cp" is a good command to use when I am outside the container but it doesn't work while in the container.
"DOCKERFILE COPY" might do the trick but I need a general shell command to double check if it really does what it is supposed to do. I must be able to reproduce the same process of my Dockerfile via manually executing the commands one by one.
Once again, I apologize for my inability to solve this problem by myself. My inexperience has caused me nothing but trouble.
Edit: I am using a Win10 64bit OS with dual monitor setup and a lefthanded mouse. My keyboard, albeit old, should possess all the necessary keys to replicate any essential keyboard-shortcuts if required. All my drivers are installed and updated.
When you build an image you need to put there everything you need for a normal work of your container. You shouldn't copy files from the host once your image is built. You might use volumes as a common storage for both the host and the container but I don't think this is your case.
Until this is not totally clear what you do I'd suggest to prepare all the data you need and put it within docker context. Then build an image. You also may find docker-compose useful as, at least, it helps separately define the context and the path to your dockerfile if needed.
Related
I've got a project where a Flask server is run as a docker service via docker-compose (other elements like other API servers, the DB, are modeled as separate services in Docker Compose).
In my dev flow there are times when it's useful for me to drop into a bash shell (via docker exec -it <container_id> bash) and do some debugging like poking around at the files in there, take some logs and write some quick scripts to do some transformations on them, etc. In these scenarios I find it would be useful to have things like my bashrc, bash_profile, and various scripts which I find useful to do this sort of thing inside the docker container.
Is there an easy way to package these things and inject them into a (running) container? I'd prefer to not have these various debug things in the main Dockerfile which is shared.
You could make a Dockerfile.debug which uses the actual Dockerfile-image as base. Then grab your bash files into that.
Alternatively, locate the relevant container directory in /var/lib/docker and just put the files there (on the host). A trick to find the correct onion slice is to exec into the container, do a touch hello.txt, and then just find that file on the host.
My question relates to best practices on how to run a script on a docker-compose up directive.
Currently I'm sharing a volume between host and container to allow for the script changes to be visible to both host and container.
Similar to a watching script polling for changes on configuration file. The script has to act on host on changes according to predefined rules.
How could I start this script on a docker-compose up directive or even from the Dockerfile of the service, so that whenever the container goes up the "watcher" can find any changes being made and writing to.
The container in question will always run over a Debian / Ubuntu OS and should be architecture independent, meaning it should be able to run on ARM as well.
I wish to run a script on the Host, not inside the container. I need the Host to change its network interface configurations to easily adapt any environment The HOST needs to change I repeat.. This should be seamless to the user, and easily editable on a Web interface running Inside a CONTAINER to adapt to new environments.
I currently do this with a script running on the host based on crontab. I just wish to know the best practices and examples of how to run a script on HOST from INSIDE a CONTAINER, so that the deploy can be as easy for the installing operator to just run docker-compose up.
I just wish to know the best practices and examples of how to run a script on HOST from INSIDE a CONTAINER, so that the deploy can be as easy for the installing operator to just run docker-compose up
It seems that there is no best practice that can be applied to your case. A workaround proposed here: How to run shell script on host from docker container? is to use a client/server trick.
The host should run a small server (choose a port and specify a request type that you should be waiting for)
The container, after it starts, should send this request to that server
The host should then run the script / trigger the changes you want
This is something that might have serious security issues, so use at your own risk.
The script needs to run continuously in the foreground.
In your Dockerfile use the CMD directive and define the script as the parameter.
When using the cli, use docker run -d IMAGE SCRIPT
You can create an alias for docker-compose up. Put something like this in ~/.bash_aliases (in Ubuntu):
alias up="docker-compose up; ~/your_script.sh"
I'm not sure if running scripts on the host from a container is possible, but if it's possible, it's a severe security flaw. Containers should be isolated, that's the point of using containers.
I have my docker container images in different directories. And I would like to specify the path of the directory in the docker -run command. There is a method to change this path by editing the '-g' option in the configuration file, but it requires to restart the docker deamon. Is there any way to specify the docker image path in the docker-run command itself?
Docker must have the knowledge of not just your image physical location, but its complete tree. because docker image is made up of layers, where each layer is built with one Dockerfile command.
Hence, you should let docker register / know all the images from the directory where the images are present. Moreover, if you have physically copied these images from another machine, they would not work unless they are registered / tagged within Docker engine.
The short answer to your question is NO, it is not possible.
Docker engine itself should manage the images, you could do all what docker engine is doing by changing all the configuration files it maintains internally, because all of them are plain text. But it is definitely not worth your time, and you are better off with docker managing the images itself.
I'm trying to create my own docker image in a ubuntu-14 system.
My docker file is like the following:
FROM scratch
RUN /bin/bash -c 'echo "hello"'
I got the error message when I run docker build .:
exec: "/bin/sh": stat /bin/sh: no such file or directory
I guess it is because /bin/sh doesn't exist in the base image "scratch". How should I solve this problem?
Docker is basically a containerising tool that helps to build systems and bring them up and running in a flash without a lot of resource utilisation as compared to Virtual Machines.
A Docker container is basically a layered container. In case you happen to read a Dockerfile, each and every command in that file will lead to a creation of a new layer in container and the final layer is what your container actually is after all the commands in the Dockerfile has been executed.
The images available on the Dockerhub are specially optimised for this sort of environment and are very easy to setup and build. In case you are building a container right from scratch i.e. without any base image, then what you basically have is an empty container. An empty container does not understand what /bin/bash actually is and hence it won't work for you.
The Docker container does not use any specifics from your underlying OS. Multiple docker containers will make use of the same underlying kernel in an effective manner. That's it. Nothing else.
( There is however a concept of volumes wherein the container shares a specific volume on the local underlying system )
So in case you want to use /bin/bash, you need a base image which will setup the nitty gritties of this command for your container and then you can successfully execute it.
However, it is recommended that you use official Docker images for say Ubuntu and then install your custom stuff on top of it. The official images are right from the makers and are highly optimised for this environment.
Base image scratch does not use /bin/bash. So you should change to:
FROM ubuntu:14.04
RUN /bin/sh -c 'echo "hello"'
Trying to fix errors and debug problems with my application that is split over several containers, I frequently edit files in containers:
either I am totally lazy and install nano and edit directly in container or
I docker cp the file out of the container, edit it, copy it back and restart the container
Those are intermediate steps before coming to new content for container build, which takes a lot longer than doing the above (which of course is only intermediate/fiddling around).
Now I frequently break the starting program of the container, which in the breaking cases is either a node script or a python webserver script, both typically fail from syntax errors.
Is there any way to save those containers? Since they do not start, I cannot docker exec into them, and thus they are lost to me. I then go the rm/rmi/build/run route after fixing the offending file in the build input.
How can I either edit files in a stopped container, or cp them in or start a shell in a stopped container - anything that allows me to fix this container?
(It seems a bit like working on a remote computer and breaking the networking configuration - connection is lost "forever" this way and one has to use a fallback, if that exists.)
How to edit Docker container files from the host? looks relevant but is outdated.
I had a problem with a container which wouldn't start due to a bad config change I made.
I was able to copy the file out of the stopped container and edit it. something like:
docker cp docker_web_1:/etc/apache2/sites-enabled/apache2.conf .
(correct the file)
docker cp apache.conf docker_web_1:/etc/apache2/sites-enabled/apache2.conf
Answering my own question.. still hoping for a better answer from a more knowledgable person!!
There are 2 possibilities.
1) Editing file system on host directly. This is somewhat dangerous and has a chance of completely breaking the container, possibly other data depending on what goes wrong.
2) Changing the startup script to something that never fails like starting a bash, doing the fixes/edits and then changing the startup program again to the desired one (like node or whatever it was before).
More details:
1) Using
docker ps
to find the running containers or
docker ps -a
to find all containers (including stopped ones) and
docker inspect (containername)
look for the "Id", one of the first values.
This is the part that contains implementation detail and might change, be aware that you may lose your container this way.
Go to
/var/lib/docker/aufs/diff/9bc343a9..(long container id)/
and there you will find all files that are changed towards the image the container is based upon. You can overwrite files, add or edit files.
Again, I would not recommend this.
2) As is described at https://stackoverflow.com/a/32353134/586754 you can find the configuration json config.json at a path like
/var/lib/docker/containers/9bc343a99..(long container id)/config.json
There you can change the args from e. g. "nodejs app.js" to "/bin/bash". Now restart the docker service and start the container (you should see that it now correctly starts up). You should use
docker start -i (containername)
to make sure it does not quit straight away. You can now work with the container and/or later attach with
docker exec -ti (containername) /bin/bash
Also, docker cp is rather useful for copying files that were edited outside of the container.
Also, one should only fall back to those measures if the container is more or less "lost" anyway, so any change would be an improvement.
You can edit container file-system directly, but I don't know if it is a good idea.
First you need to find the path of directory which is used as runtime root for container.
Run docker container inspect id/name.
Look for the key UpperDir in JSON output.
That is your directory.
If you are trying to restart an stopped container and need to alter the container because of misconfiguration but the container isn't starting you can do the following which works using the "docker cp" command (similar to previous suggestion). This procedure lets you remove files and do any other changes needed. With luck you can skip a lot of the steps below.
Use docker inspect to find entrypoint, (named Path in some versions)
Create a clone of the using docker run
Enter clone using docker exec -ti bash (if *nix container)
Locate entrypoint file location by looking though the clone to find
Copy the old entrypoint script using docker cp : ./
Modify or create a new entrypoint script for instance
#!/bin/bash
tail -f /etc/hosts
ensure the script has execution rights
Replace the old entrypoint using docker cp ./ :
start the old container using start
redo steps 6-9 until the starts
Fix issues in container
Restore entrypoint if needed and redo steps 6-9 as required
Remove clone if needed