I am running an application with a dockerfile that I made.
I run at first my image with this command:
docker run -it -p 8501:8501 99aa9d3b7cc1
Everything works fine, but I was expecting to see a file in a specific folder of my directory of the app, which is an expected behaviour. But running with docker, seems like the application cannot write in my host directory.
Then I tried to mount a volume with this command
docker 99aa9d3b7cc1:/output .
I got this error docker: invalid reference format.
Which is the right way to persist the data that the application generates?
Use docker bind mounts.
e.g.
-v "$(pwd)"/volume:/output
The files created in /output in the container will be accessible in the volume folder relative to where the docker command has been run.
Related
I created a docker image using a script. The docker image got created successfully but when I am trying to run on the browser, I get the following message
I tried to resolve the error using webapps but it is popping up the same message.
It is happening probably because the directory /usr/local/tomcat/webapps is empty. as you can see in the description in the Docker Hub official image:
You can then go to http://localhost:8888 or http://host-ip:8888 in a browser (noting that it will return a 404 since there are no webapps loaded by default).
To solve that, you can just create a new image and copy and paste what you want inside of the folder /usr/local/tomcat/webapps.
For example, you can find inside of the folder /usr/local/tomcat/webapps.dist files of the tomcat webapp manager. If you try to see what is that you can run:
$ docker run -it tomcat:10 ls /usr/local/tomcat/webapps.dist
ROOT docs examples host-manager manager
Now that you know what is inside of the folder /usr/local/tomcat/webapps.dist, create your own Dockerfile and copy and paste this folder to /usr/local/tomcat/webapps:
FROM tomcat
RUN cp -R /usr/local/tomcat/webapps.dist/* /usr/local/tomcat/webapps
CMD ["catalina.sh", "run"]
Build the image:
$ docker build . -t custom-tomcat
Execute the image:
$ docker run -d -P custom-tomcat
Check the port opened:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
58390eab3fec custom-tomcat "catalina.sh run" 9 minutes ago Up 9 minutes 0.0.0.0:49163->8080/tcp, :::49163->8080/tcp lucid_joliot
Open your browser and check if it works:
I have tried this example out on a windows 10 box which has WSL2 installed and integrated with the latest Docker version. After following the steps in the example and downloading the code in the linux subsystem, I am able to build the image and run the container. The website is also available on the browser when I browse to it on a browser running on Windows 10. However, when I create a file or folder in the container the same doesn't reflect in the host filesystem which in this case is the linux subsystem. Similarly, a file created in the host linux subsystem is not seen in the container's cli when I use the ls command.
I ran this commands to confirm that the folder has been mounted where 44711fc95366 is my container id
docker inspect -f "{{ .Mounts }}" 44711fc95366
This gives an output like so:
[{bind /home/userlab1/my-proj/getting-started/app /usr/src/app true
rprivate}]
If the mount point expressed above is correct, I should be able to create a file or folder in host subsystem on the path /home/userlab1/my-proj/getting-started/app and be able to see it at the /usr/src/app path in the container, correct?
The docker image has been created and run from the linux subsystem command line like so:
docker run -it -v ~/my-proj/getting-started/app:/usr/src/app -p 3001:3000 --name cntr-linux-todo
img-todo:in-linux
While the application runs, the files updated in the container don't reflect on the website that is running from the container, nor does a new file/folder created in the container be seen in the host subsystem and vice versa. What am I missing?
As you are using Windows's version of docker, it cannot see files/folders from WSL.
You can move ~/my-proj into C:\Users\user20358, and mount from there :
-v 'C:\Users\user20358\my-proj\getting-started\app:/usr/src/app'
I'm following the instruction on this Docker official page under "Populate a volume using a container" in an attempt to create a new volume populated with existing files in a newly launched container. I ran the following command, expecting the existing files and folders under C:\Data on the container to be available under the volume:
docker run -it --name=test -v C:\Data dataimage/test1:version1
A new volume appears to be created successfully. However, navigating to C:\Data folder on the container shows that it is completely empty. If I run the above command without the -v option instead, then I can see the original files at the same location.
Is this a fully supported feature in Docker on Windows? If so, could someone please shed a light on what I may be doing wrong?
I am using Docker Engine version is v19.03.8. And my host OS is Windows Server 2019.
Try this:
docker run -it --name=test -v '/c/Data:/data' dataimage/test1:version1
That should sync the C:\Data folder on your windows host with the /data folder in the container. If /data isn't the folder name you want in the container, change as needed.
I've reviewed the documentation here:
https://docs.docker.com/docker-for-mac/install/#install-and-run-docker-for-mac
It doesn't say anything about boot2docker, although some other questions along these lines talk about this:
Mount volume to Docker image on OSX
So the question is – the Docker for Mac application provides File Sharing via Preferences -> File Sharing; how does one make use of these shared folders from the docker image (for example if one ssh's into the docker image)? When I say how, I don't mean "what are the use-cases", I mean "please show me an example of how to access a shared folder from the command line of the running container".
Ideally I'm trying to create a similar scenario to Vagrant's synched folders whereby I can edit files on my Host env, independently of the Docker Image but these are updated automatically to the Docker image on save.
UPDATE:
To be clear, the reason for asking this question is because I couldn't get the -v docker command to work. E.g.
docker run -v /Users/geoidesic/Documents/projects/arc/mysite/djangocms_demo:/home/djangocms/djangocms/djangocms_demo -d -p 8001:8000 --name test_shared_volumes bluszcz/djangocms
With the above command the container immediately stops, so if I run docker ps the list of running containers is empty.
However, if I run the container without the -v command, then it stays running as expected:
docker run -d -p 8001:8000 --name test_shared_volumes bluszcz/djangocms
Updated:
Well, if you want to share file/directory between host and container, you're gonna use Docker's bind-mount.
For example, if I want to share my host's /etc/resolv.conf to my container, I do the following:
docker run -v /etc/resolv.conf:/etc/resolv.conf <IMAGE>
In which the -v ... part tells the container to reuse host's /etc/resolve.conf. And whenever I edit this file, the changes will be immediately visible to the container.
In Linux, you can use this way to share almost any of your host files to containers. Unfortunately, this is not the case for Mac. As I mentioned in my old answer, by default you can only share /Users/, /Volumes/, /private/, and /tmp directly.
On my Mac, saying, I want to share the /data directory to a container. I run below command:
docker run -it --rm -v /data:/data busybox sh
Then it pops up an unhappy error:
docker: Error response from daemon: Mounts denied:
The path /data
is not shared from OS X and is not known to Docker.
You can configure shared paths from Docker -> Preferences... -> File Sharing.
See https://docs.docker.com/docker-for-mac/osxfs/#namespaces for more info.
So you see, this is where File Sharing comes up.
Then comes my answers to your questions:
File Sharing does not provide you a ready-to-use way to do the sharing as you have experienced in Vagrant;
To share file/folder between host and container, use Dockers bind-mount.
Hope that helps.
Old answer:
File Sharing is used by Docker's bind-mount feature. By default, you can bind-mount files in /Users/, /Volumes/, /private/, and /tmp directly. For other paths, you need to add them to Preferences -> File Sharing first.
Use cases for bind-mount:
Persisting data generated by the running container, so that you can backup or migrate data.
Sharing data amount multiple running containers.
Share host configuration files to containers.
Share source code between host and containers, to make debugging easier.
Note: For cases #1 and #2, consider using volumes instead of bind-mount.
For the sake of simplicity, use ubuntu image as an example.
I often find it easier to use docker-compose, particularly if there's a high chance I'll want to both mount-volumes and link the container to another container at some point in the future.
Create a folder for working in, say "ubuntu".
In the "ubuntu" folder, create another folder called "files"
Create a file in that folder called "docker-compose.yml". In this file, enter:
ubuntucontainer:
image: "ubuntu:latest"
ports:
- "80:80"
volumes:
- ./files:/files
Whenever you need to start the box, navigate to "ubuntu" and type docker-compose up. To stop again, use docker-compose stop.
The advantage of using docker compose is that if you ever want to link-up a database container this can be done easily by adding another container to the yaml file, and then in the ubuntucontainer container adding a links section.
Not to mention, docker-compose up is quite minimal on the typing.
(Also, forwarding the ports with 80:80 may not be strictly necessary, it depends on what you want the box to do.)
TL;DR version:
Open Docker Quickstart Terminal. If it is already open, run $ cd ~
Run this once: $ docker run -it -v /$(pwd)/ubuntu:/windows --name ubu ubuntu
To start every time: $ docker start -i ubu
You will get an empty folder named ubuntu in your Windows user directory. You will see this folder with the name windows in your ubuntu container.
Explanation:
cd ~ is for making sure you are in Windows user directory.
-it stands for interactive, so you can interact with the container in the terminal environment. -v host_folder:container_folder enables sharing a folder between the host and the container. The host folder should be inside the Windows user folder. /$(pwd) translates to //c/Users/YOUR_USER_DIR in Windows 10. --name ubu assigns the name ubu to the container.
-i stands for interactive