I have a Spring application and I am running it inside docker with jenkins. I am moving a file from my system to the docker with:
docker cp foo.txt container_id:/foo.txt
But then I don't know how to read it:
BufferedReader br = new BufferedReader(new FileReader("foo.txt")
Throws FileNotFoundException.
Normally I point to the folder like: C:/Users... But with docker how can I point to the root.
container_id:/foo.txt means you copy file to / folder of container.
So, the correct way is:
new FileReader("/foo.txt")
You do not have to copy files into docker.
You can create a volume
docker run -v your/host/folder:/your/container/folder ....
Then you can use it
Paths.get('/your/container/folder/foo.txt')
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 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.
so i have downloaded Docker Desktop and until now i have tested out containers and stuff just executing regular commands (docker ps, docker images..., docker run...) inside my zsh terminal and it works fine but now i am in a position where i want to create a directory inside docker host so that i can put my dockerfile inside, but if i run mkdir directory-name it is going to create the directory inside my mac not docker! so what command can i use to indicate that i want the directory to be created on docker not on my own mac machine?
While your docker container is running, you can start a new shell session inside using docker exec.
docker exec -it mycontainer bash
-i means interactive - so you can type
-t allocates a pseudo-TTY - just know that you need the argument
Then inside this bash, you can create folders and files all you want and they will be placed inside your running container. Note that whenever you remove the container (e.g. to update its image), these changes will be entirely lost. For persistence, use docker volumes.
Say you have the following directory structure:
.
├── Dockerfile
└── simple-web-app
Your Dockerfile:
FROM scratch
ADD simple-web-app simple-web-app
Then you would run
docker build .
I have a docker container inside which I have jar file that is of my springBoot application . How can I overwrite the application.property file of my app. Suppose if I want to change datasource url ,how can I do that through commandline?
Run docker ps and note the initials of id of your container.
Run docker exec -it <id> <bash or sh>, you will be inside your running container.
Go to your jar directory. Place your properties file in config/ as application.properties.
Rerun your app, but make sure to do it in background, so you can exit docker.
You can't restart the primary process (PID 1). For that usecase you'll need external volume and restart the container on property file change.
Create a volume: docker volume create vol1, you will get /var/lib/docker/volumes/vol1/
Change group of directory sudo chgrp 1001 /var/lib/docker/volumes/vol1/_data
Add write access to group: sudo chmod g+w /var/lib/docker/volumes/vol1/_data
Check the permissions of the directory: sudo ls -al /var/lib/docker/volumes/vol1/. They should be: drwxrwxr-x
Next time you run your container, mount the folder containing jar file to your volume as: docker run -d --name=webApp1 --mount source=vol1,destination=/path/to/app -p port:port name
You can change the property file in /var/lib/docker/volumes/vol1/_data/ and restart container: docker restart container_name
Disclaimer: Replacing properties file outside jar is not considered a good practice and is highly discouraged. So, these steps are only recommended for testing.
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.