How to copy files from and to a running Docker container

Sometimes you want to copy files to or from a container that doesn’t have a volume previously created, in this quick tips episode, you will learn how. Above is the vid and below you will find some useful notes.

1. 1.

   Pre-reqs

   • Have Docker installed
2. 2.

   Start a Docker container

   • For this video I will be using a Jenkins image as an example, so let’s first download it by using docker pull

     docker pull jenkins/jenkins:lts
     

   • Then I will use one of the suggested ways to run the instance and do it in the background. If you don't use pull first this command will work given that it will also try to download the image if it's not found locally.

     docker run -d -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts
     

   • You can check what's the container id, you can just type docker ps for this

     docker ps
     

   • for copying something into a docker container we just need to specify which local file or folder to copy, then the container id followed by a colon and the target folder inside the container You can execute a command in a running container with the following:

     docker cp LOCAL_FILE_OR_FOLDER CONTAINER_ID:TARGET_FOLDER_INSIDE_CONTAINER
     

     If you want to copy the local "./upload/test.txt" file into the "/var/jenkins_home/secrets" folder inside the container, do the following:

     docker cp ./upload/test.txt CONTAINER_ID:/var/jenkins_home/secrets
     

   • Finally, for copying something from a container into your local file system, you just need to specify the container id, a colon, the source file or folder inside the container and then the target local folder where the files or folders will be placed

     docker cp CONTAINER_ID:SOURCE_FOLDER_INSIDE_CONTAINER LOCAL_FOLDER
     

     If you want to copy the local "/var/jenkins_home/secrets/initialAdminPassword" file, that is currently inside the container, into your local ".\download\" folder, do the following:

     docker cp CONTAINER_ID:/var/jenkins_home/secrets/initialAdminPassword .\download\
     

3. 3.

   Resources

   Jenkins - Docker Hub