DOCKER – How to copy a file from Host to Docker container and vice versa

By | 13/07/2022

In this post, we will see how to copy a file from our system to a Docker container and vice versa.

We start defining and running this docker-compose file to create a SQL Server Docker container:

[DOCKER-COMPOSE.YML]

version: "3.9"
services:
  sql-server-db:
    container_name: sqlserver
    image: mcr.microsoft.com/mssql/server:latest
    ports:
      - "1439:1433"
    environment:
      SA_PASSWORD: "password1234"
      ACCEPT_EULA: "Y"
      MSSQL_PID: Express
    volumes:
      - sqlvolume:/var/opt/mssql
 
volumes:
  sqlvolume:
    driver: local



Then, using a PowerShell console, we check everything works fine:



FROM HOST TO THE CONTAINER
First of all, we create a folder called Test where, we are going to copy a text file called file_test.txt so defined:

Test1
Test2


Then, in order to copy the file in our container, we run the command:

docker cp file_test.txt sqlserver:/file_test.txt

where sqlserver is the name of our SQL Server Docker container.

Now, for checking everything worked fine, we go inside the SQL Server Docker container using the command:

docker exec -it --privileged --user root sqlserver /bin/bash

where sqlserver is the name of our SQL Server Docker Container.


Then, with the command ls, we can verify the existence of the file:


Finally, with the command cat, we can read the file’s content:



FROM DOCKER CONTAINER TO THE HOST
In the SQL Server Docker container, we create a file txt called file_test2.txt using the command:

echo Test from Linux >> file_test2.txt


Then, we open another PowerShell terminal for copying the new file in our system, running the command:

docker cp sqlserver:/file_test2.txt .

where sqlserver is the name of our SQL Server Docker container.


Finally, in order to check everything worked fine, we can read the file’s content with the command:

 Get-content file_test2.txt



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