How to Move a PostgreSQL Database from One Container to Another in a Docker Environment.

The following section explains how to move a PostgreSQL database from one container to another in a Docker environment.

1. Open your terminal and run the following commands to back up a database inside the container.

   docker ps 
   
   docker exec -it <database container name/database ID> bash
   
   pg_dump -U postgres -d <database name> -f <database name>.sql
   
   

   Example:
   docker ps

   docker exec -it some-postgres_A bash

   pg_dump -U postgres -d bold_services -f bold_services.sql

2. Copy the backup SQL file from the container to the local machine using the following command.

   docker cp <container name>:/<backup file location inside the container> <local machine path to paste a backup file>
   

   Example:
   docker cp some-postgres_A:/bold_services.sql /root

3. Move a backup file to another container using the following command.

   docker cp <local machine path to paste a backup file> <container name>:/<backup file location inside the container> 
   

   Example:
   docker cp /root/bold_services.sql some-postgres_B:/

4. Bash a second container and navigate to that file location, then restore a database using that backup file.

   docker ps 
   
   docker exec -it -u postgres <database restore container name/database ID> bash
   
   psql
   
   Create database <database name>;
   
   exit
   
   psql <database name> < <sql file name>
   
   

   Example:
   docker ps

   docker exec -it -u postgres some-postgres_B bash

   psql

   Create database bold_services;

   exit

   psql bold_services < bold_services.sql

After following the above steps, the database was backed up and restored from one container to another.