In this article, we delve into the process of updating our server with the latest code changes. We explore the crucial aspect of database updates, commonly referred to as database migrations. Finally, we address how to efficiently view logs from our Ktor project in the server environment

Pushing our latest code changes to the server is similar to deploying for the first time minus the setup. To proceed, let’s push the latest version of our Ktor project to the server by executing the publishImage Gradle task. This task will build our Ktor project and push the updated image to DockerHub.

After successfully building and pushing the image, we can connect to our server using SSH. Once connected, we pull the updated image from DockerHub with the command:

docker pull {DOCKER_HUB_USERNAME}/{DOCKER_HUB_REPO}

Having pulled the latest image, we navigate to the project directory where the docker-compose.yml file resides.

docker compose up -d

By running the above command, we recreate the Ktor server, implementing the latest changes in the background. With this, our Ktor server is now up-to-date with the latest code changes and efficiently running on the server.

Now, let’s take a brief look at database migrations. Suppose we want to modify the data type of the “email” column from varchar(128) to “text” in the users table created in Part 1. To achieve this, we must create a new file under the src/main/resources/db/migration path and name it V2__Create_database_table.sql The critical element here is the prefix “V2__” which is incremented from our previous file, while the subsequent name can be chosen freely.

In the newly created V2__Create_database_table.sql file, we’ll include the necessary SQL query to change the data type as per our requirement.

ALTER TABLE user MODIFY email TEXT

And that’s all there is to it! Now, to deploy our latest changes, we follow the procedure described at the beginning of this article. Flyway will seamlessly manage the database migration, ensuring a smooth and successful transition

You can also follow this quick start guide for flyway: https://documentation.red-gate.com/fd/quickstart-api-184127575.html

Now, we have the capability to attach to our Ktor container and tail logs using the container name we defined in the docker-compose.yml file we setup in Part II. To do this, run the following command:

docker logs -f --tail 100 backend-ktor

In this command, 100 represents the number of the last log lines you wish to view. You can adjust this number based on your specific requirements. By executing this command, we gain access to all network and database logs from the Ktor container.

To de-attach from the container and return to the terminal, simply press Ctrl + C.

#kotlinmultiplatform #ktor #kotlin

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