In this post I’ll cover how to make a connection from a Node.js application in a Docker container to your Oracle Database in three different scenarios.

• Typical Database connection.
• Database inside a different Docker container.
• Oracle Autonomous Transaction Processing Cloud Database.

Simple Test App

When attempting something new, I find it’s best to make sure all of the pieces that are not part of the new thing, are as simple as possible.

For my examples I will be using a small Node.js application that:

• Connects to the Oracle Database.
• Runs a simple query.
• Prints the results to the console.

Create a new file named dbConfig.js to set the database connection information.

Create a new file named server.js used to test the connection.

Install the node-oracledb driver. (If you have any questions about the node-oracledb driver, you can find the answers here.)

Create environment variables for the connection information.  (Replace my values with yours)

Test the Node.js application.  You should see something similar to the following.

Create a Docker Container for the Node.js app

Create a Dockerfile

Build the image

Now that you have an image you’ll run a container and to connect it to:

Typical Oracle Database

The container will run, execute the query and stop.  You should see something similar to this output.

An Oracle Database inside a Docker Container

In a previous post I walked through how to setup both an ORDS instance and an Oracle XE instance in Docker Containers.  Follow through the section showing how to create an Oracle XE Database in a Docker container.

When you followed the steps in that post you should have also created a Docker Network.

You’ll use that same network to connect from the Node.js container to the Oracle XE container.

First, change your NODE_ORACLEDB_CONNECTIONSTRING environment variable to use the Oracle XE container name.

Now when you run a new docker container you will attach it to the same Docker Network as the Oracle XE container.

The container will run, execute the query and stop.  You should see something similar to this output.

Since both containers are using the same Docker network, you do not need to open the port when you run the Oracle XE container.  This is useful if you’d like to keep your database private inside the Docker environment.

Oracle Autonomous Transaction Processing Cloud Database

After you create an Oracle ATP Cloud Database you’ll need to download the credentials file and extract it into a secure location.

For this database, you will be using an entry in the tnsnames.ora file to make the database connection.  Change the NODE_ORACLEDB_CONNECTIONSTRING environment variable to use the tnsnames entry:

Before you run the container, you need to modify the sqlnet.ora file found in the credentials directory.  Change the wallet location to the value that will be mapped inside the Docker container.

When you run the new container for the node app you will map a volume from the directory where you extracted your credentials file to the internal container directory.  Mapping a volume makes sure that there is not a copy of the credential files inside the Docker container.

Finally, when you run the new container, you will add an additional environment variable defining where the tns admin information is located.

The full command looks like this:

The container will run, execute the query and stop.  You should see something similar to this output.

I used the same docker image for all of the examples

You may have noticed that you only built the Docker image once at the beginning of the post.  The application in the Docker image uses environment variables to connect to the database.  This allows you to run the same application in one or more containers and each container can connect to different Oracle Databases without having to rebuild the image.