Configure applications via configuration maps

Let’s learn how to configure applications via configuration maps on SPEKTRA Edge.

A configuration map allows you to decouple environment-specific configuration from your application images, so that your applications are easily portable.

You can map the application configuration to the particular containers under the application with the following steps:

1. Create a configuration map
2. Create an application with docker compose volumes service attribute to describe the configuration to be mounted on the container through the following two in-direction:
   1. Configuration map volume to map the configuration map to the application
   2. Host volume to mount the configuration to the host environment so that the application can mount the configuration to the particular container.

We’ll use the Nginx application and source the configuration file through the configuration map to demonstrate how to use the configuration map on SPEKTRA Edge.

What you need

To go through this page, you need the followings.

• an access to the SPEKTRA Edge dashboard
• an active project
• a device provisioned under the project

And also, the cuttle CLI command is necessary to complete this tutorial, which is used to access the Nginx application from the local machine for the verification purpose. However, it is not required for deploying applications on SPEKTRA Edge.

Application files

compose.yaml

It’s a simple Nginx application with mapping the port 8000 with the configuration directory mounted through the volumes attributes.

services:
  app:
    image: nginx:alpine
    ports:
    - 8000:8000
    volumes:
    - /isodevice/data/nginx/conf.d:/etc/nginx/conf.d

nginx.conf

Here is the Nginx configuration file, which will be mapped to the application through the SPEKTRA Edge configuration map.

It’s a simple configuration file, which make it listen on the port 8000, instead of port 80. Since we override the default configuration, we also sets the content root to the default Ngnix content directory with root directive.

server {
  listen 8000;
  root /usr/share/nginx/html;
}

Deploy the application

Let’s deploy the application with the configuration map on SPEKTRA Edge.

Here is the steps to follow:

1. Create a configuration map
2. Create the application with two new resources:
   • the configuration map volume to map the configuration map created above to the application
   • the host volume to mount the configuration to the host environment for the load balancer container to mount the configuration file to.

Let’s do it.

Create a configuration map

Let’s create a configuration map to store the Nginx configuration file on SPEKTRA Edge.

First, select the Config maps option of the Applications pull-down menu.

Then, create a configuration map by pasting the nginx.conf file content in the data key value field with the default.conf as the data key name.

Make sure you set:

• nginx-conf as the configuration map name
• default.conf as the configuration data key name

Those names are important because it’s referenced by the other object in the later steps.

Create the application

With the Nginx configuration map ready, let’s deploy the application.

Here is what we’ll do:

1. Paste the docker compose file content to the Docker Compose field
2. Create a volume config map for the Nginx configuration file mapping
3. Create a host volume to mount the above configuration map to the device

We’ll go over those points step-by-step below but first, let’s have a Deploy pod page ready by clicking the Deploy pod button on the Project overview page.

Docker compose file

Let’s paste the docker compose file to the Docker Compose field of the Deploy pod page.

Volume configuration map

The next is the volume configuration map, which maps the Nginx configuration file we created before to the application as a volume.

Here is the key points to highlight:

• Select the correct configuration map
  • projects/your-project/regions/us-west2/configMaps/nginx-conf for this example
• Specify the correct select key of the configuration map item
  • default.conf in this example, as we specified as the key value name for the Nginx configuration file when we created the configuration map.
• Use default.conf for the path name of the select key
  • This is the file name which will be shown in the container. Nginx expects this file name as the default Nginx configuration file.

Host volume

This is the last item to configure on the Deploy pod page.

It mounts the volume configuration map we create above to the host environment of the device. This file will be mounted to the Nginx load-balancer container through the docker compose file we explained before.

Again, there are a couple of things to make it right.

• the volume name should match the name of the volume configuration map we created above
  • nginx-conf in this example
• the Volume mount path should be matched to the one specified in the docker compose
  • /isodevice/data/nginx/conf.d in this example

Click to deploy

With all those configuration set, click the Deploy button on the Deploy pod page to deploy the application on your device.

With a minute or so, you should be able to see the application running on your device, as below.

Verify the application

Let’s verify the application by accessing it through the port forwarding.

Go to the application overview page by clicking the name of the app, Three tier web app in this example, on the Project overview page.

From there, copy the port forward command by clicking the Copy port forward as Cuttle command button on the application overview page.

Run the command on your local terminal window to make your application accessible from your browser.

cuttle devices forward-port \
  projects/your-project/regions/us-west2/devices/pp-quick-202410-dmphwxuzhh8nyw \
  8000 tcp://127.0.0.1:8000

Please note that the device name above will be different for your case.

Point your browser to http://localhost:8000 and you should be able to see the page below.

Next step

Congratulations on configuring the Nginx application with the configuration map on SPEKTRA Edge.

Let’s go ahead and understand how to monitor and control applications as the next step.