Binding is the task of finding a backing service and connecting it to an application, such as a database. There are several ways to bind applications to cloud services in Kubernetes and Red Hat OpenShift. The odo command-line interface (CLI) consolidates steps that developers normally have to perform manually, and abstracts away Kubernetes and OpenShift background concepts.
With odo, you can concentrate on creating applications instead of administering the cluster. The odo tool automates deployment configurations, build configurations, service routes, and other Kubernetes and OpenShift elements.
The Service Binding Operator, employed by odo, makes the application developer's life a lot easier by providing a consistent and declarative Service Binding method.
This two-part series demonstrates how to use odo to create an application and a database service, bind the application to the database using the Service Binding Operator, and get access to the application's REST API. This article prepares the environment with the necessary tools. In part 2, Implementation of RestAPI application with MongoDB using SBO, we will install MongoDB and the application, and bind them together.
A REST application example
We will use a REST application written in Go as an example here. The application connects to a MongoDB database using the Service Binding Operator and allows you to manage entries in the database. Data consists of place names and descriptions. The REST API's endpoints allow you to add details to the MongoDB instance and perform create, read, update, and delete (CRUD) operations.
When you request a binding, the Service Binding Operator looks at the data stored within the custom resource (CR) and its corresponding custom resource definition (CRD) inside the service. This data contains the parameters required to bind the application to the service. The Service Binding Operator then projects this binding data into the application's workload resources as environment variables or files. To learn more about the Service Binding Operator and its integration with other products, refer to the Service Binding documentation.
Prerequisites
To run and interact with the application, you must complete the following procedures successfully:
- Install Go and
odopackages - Set up an OpenShift cluster with administrator access
- Install the Percona Distribution for MongoDB Operator
- Install the Service Binding Operator
We will use the following versions of these tools to showcase the application:
- Go 1.18.7
- odo v3.0.0
- OpenShift 4.11
- Percona Distribution for MongoDB Operator 1.13.0, provided by Percona
The following steps provide instructions for each prerequisite.
Step 1: Install Go and odo packages
-
Download the latest release from the mirror site
$ curl -L https://developers.redhat.com/content-gateway/rest/mirror/pub/openshift-v4/clients/odo/v3.0.0/odo-linux-amd64 -o odo % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0 100 66.7M 100 66.7M 0 0 3261k 0 0:00:20 0:00:20 --:--:-- 3729k -
Install
odo, you might have to provide your password for root access:$ sudo install -o root -g root -m 0755 odo /usr/local/bin/odo [sudo] password for user:If you are not allowed to use
sudoor you prefer a rootless installation, you can install theodotool to a local folder, like for example~/.local/bin, and configure your shell:$ mkdir -p ~/.local/bin $ mv odo ~/.local/bin $ export PATH=${HOME}/.local/bin/odo:${PATH} -
Verify that
odois installed:$ odo version odo v3.0.0 (8694f1946)
Step 2: Set up an OpenShift cluster
$ odo create project mongodb-restapi
✓ Project "mongodb-restapi" is ready for use
✓ New project created and now using project: mongodb-restapi
Step 3: Install the Percona Distribution for MongoDB Operator
We are not installing from OperatorHub because the installation should be done to our specific mongodb-restapi OpenShift namespace.
Follow these two steps:
-
Install the Percona Distribution for MongoDB Operator:
$ oc create -f https://raw.githubusercontent.com/redhat-developer/openshift-app-services-demos/main/samples/sbo/restapi-mongodb-odo/operators/mongodb-percona-distribution.yaml subscription.operators.coreos.com/percona-server-mongodb-operator created operatorgroup.operators.coreos.com/operatorgroup created - Verify that you have successfully installed the Percona Distribution for MongoDB Operator. Figure 6 shows the output.
$ oc get csv -n mongodb-restapi NAME DISPLAY VERSION REPLACES PHASE percona-server-mongodb-operator.v1 Percona Distribution for MongoDB Operator 1.13.0 Succeeded
Step 4: Install the Service Binding Operator
The Service Binding Operator is always installed in all namespaces. Here, we are not installing from the OperatorHub because we must install the Operator in a particular namespace named openshift-operators.
The following two steps will complete the process:
-
Install the Service Binding Operator:
$ oc create -f https://raw.githubusercontent.com/redhat-developer/openshift-app-services-demos/main/samples/sbo/restapi-mongodb-odo/operators/servicebinding-operator.yaml subscription.operators.coreos.com/my-service-binding-operator created -
Verify that the Service Binding Operator is successfully installed in your namespace:
$ oc get csv -n mongodb-restapi NAME DISPLAY VERSION REPLACES PHASE percona-server-mongodb-operator.v1 Percona Distribution for MongoDB Operator 1.13.0 Succeeded service-binding-operator.v1.3.0 Service Binding Operator 1.3.0 service-binding-operator.v1.2.0 Succeeded
Summary
The installation and setup are now complete. In the next article, you will clone the application and create a database component for it. If you have questions, please comment below. We welcome your feedback.
