Add Custom Variables

5min
By default, this template comes with one predefined environment variable called BACKEND_ENDPOINT. This variable can be used in the ReactJS application with window.env.BACKEND_ENDPOINT.
You can also add more custom environment variables by following the steps below. In this example we will add a new variable called MyCustomVar.
Update the input properties in the ./.microtica/schema.json file by adding the new variable of type string.
.microtica/schema.json
{
    "properties": {
        "inputs": {
            ...
            "MyCustomVar": {
                "type": "string"
            }
        }
    },

}
{
    "properties": {
        "inputs": {
            ...
            "MyCustomVar": {
                "type": "string"
            }
        }
    },

}
﻿
Update the CloudFormation template by adding the new variable as parameter and then reference the parameter in the DeploymentCustom resource properties.
.microtica/index.json
{
    "Parameters": {
        ...
        "MyCustomVar": {
            "Type": "String"
        }
    },
    "Resources": {
        ...
        "DeploymentCustom": {
            "Type": "AWS::CloudFormation::CustomResource",
            "Properties": {
                "MyCustomVar": {
                    "Ref": "MyCustomVar"
                }
            }
        }
    }
}
{
    "Parameters": {
        ...
        "MyCustomVar": {
            "Type": "String"
        }
    },
    "Resources": {
        ...
        "DeploymentCustom": {
            "Type": "AWS::CloudFormation::CustomResource",
            "Properties": {
                "MyCustomVar": {
                    "Ref": "MyCustomVar"
                }
            }
        }
    }
}
﻿
The last step is to update the logic that provides the environment variable in your web application. This code stores a /env.js file that assigns all environment variables under window.env. The new variable can be used with window.env.MyCustomVar.
.microtica/functions/deployment/src/index.ts
async function uploadFiles(event: CloudFormationCustomResourceEvent): Promise<void> {
    ...
    await s3.upload({
        Bucket: DestinationBucket,
        Key: path,
        Body: `window.env=${JSON.stringify({
            BACKEND_ENDPOINT: event.ResourceProperties.BackendEndpoint,
            // New environment variable here
            MyCustomVar: event.ResourceProperties.MyCustomVar
        })}`,
        ContentType: mime.lookup(path) || null
    }).promise();
}
async function uploadFiles(event: CloudFormationCustomResourceEvent): Promise<void> {
    ...
    await s3.upload({
        Bucket: DestinationBucket,
        Key: path,
        Body: `window.env=${JSON.stringify({
            BACKEND_ENDPOINT: event.ResourceProperties.BackendEndpoint,
            // New environment variable here
            MyCustomVar: event.ResourceProperties.MyCustomVar
        })}`,
        ContentType: mime.lookup(path) || null
    }).promise();
}
﻿
At the end, please check if you have the /env.js file imported in the public/index.html file.
public/index.html
<html lang="en">

<head>
    <!-- 
      Import environment variabes provided through Microtica Portal.
      Variables will be assigned on window.env
      
      E.g. window.env.BACKEND_ENDPOINT
    -->
    <script src="/env.js"></script>
</head>

</html>
<html lang="en">

<head>
    <!-- 
      Import environment variabes provided through Microtica Portal.
      Variables will be assigned on window.env
      
      E.g. window.env.BACKEND_ENDPOINT
    -->
    <script src="/env.js"></script>
</head>

</html>
﻿
Commit and push your changes. Automated build and deploy should start, once the deployment is done, go to Website resource settings, enter the value of the new environment variable
Add Custom Variables in Microtica
﻿
You can repeat the same process for additional environment variables.
Updated 24 Nov 2023
Did this page help you?
Configure a Custom Domain
Amazon EKS