fn-push-notifications

A Fn Project function for sending mobile push notifications through third party integrations.

Currently, push notifications can be sent to Androind and iOS devices using Firebase Cloud Messaging (FCM).

Requirements

For sending push notifications, a Firebase Admin SDK service account is required.

Of course, also an OCI tenancy where deploy the function is required.

Constraints

Currently the most recent Firebase Admin Go SDK supported version is 4.9.0, because Go Fn FDK doesn't support go versions >1.15.

Configuration

The function supports the following configuration variables:

Variable	Description	Required	Notes
GOOGLE_APPLICATION_CREDENTIALS	The Firebase Admin SDK service account private key file, in JSON format. The variable should be base64 encoded	If GOOGLE_APPLICATION_CREDENTIALS_SECRET_ID is not specified	Configuration variables are stored in plain text, please consider using GOOGLE_APPLICATION_CREDENTIALS_SECRET_ID instead
GOOGLE_APPLICATION_CREDENTIALS_SECRET_ID	The OCID of the secret that contains the Firebase Admin SDK service account private key file, in JSON format	If GOOGLE_APPLICATION_CREDENTIALS is not specified

The function invocation payload

The function payload is a JSON with the following attributes:

Name	Description	Notes
recipients	The registration tokens of push notification recipients
data	A custom set of key-value pairs	Only strings are allowed, both for keys and values
message	The message to push to recipients
message.title	The title of the message
message.body	The body of the message

An example of function's payload is the following:

{
    "recipients": [
        "00000000"
    ],
    "data": {
        "description": "Use the data element for sending custom key-value pairs",
        "note": "Only strings are allowed, both for keys and values"
    },
    "message": {
        "title": "Hello",
        "body": "A message for you !!!"
    }
}

Running the function

Prerequisites

1. Configure your tenancy and your development environment to use OCI Functions
2. A Firebase Admin SDK service account

Deployment

For deploying the function:

1. Clone the oci-fn-push-notification repo
   • git clone https://github.com/cdivita/oci-fn-push-notification.git
2. Create the application in OCI Functions
   • fn create app <app-name> --annotation oracle.com/oci/subnetIds='["<subnet-ocid>"]'
3. Deploy the function
   • fn -v deploy --app <app-name> --no-bump
4. Configure the function
   • fn config function <app-name> fn-push-notification GOOGLE_APPLICATION_CREDENTIALS <Firebase Admin SDK service account private key>

If you stored the Google Application Credentials OCI Vault, the configuration activities are slightly different:

1. Use GOOGLE_APPLICATION_CREDENTIALS_SECRET_ID rather than GOOGLE_APPLICATION_CREDENTIALS as configuration variable
   • fn config function <app-name> fn-push-notification GOOGLE_APPLICATION_CREDENTIALS_SECRET_ID <The OCID of your Twilio Auth Token secret>
2. Create a dynamic group that includes your function resources. A matching rule that can be used is: all {resource.type = 'fnfunc'}
3. Create a policy for such dynamic group that allows the access to keys resources
   • allow dynamic-group <dynamic-group-name> to read secret-bundles in compartment <keys-compartment>