Notifications

Email notification service for Magistrala — listens to domain invitation events and sends styled HTML email notifications to users when they are invited, accept, or reject a domain invitation.

The Notifications service is an event-driven service that sends email notifications for domain invitation lifecycle events. It listens to the platform event stream (NATS or RabbitMQ), fetches user details from the Users service over gRPC, and delivers styled HTML emails via SMTP when a user is invited to a domain, accepts an invitation, or rejects one.

Events Handled

Event	Trigger
`invitation.send`	A user is invited to join a domain
`invitation.accept`	The invited user accepts the domain invitation
`invitation.reject`	The invited user rejects the domain invitation

Configuration

General

Variable	Description	Default
`MG_NOTIFICATIONS_LOG_LEVEL`	Log level (debug, info, warn, error)	info
`MG_NOTIFICATIONS_INSTANCE_ID`	Instance identifier	""
`MG_NOTIFICATIONS_DOMAIN_ALT_NAME`	Alternative label for "domain" (e.g. workspace)	domains
`MG_ES_URL`	Event store URL	nats://localhost:4222

Email (SMTP)

Variable	Description	Default
`MG_EMAIL_HOST`	SMTP server host	localhost
`MG_EMAIL_PORT`	SMTP server port	25
`MG_EMAIL_USERNAME`	SMTP username	""
`MG_EMAIL_PASSWORD`	SMTP password	""
`MG_EMAIL_FROM_ADDRESS`	Sender email address	noreply@magistrala.com
`MG_EMAIL_FROM_NAME`	Sender display name	Magistrala Notifications

Email Templates

Variable	Description
`MG_EMAIL_INVITATION_TEMPLATE`	Path to invitation sent email template
`MG_EMAIL_ACCEPTANCE_TEMPLATE`	Path to invitation accepted email template
`MG_EMAIL_REJECTION_TEMPLATE`	Path to invitation rejected email template

gRPC (Users service)

Variable	Description
`MG_USERS_GRPC_URL`	Users service gRPC URL
`MG_USERS_GRPC_TIMEOUT`	gRPC request timeout
`MG_USERS_GRPC_CLIENT_CERT`	Path to client certificate
`MG_USERS_GRPC_CLIENT_KEY`	Path to client key
`MG_USERS_GRPC_SERVER_CA_CERTS`	Path to trusted CA certificates for Users gRPC

Email Templates

The service ships three HTML email templates with Magistrala branding:

Template	Header Color	Purpose
`invitation-sent-email.tmpl`	Blue (`#083662`)	Notify user of a domain invitation
`invitation-accepted-email.tmpl`	Green	Notify inviter that user accepted
`invitation-rejected-email.tmpl`	Red	Notify inviter that user rejected

All templates are responsive HTML and include a call-to-action section. You can supply custom templates via the MG_EMAIL_*_TEMPLATE environment variables.

Deployment

The service requires NATS for the event stream and the Users service gRPC endpoint. It has no database of its own.

git clone https://github.com/absmach/magistrala
cd magistrala

go build -o notifications cmd/notifications/main.go

MG_NOTIFICATIONS_LOG_LEVEL=info \
MG_ES_URL=nats://localhost:4222 \
MG_EMAIL_HOST=smtp.example.com \
MG_EMAIL_PORT=587 \
MG_EMAIL_USERNAME=user \
MG_EMAIL_PASSWORD=pass \
MG_EMAIL_FROM_ADDRESS=noreply@example.com \
MG_USERS_GRPC_URL=localhost:7009 \
./notifications

Architecture

domains service → event store (NATS) → notifications service → users service (gRPC)
                                                 ↓
                                           SMTP Server → Email Recipients

The service is stateless — it fetches all required data per event from the Users gRPC endpoint and delivers immediately via SMTP. No local state is kept between events.

Testing

# Unit tests
go test ./notifications/... -v

# Email integration tests (requires a running SMTP server)
MG_RUN_EMAIL_TESTS=true go test ./notifications/emailer -v

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