Indus Reminder

Indus Reminder is a production-ready Go CLI automation tool that sends a daily reminder email through Gmail SMTP to ensure work trackers and personal checklists are updated consistently.

Problem It Solves

Teams and individuals often forget end-of-day hygiene tasks (tracker updates, blockers, and personal follow-ups). This project enforces a reliable reminder cadence with a deterministic GitHub Actions schedule.

How It Works

1. GitHub Actions triggers the job at a UTC cron time mapped to local 16:30.
2. The CLI loads checklist.md from the repository.
3. SMTP credentials and recipient are read from environment variables.
4. The CLI sends a styled tricolour email via Gmail SMTP with a warm message and inline visual layout.
5. Sundays are skipped both by cron (1-6) and by runtime guard.
6. Manual workflow_dispatch supports force_send=true for Sunday-only delivery testing.
7. Every push event runs a deployment test that sends 3 emails, 1 minute apart.

Scheduling (UTC to Local)

• Local timezone used: Asia/Kolkata (UTC+05:30)
• Target local send time: 16:30
• Workflow cron: 0 11 * * 1-6
• Conversion: 11:00 UTC + 05:30 = 16:30 IST
• Sunday skip: Cron runs Monday-Saturday only (1-6), and the binary also exits early on local Sunday.

Push Deployment Test Mode

• Trigger: every GitHub push event.
• Behavior: sends 3 test emails with subjects Deployment Test 1/3, 2/3, 3/3.
• Interval: 1 minute between each email.
• Sunday handling: deployment tests force-send (FORCE_SEND=true) so testing works any day.
• Daily reminder behavior remains unchanged for Monday-Saturday at 16:30 IST.

Required Environment Variables

These must be provided at runtime (typically GitHub Secrets):

• SMTP_HOST
• SMTP_PORT
• SMTP_USER
• SMTP_PASS
• MAIL_TO

Optional:

• MAIL_SUBJECT (falls back to default subject if empty)
• MAIL_FROM (header sender email shown in inbox, default SMTP_USER)
• MAIL_FROM_NAME (header sender name, default Indus Software Reminder)
• REMINDER_NAME (default Boss Hari)
• REMINDER_TZ (default Asia/Kolkata)
• CHECKLIST_FILE (default checklist.md)
• FORCE_SEND (default false, intended for manual Sunday testing)

GitHub Setup

1. Fork this repository.
2. Add repository secrets:
   • SMTP_HOST = smtp.gmail.com
   • SMTP_PORT = 587
   • SMTP_USER = your Gmail address
   • SMTP_PASS = Gmail App Password
   • MAIL_TO = recipient email address
3. Optionally add repository variables MAIL_SUBJECT, MAIL_FROM, MAIL_FROM_NAME, and REMINDER_NAME.
4. Enable Actions in your fork.
5. Run workflow manually once using workflow_dispatch to validate configuration.
6. If testing on Sunday, run manual dispatch with input force_send=true.

Local Build

go test ./...
go build ./cmd/indus-reminder

The binary is designed to run in GitHub Actions and returns an error if executed outside that environment.

Repository Structure

.
|-- cmd/indus-reminder/main.go
|-- internal/mailer/mailer.go
|-- internal/mailer/mailer_test.go
|-- internal/emailtemplate/template.go
|-- internal/emailtemplate/template_test.go
|-- checklist.md
|-- .github/workflows/reminder.yml
|-- docs/diagrams/
|-- docs/email-assets/
|-- README.md
|-- LICENSE
`-- .gitignore

Email Template Visuals

The reminder email uses an inline tricolour layout (no external image loading required in the email body). The SVG files below are design references kept in the repository:

1. Logo Header
   

2. Reminder Note Card
   

Architecture & Workflows

1) System Overview

High-level view of scheduler, CLI, checklist source, SMTP, and recipient.

2) GitHub Actions Workflow

Shows scheduled trigger, build stage, run stage, and failure behavior.

3) Sequence: Email Send Flow

End-to-end call sequence from scheduler to SMTP delivery.

4) Component Diagram

Static component relationships inside the Go project.

5) Deployment / Execution Diagram

Execution topology of GitHub-hosted runner and external SMTP endpoint.

6) Data Flow Diagram

How configuration and checklist data move through the system.

7) UML Package Diagram

Package-level dependency direction and boundaries.

Limitations

• GitHub scheduled workflows are best-effort and can be delayed by a few minutes.
• Cron is always evaluated in UTC.
• Gmail SMTP requires App Password when 2FA is enabled.
• This tool intentionally has no retry queue or persistent state.
• Push deployment tests send 3 emails per push and can increase mailbox volume.

Security Notes

• No secrets are hardcoded in source, workflow, or documentation.
• SMTP credentials are loaded only from environment variables.
• Logs avoid printing passwords or secret values.
• Gmail SMTP still authenticates with SMTP_USER/SMTP_PASS; MAIL_FROM and MAIL_FROM_NAME only control display headers.

License

MIT License. See LICENSE.