Requirements

Hardware sizing

Postmill is a Node.js monorepo application backed by PostgreSQL and Redis. Background jobs run on Inngest, so self-hosted deployments do not need a local workflow engine.

Tier	Users	CPU	RAM	Disk	Notes
Minimum	1–5	2 vCPU	4 GB	20 GB	Suitable for single-tenant or small teams
Small	5–50	4 vCPU	8 GB	50 GB	Comfortable for most self-hosters
Medium	50–200	8 vCPU	16 GB	100 GB	Add RAM for analytics cache / large orgs
Large	200+	16 vCPU+	32 GB+	200 GB+	Scale Postgres and Redis independently

The heavy pieces:

• PostgreSQL 17 — the application database is typically modest (< 5 GB for small instances), but grows with analytics snapshots, media metadata, and campaign data.
• Redis 7 — negligible memory (< 100 MB) unless analytics cache loads many orgs.
• Inngest Cloud — background jobs run outside the cluster; no local Temporal/Elasticsearch services are required.

Software prerequisites

Build toolchain

Tool	Required version	Notes
Node.js	>=24.0.0 <25.0.0	See engines in package.json
pnpm	10.34.4	Specified in packageManager; other versions may silently break
Docker	Recent stable	Only needed for Docker Compose deployment
git	Any	For cloning the repository

Runtime dependencies

Software	Version	Role
PostgreSQL	17	Application data
Redis	7.2	Session cache, throttle store, analytics cache
Inngest Cloud	—	Durable background jobs (analytics, comments, publish, token refresh)
Email provider (optional)	—	6-provider adapter system (Resend, SendGrid, Mailgun, Postmark, Amazon SES, SMTP). Configure with EMAIL_PROVIDER + standardized env vars. See Configuration.

Object storage

All media is stored locally by default (UPLOAD_DIRECTORY). Cloud providers (S3, R2, B2, IDrive e2, and other S3-compatible services — see Storage Setup) are configured per-organization via Settings → Storage. Avatars and app-internal writes always use local storage.

Provider	Notes
Local disk	Default; quota configurable per org. Simple but not redundant.
Cloudflare R2	S3-compatible, no egress fees (per-tenant, Settings → Storage)
AWS S3	S3-native API (per-tenant, Settings → Storage)
Backblaze B2	S3-compatible, low storage cost (per-tenant, Settings → Storage)
IDrive e2	S3-compatible (per-tenant, Settings → Storage)
Others	Wasabi, DigitalOcean Spaces, Hetzner, Storj, Scaleway, Vultr, Linode, generic S3-compatible, MediaLocker (per-tenant, Settings → Storage)

Storage providers are configured per-organization via the Settings UI, not environment variables. See Storage Setup and Configuration.

Network and URL requirements

• The application must be reachable at the URL you set in FRONTEND_URL. OAuth redirects from social providers resolve against this URL.
• BACKEND_INTERNAL_URL must be reachable from within the container for internal API calls. In Docker Compose this is http://localhost:3000; behind a reverse proxy, set it to the internal backend address.
• Outbound HTTPS is required — all provider API calls and webhook dispatches go through safeFetch, which enforces HTTPS and blocks private/internal IPs (unless explicitly allowlisted via SSRF_ALLOWED_PRIVATE_CIDRS for self-hosted provider instances).
• Ensure your public IP is in the allow-list for any API tokens you create via the Public API settings.

CLI commands

The apps/commands package provides NestJS CLI commands for operator tasks:

# Build the CLI
pnpm run commands:build:development

# Check configuration for issues
npx nestjs-command config:check

# Refresh all OAuth tokens
npx nestjs-command refresh

# Run the AI agent
npx nestjs-command run:agent <org>

Run these inside the application container or with the same environment variables as the backend.

Native dependency notes

macOS-only duplicate-class warning

On macOS, test or dev-server logs may show a warning similar to:

Class GNotificationCenterDelegate is implemented in both
.../sharp-darwin-arm64.../sharp-darwin-arm64.node
.../canvas.../canvas.node
One of the two will be used. Which one is undefined.

This is a benign, macOS-only conflict between the native modules sharp and canvas. Both packages register the same macOS notification-delegate class independently; the warning does not affect Linux production images or runtime correctness. No operator action is required.

Verified against v1.3.0