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blumeops/docs/reference/services/flyio-proxy.md
Erich Blume 54db8643a1 Update docs to reflect public service routing via Fly.io 
- security-model: Replace "no public access" with Fly.io proxy description
- routing: Add *.eblu.me as third DNS domain for public services
- architecture: Add Fly.io to network layer and service routing table
- CLAUDE.md: Add public routing domain to routing table
- gandi: Add public CNAME records section
- tailscale-operator: Document ProxyGroup, VIP routing, per-Ingress tags
- flyio-proxy: Clarify why Alloy uses direct Tailscale endpoints (ACL)
- Remove hardcoded Tailscale IP (100.98.163.89) from docs, use DNS names

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-02-08 21:53:07 -08:00

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title tags
Fly.io Proxy
service
networking
fly-io

Fly.io Proxy

Public reverse proxy on Fly.io that exposes selected BlumeOps services to the internet via a Tailscale tunnel back to the homelab.

Quick Reference

Property Value
App blumeops-proxy
Region sjc (San Jose)
Fly.io URL blumeops-proxy.fly.dev
Config fly/ directory in repo
IaC fly/fly.toml (app), Pulumi (DNS + auth key)

Exposed Services

Public domain Backend Service
docs.eblu.me docs.tail8d86e.ts.net docs

Architecture

Internet traffic hits Fly.io's Anycast edge, terminates TLS with a Let's Encrypt certificate, and is proxied by nginx to the backend service over a Tailscale WireGuard tunnel. See expose-service-publicly for the full architecture diagram.

Key Files

File Purpose
fly/fly.toml App configuration
fly/Dockerfile nginx + Tailscale + Alloy container
fly/nginx.conf Reverse proxy, caching, rate limiting, JSON logging
fly/alloy.river Alloy config: log tailing, metric extraction, remote_write
fly/start.sh Entrypoint: start Tailscale, Alloy, then nginx
pulumi/tailscale/__main__.py Auth key (tag:flyio-proxy)
pulumi/tailscale/policy.hujson ACL grants for proxy
pulumi/gandi/__main__.py DNS CNAMEs

Networking

Fly.io runs Firecracker microVMs which support TUN devices natively. Tailscale runs with a real TUN interface (not userspace networking), so MagicDNS and direct Tailscale IP routing work normally.

The Tailscale auth key is preauthorized=True to avoid device approval hangs on container restarts.

Observability

alloy runs inside the container alongside nginx and Tailscale, providing:

  • Logs: nginx JSON access logs tailed and pushed to loki ({instance="flyio-proxy", job="flyio-nginx"})
  • Metrics: Derived from access logs, pushed to prometheus via remote_write
    • flyio_nginx_http_requests_total — request rate by status/method/host
    • flyio_nginx_http_request_duration_seconds — latency histogram
    • flyio_nginx_http_response_bytes_total — response bandwidth
    • flyio_nginx_cache_requests_total — cache HIT/MISS/EXPIRED counts

Dashboards

Dashboard Purpose
Docs APM Per-service view for docs.eblu.me: request rate, latency percentiles, cache hit ratio, error rate, bandwidth, access logs
Fly.io Proxy Health Aggregate proxy health: connections, total request rate by host, cache performance, upstream latency, Alloy health

Alloy listens on 127.0.0.1:12345 for self-scraping its /metrics endpoint. All metrics carry instance="flyio-proxy".

Security Considerations

The tag:flyio-proxy ACL grants access only to tag:flyio-target:443. Services must explicitly opt in by adding a tailscale.com/tags: "tag:k8s,tag:flyio-target" annotation to their Tailscale Ingress. This means the proxy can only reach endpoints that have been individually tagged — a compromised nginx config cannot route to arbitrary services on the tailnet.

Currently tagged as tag:flyio-target: docs, loki, prometheus. Loki and Prometheus are tagged so that alloy (running inside the container) can push logs and metrics directly via their Tailscale Ingress endpoints — the restricted ACL means Caddy on indri (tag:homelab) is not reachable from the proxy.

To expose an additional service through the proxy, add the tag:flyio-target annotation to its Tailscale Ingress. See expose-service-publicly for the full workflow.

Secrets

Secret Source Description
TS_AUTHKEY Pulumi state → fly secrets Tailscale auth key for joining tailnet
FLY_DEPLOY_TOKEN Fly.io → 1Password Deploy token for CI

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