Erich Blume
cc54b4f565
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## Summary - Embed Grafana Alloy in the Fly.io proxy container to collect nginx JSON access logs (→ Loki) and derive request rate, latency histogram, cache status, and bandwidth metrics (→ Prometheus) - Add nginx `stub_status` endpoint for connection-level metrics (active/reading/writing/waiting) - Create two Grafana dashboards: **Docs APM** (per-service view filtered by `host="docs.eblu.me"`) and **Fly.io Proxy Health** (aggregate proxy health across all upstream services) ## Changed Files | File | Change | |------|--------| | `fly/nginx.conf` | Add JSON `log_format` + `access_log`, add `stub_status` endpoint | | `fly/Dockerfile` | COPY Alloy binary from `grafana/alloy:v1.5.1`, COPY `alloy.river` config | | `fly/alloy.river` | **New** — Alloy config: log tailing, metric extraction, remote_write | | `fly/start.sh` | Start Alloy after Tailscale, before nginx | | `argocd/manifests/grafana-config/dashboards/configmap-docs-apm.yaml` | **New** — Docs APM dashboard | | `argocd/manifests/grafana-config/dashboards/configmap-flyio.yaml` | **New** — Fly.io Proxy Health dashboard | | `argocd/manifests/grafana-config/kustomization.yaml` | Register new dashboard configmaps | | `docs/reference/services/flyio-proxy.md` | Document observability setup | ## Deployment and Testing - [ ] `mise run fly-deploy` — rebuild container with Alloy - [ ] `curl https://docs.eblu.me/` — generate traffic - [ ] `fly logs -a blumeops-proxy` — verify Alloy startup - [ ] Query Prometheus: `flyio_nginx_http_requests_total{instance="flyio-proxy"}` - [ ] Query Loki: `{instance="flyio-proxy", job="flyio-nginx"}` - [ ] `argocd app sync grafana-config` — deploy dashboards - [ ] Verify dashboards show data in Grafana - [ ] `mise run services-check` — no regressions Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/123
93 lines
4.3 KiB
Markdown
93 lines
4.3 KiB
Markdown
---
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title: Fly.io Proxy
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tags:
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- service
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- networking
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- fly-io
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---
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# Fly.io Proxy
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Public reverse proxy on [Fly.io](https://fly.io) that exposes selected BlumeOps services to the internet via a Tailscale tunnel back to the homelab.
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## Quick Reference
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| Property | Value |
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|----------|-------|
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| **App** | `blumeops-proxy` |
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| **Region** | `sjc` (San Jose) |
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| **Fly.io URL** | `blumeops-proxy.fly.dev` |
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| **Config** | `fly/` directory in repo |
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| **IaC** | `fly/fly.toml` (app), Pulumi (DNS + auth key) |
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## Exposed Services
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| Public domain | Backend | Service |
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|---------------|---------|---------|
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| `docs.eblu.me` | `docs.tail8d86e.ts.net` | [[docs]] |
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## Architecture
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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.
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## Key Files
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| File | Purpose |
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|------|---------|
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| `fly/fly.toml` | App configuration |
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| `fly/Dockerfile` | nginx + Tailscale + Alloy container |
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| `fly/nginx.conf` | Reverse proxy, caching, rate limiting, JSON logging |
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| `fly/alloy.river` | Alloy config: log tailing, metric extraction, remote_write |
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| `fly/start.sh` | Entrypoint: start Tailscale, Alloy, then nginx |
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| `pulumi/tailscale/__main__.py` | Auth key (`tag:flyio-proxy`) |
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| `pulumi/tailscale/policy.hujson` | ACL grants for proxy |
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| `pulumi/gandi/__main__.py` | DNS CNAMEs |
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## Networking
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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.
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The Tailscale auth key is `preauthorized=True` to avoid device approval hangs on container restarts.
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## Observability
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[[alloy|Alloy]] runs inside the container alongside nginx and Tailscale, providing:
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- **Logs**: nginx JSON access logs tailed and pushed to [[loki|Loki]] (`{instance="flyio-proxy", job="flyio-nginx"}`)
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- **Metrics**: Derived from access logs, pushed to [[prometheus|Prometheus]] via `remote_write`
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- `flyio_nginx_http_requests_total` — request rate by status/method/host
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- `flyio_nginx_http_request_duration_seconds` — latency histogram
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- `flyio_nginx_http_response_bytes_total` — response bandwidth
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- `flyio_nginx_cache_requests_total` — cache HIT/MISS/EXPIRED counts
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### Dashboards
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| Dashboard | Purpose |
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|-----------|---------|
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| **Docs APM** | Per-service view for `docs.eblu.me`: request rate, latency percentiles, cache hit ratio, error rate, bandwidth, access logs |
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| **Fly.io Proxy Health** | Aggregate proxy health: connections, total request rate by host, cache performance, upstream latency, Alloy health |
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Alloy listens on `127.0.0.1:12345` for self-scraping its `/metrics` endpoint. All metrics carry `instance="flyio-proxy"`.
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## Security Considerations
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The `tag:flyio-proxy` ACL grants access to both `tag:k8s:443` (for proxying public services) and `tag:homelab:443` (for pushing metrics/logs to [[caddy|Caddy]]-proxied Loki and Prometheus). This means a compromised nginx config could route traffic to **any** Caddy-proxied service — not just the intended backends. Some of those services (Loki, Prometheus) have no auth; others ([[forgejo]], [[navidrome]], [[immich]]) do.
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Exploitation requires either pushing a malicious image to Fly.io or modifying the nginx config — both of which require RCE on [[gilbert]] (where `fly` is authenticated) or access to [[1password]] (the deploy token). This is an acceptable boundary given that 1Password is already the trust root for the entire infrastructure.
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If this surface area becomes a concern, an alternative would be to add dedicated Tailscale Ingress tags for Loki/Prometheus write endpoints and restrict `tag:flyio-proxy` to only those.
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## Secrets
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| Secret | Source | Description |
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|--------|--------|-------------|
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| `TS_AUTHKEY` | Pulumi state → `fly secrets` | Tailscale auth key for joining tailnet |
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| `FLY_DEPLOY_TOKEN` | Fly.io → 1Password | Deploy token for CI |
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## Related
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- [[expose-service-publicly]] - Setup guide for adding new public services
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- [[manage-flyio-proxy]] - Operational tasks (deploy, shutoff, troubleshoot)
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- [[caddy]] - Private reverse proxy for `*.ops.eblu.me` (separate system)
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- [[tailscale]] - WireGuard mesh network
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- [[gandi]] - DNS hosting
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