blog: article on how to use tailscale + traefik

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+#+TITLE: Tailscale, Docker and HTTPS
+#+TAGS[]: docker tailscale traefik
+#+DATE: <2021-12-29 Wed>
+
+I run a number of services in my home network. For the majority of these services, I don't want to make them available on the internet, I want to only be able to access them when I'm on my home network. However, sometimes I'm not at home and I still want to access them. So far I've been using plain [[https://www.wireguard.com/][wireguard]] to achieve this. While the initial configuration for wireguard is pretty simple, it starts to be a bit more cumbersome as I add more hosts/containers. It's also not easy to share keys with other folks if I want to give access to some of the machines or services. For that reason I decided to give a look at [[https://tailscale.com/][tailscale]].
+
+There's already a lot of articles about tailscale and how to use and configure it. Their [[https://tailscale.com/kb/][documentation]] is also pretty good, so I won't cover the initial setup.
+
+As stated above, I want to access some of my services that are running as docker containers from anywhere. For web services, I want to use them through HTTPS, with a valid certificate, and without having to remember on which port the service it's listening. I also don't want to setup a PKI in my home lab for that (and I'm also not interested in configuring split DNS), and instead I prefer to use [[https://letsencrypt.org/][let's encrypt]] with a proper subdomain that is unique for each service.
+
+The [[https://tailscale.com/kb/1054/dns/][tailscale documentation]] has two suggestions for this:
+- use their magicDNS feature / split DNS
+- setup a subdomain on a public domain
+
+Since I already have a public domain that I use for my home network, I decided to go with the second option (I'm also uncertain how to achieve my goal using magicDNS without running tailscale inside the container).
+
+The public domain I'm using is managed through [[https://cloud.google.com/dns/docs/tutorials/create-domain-tutorial][Google Cloud Domain]]. I create a new record for the services I want to run (for example, ~dash~ for my instance of grafana), using the IP address from the tailscale node the service runs on (e.g. 100.83.51.12).
+
+For routing the traffic I use [[https://traefik.io/][traefik]]. The configuration for traefik looks like this:
+#+begin_src yaml
+global:
+  sendAnonymousUsage: false
+providers:
+  docker:
+    exposedByDefault: false
+entryPoints:
+  http:
+    address: ":80"
+  https:
+    address: ":443"
+certificatesResolvers:
+  dash:
+    acme:
+      email: franck@fcuny.net
+      storage: acme.json
+      dnsChallenge:
+        provider: gcloud
+#+end_src
+
+The important bit here is the ~certificatesResolvers~ part. I'll be using the [[https://doc.traefik.io/traefik/user-guides/docker-compose/acme-dns/][dnsChallenge]] instead of the [[https://doc.traefik.io/traefik/user-guides/docker-compose/acme-http/][httpChallenge]] to obtain the certificate from let's encrypt. For this to work, I need to specify the ~provider~ to be [[https://go-acme.github.io/lego/dns/gcloud/][gcloud]]. I'll also need a service account (see [[https://cloud.google.com/docs/authentication/production#providing_credentials_to_your_application][this doc]] to create it). I run ~traefik~ in a docker container, and the ~systemd~ unit file is below. The required bits for using the ~dnsChallenge~ with ~gcloud~ are:
+- the environment variable ~GCP_SERVICE_ACCOUNT_FILE~: it contains the credentials so that ~traefik~ can update the DNS record for the challenge
+- the environment variable ~GCP_PROJECT~: the name of the GCP project
+- mounting the service account file inside the container (I store it on the host under ~/data/containers/traefik/config/sa.json~)
+
+#+begin_src systemd
+[Unit]
+Description=traefik proxy
+Documentation=https://doc.traefik.io/traefik/
+After=docker.service
+Requires=docker.service
+
+[Service]
+Restart=on-failure
+ExecStartPre=-/usr/bin/docker kill traefik
+ExecStartPre=-/usr/bin/docker rm traefik
+ExecStartPre=/usr/bin/docker pull traefik:latest
+
+ExecStart=/usr/bin/docker run \
+  -p 80:80 \
+  -p 9080:8080 \
+  -p 443:443 \
+  --name=traefik \
+  -e GCE_SERVICE_ACCOUNT_FILE=/var/run/gcp-service-account.json \
+  -e GCE_PROJECT= gcp-super-project \
+  --volume=/data/containers/traefik/config/acme.json:/acme.json \
+  --volume=/data/containers/traefik/config/traefik.yml:/etc/traefik/traefik.yml:ro \
+  --volume=/data/containers/traefik/config/sa.json:/var/run/gcp-service-account.json \
+  --volume=/var/run/docker.sock:/var/run/docker.sock:ro \
+  traefik:latest
+ExecStop=/usr/bin/docker stop traefik
+
+[Install]
+WantedBy=multi-user.target
+#+end_src
+
+As an example, I run [[https://grafana.com/][grafana]] on my home network to view metrics from the various containers / hosts. Let's pretend I use ~example.net~ as my domain. I want to be able to access ~grafana~ via https://dash.example.net. Here's the ~systemd~ unit configuration I use for this:
+
+#+begin_src systemd
+[Unit]
+Description=Grafana in a docker container
+Documentation=https://grafana.com/docs/
+After=docker.service
+Requires=docker.service
+
+[Service]
+Restart=on-failure
+RuntimeDirectory=grafana
+ExecStartPre=-/usr/bin/docker kill grafana-server
+ExecStartPre=-/usr/bin/docker rm grafana-server
+ExecStartPre=-/usr/bin/docker pull grafana/grafana:latest
+
+ExecStart=/usr/bin/docker run \
+  -p 3000:3000 \
+  -e TZ='America/Los_Angeles' \
+  --name grafana-server \
+  -v /data/containers/grafana/etc/grafana:/etc/grafana \
+  -v /data/containers/grafana/var/lib/grafana:/var/lib/grafana \
+  -v /data/containers/grafana/var/log/grafana:/var/log/grafana \
+  --user=grafana \
+  --label traefik.enable=true \
+  --label traefik.http.middlewares.grafana-https-redirect.redirectscheme.scheme=https \
+  --label traefik.http.middlewares.grafana-https-redirect.redirectscheme.permanent=true \
+  --label traefik.http.routers.grafana-http.rule=Host(`dash.example.net`) \
+  --label traefik.http.routers.grafana-http.entrypoints=http \
+  --label traefik.http.routers.grafana-http.service=grafana-svc \
+  --label traefik.http.routers.grafana-http.middlewares=grafana-https-redirect \
+  --label traefik.http.routers.grafana-https.rule=Host(`dash.example.net`) \
+  --label traefik.http.routers.grafana-https.entrypoints=https \
+  --label traefik.http.routers.grafana-https.tls=true \
+  --label traefik.http.routers.grafana-https.tls.certresolver=dash \
+  --label traefik.http.routers.grafana-https.service=grafana-svc \
+  --label traefik.http.services.grafana-svc.loadbalancer.server.port=3000 \
+  grafana/grafana:latest
+
+ExecStop=/usr/bin/docker stop unifi-controller
+
+[Install]
+WantedBy=multi-user.target
+#+end_src
+
+Now I can access my grafana instance via HTTPS (and http://dash.example.net would redirect to HTTPS) while my tailscale interface is up on the machine I'm using (e.g. my desktop or my phone).