How to reverse proxy with caddy, tailscale and docker ?

Hello all, I'm taking my first steps in the realm of self-hosting and am learning as I go. I have a VM running ubuntu and I got it connected to tailscale network to fend off unwanted visitors. I also have discovered Docker and am using it to deploy two web applications: FreshRSS and Podfetch. I can deploy them through Docker and they both have their own ports which I can access through ipadrress:portnumber URL in my webbrowser. But, the connection is unsecured over HTTP. I'd like to take it a step further in order to make the connections go over HTTPS.

I thought to use Caddy to make a reverse proxy as it is supposed to have good support with Tailscale but I'm not being particularly successful. I can connect to the individual applications (FreshRSS, PodFetch) by using the given tailscale DNS name (machine.domain.ts.net) and port directly in the browsers URL, but going to the machine.domain.ts.net does only yield in a connection error.

I've attached the stdout from running Caddy, my spidersense is telling it is something to do with getting a cert from letsencrypt. Over at tailscale admin, I've ensured I have a tailnet name, MagicDNS and HTTPS certificates enabled.

Here's some relevant information, Caddy log file is at the end.

Thanks in advance

EDIT: solution to my problem at the end of this post.

sudo docker ps

    
CONTAINER ID   IMAGE                         COMMAND                  CREATED          STATUS          PORTS                                                                                         NAMES                                                                                                                 

86a72dbd2686   samuel19982/podfetch:latest   "./podfetch"             20 minutes ago   Up 18 minutes   0.0.0.0:8480->8000/tcp, :::8480->8000/tcp                                                     podfetch_podfetch_1                                                                                                   

a7dae64308f9   caddy:latest                  "caddy run --config …"   25 hours ago     Up 17 seconds   0.0.0.0:80->80/tcp, :::80->80/tcp, 0.0.0.0:443->443/tcp, :::443->443/tcp, 443/udp, 2019/tcp   caddy                                                                                                                 

141bbf69ad62   freshrss/freshrss             "./Docker/entrypoint…"   2 months ago     Up 2 months     0.0.0.0:8080->80/tcp, :::8080->80/tcp                                                         freshrss

Current Caddyfile:

    
machine.domain.ts.net

respond "hello"
file_server

docker-compose.yml for Caddy

 yaml

    
version: "3"

services:
  caddy:
    image: caddy:latest
    container_name: caddy
    restart: always
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - /home/ubuntu/caddy/caddy_data:/data
      - /home/ubuntu/caddy/caddy_config:/config
      - /home/ubuntu/caddy/Caddyfile:/etc/caddy/Caddyfile

log output from running `sudo docker-compose up` in the directory where docker-compose.yml is located

 json

    
Starting caddy ... done                                                                                                                                    

Attaching to caddy                                                                                                                                         

caddy    | {"level":"info","ts":1691499456.0689287,"msg":"using provided configuration","config_file":"/etc/caddy/Caddyfile","config_adapter":"caddyfile"} 

caddy    | {"level":"warn","ts":1691499456.0720005,"msg":"Caddyfile input is not formatted; run 'caddy fmt --overwrite' to fix inconsistencies","adapter":"

caddyfile","file":"/etc/caddy/Caddyfile","line":9}                                                                                                         

caddy    | {"level":"info","ts":1691499456.0762668,"logger":"admin","msg":"admin endpoint started","address":"localhost:2019","enforce_origin":false,"origi

ns":["//localhost:2019","//[::1]:2019","//127.0.0.1:2019"]}                                                                                                

caddy    | {"level":"info","ts":1691499456.0775971,"logger":"http.auto_https","msg":"enabling automatic HTTP->HTTPS redirects","server_name":"srv0"}       

caddy    | {"level":"info","ts":1691499456.077673,"logger":"http.auto_https","msg":"server is listening only on the HTTPS port but has no TLS connection po

licies; adding one to enable TLS","server_name":"srv1","https_port":443}                                                                                   

caddy    | {"level":"info","ts":1691499456.077703,"logger":"http.auto_https","msg":"enabling automatic HTTP->HTTPS redirects","server_name":"srv1"}        

caddy    | {"level":"info","ts":1691499456.07822,"logger":"http","msg":"enabling HTTP/3 listener","addr":":2016"}                                          

caddy    | {"level":"info","ts":1691499456.0783753,"msg":"failed to sufficiently increase receive buffer size (was: 208 kiB, wanted: 2048 kiB, got: 416 kiB

). See https://github.com/quic-go/quic-go/wiki/UDP-Buffer-Sizes for details."}                                                                             

caddy    | {"level":"info","ts":1691499456.0794368,"logger":"http.log","msg":"server running","name":"srv0","protocols":["h1","h2","h3"]}                  

caddy    | {"level":"info","ts":1691499456.079528,"logger":"http","msg":"enabling HTTP/3 listener","addr":":443"}                                          

caddy    | {"level":"info","ts":1691499456.079708,"logger":"http.log","msg":"server running","name":"srv1","protocols":["h1","h2","h3"]}                   

caddy    | {"level":"info","ts":1691499456.0798655,"logger":"http.log","msg":"server running","name":"remaining_auto_https_redirects","protocols":["h1","h2

","h3"]}                                                                                                                                                   

caddy    | {"level":"info","ts":1691499456.0800827,"msg":"autosaved config (load with --resume flag)","file":"/config/caddy/autosave.json"}                

caddy    | {"level":"info","ts":1691499456.0801237,"msg":"serving initial configuration"}                                                                  

caddy    | {"level":"info","ts":1691499456.0802798,"logger":"tls.cache.maintenance","msg":"started background certificate maintenance","cache":"0xc00032950

0"}                                                                                                                                                        

caddy    | {"level":"info","ts":1691499456.080402,"logger":"tls","msg":"cleaning storage unit","description":"FileStorage:/data/caddy"}                    

caddy    | {"level":"info","ts":1691499456.0843327,"logger":"tls","msg":"finished cleaning storage units"}                                                 

********************
***** Connection to caddy is made here                                             ********************                                                                                                      

caddy    | {"level":"warn","ts":1691499478.27926,"logger":"http","msg":"could not get status; will try to get certificate anyway","error":"Get \"http://loc

al-tailscaled.sock/localapi/v0/status\": dial unix /var/run/tailscale/tailscaled.sock: connect: no such file or directory"}                                

caddy    | {"level":"error","ts":1691499478.2793655,"logger":"tls.handshake","msg":"getting certificate from external certificate manager","remote_ip":"100

.125.48.40","remote_port":"60140","sni":"machine.domain.ts.net","cert_manager":0,"error":"Get \"http://local-tailscaled.sock/localapi/v0/cert/vaulty.tail

a5148.ts.net?type=pair\": dial unix /var/run/tailscale/tailscaled.sock: connect: no such file or directory"}                                               

caddy    | {"level":"info","ts":1691499478.2794874,"logger":"tls.on_demand","msg":"obtaining new certificate","remote_ip":"100.125.48.40","remote_port":"60

140","server_name":"machine.domain.ts.net"}                                                                                                              

caddy    | {"level":"info","ts":1691499478.2796874,"logger":"tls.obtain","msg":"acquiring lock","identifier":"machine.domain.ts.net"}                    

caddy    | {"level":"info","ts":1691499478.2826056,"logger":"tls.obtain","msg":"lock acquired","identifier":"machine.domain.ts.net"}                     

caddy    | {"level":"info","ts":1691499478.2827125,"logger":"tls.obtain","msg":"obtaining certificate","identifier":"machine.domain.ts.net"}             

caddy    | {"level":"info","ts":1691499478.285254,"logger":"tls","msg":"waiting on internal rate limiter","identifiers":["machine.domain.ts.net"],"ca":"h

ttps://acme-v02.api.letsencrypt.org/directory","account":"caddy@zerossl.com"}                                                                              

caddy    | {"level":"info","ts":1691499478.2852805,"logger":"tls","msg":"done waiting on internal rate limiter","identifiers":["machine.domain.ts.net"],"

ca":"https://acme-v02.api.letsencrypt.org/directory","account":"caddy@zerossl.com"}                                                                        

caddy    | {"level":"info","ts":1691499479.3021843,"logger":"tls.acme_client","msg":"trying to solve challenge","identifier":"machine.domain.ts.net","cha

llenge_type":"tls-alpn-01","ca":"https://acme-v02.api.letsencrypt.org/directory"}                                                                          

caddy    | {"level":"error","ts":1691499479.867296,"logger":"tls.acme_client","msg":"challenge failed","identifier":"machine.domain.ts.net","challenge_ty

pe":"tls-alpn-01","problem":{"type":"urn:ietf:params:acme:error:dns","title":"","detail":"DNS problem: NXDOMAIN looking up A for machine.domain.ts.net - 

check that a DNS record exists for this domain; DNS problem: NXDOMAIN looking up AAAA for machine.domain.ts.net - check that a DNS record exists for this

 domain","instance":"","subproblems":[]}}                                                                                                                  

caddy    | {"level":"error","ts":1691499479.867339,"logger":"tls.acme_client","msg":"validating authorization","identifier":"machine.domain.ts.net","prob

lem":{"type":"urn:ietf:params:acme:error:dns","title":"","detail":"DNS problem: NXDOMAIN looking up A for machine.domain.ts.net - check that a DNS record

 exists for this domain; DNS problem: NXDOMAIN looking up AAAA for machine.domain.ts.net - check that a DNS record exists for this domain","instance":"",

"subproblems":[]},"order":"https://acme-v02.api.letsencrypt.org/acme/order/1247308536/200246894916","attempt":1,"max_attempts":3}                          

caddy    | {"level":"info","ts":1691499481.1934462,"logger":"tls.acme_client","msg":"trying to solve challenge","identifier":"machine.domain.ts.net","cha

llenge_type":"http-01","ca":"https://acme-v02.api.letsencrypt.org/directory"}                                                                              

caddy    | {"level":"error","ts":1691499481.7219243,"logger":"tls.acme_client","msg":"challenge failed","identifier":"machine.domain.ts.net","challenge_t

ype":"http-01","problem":{"type":"urn:ietf:params:acme:error:dns","title":"","detail":"DNS problem: NXDOMAIN looking up A for machine.domain.ts.net - che

ck that a DNS record exists for this domain; DNS problem: NXDOMAIN looking up AAAA for machine.domain.ts.net - check that a DNS record exists for this do

main","instance":"","subproblems":[]}}                                                                                                                     

caddy    | {"level":"error","ts":1691499481.7219615,"logger":"tls.acme_client","msg":"validating authorization","identifier":"machine.domain.ts.net","pro

blem":{"type":"urn:ietf:params:acme:error:dns","title":"","detail":"DNS problem: NXDOMAIN looking up A for machine.domain.ts.net - check that a DNS recor

d exists for this domain; DNS problem: NXDOMAIN looking up AAAA for machine.domain.ts.net - check that a DNS record exists for this domain","instance":""

,"subproblems":[]},"order":"https://acme-v02.api.letsencrypt.org/acme/order/1247308536/200246898176","attempt":2,"max_attempts":3}

EDIT - SOLUTION: many weeks later, I've learn a few things. Running Caddy bare-metal removed the complexity of dealing with docker networks, but it wasn't as robust as I expected (lets just say - I ran into a very edge-case issue that ruined my day).

The solution to my actual problem was to actually directing the requests to the URL to the actual IP adress of the docker container running the service I want to make avaible, and ensure that both docker and the service are on the same docker network. A very obvious solution in hindsight, and to be fair, I think I've had the misfortune to run into several issues before reaching this insight.

8 comments

But, the connection is unsecured over HTTP. I’d like to take it a step further in order to make the connections go over HTTPS.
Why? You're already VPN'd into a machine you control via tailscale. Protecting the specific application TCP traffic with TLS is kind of redundant at that point. If you really care, just use nginx not Caddy because this will never work using Tailscale DNS, self sign a cert for your Tailscale domain and use nginx to serve traffic on the Tailscale network device.
Also, use docker compose. This will feed DNS records into the containers' /etc/hosts file as well as put the containers on their own network so the main containers won't be exposed directly, only caddy.
docker-compose.yml

version: "3.4" services: caddy: container_name: caddy image: ghcr.io/authp/authp:latest # I use authp for OAuth authentication instead of VPN-only access restart: unless-stopped ports: - 443:443 - 443:443/udp - 80:80 volumes: - ${ROOT}/config/caddy/Caddyfile:/etc/caddy/Caddyfile - ${ROOT}/config/caddy/data:/data/ dns: - 1.1.1.1 # set these to your local DNS if you have one, I run pihole - 8.8.8.8 - 8.8.4.4 whoami: container_name: whoami depends_on: - caddy image: containous/whoami restart: unless-stopped
~~Caddyfile~~

{ http_port 80 https_port 443 } whoami.example.com{ reverse_proxy whoami:80 }
As you can see the Caddyfile directs the Caddy container to reverse proxy whoami.example.com to http://whoami:80, which uses the /etc/hosts entry that docker-compose inserts for whoami to the whoami container's Docker IP address. In this scheme, only Caddy needs to have a port listening on the host machine. Assuming Caddy can access your tailscale network, this will work - for that. (although I worry that Tailscale mounts the network device as a unix socket, which may complicate matters - I ran into this when trying some bullshit with nginx/openresty)
The issue that you're having in your logs is that you're trying to get Caddy to get a TLS cert for machine.domain.ts.net, which will never work, because machine.domain.ts.net is not a globally recognized DNS record - it's a split zone DNS for within the Tailscale network exclusively. LetsEncrypt needs to be able to prove you own machine.domain.ts.net in order to issue a cert for it, meaning it needs to be able to resolve the domain and chat with Caddy. Since LetsEncrypt isn't on your Tailscale network, it cannot do this.
- Please do, I'd be most grateful for it.
  If you have any better suggestion for how I should handle reverse proxying (maybe there's a easier way than through Caddy?), I'm all ears.
  
  {"level":"error","ts":1691499478.2793655,"logger":"tls.handshake","msg":"getting certificate from external certificate manager","remote_ip":"100
  .125.48.40","remote_port":"60140","sni":"machine.domain.ts.net","cert_manager":0,"error":"Get http://local-tailscaled.sock/localapi/v0/cert/vaulty.tail
  a5148.ts.net?type=pair\": dial unix /var/run/tailscale/tailscaled.sock: connect: no such file or directory"}
  This is your main issue - looks like Caddy can't access the tailscale socket in order to serve their TLS cert. check you're running caddy>2.5, check the socket exists and check the user running the caddy process has access to it. docs
  Are you running Caddy with docker?
  
  ~~I read your comment in more detail, you're going down the wrong path. What you're looking for cannot function the way you want the way you want to achieve it, and may not even make sense to want.~~ I am wrong, I didn't realize Caddy could just serve their cert over the socket. What user is the caddy process on your VM being run as?
  If you want to use Tailscale DNS, you can use their TLS cert (assuming it gives a valid cert for machine.domain.ts.net) and just reverse proxy HTTP traffic with nginx on the VPS/VM (assuming nginx can listen on their network device. I've fought with that with openresty before, but that may be because I was trying to host it in another docker container lol).