Let invites, SSO and health checks past Vouch

location / covered /invite/{token}, /oidc/callback, /device and
/healthz along with the web interface, so Vouch stood in front of all
of them. An invite link was the worst of it: it goes to somebody who has
no account anywhere yet, and Vouch bounced them to a login they cannot
pass. The OIDC callback was fragile for a different reason — the
authorization code it carries is single-use and short-lived, and a
second login round trip is a poor place to spend it.

Those four paths now proxy straight through. KeepOrg authenticates each
of them itself: an invite is a capability token, the callback is checked
against its state, a device code expires in ten minutes, and /healthz is
unauthenticated by design. /web keeps Vouch in front of it, and /api was
already exempt.

The proxy settings move to the server block, where every location
inherits them, and the upstream becomes a named block. location / has to
repeat the headers in full: a location that sets one proxy_set_header
replaces the inherited set rather than adding to it.

Checked with nginx -t and against a running keeporgd with a 401 standing
in for Vouch: /, /web and /web/* redirect to auth.tiredsysadmin.cc,
while /healthz, /invite/, /device and /oidc/* serve KeepOrg's own pages
and /api returns KeepOrg's 401.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

config/nginx/keeporg.conf.tmpl

@@ -1,5 +1,9 @@
 ### Deployed by https://git.rcmd.space/rcmd/keeporg
 
+upstream keeporg {
+    server 10.200.1.3:32970;
+}
+
 server {
   listen 80;
   listen [::]:80;
@@ -24,6 +28,27 @@ server {
 
     server_name keeporg.tiredsysadmin.cc;
 
+    # Shared by every proxied location below. A location that sets any
+    # proxy_set_header of its own replaces this whole set instead of adding to
+    # it, which is why the Vouch-protected location repeats them.
+    proxy_set_header Host $host;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    proxy_set_header X-Forwarded-Proto $scheme;
+    proxy_set_header Upgrade $http_upgrade;
+    proxy_set_header Connection "upgrade";
+
+    proxy_http_version 1.1;
+    proxy_redirect     off;
+
+    # disable buffering uploads to prevent OOM on reverse proxy server and make uploads twice as fast (no pause)
+    proxy_request_buffering off;
+
+    # set timeout
+    proxy_read_timeout 600s;
+    proxy_send_timeout 600s;
+    send_timeout       600s;
+
     location = /validate {
         proxy_pass http://127.0.0.1:30021/validate;
         proxy_set_header Host $http_host;
@@ -39,48 +64,48 @@ server {
         return 302 https://auth.tiredsysadmin.cc/login?url=$scheme://$http_host$request_uri&vouch-failcount=$auth_resp_failcount&X-Vouch-Token=$auth_resp_jwt&error=$auth_resp_err;
     }
 
+    # The web interface, behind Vouch.
     location / {
         auth_request /validate;
         proxy_set_header X-Vouch-User $auth_resp_x_vouch_user;
-        proxy_pass http://10.200.1.3:32970;
-
         proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
         proxy_set_header X-Forwarded-Proto $scheme;
+        proxy_set_header Upgrade $http_upgrade;
+        proxy_set_header Connection "upgrade";
 
-        proxy_http_version 1.1;
+        proxy_pass http://keeporg;
-        proxy_redirect     off;
-
-        # disable buffering uploads to prevent OOM on reverse proxy server and make uploads twice as fast (no pause)
-        proxy_request_buffering off;
-
-        # set timeout
-        proxy_read_timeout 600s;
-        proxy_send_timeout 600s;
-        send_timeout       600s;
-        proxy_set_header   Upgrade    $http_upgrade;
-        proxy_set_header   Connection "upgrade";
     }
+
+    # Desktop and Android clients, which authenticate to KeepOrg itself with a
+    # bearer token. Sending them to a Vouch login page would break sync.
     location /api {
-        proxy_pass http://10.200.1.3:32970;
+        proxy_pass http://keeporg;
+    }
 
-        proxy_set_header Host $host;
+    # Paths that have to work for somebody who has no Vouch account, or no
-        proxy_set_header X-Real-IP $remote_addr;
+    # account at all. KeepOrg authenticates each of them itself.
-        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    #
-        proxy_set_header X-Forwarded-Proto $scheme;
+    #   /healthz   uptime and container checks, unauthenticated by design
+    #   /invite/   the invited person is signing up; an account is what they
+    #              have come here to create
+    #   /oidc/     the identity provider redirects back with a single-use
+    #              authorization code, which a second login round trip spends
+    #   /device    a client device being approved from a browser
+    location = /healthz {
+        proxy_pass http://keeporg;
+    }
 
-        proxy_http_version 1.1;
+    location /invite/ {
-        proxy_redirect     off;
+        proxy_pass http://keeporg;
+    }
 
-        # disable buffering uploads to prevent OOM on reverse proxy server and make uploads twice as fast (no pause)
+    location /oidc/ {
-        proxy_request_buffering off;
+        proxy_pass http://keeporg;
+    }
 
-        # set timeout
+    location = /device {
-        proxy_read_timeout 600s;
+        proxy_pass http://keeporg;
-        proxy_send_timeout 600s;
-        send_timeout       600s;
-        proxy_set_header   Upgrade    $http_upgrade;
-        proxy_set_header   Connection "upgrade";
     }
 }