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auth: support tagged nodes in tailscale_auth #130

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6ec2516
auth: support tagged nodes in tailscale_auth
ryantm Feb 11, 2026
09fbd64
auth: remove replit comment, always include tailscale_tags in metadata
ryantm Feb 11, 2026
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41 changes: 27 additions & 14 deletions auth.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@ package tscaddy
// auth.go contains the TailscaleAuth module and supporting logic.

import (
"fmt"
"net"
"net/http"
"reflect"
Expand Down Expand Up @@ -126,12 +125,18 @@ type tsnetListener interface {

// Authenticate authenticates the request and sets Tailscale user data on the caddy User object.
//
// This method will set the following user metadata:
// For regular (non-tagged) users, the following metadata is set:
// - tailscale_login: the user's login name without the domain
// - tailscale_user: the user's full login name
// - tailscale_name: the user's display name
// - tailscale_profile_picture: the user's profile picture URL
// - tailscale_tailnet: the user's tailnet name (if the user is not connecting to a shared node)
// - tailscale_tailnet: the user's tailnet name
//
// For tagged nodes, the following metadata is set:
// - tailscale_tags: comma-separated list of node tags (e.g. "tag:zergbot,tag:ci")
// - tailscale_tailnet: the tailnet name
//
// The user ID is set to the login name for regular users, or the first tag for tagged nodes.
func (ta Auth) Authenticate(w http.ResponseWriter, r *http.Request) (caddyauth.User, bool, error) {
user := caddyauth.User{}

Expand All @@ -145,25 +150,33 @@ func (ta Auth) Authenticate(w http.ResponseWriter, r *http.Request) (caddyauth.U
return user, false, err
}

if len(info.Node.Tags) != 0 {
return user, false, fmt.Errorf("node %s has tags", info.Node.Hostinfo.Hostname())
}

var tailnet string
if !info.Node.Hostinfo.ShareeNode() {
if s, found := strings.CutPrefix(info.Node.Name, info.Node.ComputedName+"."); found {
tailnet = strings.TrimSuffix(s, ".")
}
}

user.ID = info.UserProfile.LoginName
user.Metadata = map[string]string{
"tailscale_login": strings.Split(info.UserProfile.LoginName, "@")[0],
"tailscale_user": info.UserProfile.LoginName,
"tailscale_name": info.UserProfile.DisplayName,
"tailscale_profile_picture": info.UserProfile.ProfilePicURL,
"tailscale_tailnet": tailnet,
if len(info.Node.Tags) != 0 {
// Tagged node: expose tags as metadata for Caddy expression matching.
// user.ID is set to the first tag for convenient @matcher expressions.
user.ID = info.Node.Tags[0]
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@willnorris willnorris Feb 17, 2026

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I think this is the one part I'm uncertain about, and is largely what stalled #2 . We've never really decided how to identify tagged nodes, and I never felt comfortable just using the first tag.

Interestingly, in Tailscale Serve, we just don't populate identity headers at all. We probably don't need to go that far... a lot of these other headers are super useful, especially tags.

I wonder if it would break things if we just didn't populate user.ID at all in this case? I worry that this would be uncommon enough that downstream users may assume that it's always present. If we have to pick something, I think I'd prefer we use the device name, probably prefixed with device: to make clear that this is not a regular user.

user.Metadata = map[string]string{
"tailscale_tags": strings.Join(info.Node.Tags, ","),
"tailscale_tailnet": tailnet,
}
} else {
user.ID = info.UserProfile.LoginName
user.Metadata = map[string]string{
"tailscale_login": strings.Split(info.UserProfile.LoginName, "@")[0],
"tailscale_user": info.UserProfile.LoginName,
"tailscale_name": info.UserProfile.DisplayName,
"tailscale_profile_picture": info.UserProfile.ProfilePicURL,
"tailscale_tailnet": tailnet,
"tailscale_tags": "",
}
}

return user, true, nil
}

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