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ethanndicksonethanndickson
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chore: add generic DNS record for checking if Coder Connect is running (#17298)
Closes coder/internal#466 ``` $ dig -6 @fD60:627a:a42b::53 is.coder--connect--enabled--right--now.coder AAAA ; <<>> DiG 9.10.6 <<>> -6 @fD60:627a:a42b::53 is.coder--connect--enabled--right--now.coder AAAA ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62390 ;; flags: qr aa rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;is.coder--connect--enabled--right--now.coder. IN AAAA ;; ANSWER SECTION: is.coder--connect--enabled--right--now.coder. 2 IN AAAA fd60:627a:a42b::53 ;; Query time: 3 msec ;; SERVER: fd60:627a:a42b::53#53(fd60:627a:a42b::53) ;; WHEN: Wed Apr 09 16:59:18 AEST 2025 ;; MSG SIZE rcvd: 134 ``` Hostname considerations: - Workspace names, usernames, and agent names can't have double hyphens, so this name can't conflict with a real Coder Connect hostname. - Components can't start or end with hyphens according to [RFC 952](https://www.rfc-editor.org/rfc/rfc952.html) - DNS records can't have hyphens in the 3rd and 4th positions, as to not conflict with IDNs https://datatracker.ietf.org/doc/html/rfc5891
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+30
-16
lines changed

3 files changed

+30
-16
lines changed

‎tailnet/conn.go

+7
Original file line numberDiff line numberDiff line change
@@ -354,6 +354,13 @@ func NewConn(options *Options) (conn *Conn, err error) {
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return server, nil
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}
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357+
// A FQDN to be mapped to `tsaddr.CoderServiceIPv6`. This address can be used
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// when you want to know if Coder Connect is running, but are not trying to
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// connect to a specific known workspace.
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const IsCoderConnectEnabledFQDNString = "is.coder--connect--enabled--right--now.coder."
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var IsCoderConnectEnabledFQDN, _ = dnsname.ToFQDN(IsCoderConnectEnabledFQDNString)
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357364
type ServicePrefix [6]byte
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var (

‎tailnet/controllers.go

+2
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,7 @@ import (
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"golang.org/x/xerrors"
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"storj.io/drpc"
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"storj.io/drpc/drpcerr"
19+
"tailscale.com/net/tsaddr"
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"tailscale.com/tailcfg"
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"tailscale.com/util/dnsname"
2122

@@ -1265,6 +1266,7 @@ func (t *tunnelUpdater) updateDNSNamesLocked() map[dnsname.FQDN][]netip.Addr {
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}
12661267
}
12671268
}
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names[IsCoderConnectEnabledFQDN] = []netip.Addr{tsaddr.CoderServiceIPv6()}
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return names
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}
12701272

‎tailnet/controllers_test.go

+21-16
Original file line numberDiff line numberDiff line change
@@ -22,6 +22,7 @@ import (
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"google.golang.org/protobuf/types/known/timestamppb"
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"storj.io/drpc"
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"storj.io/drpc/drpcerr"
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"tailscale.com/net/tsaddr"
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"tailscale.com/tailcfg"
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"tailscale.com/types/key"
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"tailscale.com/util/dnsname"
@@ -1563,13 +1564,14 @@ func TestTunnelAllWorkspaceUpdatesController_Initial(t *testing.T) {
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// Also triggers setting DNS hosts
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expectedDNS := map[dnsname.FQDN][]netip.Addr{
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"w1a1.w1.me.coder.": {ws1a1IP},
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"w2a1.w2.me.coder.": {w2a1IP},
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"w2a2.w2.me.coder.": {w2a2IP},
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"w1a1.w1.testy.coder.": {ws1a1IP},
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"w2a1.w2.testy.coder.": {w2a1IP},
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"w2a2.w2.testy.coder.": {w2a2IP},
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"w1.coder.": {ws1a1IP},
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"w1a1.w1.me.coder.": {ws1a1IP},
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"w2a1.w2.me.coder.": {w2a1IP},
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"w2a2.w2.me.coder.": {w2a2IP},
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"w1a1.w1.testy.coder.": {ws1a1IP},
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"w2a1.w2.testy.coder.": {w2a1IP},
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"w2a2.w2.testy.coder.": {w2a2IP},
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"w1.coder.": {ws1a1IP},
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tailnet.IsCoderConnectEnabledFQDNString: {tsaddr.CoderServiceIPv6()},
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}
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dnsCall := testutil.RequireRecvCtx(ctx, t, fDNS.calls)
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require.Equal(t, expectedDNS, dnsCall.hosts)
@@ -1661,9 +1663,10 @@ func TestTunnelAllWorkspaceUpdatesController_DeleteAgent(t *testing.T) {
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// DNS for w1a1
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expectedDNS := map[dnsname.FQDN][]netip.Addr{
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"w1a1.w1.testy.coder.": {ws1a1IP},
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"w1a1.w1.me.coder.": {ws1a1IP},
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"w1.coder.": {ws1a1IP},
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"w1a1.w1.testy.coder.": {ws1a1IP},
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"w1a1.w1.me.coder.": {ws1a1IP},
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"w1.coder.": {ws1a1IP},
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tailnet.IsCoderConnectEnabledFQDNString: {tsaddr.CoderServiceIPv6()},
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}
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dnsCall := testutil.RequireRecvCtx(ctx, t, fDNS.calls)
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require.Equal(t, expectedDNS, dnsCall.hosts)
@@ -1716,9 +1719,10 @@ func TestTunnelAllWorkspaceUpdatesController_DeleteAgent(t *testing.T) {
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// DNS contains only w1a2
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expectedDNS = map[dnsname.FQDN][]netip.Addr{
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"w1a2.w1.testy.coder.": {ws1a2IP},
1720-
"w1a2.w1.me.coder.": {ws1a2IP},
1721-
"w1.coder.": {ws1a2IP},
1722+
"w1a2.w1.testy.coder.": {ws1a2IP},
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"w1a2.w1.me.coder.": {ws1a2IP},
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"w1.coder.": {ws1a2IP},
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tailnet.IsCoderConnectEnabledFQDNString: {tsaddr.CoderServiceIPv6()},
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}
17231727
dnsCall = testutil.RequireRecvCtx(ctx, t, fDNS.calls)
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require.Equal(t, expectedDNS, dnsCall.hosts)
@@ -1798,9 +1802,10 @@ func TestTunnelAllWorkspaceUpdatesController_DNSError(t *testing.T) {
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17991803
// DNS for w1a1
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expectedDNS := map[dnsname.FQDN][]netip.Addr{
1801-
"w1a1.w1.me.coder.": {ws1a1IP},
1802-
"w1a1.w1.testy.coder.": {ws1a1IP},
1803-
"w1.coder.": {ws1a1IP},
1805+
"w1a1.w1.me.coder.": {ws1a1IP},
1806+
"w1a1.w1.testy.coder.": {ws1a1IP},
1807+
"w1.coder.": {ws1a1IP},
1808+
tailnet.IsCoderConnectEnabledFQDNString: {tsaddr.CoderServiceIPv6()},
18041809
}
18051810
dnsCall := testutil.RequireRecvCtx(ctx, t, fDNS.calls)
18061811
require.Equal(t, expectedDNS, dnsCall.hosts)

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