tailscale/cmd
Brad Fitzpatrick 88c2afd1e3 ipn/ipnlocal, net/dns*, util/cloudenv: specialize DNS config on Google Cloud
This does three things:

* If you're on GCP, it adds a *.internal DNS split route to the
  metadata server, so we never break GCP DNS names. This lets people
  have some Tailscale nodes on GCP and some not (e.g. laptops at home)
  without having to add a Tailnet-wide *.internal DNS route.
  If you already have such a route, though, it won't overwrite it.

* If the 100.100.100.100 DNS forwarder has nowhere to forward to,
  it forwards it to the GCP metadata IP, which forwards to 8.8.8.8.
  This means there are never errNoUpstreams ("upstream nameservers not set")
  errors on GCP due to e.g. mangled /etc/resolv.conf (GCP default VMs
  don't have systemd-resolved, so it's likely a DNS supremacy fight)

* makes the DNS fallback mechanism use the GCP metadata IP as a
  fallback before our hosted HTTP-based fallbacks

I created a default GCP VM from their web wizard. It has no
systemd-resolved.

I then made its /etc/resolv.conf be empty and deleted its GCP
hostnames in /etc/hosts.

I then logged in to a tailnet with no global DNS settings.

With this, tailscaled writes /etc/resolv.conf (direct mode, as no
systemd-resolved) and sets it to 100.100.100.100, which then has
regular DNS via the metadata IP and *.internal DNS via the metadata IP
as well. If the tailnet configures explicit DNS servers, those are used
instead, except for *.internal.

This also adds a new util/cloudenv package based on version/distro
where the cloud type is only detected once. We'll likely expand it in
the future for other clouds, doing variants of this change for other
popular cloud environments.

Fixes #4911

RELNOTES=Google Cloud DNS improvements

Change-Id: I19f3c2075983669b2b2c0f29a548da8de373c7cf
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2022-06-29 17:39:13 -07:00
..
addlicense cmd/addlicense: add command to add licenseheaders to generated code 2021-07-19 15:31:56 -07:00
cloner cmd/viewer: add codegen tool for Views 2022-05-06 10:58:10 -07:00
derper net/wsconn: remove homegrown wrapper for turning a websocket.Conn into a net.Conn 2022-06-07 09:28:56 -07:00
derpprobe all: use any instead of interface{} 2022-03-17 11:35:09 -07:00
gitops-pusher cmd/gitops-pusher: add new GitOps assistant (#4893) 2022-06-21 16:04:48 -04:00
hello all: use strings.Cut even more 2022-03-19 13:02:38 -07:00
mkpkg cmd/mkpkg: use package flag (#4373) 2022-04-07 16:38:33 -04:00
nginx-auth cmd/nginx-auth: maintainer scripts and tailnet checking (#4460) 2022-04-20 13:06:05 -04:00
printdep Docker: add ALPINE.txt to manage alpine versions 2022-06-29 11:47:09 -07:00
proxy-to-grafana client/tailscale: move/copy all package funcs to new LocalClient type 2022-04-29 13:57:52 -07:00
speedtest cmd: upgrade to ffcli v3 2021-09-14 13:21:55 -07:00
tailscale ipn/ipnlocal, net/dns*, util/cloudenv: specialize DNS config on Google Cloud 2022-06-29 17:39:13 -07:00
tailscaled ipn/ipnlocal, net/dns*, util/cloudenv: specialize DNS config on Google Cloud 2022-06-29 17:39:13 -07:00
testcontrol all: use any instead of interface{} 2022-03-17 11:35:09 -07:00
tsshd cmd/tsshd: delete, leaving only forwarding docs 2022-05-16 11:52:44 -07:00
viewer cmd/viewer,types/views: add support for views of maps 2022-05-09 19:49:31 -07:00