b003d06003
* For caddy v1 in our org This RP changes all imports for caddyserver/caddy to coredns/caddy. This is the v1 code of caddy. For the coredns/caddy repo the following changes have been made: * anything not needed by us is deleted * all `telemetry` stuff is deleted * all its import paths are also changed to point to coredns/caddy * the v1 branch has been moved to the master branch * a v1.1.0 tag has been added to signal the latest release Signed-off-by: Miek Gieben <miek@miek.nl> * Fix imports Signed-off-by: Miek Gieben <miek@miek.nl> * Group coredns/caddy with out plugins Signed-off-by: Miek Gieben <miek@miek.nl> * remove this file Signed-off-by: Miek Gieben <miek@miek.nl> * Relax import ordering github.com/coredns is now also a coredns dep, this makes github.com/coredns/caddy fit more natural in the list. Signed-off-by: Miek Gieben <miek@miek.nl> * Fix final import Signed-off-by: Miek Gieben <miek@miek.nl> |
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| .. | ||
| autopath.go | ||
| autopath_test.go | ||
| cname.go | ||
| metrics.go | ||
| README.md | ||
| setup.go | ||
| setup_test.go | ||
autopath
Name
autopath - allows for server-side search path completion.
Description
If it sees a query that matches the first element of the configured search path, autopath will follow the chain of search path elements and return the first reply that is not NXDOMAIN. On any failures, the original reply is returned. Because autopath returns a reply for a name that wasn't the original question it will add a CNAME that points from the original name (with the search path element in it) to the name of this answer.
Note: There are several known issues. See section below.
Syntax
autopath [ZONE...] RESOLV-CONF
- ZONES zones autopath should be authoritative for.
- RESOLV-CONF points to a
resolv.conflike file or uses a special syntax to point to another plugin. For instance@kubernetes, will call out to the kubernetes plugin (for each query) to retrieve the search list it should use.
If a plugin implements the AutoPather interface then it can be used.
Metrics
If monitoring is enabled (via the prometheus plugin) then the following metric is exported:
coredns_autopath_success_total{server}- counter of successfully autopath-ed queries.
The server label is explained in the metrics plugin documentation.
Examples
autopath my-resolv.conf
Use my-resolv.conf as the file to get the search path from. This file only needs to have one line:
search domain1 domain2 ...
autopath @kubernetes
Use the search path dynamically retrieved from the kubernetes plugin.
Known Issues
In Kubernetes, autopath can derive the wrong namespace of a client Pod (and therefore wrong search path) in the following case. To properly build the search path of a client autopath needs to know the namespace of the a Pod making a DNS request. To do this, it relies on the kubernetes plugin's Pod cache to resolve the client's IP address to a Pod. The Pod cache is maintained by an API watch on Pods. When Pod IP assignments change, the Kubernetes API notifies CoreDNS via the API watch. However, that notification is not instantaneous. In the case that a Pod is deleted, and it's IP is immediately provisioned to a Pod in another namespace, and that new Pod make a DNS lookup before the API watch can notify CoreDNS of the change, autopath will resolve the IP to the previous Pod's namespace.
In Kubernetes, autopath is not compatible with Pods running from Windows nodes.
If the server side search ultimately results in a negative answer (e.g. NXDOMAIN), then the client will
fruitlessly search all paths manually, thus negating the autopath optimization.