9c16ed1d14
* Default to upstream to self This is a backwards incompatible change. This is a massive (cleanup) PR where we default to resolving external names by the coredns process itself, instead of directly forwarding them to some upstream. This ignores any arguments `upstream` may have had and makes it depend on proxy/forward configuration in the Corefile. This allows resolved upstream names to be cached and we have better healthchecking of the upstreams. It also means there is only one way to resolve names, by either using the proxy or forward plugin. The proxy/forward lookup.go functions have been removed. This also lessen the dependency on proxy, meaning deprecating proxy will become easier. Some tests have been removed as well, or moved to the top-level test directory as they now require a full coredns process instead of just the plugin. For the etcd plugin, the entire StubZone resolving is *dropped*! This was a hacky (but working) solution to say the least. If someone cares deeply it can be brought back (maybe)? The pkg/upstream is now very small and almost does nothing. Also the New() function was changed to return a pointer to upstream.Upstream. It also returns only one parameter, so any stragglers using it will encounter a compile error. All documentation has been adapted. This affected the following plugins: * etcd * file * auto * secondary * federation * template * route53 A followup PR will make any upstream directives with arguments an error, right now they are ignored. Signed-off-by: Miek Gieben <miek@miek.nl> * Fix etcd build - probably still fails unit test Signed-off-by: Miek Gieben <miek@miek.nl> * Slightly smarter lookup check in upstream Signed-off-by: Miek Gieben <miek@miek.nl> * Compilez Signed-off-by: Miek Gieben <miek@miek.nl>
67 lines
1.8 KiB
Markdown
67 lines
1.8 KiB
Markdown
# secondary
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## Name
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*secondary* - enables serving a zone retrieved from a primary server.
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## Description
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With *secondary* you can transfer (via AXFR) a zone from another server. The retrieved zone is
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*not committed* to disk (a violation of the RFC). This means restarting CoreDNS will cause it to
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retrieve all secondary zones.
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~~~
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secondary [ZONES...]
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~~~
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* **ZONES** zones it should be authoritative for. If empty, the zones from the configuration block
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are used. Note that without a remote address to *get* the zone from, the above is not that useful.
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A working syntax would be:
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~~~
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secondary [zones...] {
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transfer from ADDRESS
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transfer to ADDRESS
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upstream
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}
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~~~
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* `transfer from` specifies from which address to fetch the zone. It can be specified multiple times;
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if one does not work, another will be tried.
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* `transfer to` can be enabled to allow this secondary zone to be transferred again.
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* `upstream` resolve external names found (think CNAMEs) pointing to external names. This is only
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really useful when CoreDNS is configured as a proxy; for normal authoritative serving you don't
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need *or* want to use this. CoreDNS will resolve CNAMEs against itself.
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When a zone is due to be refreshed (Refresh timer fires) a random jitter of 5 seconds is
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applied, before fetching. In the case of retry this will be 2 seconds. If there are any errors
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during the transfer the transfer fails; this will be logged.
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## Examples
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Transfer `example.org` from 10.0.1.1, and if that fails try 10.1.2.1.
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~~~ corefile
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example.org {
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secondary {
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transfer from 10.0.1.1
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transfer from 10.1.2.1
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}
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}
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~~~
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Or re-export the retrieved zone to other secondaries.
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~~~ corefile
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. {
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secondary example.net {
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transfer from 10.1.2.1
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transfer to *
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}
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}
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~~~
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## Bugs
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Only AXFR is supported and the retrieved zone is not committed to disk.
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