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85457cf50d
Fix the error handling. Log when we have an error during any of the transfer state. And if there isn't an error transfer the zones. Also fix the tests in test/ so we, at least, check the initial transfer. Update the docs to show more about how errors are handled. Ref #1400
69 lines
2.0 KiB
Markdown
69 lines
2.0 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 ADDRESS...
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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` defines upstream resolvers to be used resolve external names found (think CNAMEs)
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pointing to external names. This is only really useful when CoreDNS is configured as a proxy, for
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normal authoritative serving you don't need *or* want to use this. **ADDRESS** can be an IP
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address, and IP:port or a string pointing to a file that is structured as /etc/resolv.conf.
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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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