Hacker News Reader

Comment by chrxr | Hacker News Reader

I'm always interested to know how long these infrastructure changes took from project initiation to launch, and whether it was a dedicated project team or something completed alongside BAU tasks.

These details are almost never included in these write-ups. Anyone have any guesses?

View on HN

This was a roughly six month project for a single engineer working around 75% of the time on it, with help from other folks along the way for code reviews and etc. The first three months was research, planning, implementation, etc and the latter three months was a very careful roll out and migration from the old system to the new and finally decommissioning the old system.

I noticed PowerDNS in the mix, can you say what backend you are using with PowerDNS and how that has been?

We use the mysql backend and http API, a few small nits but for our purposes it has worked very well thus far. Note that our authorities never see production traffic outside of AXFRs from our "edge" hosts so I can't say how well it works for other use cases.

Thanks!

What's the reason you've chosen MySQL over the bind backend when you are using the API anyways? I have to make a similar decision soon and I am not really sure yet, any insight would be appreciated.

Full access (read and write) to the PowerDNS HTTP API requires one of their generic SQL backends (via https://docs.powerdns.com/md/httpapi/README/), such as MySQL. The bind backend only supports reading from the API, changes to zones would need to be done on the file system and/or using pdns_control. Beyond that having all our records queryable via SQL has been nice for debugging and researching our own DNS records, types and etc. Lastly, backends like the MySQL one allow for things like auto generating serials and adding comments to the DNS data.

PowerDNS developer here - any nits we should know about?

Thanks very much for the reply. Very useful. I think these kinds of details really help people in other organizations who might want to undertake similar projects.

Do queries to github.net stay internal or do you also sync github.net zones to Route53/Dynect ... just in case?

We have a similar setup with unbound and nsd (no need for powerdns for us). Even then it took a while to get it right because JVM apps especially love to hang for no reason doing NS lookups. You also need to specify -Dnetworkaddress.cache.ttl= etc since they don't listen to TTLs.

Running unbound on every single machine has saved us a lot of downtime.

Nearly all of our internal zones are internal and not sync'd to an external provider. In a few cases we need to perform lookups of internal zones external to our network and those zones live both internal and external.

Do you still run a local caching DNS daemon on every server? If not, why the change?

Yes, we still use local caches on each host.

Reply on news.ycombinator.com