For Kubernetes environments, the DNS caching concerns could be covered by using NodeLocal DNSCache [1]. I wonder if that gets configured by default in cloud provider managed k8s services?
-Lari 1 - https://kubernetes.io/docs/tasks/administer-cluster/nodelocaldns/ On 2023/12/13 13:16:45 Lari Hotari wrote: > +1 > > Before switching to Alpine completely, it would be worth running extensive > system tests in production-like environments. > > Alpine comes with musl, which makes the JVM behave slightly differently. > > One of the common DNS issues with Alpine was fixed in May 2023 with the > Alpine 3.18 release. Alpine finally got full DNS protocol support that > impacts usage when there are DNS responses larger than 512 bytes [1]. > > Alpine 3.18 comes with musl 1.2.4 with TCP fallback in the DNS resolver. The > official Kubernetes docs also contain the recommendation [2] to upgrade > Alpine to 3.18+ (newest is currently 3.19) on Kubernetes. I'm no longer > concerned about possible DNS resolution issues with Alpine. > > However, one remaining concern related to DNS is the lack of local DNS > caching in Alpine. In Pulsar, most of the DNS resolution happens with Netty's > DNS resolver that has caching. I'm not sure what the broader impact could be > when switching to Alpine that doesn't have DNS caching at the OS level. In > Kubernetes environments, most DNS lookups go through a lot of search domains > and it puts a lot of load on the DNS server unless clients do caching. It is > possible to have a local caching DNS server in Alpine [1], but that doesn't > seem to be very convenient. > > The third area where there are differences in musl is in malloc. It's hard to > know beforehand how the different malloc algorithm impacts the actual > resident memory (RSS) usage. Different malloc algorithms handle memory > fragmentation in different ways and there are behavioral differences. System > testing could help verify the actual impact. > > -Lari > > 1 - > https://bell-sw.com/blog/how-to-deal-with-alpine-dns-issues/#mcetoc_1gtd8v3lt2b > 2 - > https://kubernetes.io/docs/tasks/administer-cluster/dns-debugging-resolution/#known-issues > > On 2023/12/12 18:58:49 Matteo Merli wrote: > > Hello, > > > > I've created a new proposal to switch Pulsar base docker images from Ubuntu > > to Alpine Linux. > > > > Details and motivation in the PIP: > > https://github.com/apache/pulsar/pull/21716 > > > > Matteo > > > > -- > > Matteo Merli > > <mme...@apache.org> > > >
