Open Source Load Balancers

CoreDNS is a DNS server/forwarder, written in Go, that chains plugins. Each plugin performs a (DNS) function. CoreDNS is a Cloud Native Computing Foundation graduated project. CoreDNS is a fast and flexible DNS server. The key word here is flexible: with CoreDNS you are able to do what you want with your DNS data by utilizing plugins. If some functionality is not provided out of the box you can add it by writing a plugin. CoreDNS can listen for DNS requests coming in over UDP/TCP (go'old DNS), TLS (RFC 7858), also called DoT, DNS over HTTP/2 - DoH - (RFC 8484) and gRPC (not a standard). Serve zone data from a file; both DNSSEC (NSEC only) and DNS are supported (file and auto). Retrieve zone data from primaries, i.e., act as a secondary server (AXFR only) (secondary). Sign zone data on-the-fly (dnssec). Load balancing of responses (loadbalance). Allow for zone transfers, i.e., act as a primary server (file + transfer). Automatically load zone files from disk (auto).

It is a versatile DNS Proxy server with DNS firewall which filters DNS traffic between local computer and DNS servers with flexible rules, supports blocking by IP geography, caching, import/export rules into XML. With a click of a button acts as a DNS proxy (or DNS server), supports multiple client authentication methods, calculates statistics for DNS servers and proxy clients, supports load balancing between multiple upstream DNS servers.

Eddie acts as a high availability WAN and LAN clustering tool for web servers (including Apache). It provides load balancing at two levels (DNS and LAN), failover redundancy, and admission control to maintain quality of service levels.

ExternalDNS synchronizes exposed Kubernetes Services and Ingresses with DNS providers. Inspired by Kubernetes DNS, Kubernetes' cluster-internal DNS server, ExternalDNS makes Kubernetes resources discoverable via public DNS servers. Like KubeDNS, it retrieves a list of resources (Services, Ingresses, etc.) from the Kubernetes API to determine the desired list of DNS records. Unlike KubeDNS, however, it's not a DNS server itself, but merely configures other DNS providers accordingly, e.g. AWS Route 53 or Google Cloud DNS. In a broader sense, ExternalDNS allows you to control DNS records dynamically via Kubernetes resources in a DNS provider-agnostic way. ExternalDNS' allows you to keep selected zones (via domain-filter) synchronized with Ingresses and Services of type=LoadBalancer in various cloud providers. ExternalDNS can become aware of the records it is managing therefore ExternalDNS can safely manage non-empty hosted zones.