This section summarizes steps required for upgrade to newer Knot Resolver versions. We advise users to also read Release notes for respective versions.

3.x to 4.x


  • DNSSEC validation is now turned on by default. If you need to disable it, see Trust anchors and DNSSEC.
  • -k/--keyfile and -K/--keyfile-ro daemon options were removed. If needed, use trust_anchors.add_file() in configuration file instead.
  • Configuration for HTTP module changed significantly as result of adding DNS-over-HTTP (DoH) support. Please see examples below.
  • In case you are using your own custom modules, move them to the new module location. The exact location depends on your distribution. Generally, modules previously in /usr/lib/kdns_modules should be moved to /usr/lib/knot-resolver/kres_modules.

Configuration file

  • trust_anchors.file, trust_anchors.config() and trust_anchors.negative aliases were removed to avoid duplicity and confusion. Migration table:

    3.x configuration 4.x configuration
    trust_anchors.file = path trust_anchors.add_file(path)
    trust_anchors.config(path, readonly) trust_anchors.add_file(path, readonly)
    trust_anchors.negative = nta_set trust_anchors.set_insecure(nta_set)
  • trust_anchors.keyfile_default is no longer accessible and is can be set only at compile time. To turn off DNSSEC, use trust_anchors.remove().

    3.x configuration 4.x configuration
    trust_anchors.keyfile_default = nil trust_anchors.remove('.')
  • Network for HTTP endpoints is now configured using same mechanism as for normal DNS enpoints, please refer to chapter Network configuration. Migration table:

    3.x configuration 4.x configuration
    modules = { http = { host = '', port = 443 }} see chapter Network configuration
    http.config({ host = '', port = 443 }) see chapter Network configuration
    modules = { http = { endpoints = ... }} see chapter How to expose custom services over HTTP
    http.config({ endpoints = ... }) see chapter How to expose custom services over HTTP

Packagers & Developers

  • Knot DNS >= 2.8 is required.
  • meson >= 0.46 and ninja is required.
  • meson build system is now used for compiling the project. For instructions, see the Building from sources. Packagers should pay attention to section Packaging for information about systemd unit files and trust anchors.
  • Embedding LMDB is no longer supported, lmdb is now required as an external dependency.
  • Trust anchors file from upstream is installed and used as default unless you override keyfile_default during build.

Module changes

  • Default module location has changed from {libdir}/kdns_modules to {libdir}/knot-resolver/kres_modules. Modules are now in the lua namespace kres_modules.*.
  • kr_straddr_split() API has changed.
  • C modules defining *_layer or *_props symbols need to use a different style, but it’s typically a trivial change. Instead of exporting the corresponding symbols, the module should assign pointers to its static structures inside its *_init() function. Example migration: bogus_log module.

2.x to 3.x


  • Module Static hints has option hints.use_nodata() enabled by default, which is what most users expect. Add hints.use_nodata(false) to your config to revert to the old behavior.
  • Modules cookie and version were removed. Please remove relevant configuration lines with modules.load() and modules = from configuration file.
  • Valid configuration must open cache using cache.open() or cache.size = before executing cache operations like cache.clear(). (Older versions were silently ignoring such cache operations.)

Packagers & Developers

  • Knot DNS >= 2.7.2 is required.

Module changes

  • API for Lua modules was refactored, please see Significant Lua API changes.
  • New layer was added: answer_finalize.
  • kr_request keeps ::qsource.packet beyond the begin layer.
  • kr_request::qsource.tcp renamed to ::qsource.flags.tcp.
  • kr_request::has_tls renamed to ::qsource.flags.tls.
  • kr_zonecut_add(), kr_zonecut_del() and kr_nsrep_sort() changed parameters slightly.