Add a new tailcfg.NodeCapability (NodeAttrCacheNetworkMaps) to control whether
a node with support for caching network maps will attempt to do so. Update the
capability version to reflect this change (mainly as a safety measure, as the
control plane does not currently need to know about it).
Use the presence (or absence) of the node attribute to decide whether to create
and update a netmap cache for each profile. If caching is disabled, discard the
cached data; this allows us to use the presence of a cached netmap as an
indicator it should be used (unless explicitly overridden). Add a test that
verifies the attribute is respected. Reverse the sense of the environment knob
to be true by default, with an override to disable caching at the client
regardless what the node attribute says.
Move the creation/update of the netmap cache (when enabled) until after
successfully applying the network map, to reduce the possibility that we will
cache (and thus reuse after a restart) a network map that fails to correctly
configure the client.
Updates #12639
Change-Id: I1df4dd791fdb485c6472a9f741037db6ed20c47e
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
This commit is based on ff0978ab, and extends #18497 to connect network map
caching to the LocalBackend. As implemented, only "whole" netmap values are
stored, and we do not yet handle incremental updates. As-written, the feature must
be explicitly enabled via the TS_USE_CACHED_NETMAP envknob, and must be
considered experimental.
Updates #12639
Co-Authored-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Change-Id: I48a1e92facfbf7fb3a8e67cff7f2c9ab4ed62c83
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
