This is the OSS portion of enterprise PR 2141.
This commit provides a server-local implementation of the `proxycfg.Intentions`
interface that sources data from streaming events.
It adds events for the `service-intentions` config entry type, and then consumes
event streams (via materialized views) for the service's explicit intentions and
any applicable wildcard intentions, merging them into a single list of intentions.
An alternative approach I considered was to consume _all_ intention events (via
`SubjectWildcard`) and filter out the irrelevant ones. This would admittedly
remove some complexity in the `agent/proxycfg-glue` package but at the expense
of considerable overhead from waking potentially many thousands of connect
proxies every time any intention is updated.
For initial cluster peering TProxy support we consider all imported services of a partition to be potential upstreams.
We leverage the VirtualIP table because it stores plain service names (e.g. "api", not "api-sidecar-proxy").
Mesh gateways will now enable tcp connections with SNI names including peering information so that those connections may be proxied.
Note: this does not change the callers to use these mesh gateways.
Envoy's SPIFFE certificate validation extension allows for us to
validate against different root certificates depending on the trust
domain of the dialing proxy.
If there are any trust bundles from peers in the config snapshot then we
use the SPIFFE validator as the validation context, rather than the
usual TrustedCA.
The injected validation config includes the local root certificates as
well.
For mTLS to work between two proxies in peered clusters with different root CAs,
proxies need to configure their outbound listener to use different root certificates
for validation.
Up until peering was introduced proxies would only ever use one set of root certificates
to validate all mesh traffic, both inbound and outbound. Now an upstream proxy
may have a leaf certificate signed by a CA that's different from the dialing proxy's.
This PR makes changes to proxycfg and xds so that the upstream TLS validation
uses different root certificates depending on which cluster is being dialed.
This is the OSS portion of enterprise PRs 1904, 1905, 1906, 1907, 1949,
and 1971.
It replaces the proxycfg manager's direct dependency on the agent cache
with interfaces that will be implemented differently when serving xDS
sessions from a Consul server.
Chris S. Kim