Co-authored-by: Ashvitha Sridharan <ashvitha.sridharan@hashicorp.com>
Co-authored-by: Freddy <freddygv@users.noreply.github.com>
Add a new envoy flag: "envoy_hcp_metrics_bind_socket_dir", a directory
where a unix socket will be created with the name
`<namespace>_<proxy_id>.sock` to forward Envoy metrics.
If set, this will configure:
- In bootstrap configuration a local stats_sink and static cluster.
These will forward metrics to a loopback listener sent over xDS.
- A dynamic listener listening at the socket path that the previously
defined static cluster is sending metrics to.
- A dynamic cluster that will forward traffic received at this listener
to the hcp-metrics-collector service.
Reasons for having a static cluster pointing at a dynamic listener:
- We want to secure the metrics stream using TLS, but the stats sink can
only be defined in bootstrap config. With dynamic listeners/clusters
we can use the proxy's leaf certificate issued by the Connect CA,
which isn't available at bootstrap time.
- We want to intelligently route to the HCP collector. Configuring its
addreess at bootstrap time limits our flexibility routing-wise. More
on this below.
Reasons for defining the collector as an upstream in `proxycfg`:
- The HCP collector will be deployed as a mesh service.
- Certificate management is taken care of, as mentioned above.
- Service discovery and routing logic is automatically taken care of,
meaning that no code changes are required in the xds package.
- Custom routing rules can be added for the collector using discovery
chain config entries. Initially the collector is expected to be
deployed to each admin partition, but in the future could be deployed
centrally in the default partition. These config entries could even be
managed by HCP itself.
* Leverage ServiceResolver ConnectTimeout for route timeouts to make TerminatingGateway upstream timeouts configurable
* Regenerate golden files
* Add RequestTimeout field
* Add changelog entry
Protobuf Refactoring for Multi-Module Cleanliness
This commit includes the following:
Moves all packages that were within proto/ to proto/private
Rewrites imports to account for the packages being moved
Adds in buf.work.yaml to enable buf workspaces
Names the proto-public buf module so that we can override the Go package imports within proto/buf.yaml
Bumps the buf version dependency to 1.14.0 (I was trying out the version to see if it would get around an issue - it didn't but it also doesn't break things and it seemed best to keep up with the toolchain changes)
Why:
In the future we will need to consume other protobuf dependencies such as the Google HTTP annotations for openapi generation or grpc-gateway usage.
There were some recent changes to have our own ratelimiting annotations.
The two combined were not working when I was trying to use them together (attempting to rebase another branch)
Buf workspaces should be the solution to the problem
Buf workspaces means that each module will have generated Go code that embeds proto file names relative to the proto dir and not the top level repo root.
This resulted in proto file name conflicts in the Go global protobuf type registry.
The solution to that was to add in a private/ directory into the path within the proto/ directory.
That then required rewriting all the imports.
Is this safe?
AFAICT yes
The gRPC wire protocol doesn't seem to care about the proto file names (although the Go grpc code does tack on the proto file name as Metadata in the ServiceDesc)
Other than imports, there were no changes to any generated code as a result of this.
* Include secret type when building resources from config snapshot
* First pass at generating envoy secrets from api-gateway snapshot
* Update comments for xDS update order
* Add secret type + corresponding golden files to existing tests
* Initialize test helpers for testing api-gateway resource generation
* Generate golden files for new api-gateway xDS resource test
* Support ADS for TLS certificates on api-gateway
* Configure TLS on api-gateway listeners
* Inline TLS cert code
* update tests
* Add SNI support so we can have multiple certificates
* Remove commented out section from helper
* regen deep-copy
* Add tcp tls test
---------
Co-authored-by: Nathan Coleman <nathan.coleman@hashicorp.com>
* Simple API Gateway e2e test for tcp routes
* Drop DNSSans since we don't front the Gateway with a leaf cert
* WIP listener tests for api-gateway
* Return early if no routes
* Add back in leaf cert to testing
* Fix merge conflicts
* Re-add kind to setup
* Fix iteration over listener upstreams
* New tcp listener test
* Add tests for API Gateway with TCP and HTTP routes
* Move zero-route check back
* Drop generateIngressDNSSANs
* Check for chains not routes
---------
Co-authored-by: Andrew Stucki <andrew.stucki@hashicorp.com>
Fix mesh gateways incorrectly matching peer locality.
This fixes an issue where local mesh gateways use an
incorrect address when attempting to forward traffic to a
peered datacenter. Prior to this change it would use the
lan address instead of the wan if the locality matched. This
should never be done for peering, since we must route all
traffic through the remote mesh gateway.
* Stub proxycfg handler for API gateway
* Add Service Kind constants/handling for API Gateway
* Begin stubbing for SDS
* Add new Secret type to xDS order of operations
* Continue stubbing of SDS
* Iterate on proxycfg handler for API gateway
* Handle BoundAPIGateway config entry subscription in proxycfg-glue
* Add API gateway to config snapshot validation
* Add API gateway to config snapshot clone, leaf, etc.
* Subscribe to bound route + cert config entries on bound-api-gateway
* Track routes + certs on API gateway config snapshot
* Generate DeepCopy() for types used in watch.Map
* Watch all active references on api-gateway, unwatch inactive
* Track loading of initial bound-api-gateway config entry
* Use proper proto package for SDS mapping
* Use ResourceReference instead of ServiceName, collect resources
* Fix typo, add + remove TODOs
* Watch discovery chains for TCPRoute
* Add TODO for updating gateway services for api-gateway
* make proto
* Regenerate deep-copy for proxycfg
* Set datacenter on upstream ID from query source
* Watch discovery chains for http-route service backends
* Add ServiceName getter to HTTP+TCP Service structs
* Clean up unwatched discovery chains on API Gateway
* Implement watch for ingress leaf certificate
* Collect upstreams on http-route + tcp-route updates
* Remove unused GatewayServices update handler
* Remove unnecessary gateway services logic for API Gateway
* Remove outdate TODO
* Use .ToIngress where appropriate, including TODO for cleaning up
* Cancel before returning error
* Remove GatewayServices subscription
* Add godoc for handlerAPIGateway functions
* Update terminology from Connect => Consul Service Mesh
Consistent with terminology changes in https://github.com/hashicorp/consul/pull/12690
* Add missing TODO
* Remove duplicate switch case
* Rerun deep-copy generator
* Use correct property on config snapshot
* Remove unnecessary leaf cert watch
* Clean up based on code review feedback
* Note handler properties that are initialized but set elsewhere
* Add TODO for moving helper func into structs pkg
* Update generated DeepCopy code
* gofmt
* Begin stubbing for SDS
* Start adding tests
* Remove second BoundAPIGateway case in glue
* TO BE PICKED: fix formatting of str
* WIP
* Fix merge conflict
* Implement HTTP Route to Discovery Chain config entries
* Stub out function to create discovery chain
* Add discovery chain merging code (#16131)
* Test adding TCP and HTTP routes
* Add some tests for the synthesizer
* Run go mod tidy
* Pairing with N8
* Run deep copy
* Clean up GatewayChainSynthesizer
* Fix missing assignment of BoundAPIGateway topic
* Separate out synthesizeChains and toIngressTLS
* Fix build errors
* Ensure synthesizer skips non-matching routes by protocol
* Rebase on N8s work
* Generate DeepCopy() for API gateway listener types
* Improve variable name
* Regenerate DeepCopy() code
* Fix linting issue
* fix protobuf import
* Fix more merge conflict errors
* Fix synthesize test
* Run deep copy
* Add URLRewrite to proto
* Update agent/consul/discoverychain/gateway_tcproute.go
Co-authored-by: Nathan Coleman <nathan.coleman@hashicorp.com>
* Remove APIGatewayConfigEntry that was extra
* Error out if route kind is unknown
* Fix formatting errors in proto
---------
Co-authored-by: Nathan Coleman <nathan.coleman@hashicorp.com>
Co-authored-by: Andrew Stucki <andrew.stucki@hashicorp.com>
* Stub proxycfg handler for API gateway
* Add Service Kind constants/handling for API Gateway
* Begin stubbing for SDS
* Add new Secret type to xDS order of operations
* Continue stubbing of SDS
* Iterate on proxycfg handler for API gateway
* Handle BoundAPIGateway config entry subscription in proxycfg-glue
* Add API gateway to config snapshot validation
* Add API gateway to config snapshot clone, leaf, etc.
* Subscribe to bound route + cert config entries on bound-api-gateway
* Track routes + certs on API gateway config snapshot
* Generate DeepCopy() for types used in watch.Map
* Watch all active references on api-gateway, unwatch inactive
* Track loading of initial bound-api-gateway config entry
* Use proper proto package for SDS mapping
* Use ResourceReference instead of ServiceName, collect resources
* Fix typo, add + remove TODOs
* Watch discovery chains for TCPRoute
* Add TODO for updating gateway services for api-gateway
* make proto
* Regenerate deep-copy for proxycfg
* Set datacenter on upstream ID from query source
* Watch discovery chains for http-route service backends
* Add ServiceName getter to HTTP+TCP Service structs
* Clean up unwatched discovery chains on API Gateway
* Implement watch for ingress leaf certificate
* Collect upstreams on http-route + tcp-route updates
* Remove unused GatewayServices update handler
* Remove unnecessary gateway services logic for API Gateway
* Remove outdate TODO
* Use .ToIngress where appropriate, including TODO for cleaning up
* Cancel before returning error
* Remove GatewayServices subscription
* Add godoc for handlerAPIGateway functions
* Update terminology from Connect => Consul Service Mesh
Consistent with terminology changes in https://github.com/hashicorp/consul/pull/12690
* Add missing TODO
* Remove duplicate switch case
* Rerun deep-copy generator
* Use correct property on config snapshot
* Remove unnecessary leaf cert watch
* Clean up based on code review feedback
* Note handler properties that are initialized but set elsewhere
* Add TODO for moving helper func into structs pkg
* Update generated DeepCopy code
* gofmt
* Generate DeepCopy() for API gateway listener types
* Improve variable name
* Regenerate DeepCopy() code
* Fix linting issue
* Temporarily remove the secret type from resource generation
* remove legacy tokens
* remove lingering legacy token references from docs
* update language and naming for token secrets and accessor IDs
* updates all tokenID references to clarify accessorID
* remove token type references and lookup tokens by accessorID index
* remove unnecessary constants
* replace additional tokenID param names
* Add warning info for deprecated -id parameter
Co-authored-by: Paul Glass <pglass@hashicorp.com>
* Update field comment
Co-authored-by: Paul Glass <pglass@hashicorp.com>
---------
Co-authored-by: Paul Glass <pglass@hashicorp.com>
Ensure nothing in the troubleshoot go module depends on consul's top level module. This is so we can import troubleshoot into consul-k8s and not import all of consul.
* turns troubleshoot into a go module [authored by @curtbushko]
* gets the envoy protos into the troubleshoot module [authored by @curtbushko]
* adds a new go module `envoyextensions` which has xdscommon and extensioncommon folders that both the xds package and the troubleshoot package can import
* adds testing and linting for the new go modules
* moves the unit tests in `troubleshoot/validateupstream` that depend on proxycfg/xds into the xds package, with a comment describing why those tests cannot be in the troubleshoot package
* fixes all the imports everywhere as a result of these changes
Co-authored-by: Curt Bushko <cbushko@gmail.com>
* Add Peer field to service-defaults upstream overrides.
* add api changes, compat mode for service default overrides
* Fixes based on testing
---------
Co-authored-by: DanStough <dan.stough@hashicorp.com>
* Add Tproxy support to Envoy Extensions (this is needed for service to service validation)
* Add validation for Envoy configuration for an upstream service
* Use both /config_dump and /cluster to validate Envoy configuration
This is because of a bug in Envoy where the EndpointsConfigDump does not
include a cluster_name, making it impossible to match an endpoint to
verify it exists.
This removes endpoints support for builtin extensions since only the
validate plugin was using it, and it is no longer used. It also removes
test cases for endpoint validation. Endpoints validation now only occurs
in the top level test from config_dump and clusters json files.
Co-authored-by: Eric <eric@haberkorn.co>
* updated builtin extension to parse region directly from ARN
- added a unit test
- added some comments/light refactoring
* updated golden files with proper ARNs
- ARNs need to be right format now that they are being processed
* updated tests and integration tests
- removed 'region' from all EnvoyExtension arguments
- added properly formatted ARN which includes the same region found in the removed "Region" field: 'us-east-1'
Fix configuration merging for implicit tproxy upstreams.
Change the merging logic so that the wildcard upstream has correct proxy-defaults
and service-defaults values combined into it. It did not previously merge all fields,
and the wildcard upstream did not exist unless service-defaults existed (it ignored
proxy-defaults, essentially).
Change the way we fetch upstream configuration in the xDS layer so that it falls back
to the wildcard when no matching upstream is found. This is what allows implicit peer
upstreams to have the correct "merged" config.
Change proxycfg to always watch local mesh gateway endpoints whenever a peer upstream
is found. This simplifies the logic so that we do not have to inspect the "merged"
configuration on peer upstreams to extract the mesh gateway mode.
Previously, we'd begin a session with the xDS concurrency limiter
regardless of whether the proxy was registered in the catalog or in
the server's local agent state.
This caused problems for users who run `consul connect envoy` directly
against a server rather than a client agent, as the server's locally
registered proxies wouldn't be included in the limiter's capacity.
Now, the `ConfigSource` is responsible for beginning the session and we
only do so for services in the catalog.
Fixes: https://github.com/hashicorp/consul/issues/15753
* Protobuf Modernization
Remove direct usage of golang/protobuf in favor of google.golang.org/protobuf
Marshallers (protobuf and json) needed some changes to account for different APIs.
Moved to using the google.golang.org/protobuf/types/known/* for the well known types including replacing some custom Struct manipulation with whats available in the structpb well known type package.
This also updates our devtools script to install protoc-gen-go from the right location so that files it generates conform to the correct interfaces.
* Fix go-mod-tidy make target to work on all modules
This gets the extensions information for the local service into the snapshot and ExtensionConfigurations for a proxy. It grabs the extensions from config entries and puts them in structs.NodeService.Proxy field, which already is copied into the config snapshot.
Also:
* add EnvoyExtensions to api.AgentService so that it matches structs.NodeService
* extensions: refactor PluginConfiguration into a more generic type
ExtensionConfiguration
Also:
* adds endpoints configuration to lambda golden tests
* uses string constant for builtin/aws/lambda
Co-authored-by: Eric <eric@haberkorn.co>
* add functions for returning the max and min Envoy major versions
- added an UnsupportedEnvoyVersions list
- removed an unused error from TestDetermineSupportedProxyFeaturesFromString
- modified minSupportedVersion to use the function for getting the Min Envoy major version. Using just the major version without the patch is equivalent to using `.0`
* added a function for executing the envoy --version command
- added a new exec.go file to not be locked to unix system
* added envoy version check when using consul connect envoy
* added changelog entry
* added docs change
* feat(ingress-gateway): support outlier detection of upstream service for ingress gateway
* changelog
Co-authored-by: Eric Haberkorn <erichaberkorn@gmail.com>
* integ-test: fix flaky test - case-cfg-splitter-peering-ingress-gateways
* add retry peering to all peering cases
Co-authored-by: Dan Stough <dan.stough@hashicorp.com>
Fix local mesh gateway with peering discovery chains.
Prior to this patch, discovery chains with peers would not
properly honor the mesh gateway mode for two reasons.
1. An incorrect target upstream ID was used to lookup the
mesh gateway mode. To fix this, the parent upstream uid is
now used instead of the discovery-chain-target-uid to find
the intended mesh gateway mode.
2. The watch for local mesh gateways was never initialized
for discovery chains. To fix this, the discovery chains are
now scanned, and a local GW watch is spawned if: the mesh
gateway mode is local and the target is a peering connection.
* update go version to 1.18 for api and sdk, go mod tidy
* removes ioutil usage everywhere which was deprecated in go1.16 in favour of io and os packages. Also introduces a lint rule which forbids use of ioutil going forward.
Co-authored-by: R.B. Boyer <4903+rboyer@users.noreply.github.com>
* Fix mesh gateway proxy-defaults not affecting upstreams.
* Clarify distinction with upstream settings
Top-level mesh gateway mode in proxy-defaults and service-defaults gets
merged into NodeService.Proxy.MeshGateway, and only gets merged with
the mode attached to an an upstream in proxycfg/xds.
* Fix mgw mode usage for peered upstreams
There were a couple issues with how mgw mode was being handled for
peered upstreams.
For starters, mesh gateway mode from proxy-defaults
and the top-level of service-defaults gets stored in
NodeService.Proxy.MeshGateway, but the upstream watch for peered data
was only considering the mesh gateway config attached in
NodeService.Proxy.Upstreams[i]. This means that applying a mesh gateway
mode via global proxy-defaults or service-defaults on the downstream
would not have an effect.
Separately, transparent proxy watches for peered upstreams didn't
consider mesh gateway mode at all.
This commit addresses the first issue by ensuring that we overlay the
upstream config for peered upstreams as we do for non-peered. The second
issue is addressed by re-using setupWatchesForPeeredUpstream when
handling transparent proxy updates.
Note that for transparent proxies we do not yet support mesh gateway
mode per upstream, so the NodeService.Proxy.MeshGateway mode is used.
* Fix upstream mesh gateway mode handling in xds
This commit ensures that when determining the mesh gateway mode for
peered upstreams we consider the NodeService.Proxy.MeshGateway config as
a baseline.
In absense of this change, setting a mesh gateway mode via
proxy-defaults or the top-level of service-defaults will not have an
effect for peered upstreams.
* Merge service/proxy defaults in cfg resolver
Previously the mesh gateway mode for connect proxies would be
merged at three points:
1. On servers, in ComputeResolvedServiceConfig.
2. On clients, in MergeServiceConfig.
3. On clients, in proxycfg/xds.
The first merge returns a ServiceConfigResponse where there is a
top-level MeshGateway config from proxy/service-defaults, along with
per-upstream config.
The second merge combines per-upstream config specified at the service
instance with per-upstream config specified centrally.
The third merge combines the NodeService.Proxy.MeshGateway
config containing proxy/service-defaults data with the per-upstream
mode. This third merge is easy to miss, which led to peered upstreams
not considering the mesh gateway mode from proxy-defaults.
This commit removes the third merge, and ensures that all mesh gateway
config is available at the upstream. This way proxycfg/xds do not need
to do additional overlays.
* Ensure that proxy-defaults is considered in wc
Upstream defaults become a synthetic Upstream definition under a
wildcard key "*". Now that proxycfg/xds expect Upstream definitions to
have the final MeshGateway values, this commit ensures that values from
proxy-defaults/service-defaults are the default for this synthetic
upstream.
* Add changelog.
Co-authored-by: freddygv <freddy@hashicorp.com>
* Regenerate golden files.
* Backport from ENT: "Avoid race"
Original commit: 5006c8c858b0e332be95271ef9ba35122453315b
Original author: freddygv
* Backport from ENT: "chore: fix flake peerstream test"
Original commit: b74097e7135eca48cc289798c5739f9ef72c0cc8
Original author: DanStough
* ingress-gateways: don't log error when registering gateway
Previously, when an ingress gateway was registered without a
corresponding ingress gateway config entry, an error was logged
because the watch on the config entry returned a nil result.
This is expected so don't log an error.
* Configure Envoy alpn_protocols based on service protocol
* define alpnProtocols in a more standard way
* http2 protocol should be h2 only
* formatting
* add test for getAlpnProtocol()
* create changelog entry
* change scope is connect-proxy
* ignore errors on ParseProxyConfig; fixes linter
* add tests for grpc and http2 public listeners
* remove newlines from PR
* Add alpn_protocol configuration for ingress gateway
* Guard against nil tlsContext
* add ingress gateway w/ TLS tests for gRPC and HTTP2
* getAlpnProtocols: add TCP protocol test
* add tests for ingress gateway with grpc/http2 and per-listener TLS config
* add tests for ingress gateway with grpc/http2 and per-listener TLS config
* add Gateway level TLS config with mixed protocol listeners to validate ALPN
* update changelog to include ingress-gateway
* add http/1.1 to http2 ALPN
* go fmt
* fix test on custom-trace-listener
This commit adds the xDS resources needed for INBOUND traffic from peer
clusters:
- 1 filter chain for all inbound peering requests.
- 1 cluster for all inbound peering requests.
- 1 endpoint per voting server with the gRPC TLS port configured.
There is one filter chain and cluster because unlike with WAN
federation, peer clusters will not attempt to dial individual servers.
Peer clusters will only dial the local mesh gateway addresses.
* feat(ingress gateway: support configuring limits in ingress-gateway config entry
- a new Defaults field with max_connections, max_pending_connections, max_requests
is added to ingress gateway config entry
- new field max_connections, max_pending_connections, max_requests in
individual services to overwrite the value in Default
- added unit test and integration test
- updated doc
Co-authored-by: Chris S. Kim <ckim@hashicorp.com>
Co-authored-by: Jeff Boruszak <104028618+boruszak@users.noreply.github.com>
Co-authored-by: Dan Stough <dan.stough@hashicorp.com>
Routing peering control plane traffic through mesh gateways can be
enabled or disabled at runtime with the mesh config entry.
This commit updates proxycfg to add or cancel watches for local servers
depending on this central config.
Note that WAN federation over mesh gateways is determined by a service
metadata flag, and any updates to the gateway service registration will
force the creation of a new snapshot. If enabled, WAN-fed over mesh
gateways will trigger a local server watch on initialize().
Because of this we will only add/remove server watches if WAN federation
over mesh gateways is disabled.
Prior to #13244, connect proxies and gateways could only be configured by an
xDS session served by the local client agent.
In an upcoming release, it will be possible to deploy a Consul service mesh
without client agents. In this model, xDS sessions will be handled by the
servers themselves, which necessitates load-balancing to prevent a single
server from receiving a disproportionate amount of load and becoming
overwhelmed.
This introduces a simple form of load-balancing where Consul will attempt to
achieve an even spread of load (xDS sessions) between all healthy servers.
It does so by implementing a concurrent session limiter (limiter.SessionLimiter)
and adjusting the limit according to autopilot state and proxy service
registrations in the catalog.
If a server is already over capacity (i.e. the session limit is lowered),
Consul will begin draining sessions to rebalance the load. This will result
in the client receiving a `RESOURCE_EXHAUSTED` status code. It is the client's
responsibility to observe this response and reconnect to a different server.
Users of the gRPC client connection brokered by the
consul-server-connection-manager library will get this for free.
The rate at which Consul will drain sessions to rebalance load is scaled
dynamically based on the number of proxies in the catalog.
* draft commit
* add changelog, update test
* remove extra param
* fix test
* update type to account for nil value
* add test for custom passive health check
* update comments and tests
* update description in docs
* fix missing commas
This is the OSS portion of enterprise PR 2339.
It improves our handling of "irrecoverable" errors in proxycfg data sources.
The canonical example of this is what happens when the ACL token presented by
Envoy is deleted/revoked. Previously, the stream would get "stuck" until the
xDS server re-checked the token (after 5 minutes) and terminated the stream.
Materializers would also sit burning resources retrying something that could
never succeed.
Now, it is possible for data sources to mark errors as "terminal" which causes
the xDS stream to be closed immediately. Similarly, the submatview.Store will
evict materializers when it observes they have encountered such an error.
* add golden files
* add support to http in tgateway egress destination
* fix slice sorting to include both address and port when using server_names
* fix listener loop for http destination
* fix routes to generate a route per port and a virtualhost per port-address combination
* sort virtual hosts list to have a stable order
* extract redundant serviceNode
Now that peered upstreams can generate envoy resources (#13758), we need a way to disambiguate local from peered resources in our metrics. The key difference is that datacenter and partition will be replaced with peer, since in the context of peered resources partition is ambiguous (could refer to the partition in a remote cluster or one that exists locally). The partition and datacenter of the proxy will always be that of the source service.
Regexes were updated to make emitting datacenter and partition labels mutually exclusive with peer labels.
Listener filter names were updated to better match the existing regex.
Cluster names assigned to peered upstreams were updated to be synthesized from local peer name (it previously used the externally provided primary SNI, which contained the peer name from the other side of the peering). Integration tests were updated to assert for the new peer labels.
Peered upstreams has a separate loop in xds from discovery chain upstreams. This PR adds similar but slightly modified code to add filters for peered upstream listeners, clusters, and endpoints in the case of transparent proxy.
Previously, public referred to gRPC services that are both exposed on
the dedicated gRPC port and have their definitions in the proto-public
directory (so were considered usable by 3rd parties). Whereas private
referred to services on the multiplexed server port that are only usable
by agents and other servers.
Now, we're splitting these definitions, such that external/internal
refers to the port and public/private refers to whether they can be used
by 3rd parties.
This is necessary because the peering replication API needs to be
exposed on the dedicated port, but is not (yet) suitable for use by 3rd
parties.
Because peerings are pairwise, between two tuples of (datacenter,
partition) having any exported reference via a discovery chain that
crosses out of the peered datacenter or partition will ultimately not be
able to work for various reasons. The biggest one is that there is no
way in the ultimate destination to configure an intention that can allow
an external SpiffeID to access a service.
This PR ensures that a user simply cannot do this, so they won't run
into weird situations like this.
