Fixes#8466
Since Consul 1.8.0 there was a bug in how ingress gateway protocol
compatibility was enforced. At the point in time that an ingress-gateway
config entry was modified the discovery chain for each upstream was
checked to ensure the ingress gateway protocol matched. Unfortunately
future modifications of other config entries were not validated against
existing ingress-gateway definitions, such as:
1. create tcp ingress-gateway pointing to 'api' (ok)
2. create service-defaults for 'api' setting protocol=http (worked, but not ok)
3. create service-splitter or service-router for 'api' (worked, but caused an agent panic)
If you were to do these in a different order, it would fail without a
crash:
1. create service-defaults for 'api' setting protocol=http (ok)
2. create service-splitter or service-router for 'api' (ok)
3. create tcp ingress-gateway pointing to 'api' (fail with message about
protocol mismatch)
This PR introduces the missing validation. The two new behaviors are:
1. create tcp ingress-gateway pointing to 'api' (ok)
2. (NEW) create service-defaults for 'api' setting protocol=http ("ok" for back compat)
3. (NEW) create service-splitter or service-router for 'api' (fail with
message about protocol mismatch)
In consideration for any existing users that may be inadvertently be
falling into item (2) above, that is now officiall a valid configuration
to be in. For anyone falling into item (3) above while you cannot use
the API to manufacture that scenario anymore, anyone that has old (now
bad) data will still be able to have the agent use them just enough to
generate a new agent/proxycfg error message rather than a panic.
Unfortunately we just don't have enough information to properly fix the
config entries.
Related changes:
- hard-fail the xDS connection attempt if the envoy version is known to be too old to be supported
- remove the RouterMatchSafeRegex proxy feature since all supported envoy versions have it
- stop using --max-obj-name-len (due to: envoyproxy/envoy#11740)
A port can be sent in the Host header as defined in the HTTP RFC, so we
take any hosts that we want to match traffic to and also add another
host with the listener port added.
Also fix an issue with envoy integration tests not running the
case-ingress-gateway-tls test.
Co-authored-by: Matt Keeler <mkeeler@users.noreply.github.com>
Currently when passing hostname clusters to Envoy, we set each service instance registered with Consul as an LbEndpoint for the cluster.
However, Envoy can only handle one per cluster:
[2020-06-04 18:32:34.094][1][warning][config] [source/common/config/grpc_subscription_impl.cc:87] gRPC config for type.googleapis.com/envoy.api.v2.Cluster rejected: Error adding/updating cluster(s) dc2.internal.ddd90499-9b47-91c5-4616-c0cbf0fc358a.consul: LOGICAL_DNS clusters must have a single locality_lb_endpoint and a single lb_endpoint, server.dc2.consul: LOGICAL_DNS clusters must have a single locality_lb_endpoint and a single lb_endpoint
Envoy is currently handling this gracefully by only picking one of the endpoints. However, we should avoid passing multiple to avoid these warning logs.
This PR:
* Ensures we only pass one endpoint, which is tied to one service instance.
* We prefer sending an endpoint which is marked as Healthy by Consul.
* If no endpoints are healthy we emit a warning and skip the cluster.
* If multiple unique hostnames are spread across service instances we emit a warning and let the user know which will be resolved.
Currently opaque config blocks (config entries, and CA provider config) are
modified by PatchSliceOfMaps, making it impossible for these opaque
config sections to contain slices of maps.
In order to fix this problem, any lazy-decoding of these blocks needs to support
weak decoding of []map[string]interface{} to a struct type before
PatchSliceOfMaps is replaces. This is necessary because these config
blobs are persisted, and during an upgrade an older version of Consul
could read one of the new configuration values, which would cause an error.
To support the upgrade path, this commit first introduces the new hooks
for weak decoding of []map[string]interface{} and uses them only in the
lazy-decode paths. That way, in a future release, new style
configuration will be supported by the older version of Consul.
This decode hook has a number of advantages:
1. It no longer panics. It allows mapstructure to report the error
2. It no longer requires the user to declare which fields are slices of
structs. It can deduce that information from the 'to' value.
3. It will make it possible to preserve opaque configuration, allowing
for structured opaque config.
Previously, we did not require the 'service-name.*' host header value
when on a single http service was exposed. However, this allows a user
to get into a situation where, if they add another service to the
listener, suddenly the previous service's traffic might not be routed
correctly. Thus, we always require the Host header, even if there is
only 1 service.
Also, we add the make the default domain matching more restrictive by
matching "service-name.ingress.*" by default. This lines up better with
the namespace case and more accurately matches the Consul DNS value we
expect people to use in this case.
The DNS resolution will be handled by Envoy and defaults to LOGICAL_DNS. This discovery type can be overridden on a per-gateway basis with the envoy_dns_discovery_type Gateway Option.
If a service contains an instance with a hostname as an address we set the Envoy cluster to use DNS as the discovery type rather than EDS. Since both mesh gateways and terminating gateways route to clusters using SNI, whenever there is a mix of hostnames and IP addresses associated with a service we use the hostname + CDS rather than the IPs + EDS.
Note that we detect hostnames by attempting to parse the service instance's address as an IP. If it is not a valid IP we assume it is a hostname.
* Standardize support for Tagged and BindAddresses in Ingress Gateways
This updates the TaggedAddresses and BindAddresses behavior for Ingress
to match Mesh/Terminating gateways. The `consul connect envoy` command
now also allows passing an address without a port for tagged/bind
addresses.
* Update command/connect/envoy/envoy.go
Co-authored-by: Freddy <freddygv@users.noreply.github.com>
* PR comments
* Check to see if address is an actual IP address
* Update agent/xds/listeners.go
Co-authored-by: Freddy <freddygv@users.noreply.github.com>
* fix whitespace
Co-authored-by: Chris Piraino <cpiraino@hashicorp.com>
Co-authored-by: Freddy <freddygv@users.noreply.github.com>
The usage was removed in 8e22d80e3550592a32144f2d1c84ebf6becb957b,
however it seems there may be a bug here because the cluster name
is not updated when the target changes.
Some of these problems are minor (unused vars), but others are real bugs (ignored errors).
Co-authored-by: Matt Keeler <mkeeler@users.noreply.github.com>
This is useful when updating an config entry with no services, and the
expected behavior is that envoy closes all listeners and clusters.
We also allow empty routes because ingress gateways name route
configurations based on the port of the listener, so it is important we
remove any stale routes. Then, if a new listener with an old port is
added, we will not have to deal with stale routes hanging around routing
to the wrong place.
Endpoints are associated with clusters, and thus by deleting the
clusters we don't have to care about sending empty endpoint responses.
- Validate that this cannot be set on a 'tcp' listener nor on a wildcard
service.
- Add Hosts field to api and test in consul config write CLI
- xds: Configure envoy with user-provided hosts from ingress gateways
This commit adds the necessary changes to allow an ingress gateway to
route traffic from a single defined port to multiple different upstream
services in the Consul mesh.
To do this, we now require all HTTP requests coming into the ingress
gateway to specify a Host header that matches "<service-name>.*" in
order to correctly route traffic to the correct service.
- Differentiate multiple listener's route names by port
- Adds a case in xds for allowing default discovery chains to create a
route configuration when on an ingress gateway. This allows default
services to easily use host header routing
- ingress-gateways have a single route config for each listener
that utilizes domain matching to route to different services.
This commit copies many of the connect-proxy xds testcases and reuses
for ingress gateways. This allows us to more easily see changes to the
envoy configuration when make updates to ingress gateways.
* Implements a simple, tcp ingress gateway workflow
This adds a new type of gateway for allowing Ingress traffic into Connect from external services.
Co-authored-by: Chris Piraino <cpiraino@hashicorp.com>
If a proxied service is a gRPC or HTTP2 service, but a path is exposed
using the HTTP1 or TCP protocol, Envoy should not be configured with
`http2ProtocolOptions` for the cluster backing the path.
A situation where this comes up is a gRPC service whose healthcheck or
metrics route (e.g. for Prometheus) is an HTTP1 service running on
a different port. Previously, if these were exposed either using
`Expose: { Checks: true }` or `Expose: { Paths: ... }`, Envoy would
still be configured to communicate with the path over HTTP2, which would
not work properly.
This is like a Möbius strip of code due to the fact that low-level components (serf/memberlist) are connected to high-level components (the catalog and mesh-gateways) in a twisty maze of references which make it hard to dive into. With that in mind here's a high level summary of what you'll find in the patch:
There are several distinct chunks of code that are affected:
* new flags and config options for the server
* retry join WAN is slightly different
* retry join code is shared to discover primary mesh gateways from secondary datacenters
* because retry join logic runs in the *agent* and the results of that
operation for primary mesh gateways are needed in the *server* there are
some methods like `RefreshPrimaryGatewayFallbackAddresses` that must occur
at multiple layers of abstraction just to pass the data down to the right
layer.
* new cache type `FederationStateListMeshGatewaysName` for use in `proxycfg/xds` layers
* the function signature for RPC dialing picked up a new required field (the
node name of the destination)
* several new RPCs for manipulating a FederationState object:
`FederationState:{Apply,Get,List,ListMeshGateways}`
* 3 read-only internal APIs for debugging use to invoke those RPCs from curl
* raft and fsm changes to persist these FederationStates
* replication for FederationStates as they are canonically stored in the
Primary and replicated to the Secondaries.
* a special derivative of anti-entropy that runs in secondaries to snapshot
their local mesh gateway `CheckServiceNodes` and sync them into their upstream
FederationState in the primary (this works in conjunction with the
replication to distribute addresses for all mesh gateways in all DCs to all
other DCs)
* a "gateway locator" convenience object to make use of this data to choose
the addresses of gateways to use for any given RPC or gossip operation to a
remote DC. This gets data from the "retry join" logic in the agent and also
directly calls into the FSM.
* RPC (`:8300`) on the server sniffs the first byte of a new connection to
determine if it's actually doing native TLS. If so it checks the ALPN header
for protocol determination (just like how the existing system uses the
type-byte marker).
* 2 new kinds of protocols are exclusively decoded via this native TLS
mechanism: one for ferrying "packet" operations (udp-like) from the gossip
layer and one for "stream" operations (tcp-like). The packet operations
re-use sockets (using length-prefixing) to cut down on TLS re-negotiation
overhead.
* the server instances specially wrap the `memberlist.NetTransport` when running
with gateway federation enabled (in a `wanfed.Transport`). The general gist is
that if it tries to dial a node in the SAME datacenter (deduced by looking
at the suffix of the node name) there is no change. If dialing a DIFFERENT
datacenter it is wrapped up in a TLS+ALPN blob and sent through some mesh
gateways to eventually end up in a server's :8300 port.
* a new flag when launching a mesh gateway via `consul connect envoy` to
indicate that the servers are to be exposed. This sets a special service
meta when registering the gateway into the catalog.
* `proxycfg/xds` notice this metadata blob to activate additional watches for
the FederationState objects as well as the location of all of the consul
servers in that datacenter.
* `xds:` if the extra metadata is in place additional clusters are defined in a
DC to bulk sink all traffic to another DC's gateways. For the current
datacenter we listen on a wildcard name (`server.<dc>.consul`) that load
balances all servers as well as one mini-cluster per node
(`<node>.server.<dc>.consul`)
* the `consul tls cert create` command got a new flag (`-node`) to help create
an additional SAN in certs that can be used with this flavor of federation.
* xDS Mesh Gateway Resolver Subset Fixes
The first fix was that clusters were being generated for every service resolver subset regardless of there being any service instances of the associated service in that dc. The previous logic didn’t care at all but now it will omit generating those clusters unless we also have service instances that should be proxied.
The second fix was to respect the DefaultSubset of a service resolver so that mesh-gateways would configure the endpoints of the unnamed subset cluster to only those endpoints matched by the default subsets filters.
* Refactor the gateway endpoint generation to be a little easier to read
* Adds 'limits' field to the upstream configuration of a connect proxy
This allows a user to configure the envoy connect proxy with
'max_connections', 'max_queued_requests', and 'max_concurrent_requests'. These
values are defined in the local proxy on a per-service instance basis
and should thus NOT be thought of as a global-level or even service-level value.
Main Changes:
• method signature updates everywhere to account for passing around enterprise meta.
• populate the EnterpriseAuthorizerContext for all ACL related authorizations.
• ACL resource listings now operate like the catalog or kv listings in that the returned entries are filtered down to what the token is allowed to see. With Namespaces its no longer all or nothing.
• Modified the acl.Policy parsing to abstract away basic decoding so that enterprise can do it slightly differently. Also updated method signatures so that when parsing a policy it can take extra ent metadata to use during rules validation and policy creation.
Secondary Changes:
• Moved protobuf encoding functions out of the agentpb package to eliminate circular dependencies.
• Added custom JSON unmarshalers for a few ACL resource types (to support snake case and to get rid of mapstructure)
• AuthMethod validator cache is now an interface as these will be cached per-namespace for Consul Enterprise.
• Added checks for policy/role link existence at the RPC API so we don’t push the request through raft to have it fail internally.
• Forward ACL token delete request to the primary datacenter when the secondary DC doesn’t have the token.
• Added a bunch of ACL test helpers for inserting ACL resource test data.
Previously the logic for configuring RDS during LDS for L7 upstreams was
overapplied to TCP proxies resulting in a cluster name of <emptystring>
being used incorrectly.
Fixes#6621
* ACL Authorizer overhaul
To account for upcoming features every Authorization function can now take an extra *acl.EnterpriseAuthorizerContext. These are unused in OSS and will always be nil.
Additionally the acl package has received some thorough refactoring to enable all of the extra Consul Enterprise specific authorizations including moving sentinel enforcement into the stubbed structs. The Authorizer funcs now return an acl.EnforcementDecision instead of a boolean. This improves the overall interface as it makes multiple Authorizers easily chainable as they now indicate whether they had an authoritative decision or should use some other defaults. A ChainedAuthorizer was added to handle this Authorizer enforcement chain and will never itself return a non-authoritative decision.
* Include stub for extra enterprise rules in the global management policy
* Allow for an upgrade of the global-management policy
Fixes: #5396
This PR adds a proxy configuration stanza called expose. These flags register
listeners in Connect sidecar proxies to allow requests to specific HTTP paths from outside of the node. This allows services to protect themselves by only
listening on the loopback interface, while still accepting traffic from non
Connect-enabled services.
Under expose there is a boolean checks flag that would automatically expose all
registered HTTP and gRPC check paths.
This stanza also accepts a paths list to expose individual paths. The primary
use case for this functionality would be to expose paths for third parties like
Prometheus or the kubelet.
Listeners for requests to exposed paths are be configured dynamically at run
time. Any time a proxy, or check can be registered, a listener can also be
created.
In this initial implementation requests to these paths are not
authenticated/encrypted.
- Bootstrap escape hatches are OK.
- Public listener/cluster escape hatches are OK.
- Upstream listener/cluster escape hatches are not supported.
If an unsupported escape hatch is configured and the discovery chain is
activated log a warning and act like it was not configured.
Fixes#6160
Compiling this will set an optional SNI field on each DiscoveryTarget.
When set this value should be used for TLS connections to the instances
of the target. If not set the default should be used.
Setting ExternalSNI will disable mesh gateway use for that target. It also
disables several service-resolver features that do not make sense for an
external service.
Since generated envoy clusters all are named using (mostly) SNI syntax
we can have envoy read the various fields out of that structure and emit
it as stats labels to the various telemetry backends.
I changed the delimiter for the 'customization hash' from ':' to '~'
because ':' is always reencoded by envoy as '_' when generating metrics
keys.
Failover is pushed entirely down to the data plane by creating envoy
clusters and putting each successive destination in a different load
assignment priority band. For example this shows that normally requests
go to 1.2.3.4:8080 but when that fails they go to 6.7.8.9:8080:
- name: foo
load_assignment:
cluster_name: foo
policy:
overprovisioning_factor: 100000
endpoints:
- priority: 0
lb_endpoints:
- endpoint:
address:
socket_address:
address: 1.2.3.4
port_value: 8080
- priority: 1
lb_endpoints:
- endpoint:
address:
socket_address:
address: 6.7.8.9
port_value: 8080
Mesh gateways route requests based solely on the SNI header tacked onto
the TLS layer. Envoy currently only lets you configure the outbound SNI
header at the cluster layer.
If you try to failover through a mesh gateway you ideally would
configure the SNI value per endpoint, but that's not possible in envoy
today.
This PR introduces a simpler way around the problem for now:
1. We identify any target of failover that will use mesh gateway mode local or
remote and then further isolate any resolver node in the compiled discovery
chain that has a failover destination set to one of those targets.
2. For each of these resolvers we will perform a small measurement of
comparative healths of the endpoints that come back from the health API for the
set of primary target and serial failover targets. We walk the list of targets
in order and if any endpoint is healthy we return that target, otherwise we
move on to the next target.
3. The CDS and EDS endpoints both perform the measurements in (2) for the
affected resolver nodes.
4. For CDS this measurement selects which TLS SNI field to use for the cluster
(note the cluster is always going to be named for the primary target)
5. For EDS this measurement selects which set of endpoints will populate the
cluster. Priority tiered failover is ignored.
One of the big downsides to this approach to failover is that the failover
detection and correction is going to be controlled by consul rather than
deferring that entirely to the data plane as with the prior version. This also
means that we are bound to only failover using official health signals and
cannot make use of data plane signals like outlier detection to affect
failover.
In this specific scenario the lack of data plane signals is ok because the
effectiveness is already muted by the fact that the ultimate destination
endpoints will have their data plane signals scrambled when they pass through
the mesh gateway wrapper anyway so we're not losing much.
Another related fix is that we now use the endpoint health from the
underlying service, not the health of the gateway (regardless of
failover mode).
In addition to exposing compilation over the API cleaned up the structures that would be exchanged to be cleaner and easier to support and understand.
Also removed ability to configure the envoy OverprovisioningFactor.
This should make them better for sending over RPC or the API.
Instead of a chain implemented explicitly like a linked list (nodes
holding pointers to other nodes) instead switch to a flat map of named
nodes with nodes linking other other nodes by name. The shipped
structure is just a map and a string to indicate which key to start
from.
Other changes:
* inline the compiler option InferDefaults as true
* introduce compiled target config to avoid needing to send back
additional maps of Resolvers; future target-specific compiled state
can go here
* move compiled MeshGateway out of the Resolver and into the
TargetConfig where it makes more sense.
* connect: reconcile how upstream configuration works with discovery chains
The following upstream config fields for connect sidecars sanely
integrate into discovery chain resolution:
- Destination Namespace/Datacenter: Compilation occurs locally but using
different default values for namespaces and datacenters. The xDS
clusters that are created are named as they normally would be.
- Mesh Gateway Mode (single upstream): If set this value overrides any
value computed for any resolver for the entire discovery chain. The xDS
clusters that are created may be named differently (see below).
- Mesh Gateway Mode (whole sidecar): If set this value overrides any
value computed for any resolver for the entire discovery chain. If this
is specifically overridden for a single upstream this value is ignored
in that case. The xDS clusters that are created may be named differently
(see below).
- Protocol (in opaque config): If set this value overrides the value
computed when evaluating the entire discovery chain. If the normal chain
would be TCP or if this override is set to TCP then the result is that
we explicitly disable L7 Routing and Splitting. The xDS clusters that
are created may be named differently (see below).
- Connect Timeout (in opaque config): If set this value overrides the
value for any resolver in the entire discovery chain. The xDS clusters
that are created may be named differently (see below).
If any of the above overrides affect the actual result of compiling the
discovery chain (i.e. "tcp" becomes "grpc" instead of being a no-op
override to "tcp") then the relevant parameters are hashed and provided
to the xDS layer as a prefix for use in naming the Clusters. This is to
ensure that if one Upstream discovery chain has no overrides and
tangentially needs a cluster named "api.default.XXX", and another
Upstream does have overrides for "api.default.XXX" that they won't
cross-pollinate against the operator's wishes.
Fixes#6159
The main change is that we no longer filter service instances by health,
preferring instead to render all results down into EDS endpoints in
envoy and merely label the endpoints as HEALTHY or UNHEALTHY.
When OnlyPassing is set to true we will force consul checks in a
'warning' state to render as UNHEALTHY in envoy.
Fixes#6171
* Make cluster names SNI always
* Update some tests
* Ensure we check for prepared query types
* Use sni for route cluster names
* Proper mesh gateway mode defaulting when the discovery chain is used
* Ignore service splits from PatchSliceOfMaps
* Update some xds golden files for proper test output
* Allow for grpc/http listeners/cluster configs with the disco chain
* Update stats expectation
* connect: allow overriding envoy listener bind_address
* Update agent/xds/config.go
Co-Authored-By: Kyle Havlovitz <kylehav@gmail.com>
* connect: allow overriding envoy listener bind_port
* envoy: support unix sockets for grpc in bootstrap
Add AgentSocket BootstrapTplArgs which if set overrides the AgentAddress
and AgentPort to generate a bootstrap which points Envoy to a unix
socket file instead of an ip:port.
* Add a test for passing the consul addr as a unix socket
* Fix config formatting for envoy bootstrap tests
* Fix listeners test cases for bind addr/port
* Update website/source/docs/connect/proxies/envoy.md
The clusters/endpoints test were still relying on deterministic ordering of clusters/endpoints which cannot be relied upon due to golang purposefully not providing any guarantee about consistent interation ordering of maps.
Also fixed a small bug in the connect proxy cluster generation that was causing the clusters slice to be double the size it needed to with the first half being all nil pointers.
* Upgrade xDS (go-control-plane) API to support Envoy 1.10.
This includes backwards compatibility shim to work around the ext_authz package rename in 1.10.
It also adds integration test support in CI for 1.10.0.
* Fix go vet complaints
* go mod vendor
* Update Envoy version info in docs
* Update website/source/docs/connect/proxies/envoy.md
* Add support for HTTP proxy listeners
* Add customizable bootstrap configuration options
* Debug logging for xDS AuthZ
* Add Envoy Integration test suite with basic test coverage
* Add envoy command tests to cover new cases
* Add tracing integration test
* Add gRPC support WIP
* Merged changes from master Docker. get CI integration to work with same Dockerfile now
* Make docker build optional for integration
* Enable integration tests again!
* http2 and grpc integration tests and fixes
* Fix up command config tests
* Store all container logs as artifacts in circle on fail
* Add retries to outer part of stats measurements as we keep missing them in CI
* Only dump logs on failing cases
* Fix typos from code review
* Review tidying and make tests pass again
* Add debug logs to exec test.
* Fix legit test failure caused by upstream rename in envoy config
* Attempt to reduce cases of bad TLS handshake in CI integration tests
* bring up the right service
* Add prometheus integration test
* Add test for denied AuthZ both HTTP and TCP
* Try ANSI term for Circle
* Connect: Fix Envoy getting stuck during load
Also in this PR:
- Enabled outlier detection on upstreams which will mark instances unhealthy after 5 failures (using Envoy's defaults)
- Enable weighted load balancing where DNS weights are configured
* Fix empty load assignments in the right place
* Fix import names from review
* Move millisecond parse to a helper function
* Start adding tests for cluster override
* Refactor tests for clusters
* Passing tests for custom upstream cluster override
* Added capability to customise local app cluster
* Rename config for local cluster override
For established xDS gRPC streams recheck ACLs for each DiscoveryRequest
or DiscoveryResponse. If more than 5 minutes has elapsed since the last
ACL check, recheck even without an incoming DiscoveryRequest or
DiscoveryResponse. ACL failures will terminate the stream.
This PR is almost a complete rewrite of the ACL system within Consul. It brings the features more in line with other HashiCorp products. Obviously there is quite a bit left to do here but most of it is related docs, testing and finishing the last few commands in the CLI. I will update the PR description and check off the todos as I finish them over the next few days/week.
Description
At a high level this PR is mainly to split ACL tokens from Policies and to split the concepts of Authorization from Identities. A lot of this PR is mostly just to support CRUD operations on ACLTokens and ACLPolicies. These in and of themselves are not particularly interesting. The bigger conceptual changes are in how tokens get resolved, how backwards compatibility is handled and the separation of policy from identity which could lead the way to allowing for alternative identity providers.
On the surface and with a new cluster the ACL system will look very similar to that of Nomads. Both have tokens and policies. Both have local tokens. The ACL management APIs for both are very similar. I even ripped off Nomad's ACL bootstrap resetting procedure. There are a few key differences though.
Nomad requires token and policy replication where Consul only requires policy replication with token replication being opt-in. In Consul local tokens only work with token replication being enabled though.
All policies in Nomad are globally applicable. In Consul all policies are stored and replicated globally but can be scoped to a subset of the datacenters. This allows for more granular access management.
Unlike Nomad, Consul has legacy baggage in the form of the original ACL system. The ramifications of this are:
A server running the new system must still support other clients using the legacy system.
A client running the new system must be able to use the legacy RPCs when the servers in its datacenter are running the legacy system.
The primary ACL DC's servers running in legacy mode needs to be a gate that keeps everything else in the entire multi-DC cluster running in legacy mode.
So not only does this PR implement the new ACL system but has a legacy mode built in for when the cluster isn't ready for new ACLs. Also detecting that new ACLs can be used is automatic and requires no configuration on the part of administrators. This process is detailed more in the "Transitioning from Legacy to New ACL Mode" section below.
* Plumb xDS server and proxyxfg into the agent startup
* Add `consul connect envoy` command to allow running Envoy as a connect sidecar.
* Add test for help tabs; typos and style fixups from review
* Vendor updates for gRPC and xDS server
* xDS server implementation for serving Envoy as a Connect proxy
* Address initial review comments
* consistent envoy package aliases; typos fixed; override TLS and authz for custom listeners
* Moar Typos
* Moar typos
freddygv