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.
To ease the transition for users, the original gRPC
port can still operate in a deprecated mode as either
plain-text or TLS mode. This behavior should be removed
in a future release whenever we no longer support this.
The resulting behavior from this commit is:
`ports.grpc > 0 && ports.grpc_tls > 0` spawns both plain-text and tls ports.
`ports.grpc > 0 && grpc.tls == undefined` spawns a single plain-text port.
`ports.grpc > 0 && grpc.tls != undefined` spawns a single tls port (backwards compat mode).
Contains 2 changes to the GetEnvoyBootstrapParams response to support
consul-dataplane.
Exposing node_name and node_id:
consul-dataplane will support providing either the node_id or node_name in its
configuration. Unfortunately, supporting both in the xDS meta adds a fair amount
of complexity (partly because most tables are currently indexed on node_name)
so for now we're going to return them both from the bootstrap params endpoint,
allowing consul-dataplane to exchange a node_id for a node_name (which it will
supply in the xDS meta).
Properly setting service for gateways:
To avoid the need to special case gateways in consul-dataplane, service will now
either be the destination service name for connect proxies, or the gateway
service name. This means it can be used as-is in Envoy configuration (i.e. as a
cluster name or in metric tags).
newMockSnapshotHandler has an assertion on t.Cleanup which gets called before the event publisher is cancelled. This commit reorders the context.WithCancel so it properly gets cancelled before the assertion is made.
Previously establishment and pending secrets were only checked at the
RPC layer. However, given that these are Check-and-Set transactions we
should ensure that the given secrets are still valid when persisting a
secret exchange or promotion.
Otherwise it would be possible for concurrent requests to overwrite each
other.
Previously there was a field indicating the operation that triggered a
secrets write. Now there is a message for each operation and it contains
the secret ID being persisted.
Previously the updates to the peering secrets UUID table relied on
inferring what action triggered the update based on a reconciliation
against the existing secrets.
Instead we now explicitly require the operation to be given so that the
inference isn't necessary. This makes the UUID table logic easier to
reason about and fixes some related bugs.
There is also an update so that the peering secrets get handled on
snapshots/restores.
* Avoid logging StreamSecretID
* Wrap additional errors in stream handler
* Fix flakiness in leader test and rename servers for clarity. There was
a race condition where the peering was being deleted in the test
before the stream was active. Now the test waits for the stream to be
connected on both sides before deleting the associated peering.
* Run flaky test serially
When we receive a FailedPrecondition error, retry that more quickly
because we expect it will resolve shortly. This is particularly
important in the context of Consul servers behind a load balancer
because when establishing a connection we have to retry until we
randomly land on a leader node.
The default retry backoff goes from 2s, 4s, 8s, etc. which can result in
very long delays quite quickly. Instead, this backoff retries in 8ms
five times, then goes exponentially from there: 16ms, 32ms, ... up to a
max of 8152ms.
The client is set to send keepalive pings every 30s. The server
keepalive enforcement must be set to a number less than that,
otherwise it will disconnect clients for sending pings too often.
MinTime governs the minimum amount of time between pings.
This mimics xDS's discovery protocol where you must request a resource
explicitly for the exporting side to send those events to you.
As part of this I aligned the overall ResourceURL with the TypeURL that
gets embedded into the encoded protobuf Any construct. The
CheckServiceNodes is now wrapped in a better named "ExportedService"
struct now.
Chris Chapman