feat: Add high availability for multiple replicas (#4555)

* feat: HA tailnet coordinator

* fixup! feat: HA tailnet coordinator

* fixup! feat: HA tailnet coordinator

* remove printlns

* close all connections on coordinator

* impelement high availability feature

* fixup! impelement high availability feature

* fixup! impelement high availability feature

* fixup! impelement high availability feature

* fixup! impelement high availability feature

* Add replicas

* Add DERP meshing to arbitrary addresses

* Move packages to highavailability folder

* Move coordinator to high availability package

* Add flags for HA

* Rename to replicasync

* Denest packages for replicas

* Add test for multiple replicas

* Fix coordination test

* Add HA to the helm chart

* Rename function pointer

* Add warnings for HA

* Add the ability to block endpoints

* Add flag to disable P2P connections

* Wow, I made the tests pass

* Add replicas endpoint

* Ensure close kills replica

* Update sql

* Add database latency to high availability

* Pipe TLS to DERP mesh

* Fix DERP mesh with TLS

* Add tests for TLS

* Fix replica sync TLS

* Fix RootCA for replica meshing

* Remove ID from replicasync

* Fix getting certificates for meshing

* Remove excessive locking

* Fix linting

* Store mesh key in the database

* Fix replica key for tests

* Fix types gen

* Fix unlocking unlocked

* Fix race in tests

* Update enterprise/derpmesh/derpmesh.go

Co-authored-by: Colin Adler <colin1adler@gmail.com>

* Rename to syncReplicas

* Reuse http client

* Delete old replicas on a CRON

* Fix race condition in connection tests

* Fix linting

* Fix nil type

* Move pubsub to in-memory for twenty test

* Add comment for configuration tweaking

* Fix leak with transport

* Fix close leak in derpmesh

* Fix race when creating server

* Remove handler update

* Skip test on Windows

* Fix DERP mesh test

* Wrap HTTP handler replacement in mutex

* Fix error message for relay

* Fix API handler for normal tests

* Fix speedtest

* Fix replica resend

* Fix derpmesh send

* Ping async

* Increase wait time of template version jobd

* Fix race when closing replica sync

* Add name to client

* Log the derpmap being used

* Don't connect if DERP is empty

* Improve agent coordinator logging

* Fix lock in coordinator

* Fix relay addr

* Fix race when updating durations

* Fix client publish race

* Run pubsub loop in a queue

* Store agent nodes in order

* Fix coordinator locking

* Check for closed pipe

Co-authored-by: Colin Adler <colin1adler@gmail.com>

coderd/database/db.go

@@ -12,6 +12,7 @@ import (
 	"context"
 	"database/sql"
 	"errors"
+	"time"
 
 	"github.com/jmoiron/sqlx"
 	"golang.org/x/xerrors"
@@ -24,6 +25,7 @@ type Store interface {
 	// customQuerier contains custom queries that are not generated.
 	customQuerier
 
+	Ping(ctx context.Context) (time.Duration, error)
 	InTx(func(Store) error) error
 }
 
@@ -58,6 +60,13 @@ type sqlQuerier struct {
 	db  DBTX
 }
 
+// Ping returns the time it takes to ping the database.
+func (q *sqlQuerier) Ping(ctx context.Context) (time.Duration, error) {
+	start := time.Now()
+	err := q.sdb.PingContext(ctx)
+	return time.Since(start), err
+}
+
 // InTx performs database operations inside a transaction.
 func (q *sqlQuerier) InTx(function func(Store) error) error {
 	if _, ok := q.db.(*sqlx.Tx); ok {