feat: gossip config reload information

cmd/refinery/main.go

@@ -25,6 +25,7 @@ import (
 	"github.com/honeycombio/refinery/app"
 	"github.com/honeycombio/refinery/collect"
 	"github.com/honeycombio/refinery/config"
+	"github.com/honeycombio/refinery/internal/configwatcher"
 	"github.com/honeycombio/refinery/internal/health"
 	"github.com/honeycombio/refinery/internal/otelutil"
 	"github.com/honeycombio/refinery/internal/peer"
@@ -266,6 +267,7 @@ func main() {
 		{Value: samplerFactory},
 		{Value: stressRelief, Name: "stressRelief"},
 		{Value: &health.Health{}},
+		{Value: &configwatcher.ConfigWatcher{}},
 		{Value: &a},
 	}
 	err = g.Provide(objects...)

collect/collect_test.go

@@ -92,12 +92,13 @@ func TestAddRootSpan(t *testing.T) {
 		},
 	}
 	coll.AddSpan(span)
-
 	time.Sleep(conf.SendTickerVal * 2)
+
 	// adding one span with no parent ID should:
 	// * create the trace in the cache
 	// * send the trace
 	// * remove the trace from the cache
+	// * remove the trace from the cache
 	assert.Nil(t, coll.getFromCache(traceID1), "after sending the span, it should be removed from the cache")
 	transmission.Mux.RLock()
 	assert.Equal(t, 1, len(transmission.Events), "adding a root span should send the span")
@@ -508,7 +509,7 @@ func TestCacheSizeReload(t *testing.T) {
 	conf.Mux.Lock()
 	conf.GetCollectionConfigVal.CacheCapacity = 2
 	conf.Mux.Unlock()
-	conf.ReloadConfig()
+	conf.Reload()
 
 	assert.Eventually(t, func() bool {
 		coll.mutex.RLock()
@@ -525,7 +526,7 @@ func TestCacheSizeReload(t *testing.T) {
 	conf.Mux.Lock()
 	conf.GetCollectionConfigVal.CacheCapacity = 1
 	conf.Mux.Unlock()
-	conf.ReloadConfig()
+	conf.Reload()
 
 	expectedEvents = 2
 	assert.Eventually(t, check, 60*wait, wait, "expected another trace evicted and sent")
@@ -574,7 +575,7 @@ func TestSampleConfigReload(t *testing.T) {
 		return ok
 	}, conf.GetTraceTimeoutVal*2, conf.SendTickerVal)
 
-	conf.ReloadConfig()
+	conf.Reload()
 
 	assert.Eventually(t, func() bool {
 		coll.mutex.Lock()

config/config.go

@@ -10,19 +10,25 @@ const (
 
 // Config defines the interface the rest of the code uses to get items from the
 // config. There are different implementations of the config using different
-// backends to store the config. FileConfig is the default and uses a
-// TOML-formatted config file. RedisPeerFileConfig uses a redis cluster to store
-// the list of peers and then falls back to a filesystem config file for all
-// other config elements.
+// backends to store the config.
 
 type Config interface {
 	// RegisterReloadCallback takes a name and a function that will be called
-	// when the configuration is reloaded. This will happen infrequently. If
+	// whenever the configuration is reloaded. This will happen infrequently. If
 	// consumers of configuration set config values on startup, they should
 	// check their values haven't changed and re-start anything that needs
-	// restarting with the new values.
+	// restarting with the new values. The callback is passed the two hashes
+	// for config and rules so that the caller can decide if they need to
+	// reconfigure anything.
 	RegisterReloadCallback(callback ConfigReloadCallback)
 
+	// Reload forces the config to attempt to reload its values. If the config
+	// checksum has changed, the reload callbacks will be called.
+	Reload()
+
+	// GetHashes returns the current config and rule hashes
+	GetHashes() (cfg string, rules string)
+
 	// GetListenAddr returns the address and port on which to listen for
 	// incoming events
 	GetListenAddr() (string, error)
@@ -128,6 +134,9 @@ type Config interface {
 	// GetAllSamplerRules returns all rules in a single map, including the default rules
 	GetAllSamplerRules() (*V2SamplerConfig, error)
 
+	// GetGeneralConfig returns the config specific to General
+	GetGeneralConfig() GeneralConfig
+
 	// GetLegacyMetricsConfig returns the config specific to LegacyMetrics
 	GetLegacyMetricsConfig() LegacyMetricsConfig