CIRC-9964: Implement deny hosts configuration item (#99)

* CIRC-9964: Implement deny hosts configuration item

* CIRC-9964: Additional place to check deny hosts list

* CIRC-9964: Check servers during new client

ChangeLog.md

@@ -6,6 +6,11 @@ to [Semantic Versioning](http://semver.org/) rules.
 
 ## [Next Release]
 
+## [v1.13.2] - 2023-03-09
+
+* add: Adds a configuration item, DenyHosts, to allow a list of hosts to
+always be considered inactive, regardless of topology discovery.
+
 ## [v1.13.1] - 2023-02-23
 
 * upd: Modifies the PromQLResponse and PromQLError types to support more types
@@ -460,6 +465,7 @@ writing to histogram endpoints.
 any delay, once started. Created: 2019-03-12. Fixed: 2019-03-13.
 
 [Next Release]: https://github.com/circonus-labs/gosnowth
+[v1.13.2]: https://github.com/circonus-labs/gosnowth/releases/tag/v1.13.2
 [v1.13.1]: https://github.com/circonus-labs/gosnowth/releases/tag/v1.13.1
 [v1.13.0]: https://github.com/circonus-labs/gosnowth/releases/tag/v1.13.0
 [v1.12.5]: https://github.com/circonus-labs/gosnowth/releases/tag/v1.12.5

client.go

@@ -72,6 +72,7 @@ type Config struct {
 	Retries        int64         `json:"retries,omitempty"`
 	ConnectRetries int64         `json:"connect_retries,omitempty"`
 	Servers        []string      `json:"servers,omitempty"`
+	DenyHosts      []string      `json:"deny_hosts,omitempty"`
 	CtxKeyTraceID  interface{}   `json:"-"`
 }
 
@@ -109,6 +110,9 @@ type SnowthClient struct {
 	activeNodes   []*SnowthNode
 	inactiveNodes []*SnowthNode
 
+	// denyHosts are a list of hosts to always keep inactive.
+	denyHosts []string
+
 	// watchInterval is the duration between checks to tell if a node is active
 	// or inactive.
 	watchInterval time.Duration
@@ -181,6 +185,7 @@ func NewClient(ctx context.Context, cfg *Config,
 		connRetries:   cfg.ConnectRetries,
 		dumpRequests:  os.Getenv("GOSNOWTH_DUMP_REQUESTS"),
 		traceRequests: os.Getenv("GOSNOWTH_TRACE_REQUESTS"),
+		denyHosts:     cfg.DenyHosts,
 		ctxKeyTraceID: cfg.CtxKeyTraceID,
 	}
 
@@ -217,6 +222,15 @@ func NewClient(ctx context.Context, cfg *Config,
 					return
 				}
 
+				for _, dh := range cfg.DenyHosts {
+					if url.Host == dh {
+						errCh <- fmt.Errorf("deny host found in servers: %s",
+							url.Host)
+
+						return
+					}
+				}
+
 				node := &SnowthNode{url: url}
 
 				stats, err := sc.GetStatsNodeContext(ctx, node)
@@ -423,6 +437,19 @@ func (sc *SnowthClient) FindMetricNodeIDs(uuid, metric string) []string {
 func (sc *SnowthClient) isNodeActive(ctx context.Context,
 	node *SnowthNode,
 ) bool {
+	sc.RLock()
+	dhosts := sc.denyHosts
+	sc.RUnlock()
+
+	for _, dh := range dhosts {
+		if node.GetURL().Host == dh {
+			sc.LogWarnf("deny host from active node check: %s",
+				node.GetURL().Host)
+
+			return false
+		}
+	}
+
 	if node.identifier == "" || node.semVer == "" {
 		// go get state to figure out identity
 		stats, err := sc.GetStatsNodeContext(ctx, node)
@@ -598,6 +625,8 @@ func (sc *SnowthClient) populateNodeInfo(ctx context.Context, hash string,
 		sc.currentTopologyCompiled = nil
 	}
 
+	dhosts := sc.denyHosts
+
 	sc.Unlock()
 
 	if !found {
@@ -611,17 +640,28 @@ func (sc *SnowthClient) populateNodeInfo(ctx context.Context, hash string,
 			currentTopology: hash,
 		}
 
+		for _, dh := range dhosts {
+			if newNode.GetURL().Host == dh {
+				sc.LogWarnf("deny host found from topology: %s",
+					newNode.GetURL().Host)
+
+				return
+			}
+		}
+
 		stats, err := sc.GetStatsNodeContext(ctx, newNode)
 		if err != nil {
 			// This node is not returning stats, put it on the inactive list.
 			sc.AddNodes(newNode)
-		} else {
-			newNode.identifier = stats.Identity()
-			newNode.semVer = stats.SemVer()
 
-			sc.AddNodes(newNode)
-			sc.ActivateNodes(newNode)
+			return
 		}
+
+		newNode.identifier = stats.Identity()
+		newNode.semVer = stats.SemVer()
+
+		sc.AddNodes(newNode)
+		sc.ActivateNodes(newNode)
 	}
 }