Merge pull request #43 from ElderOrb/diagnostics

Diagnositcs package

Author: lukasz-zimnoch

pkg/diagnostics/diagnostics.go

@@ -0,0 +1,85 @@
+// Package `diagnostics` provides some tools useful for gathering and
+// exposing arbitrary diagnositcs information for external monitoring tools.
+//
+// Possible usage: integration nodes list into dashboard
+package diagnostics
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"strconv"
+	"sync"
+
+	"github.com/ipfs/go-log"
+)
+
+var logger = log.Logger("keep-diagnostics")
+
+// Registry performs all management of diagnostic. Specifically, it allows
+// to registering new diagnostics sources and exposing them through the diagnostics server.
+type DiagnosticsRegistry struct {
+	diagnosticsSources map[string]func() string
+	diagnosticsMutex   sync.RWMutex
+}
+
+// NewRegistry creates a new metrics registry.
+func NewRegistry() *DiagnosticsRegistry {
+	return &DiagnosticsRegistry{
+		diagnosticsSources: make(map[string]func() string),
+	}
+}
+
+// EnableServer enables the diagnostics server on the given port. Data will
+// be exposed on `/diagnostics` path in JSON format.
+func (r *DiagnosticsRegistry) EnableServer(port int) {
+	server := &http.Server{Addr: ":" + strconv.Itoa(port)}
+
+	http.HandleFunc("/diagnostics", func(response http.ResponseWriter, _ *http.Request) {
+		if _, err := io.WriteString(response, r.exposeDiagnostics()); err != nil {
+			logger.Errorf("could not write response: [%v]", err)
+		}
+	})
+
+	go func() {
+		if err := server.ListenAndServe(); err != http.ErrServerClosed {
+			logger.Errorf("diagnostics server error: [%v]", err)
+		}
+	}()
+}
+
+// Registers diagnostics source callback with a given name. 
+// Name will be used as a key and callback result as a value in JSON object
+// during composing diagnostics JSON. 
+// Note: function will override existing diagnostics source on attempt 
+// to register another one with the same name.
+func (r *DiagnosticsRegistry) RegisterSource(name string, source func() string) {
+	r.diagnosticsMutex.Lock()
+	defer r.diagnosticsMutex.Unlock()
+
+	r.diagnosticsSources[name] = source
+}
+
+// Exposes all registered diagnostics sources in a single JSON document.
+func (r *DiagnosticsRegistry) exposeDiagnostics() string {
+	r.diagnosticsMutex.RLock()
+	defer r.diagnosticsMutex.RUnlock()
+
+	diagnostics := make(map[string]interface{})
+	for sourceName, sourceGetter := range r.diagnosticsSources {
+		var jsonString = sourceGetter()
+		var jsonObject interface{}
+		err := json.Unmarshal([]byte(jsonString), &jsonObject)
+		if err == nil {
+			diagnostics[sourceName] = jsonObject
+		}
+	}
+
+	bytes, err := json.Marshal(diagnostics)
+	if err != nil {
+		logger.Errorf("diagnostics JSON serialization error: [%v]", err)
+		return ""
+	}
+
+	return string(bytes)
+}