Add Prometheus support

README.md

@@ -2,7 +2,7 @@
 
 A terminal OpenTelemetry viewer inspired by [otel-desktop-viewer](https://github.com/CtrlSpice/otel-desktop-viewer/tree/main).
 
-This tool currently supports OpenTelemetry and Zipkin formats.
+This tool currently supports OpenTelemetry, Zipkin (Traces) and Prometheus (Metrics) formats.
 
 Traces
 ![Traces](./docs/traces.png)
@@ -27,12 +27,14 @@ Usage:
   otel-tui [flags]
 
 Flags:
-      --enable-zipkin   Enable the zipkin receiver
-      --grpc int        The port number on which we listen for OTLP grpc payloads (default 4317)
-  -h, --help            help for otel-tui
-      --host string     The host where we expose our OTLP endpoints (default "0.0.0.0")
-      --http int        The port number on which we listen for OTLP http payloads (default 4318)
-  -v, --version         version for otel-tui
+      --enable-prom               Enable the prometheus receiver
+      --enable-zipkin             Enable the zipkin receiver
+      --grpc int                  The port number on which we listen for OTLP grpc payloads (default 4317)
+  -h, --help                      help for otel-tui
+      --host string               The host where we expose our OTLP endpoints (default "0.0.0.0")
+      --http int                  The port number on which we listen for OTLP http payloads (default 4318)
+      --prom-target stringArray   The target endpoints for the prometheus receiver (--prom-target "localhost:9000" --prom-target "other-host:9000")
+  -v, --version                   version for otel-tui
 ```
 
 ### Homebrew
@@ -131,7 +133,7 @@ There're a lot of things to do. Here are some of them:
     - [ ] Display basic chart of the selected metric
       - [x] Gauge
       - [x] Sum
-      - [ ] Histogram
+      - [x] Histogram
       - [ ] ExponentialHistogram
       - [ ] Summary
   - [ ] Metric list
@@ -155,7 +157,7 @@ There're a lot of things to do. Here are some of them:
   - [x] Data rotation (current buffer size: 1000 service root spans and logs)
   - [ ] ...
 - Configurations
-  - [ ] Port
+  - [x] Port
   - [ ] Refresh interval
   - [ ] Buffer size
   - [ ] ...

config.go

@@ -3,6 +3,7 @@ package main
 import (
 	_ "embed"
 	"encoding/json"
+	"errors"
 	"html/template"
 	"strings"
 )
@@ -15,6 +16,8 @@ type Config struct {
 	OTLPHTTPPort int
 	OTLPGRPCPort int
 	EnableZipkin bool
+	EnableProm   bool
+	PromTarget   []string
 }
 
 func (c *Config) RenderYml() (string, error) {
@@ -51,3 +54,12 @@ func structToMap(s interface{}) (map[string]any, error) {
 
 	return result, nil
 }
+
+// Validate checks if the otel-tui configuration is valid
+func (cfg *Config) Validate() error {
+	if cfg.EnableProm && len(cfg.PromTarget) == 0 {
+		return errors.New("the target endpoints for the prometheus receiver (--prom-target) must be specified when prometheus receiver enabled")
+	}
+
+	return nil
+}

config.yml.tpl

@@ -6,8 +6,22 @@ receivers:
         endpoint: {{ .OTLPHost }}:{{ .OTLPHTTPPort }}
       grpc:
         endpoint: {{ .OTLPHost }}:{{ .OTLPGRPCPort }}
-{{if .EnableZipkin}}  zipkin:
-    endpoint: 0.0.0.0:9411{{end}}
+{{- if .EnableZipkin}}
+  zipkin:
+    endpoint: 0.0.0.0:9411
+{{- end}}
+{{- if .EnableProm}}
+  prometheus:
+    config:
+      scrape_configs:
+        - job_name: 'prometheus'
+          scrape_interval: 15s
+          static_configs:
+            - targets:
+{{- range $idx, $target := .PromTarget}}
+              - '{{ $target -}}'
+{{- end}}
+{{- end}}
 processors:
 exporters:
   tui:
@@ -16,7 +30,9 @@ service:
     traces:
       receivers: 
         - otlp
-{{if .EnableZipkin}}        - zipkin{{end}}
+{{- if .EnableZipkin}}
+        - zipkin
+{{- end}}
       processors:
       exporters:
         - tui
@@ -29,6 +45,9 @@ service:
     metrics:
       receivers:
         - otlp
+{{- if .EnableProm}}
+        - prometheus
+{{- end}}
       processors:
       exporters:
         - tui

config_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -12,6 +13,11 @@ func TestConfigRenderYml(t *testing.T) {
 		OTLPHTTPPort: 4318,
 		OTLPGRPCPort: 4317,
 		EnableZipkin: true,
+		EnableProm:   true,
+		PromTarget: []string{
+			"localhost:9000",
+			"other-host:9000",
+		},
 	}
 	want := `yaml:
 receivers:
@@ -23,6 +29,15 @@ receivers:
         endpoint: 0.0.0.0:4317
   zipkin:
     endpoint: 0.0.0.0:9411
+  prometheus:
+    config:
+      scrape_configs:
+        - job_name: 'prometheus'
+          scrape_interval: 15s
+          static_configs:
+            - targets:
+              - 'localhost:9000'
+              - 'other-host:9000'
 processors:
 exporters:
   tui:
@@ -44,6 +59,7 @@ service:
     metrics:
       receivers:
         - otlp
+        - prometheus
       processors:
       exporters:
         - tui
@@ -53,12 +69,13 @@ service:
 	assert.Equal(t, want, got)
 }
 
-func TestConfigRenderYmlZipkinDisabled(t *testing.T) {
+func TestConfigRenderYmlMinimum(t *testing.T) {
 	cfg := &Config{
 		OTLPHost:     "0.0.0.0",
 		OTLPHTTPPort: 4318,
 		OTLPGRPCPort: 4317,
 		EnableZipkin: false,
+		EnableProm:   false,
 	}
 	want := `yaml:
 receivers:
@@ -68,7 +85,6 @@ receivers:
         endpoint: 0.0.0.0:4318
       grpc:
         endpoint: 0.0.0.0:4317
-
 processors:
 exporters:
   tui:
@@ -77,7 +93,6 @@ service:
     traces:
       receivers: 
         - otlp
-
       processors:
       exporters:
         - tui
@@ -98,3 +113,48 @@ service:
 	assert.Nil(t, err)
 	assert.Equal(t, want, got)
 }
+
+func TestValidate(t *testing.T) {
+	tests := []struct {
+		name string
+		cfg  *Config
+		want error
+	}{
+		{
+			name: "OK_Minimum",
+			cfg:  &Config{},
+			want: nil,
+		},
+		{
+			name: "OK_Maximum",
+			cfg: &Config{
+				OTLPHost:     "0.0.0.0",
+				OTLPHTTPPort: 4318,
+				OTLPGRPCPort: 4317,
+				EnableZipkin: true,
+				EnableProm:   true,
+				PromTarget: []string{
+					"localhost:9000",
+					"other-host:9000",
+				},
+			},
+			want: nil,
+		},
+		{
+			name: "NG_Prom",
+			cfg: &Config{
+				OTLPHost:     "0.0.0.0",
+				OTLPHTTPPort: 4318,
+				OTLPGRPCPort: 4317,
+				EnableProm:   true,
+			},
+			want: errors.New("the target endpoints for the prometheus receiver (--prom-target) must be specified when prometheus receiver enabled"),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, tt.cfg.Validate())
+		})
+	}
+}