Add library logic

Signed-off-by: Igor Shishkin <me@teran.ru>

.github/dependabot.yml

@@ -0,0 +1,11 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
+
+version: 2
+updates:
+  - package-ecosystem: "gomod" # See documentation for possible values
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "weekly"

.github/workflows/verify.yml

@@ -0,0 +1,46 @@
+---
+name: verify
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    types:
+      - opened
+      - reopened
+      - edited
+      - synchronize
+
+jobs:
+  markdownlint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: articulate/actions-markdownlint@v1
+
+  unittests:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '1.23.x'
+      - name: Install dependencies
+        run: go mod download
+      - name: Test with the Go CLI
+        run: go test -parallel 1 ./...
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '1.23.x'
+      - name: Install dependencies
+        run: go mod download
+      - name: Test with the Go CLI
+        run: go build ./...

appmetrics.go

@@ -0,0 +1,72 @@
+package appmetrics
+
+import (
+	"net/http"
+
+	"github.com/labstack/echo/v4"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+const (
+	livenessProbeURL  = "/healthz/liveness"
+	readinessProbeURL = "/healthz/readiness"
+	startupProbeURL   = "/healthz/startup"
+	metricsURL        = "/metrics"
+)
+
+type AppMetrics interface {
+	Register(e *echo.Echo)
+}
+
+type appMetrics struct {
+	livenessProbeFn  func() error
+	readinessProbeFn func() error
+	startupProbeFn   func() error
+}
+
+func New(livenessProbeFn, readinessProbeFn, startupProbeFn func() error) AppMetrics {
+	return &appMetrics{
+		livenessProbeFn:  livenessProbeFn,
+		readinessProbeFn: readinessProbeFn,
+		startupProbeFn:   startupProbeFn,
+	}
+}
+
+func (m *appMetrics) livenessProbe(c echo.Context) error {
+	return check(c, m.livenessProbeFn)
+}
+
+func (m *appMetrics) readinessProbe(c echo.Context) error {
+	return check(c, m.readinessProbeFn)
+}
+
+func (m *appMetrics) startupProbe(c echo.Context) error {
+	return check(c, m.startupProbeFn)
+}
+
+func (m *appMetrics) metrics(c echo.Context) error {
+	return echo.WrapHandler(promhttp.Handler())(c)
+}
+
+func (m *appMetrics) Register(e *echo.Echo) {
+	e.GET(livenessProbeURL, m.livenessProbe)
+	e.GET(readinessProbeURL, m.readinessProbe)
+	e.GET(startupProbeURL, m.startupProbe)
+	e.GET(metricsURL, m.metrics)
+}
+
+func check(c echo.Context, fn func() error) error {
+	if fn == nil {
+		return c.JSON(http.StatusNotImplemented, echo.Map{
+			"status": "failed", "error": "not implemented: check function is not provided",
+		})
+	}
+
+	if err := fn(); err != nil {
+		return c.JSON(http.StatusServiceUnavailable, echo.Map{
+			"status": "failed", "error": err.Error(),
+		})
+	}
+
+	return c.JSON(http.StatusOK, echo.Map{"status": "ok"})
+}

appmetrics_test.go

@@ -0,0 +1,194 @@
+package appmetrics
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	echo "github.com/labstack/echo/v4"
+	"github.com/labstack/echo/v4/middleware"
+	"github.com/pkg/errors"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAll(t *testing.T) {
+	type testCase struct {
+		name             string
+		livenessProbeFn  func() error
+		readinessProbeFn func() error
+		startupProbeFn   func() error
+		url              string
+		expCode          int
+		expData          map[string]any
+	}
+
+	tcs := []testCase{
+		// Happy path
+		{
+			name:            "liveness probe",
+			livenessProbeFn: func() error { return nil },
+			url:             livenessProbeURL,
+			expCode:         http.StatusOK,
+			expData: map[string]any{
+				"status": "ok",
+			},
+		},
+		{
+			name:             "readiness probe",
+			readinessProbeFn: func() error { return nil },
+			url:              readinessProbeURL,
+			expCode:          http.StatusOK,
+			expData: map[string]any{
+				"status": "ok",
+			},
+		},
+		{
+			name:           "startup probe",
+			startupProbeFn: func() error { return nil },
+			url:            startupProbeURL,
+			expCode:        http.StatusOK,
+			expData: map[string]any{
+				"status": "ok",
+			},
+		},
+
+		// Not implemented
+		{
+			name:             "liveness probe not implemented",
+			readinessProbeFn: func() error { return nil },
+			startupProbeFn:   func() error { return nil },
+			url:              livenessProbeURL,
+			expCode:          http.StatusNotImplemented,
+			expData: map[string]any{
+				"status": "failed",
+				"error":  "not implemented: check function is not provided",
+			},
+		},
+		{
+			name:            "readiness probe not implemented",
+			livenessProbeFn: func() error { return nil },
+			startupProbeFn:  func() error { return nil },
+			url:             readinessProbeURL,
+			expCode:         http.StatusNotImplemented,
+			expData: map[string]any{
+				"status": "failed",
+				"error":  "not implemented: check function is not provided",
+			},
+		},
+		{
+			name:             "startup probe not implemented",
+			livenessProbeFn:  func() error { return nil },
+			readinessProbeFn: func() error { return nil },
+			url:              startupProbeURL,
+			expCode:          http.StatusNotImplemented,
+			expData: map[string]any{
+				"status": "failed",
+				"error":  "not implemented: check function is not provided",
+			},
+		},
+
+		// Check error
+		{
+			name:            "liveness probe error",
+			livenessProbeFn: func() error { return errors.New("blah") },
+			url:             livenessProbeURL,
+			expCode:         http.StatusServiceUnavailable,
+			expData: map[string]any{
+				"status": "failed",
+				"error":  "blah",
+			},
+		},
+		{
+			name:             "readiness probe error",
+			readinessProbeFn: func() error { return errors.New("blah") },
+			url:              readinessProbeURL,
+			expCode:          http.StatusServiceUnavailable,
+			expData: map[string]any{
+				"status": "failed",
+				"error":  "blah",
+			},
+		},
+		{
+			name:           "startup probe error",
+			startupProbeFn: func() error { return errors.New("blah") },
+			url:            startupProbeURL,
+			expCode:        http.StatusServiceUnavailable,
+			expData: map[string]any{
+				"status": "failed",
+				"error":  "blah",
+			},
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			r := require.New(t)
+
+			e := echo.New()
+			e.Use(middleware.Logger())
+			e.Use(middleware.Recover())
+
+			appMetrics := New(tc.livenessProbeFn, tc.readinessProbeFn, tc.startupProbeFn)
+			appMetrics.Register(e)
+
+			srv := httptest.NewServer(e)
+			defer srv.Close()
+
+			ctx := context.TODO()
+
+			code, v, err := get(ctx, srv.URL+tc.url)
+			r.NoError(err)
+			r.Equal(tc.expCode, code)
+			r.Equal(tc.expData, v)
+		})
+	}
+}
+
+func TestMetrics(t *testing.T) {
+	r := require.New(t)
+
+	e := echo.New()
+	e.Use(middleware.Logger())
+	e.Use(middleware.Recover())
+
+	appMetrics := New(nil, nil, nil)
+	appMetrics.Register(e)
+
+	srv := httptest.NewServer(e)
+	defer srv.Close()
+
+	req, err := http.NewRequestWithContext(context.TODO(), http.MethodGet, srv.URL+metricsURL, nil)
+	r.NoError(err)
+
+	resp, err := http.DefaultClient.Do(req)
+	r.NoError(err)
+	defer resp.Body.Close()
+
+	data, err := io.ReadAll(resp.Body)
+	r.NoError(err)
+	r.True(strings.HasPrefix(string(data), "# HELP"))
+}
+
+func get(ctx context.Context, url string) (int, map[string]any, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return 0, nil, err
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return 0, nil, err
+	}
+	defer resp.Body.Close()
+
+	v := map[string]any{}
+	if err := json.NewDecoder(resp.Body).Decode(&v); err != nil {
+		return 0, nil, err
+	}
+
+	return resp.StatusCode, v, nil
+}

go.mod

@@ -0,0 +1,36 @@
+module github.com/teran/appmetrics
+
+go 1.23.3
+
+require (
+	github.com/labstack/echo/v4 v4.12.0
+	github.com/pkg/errors v0.9.1
+	github.com/prometheus/client_golang v1.20.5
+	github.com/stretchr/testify v1.9.0
+)
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/golang-jwt/jwt v3.2.2+incompatible // indirect
+	github.com/klauspost/compress v1.17.9 // indirect
+	github.com/kr/text v0.2.0 // indirect
+	github.com/labstack/gommon v0.4.2 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_model v0.6.1 // indirect
+	github.com/prometheus/common v0.55.0 // indirect
+	github.com/prometheus/procfs v0.15.1 // indirect
+	github.com/valyala/bytebufferpool v1.0.0 // indirect
+	github.com/valyala/fasttemplate v1.2.2 // indirect
+	golang.org/x/crypto v0.24.0 // indirect
+	golang.org/x/net v0.26.0 // indirect
+	golang.org/x/sys v0.22.0 // indirect
+	golang.org/x/text v0.16.0 // indirect
+	golang.org/x/time v0.5.0 // indirect
+	google.golang.org/protobuf v1.34.2 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)