feat(health): add health checking endpoints and logic

Introduce health checking functionality with liveness and readiness 
endpoints to monitor the application's status. Implement a health 
checker that verifies database connectivity and provides a simple 
liveness check. Update service routing to use the new health 
checker functionality. Add corresponding unit tests for validation.

.gitignore

@@ -6,5 +6,6 @@ coverage.html
 /exported
 /release
 /schemactl
+/service
 CHANGES.md
 VERSION

cmd/service/service.go

@@ -30,6 +30,7 @@ import (
 	"gitlab.com/unboundsoftware/schemas/domain"
 	"gitlab.com/unboundsoftware/schemas/graph"
 	"gitlab.com/unboundsoftware/schemas/graph/generated"
+	"gitlab.com/unboundsoftware/schemas/health"
 	"gitlab.com/unboundsoftware/schemas/logging"
 	"gitlab.com/unboundsoftware/schemas/middleware"
 	"gitlab.com/unboundsoftware/schemas/monitoring"
@@ -241,8 +242,12 @@ func start(closeEvents chan error, logger *slog.Logger, connectToAmqpFunc func(u
 			Cache: lru.New[string](100),
 		})
 
+		healthChecker := health.New(db.DB, logger)
+
 		mux.Handle("/", monitoring.Handler(playground.Handler("GraphQL playground", "/query")))
-		mux.Handle("/health", http.HandlerFunc(healthFunc))
+		mux.Handle("/health", http.HandlerFunc(healthChecker.LivenessHandler))
+		mux.Handle("/health/live", http.HandlerFunc(healthChecker.LivenessHandler))
+		mux.Handle("/health/ready", http.HandlerFunc(healthChecker.ReadinessHandler))
 		mux.Handle("/query", cors.AllowAll().Handler(
 			monitoring.Handler(
 				mw.Middleware().CheckJWT(
@@ -301,10 +306,6 @@ func loadSubGraphs(ctx context.Context, eventStore eventsourced.EventStore, serv
 	return nil
 }
 
-func healthFunc(w http.ResponseWriter, _ *http.Request) {
-	_, _ = w.Write([]byte("OK"))
-}
-
 func ConnectAMQP(url string) (Connection, error) {
 	return goamqp.NewFromURL(serviceName, url)
 }

go.mod

@@ -4,6 +4,7 @@ go 1.25
 
 require (
 	github.com/99designs/gqlgen v0.17.83
+	github.com/DATA-DOG/go-sqlmock v1.5.2
 	github.com/Khan/genqlient v0.8.1
 	github.com/alecthomas/kong v1.13.0
 	github.com/apex/log v1.9.0

go.sum

@@ -83,6 +83,7 @@ github.com/jmespath/go-jmespath v0.0.0-20180206201540-c2b33e8439af/go.mod h1:Nht
 github.com/jmoiron/sqlx v1.4.0 h1:1PLqN7S1UYp5t4SrVVnt4nUVNemrDAtxlulVe+Qgm3o=
 github.com/jmoiron/sqlx v1.4.0/go.mod h1:ZrZ7UsYB/weZdl2Bxg6jCRO9c3YHl8r3ahlKmRT4JLY=
 github.com/jpillora/backoff v0.0.0-20180909062703-3050d21c67d7/go.mod h1:2iMrUgbbvHEiQClaW2NsSzMyGHqN+rDFqY705q49KG0=
+github.com/kisielk/sqlstruct v0.0.0-20201105191214-5f3e10d3ab46/go.mod h1:yyMNCyc/Ib3bDTKd379tNMpB/7/H5TjM2Y9QJ5THLbE=
 github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
 github.com/kr/pretty v0.2.0/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=

health/health.go

@@ -0,0 +1,73 @@
+package health
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"log/slog"
+	"net/http"
+	"time"
+)
+
+type Checker struct {
+	db     *sql.DB
+	logger *slog.Logger
+}
+
+func New(db *sql.DB, logger *slog.Logger) *Checker {
+	return &Checker{
+		db:     db,
+		logger: logger,
+	}
+}
+
+type HealthStatus struct {
+	Status string            `json:"status"`
+	Checks map[string]string `json:"checks,omitempty"`
+}
+
+// LivenessHandler checks if the application is running
+// This is a simple check that always returns OK if the handler is reached
+func (h *Checker) LivenessHandler(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	_ = json.NewEncoder(w).Encode(HealthStatus{
+		Status: "UP",
+	})
+}
+
+// ReadinessHandler checks if the application is ready to accept traffic
+// This checks database connectivity and other critical dependencies
+func (h *Checker) ReadinessHandler(w http.ResponseWriter, r *http.Request) {
+	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
+	defer cancel()
+
+	checks := make(map[string]string)
+	allHealthy := true
+
+	// Check database connectivity
+	if err := h.db.PingContext(ctx); err != nil {
+		h.logger.With("error", err).Warn("database health check failed")
+		checks["database"] = "DOWN"
+		allHealthy = false
+	} else {
+		checks["database"] = "UP"
+	}
+
+	status := HealthStatus{
+		Status: "UP",
+		Checks: checks,
+	}
+
+	if !allHealthy {
+		status.Status = "DOWN"
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusServiceUnavailable)
+		_ = json.NewEncoder(w).Encode(status)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	_ = json.NewEncoder(w).Encode(status)
+}

health/health_test.go

@@ -0,0 +1,75 @@
+package health
+
+import (
+	"database/sql"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLivenessHandler(t *testing.T) {
+	logger := slog.New(slog.NewTextHandler(os.Stdout, nil))
+	db, _, err := sqlmock.New()
+	require.NoError(t, err)
+	defer db.Close()
+
+	checker := New(db, logger)
+
+	req := httptest.NewRequest(http.MethodGet, "/health/live", nil)
+	rec := httptest.NewRecorder()
+
+	checker.LivenessHandler(rec, req)
+
+	assert.Equal(t, http.StatusOK, rec.Code)
+	assert.Contains(t, rec.Body.String(), `"status":"UP"`)
+}
+
+func TestReadinessHandler_Healthy(t *testing.T) {
+	logger := slog.New(slog.NewTextHandler(os.Stdout, nil))
+	db, mock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	require.NoError(t, err)
+	defer db.Close()
+
+	// Expect a ping and return success
+	mock.ExpectPing().WillReturnError(nil)
+
+	checker := New(db, logger)
+
+	req := httptest.NewRequest(http.MethodGet, "/health/ready", nil)
+	rec := httptest.NewRecorder()
+
+	checker.ReadinessHandler(rec, req)
+
+	assert.Equal(t, http.StatusOK, rec.Code)
+	assert.Contains(t, rec.Body.String(), `"status":"UP"`)
+	assert.Contains(t, rec.Body.String(), `"database":"UP"`)
+	assert.NoError(t, mock.ExpectationsWereMet())
+}
+
+func TestReadinessHandler_DatabaseDown(t *testing.T) {
+	logger := slog.New(slog.NewTextHandler(os.Stdout, nil))
+	db, mock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	require.NoError(t, err)
+	defer db.Close()
+
+	// Expect a ping and return error
+	mock.ExpectPing().WillReturnError(sql.ErrConnDone)
+
+	checker := New(db, logger)
+
+	req := httptest.NewRequest(http.MethodGet, "/health/ready", nil)
+	rec := httptest.NewRecorder()
+
+	checker.ReadinessHandler(rec, req)
+
+	assert.Equal(t, http.StatusServiceUnavailable, rec.Code)
+	assert.Contains(t, rec.Body.String(), `"status":"DOWN"`)
+	assert.Contains(t, rec.Body.String(), `"database":"DOWN"`)
+	assert.NoError(t, mock.ExpectationsWereMet())
+}

k8s/deploy.yaml

@@ -44,13 +44,22 @@ spec:
           requests:
             cpu: "20m"
             memory: "20Mi"
+        livenessProbe:
+          httpGet:
+            path: /health/live
+            port: 8080
+          initialDelaySeconds: 10
+          periodSeconds: 10
+          timeoutSeconds: 5
+          failureThreshold: 3
         readinessProbe:
           httpGet:
-            path: /health
+            path: /health/ready
             port: 8080
           initialDelaySeconds: 5
           periodSeconds: 5
           timeoutSeconds: 5
+          failureThreshold: 3
         imagePullPolicy: IfNotPresent
         image: registry.gitlab.com/unboundsoftware/schemas:${COMMIT}
         ports: