feat: add http basic auth for receive

CHANGELOG.md

@@ -19,6 +19,8 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 - [#7907](https://github.com/thanos-io/thanos/pull/7907) Receive: Add `--receive.grpc-service-config` flag to configure gRPC service config for the receivers.
 - [#7961](https://github.com/thanos-io/thanos/pull/7961) Store Gateway: Add `--store.posting-group-max-keys` flag to mark posting group as lazy if it exceeds number of keys limit. Added `thanos_bucket_store_lazy_expanded_posting_groups_total` for total number of lazy posting groups and corresponding reasons.
 - [#8000](https://github.com/thanos-io/thanos/pull/8000) Query: Bump promql-engine, pass partial response through options
+- [#8012](https://github.com/thanos-io/thanos/pull/8012) Receive: Add optional HTTP Basic Auth checks for incoming write requests via `--receive.basic-auth-username` and `--receive.basic-auth-password` flags.
+
 
 ### Changed
 

cmd/thanos/receive.go

@@ -264,6 +264,8 @@ func runReceive(
 		Registry:             reg,
 		Endpoint:             conf.endpoint,
 		TenantHeader:         conf.tenantHeader,
+		BasicAuthUsername:    conf.basicAuthUsername,
+		BasicAuthPassword:    conf.basicAuthPassword,
 		TenantField:          conf.tenantField,
 		DefaultTenantID:      conf.defaultTenantID,
 		ReplicaHeader:        conf.replicaHeader,
@@ -851,6 +853,8 @@ type receiveConfig struct {
 	refreshInterval     *model.Duration
 	endpoint            string
 	tenantHeader        string
+	basicAuthUsername   string
+	basicAuthPassword   string
 	tenantField         string
 	tenantLabelName     string
 	defaultTenantID     string
@@ -952,6 +956,10 @@ func (rc *receiveConfig) registerFlag(cmd extkingpin.FlagClause) {
 
 	cmd.Flag("receive.tenant-header", "HTTP header to determine tenant for write requests.").Default(tenancy.DefaultTenantHeader).StringVar(&rc.tenantHeader)
 
+	cmd.Flag("receive.basic-auth-username", "HTTP Basic Auth username for write requests.").Default("").StringVar(&rc.basicAuthUsername)
+
+	cmd.Flag("receive.basic-auth-password", "HTTP Basic Auth password for write requests.").Default("").StringVar(&rc.basicAuthPassword)
+
 	cmd.Flag("receive.tenant-certificate-field", "Use TLS client's certificate field to determine tenant for write requests. Must be one of "+tenancy.CertificateFieldOrganization+", "+tenancy.CertificateFieldOrganizationalUnit+" or "+tenancy.CertificateFieldCommonName+". This setting will cause the receive.tenant-header flag value to be ignored.").Default("").EnumVar(&rc.tenantField, "", tenancy.CertificateFieldOrganization, tenancy.CertificateFieldOrganizationalUnit, tenancy.CertificateFieldCommonName)
 
 	cmd.Flag("receive.default-tenant-id", "Default tenant ID to use when none is provided via a header.").Default(tenancy.DefaultTenant).StringVar(&rc.defaultTenantID)

pkg/receive/handler.go

@@ -99,6 +99,8 @@ type Options struct {
 	ListenAddress           string
 	Registry                *prometheus.Registry
 	TenantHeader            string
+	BasicAuthUsername       string
+	BasicAuthPassword       string
 	TenantField             string
 	DefaultTenantID         string
 	ReplicaHeader           string
@@ -262,16 +264,20 @@ func NewHandler(logger log.Logger, o *Options) *Handler {
 		}
 		return next
 	}
+	handler := http.HandlerFunc(h.receiveHTTP)
+
+	// Conditionally apply BasicAuth
+	if o.BasicAuthUsername != "" && o.BasicAuthPassword != "" {
+		level.Info(logger).Log("msg", "Basic Auth enabled for incoming requests")
+		handler = middleware.BasicAuth(handler, o.BasicAuthUsername, o.BasicAuthPassword)
+	}
+	handler = middleware.RequestID(handler)
 
 	h.router.Post(
 		"/api/v1/receive",
 		instrf(
 			"receive",
-			readyf(
-				middleware.RequestID(
-					http.HandlerFunc(h.receiveHTTP),
-				),
-			),
+			readyf(handler),
 		),
 	)
 

pkg/server/http/middleware/basic_auth.go

@@ -0,0 +1,20 @@
+package middleware
+
+import (
+	"net/http"
+)
+
+// BasicAuth returns a middleware that checks HTTP Basic Authentication.
+// If the username or password do not match the expected credentials,
+// a 401 Unauthorized response is returned. Otherwise, the wrapped handler
+// is invoked.
+func BasicAuth(next http.HandlerFunc, expectedUser, expectedPassword string) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		user, pass, ok := r.BasicAuth()
+		if !ok || user != expectedUser || pass != expectedPassword {
+			http.Error(w, "Unauthorized", http.StatusUnauthorized)
+			return
+		}
+		next(w, r)
+	}
+}