Add HEAD request support to check if metadata/userdata exists

This allows an authenticated user/service to check the existance of
metadata or userdata while generating minimal network traffic.

Signed-off-by: Scott Garman <[email protected]>

go.sum

@@ -248,7 +248,6 @@ github.com/golang/protobuf v1.4.2/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw
 github.com/golang/protobuf v1.4.3/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw735rRwI=
 github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
 github.com/golang/protobuf v1.5.1/go.mod h1:DopwsBzvsk0Fs44TXzsVbJyPhcCPeIwnvohx4u74HPM=
-github.com/golang/protobuf v1.5.2 h1:ROPKBNFfQgOUMifHyP+KYbvpjbdoFNs+aK7DXlji0Tw=
 github.com/golang/protobuf v1.5.2/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
 github.com/golang/protobuf v1.5.3 h1:KhyjKVUg7Usr/dYsdSqoFveMYd5ko72D+zANwlG1mmg=
 github.com/golang/protobuf v1.5.3/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
@@ -423,8 +422,8 @@ github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFB
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pretty v0.2.0/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
-github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
 github.com/kr/pretty v0.3.0/go.mod h1:640gp4NfQd8pI5XOwp5fnNeVWj67G7CFk/SaSQn7NBk=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/pty v1.1.8/go.mod h1:O1sed60cT9XZ5uDucP5qwvh+TE3NnUj51EiZO/lmSfw=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
@@ -522,8 +521,6 @@ github.com/prometheus/client_golang v1.0.0/go.mod h1:db9x61etRT2tGnBNRi70OPL5Fsn
 github.com/prometheus/client_golang v1.4.0/go.mod h1:e9GMxYsXl05ICDXkRhurwBS4Q3OK1iX/F2sw+iXX5zU=
 github.com/prometheus/client_golang v1.7.1/go.mod h1:PY5Wy2awLA44sXw4AOSfFBetzPP4j5+D6mVACh+pe2M=
 github.com/prometheus/client_golang v1.11.1/go.mod h1:Z6t4BnS23TR94PD6BsDNk8yVqroYurpAkEiz0P2BEV0=
-github.com/prometheus/client_golang v1.14.0 h1:nJdhIvne2eSX/XRAFV9PcvFFRbrjbcTUj0VP62TMhnw=
-github.com/prometheus/client_golang v1.14.0/go.mod h1:8vpkKitgIVNcqrRBWh1C4TIUQgYNtG/XQE4E/Zae36Y=
 github.com/prometheus/client_golang v1.15.0 h1:5fCgGYogn0hFdhyhLbw7hEsWxufKtY9klyvdNfFlFhM=
 github.com/prometheus/client_golang v1.15.0/go.mod h1:e9yaBhRPU2pPNsZwE+JdQl0KEt1N9XgF6zxWmaC0xOk=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
@@ -536,17 +533,13 @@ github.com/prometheus/common v0.4.1/go.mod h1:TNfzLD0ON7rHzMJeJkieUDPYmFC7Snx/y8
 github.com/prometheus/common v0.9.1/go.mod h1:yhUN8i9wzaXS3w1O07YhxHEBxD+W35wd8bs7vj7HSQ4=
 github.com/prometheus/common v0.10.0/go.mod h1:Tlit/dnDKsSWFlCLTWaA1cyBgKHSMdTB80sz/V91rCo=
 github.com/prometheus/common v0.26.0/go.mod h1:M7rCNAaPfAosfx8veZJCuw84e35h3Cfd9VFqTh1DIvc=
-github.com/prometheus/common v0.39.0 h1:oOyhkDq05hPZKItWVBkJ6g6AtGxi+fy7F4JvUV8uhsI=
-github.com/prometheus/common v0.39.0/go.mod h1:6XBZ7lYdLCbkAVhwRsWTZn+IN5AB9F/NXd5w0BbEX0Y=
 github.com/prometheus/common v0.42.0 h1:EKsfXEYo4JpWMHH5cg+KOUWeuJSov1Id8zGR8eeI1YM=
 github.com/prometheus/common v0.42.0/go.mod h1:xBwqVerjNdUDjgODMpudtOMwlOwf2SaTr1yjz4b7Zbc=
 github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/prometheus/procfs v0.0.2/go.mod h1:TjEm7ze935MbeOT/UhFTIMYKhuLP4wbCsTZCD3I8kEA=
 github.com/prometheus/procfs v0.0.8/go.mod h1:7Qr8sr6344vo1JqZ6HhLceV9o3AJ1Ff+GxbHq6oeK9A=
 github.com/prometheus/procfs v0.1.3/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4OA4YeYWdaU=
 github.com/prometheus/procfs v0.6.0/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
-github.com/prometheus/procfs v0.8.0 h1:ODq8ZFEaYeCaZOJlZZdJA2AbQR98dSHSM1KW/You5mo=
-github.com/prometheus/procfs v0.8.0/go.mod h1:z7EfXMXOkbkqb9IINtpCn86r/to3BnA0uaxHdg830/4=
 github.com/prometheus/procfs v0.9.0 h1:wzCHvIvM5SxWqYvwgVL7yJY8Lz3PKn49KQtpgMYJfhI=
 github.com/prometheus/procfs v0.9.0/go.mod h1:+pB4zwohETzFnmlpe6yd2lSc+0/46IYZRB/chUwxUZY=
 github.com/remyoudompheng/bigfft v0.0.0-20200410134404-eec4a21b6bb0 h1:OdAsTTz6OkFY5QxjkYwrChwuRruF69c169dPK26NUlk=
@@ -1221,8 +1214,6 @@ google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp0
 google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
 google.golang.org/protobuf v1.27.1/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
 google.golang.org/protobuf v1.28.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
-google.golang.org/protobuf v1.28.1 h1:d0NfwRgPtno5B1Wa6L2DAG+KivqkdutMf1UhdNx175w=
-google.golang.org/protobuf v1.28.1/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 google.golang.org/protobuf v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cng=
 google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=

pkg/api/v1/router.go

@@ -89,6 +89,9 @@ func (r *Router) Routes(rg *gin.RouterGroup) {
 	rg.POST(InternalMetadataURI, authMw.AuthRequired(), authMw.RequiredScopes(upsertScopes("metadata")), r.instanceMetadataSet)
 	rg.POST(InternalUserdataURI, authMw.AuthRequired(), authMw.RequiredScopes(upsertScopes("userdata")), r.instanceUserdataSet)
 
+	rg.HEAD(InternalMetadataWithIDURI, authMw.AuthRequired(), authMw.RequiredScopes(readScopes("metadata")), r.instanceMetadataExistsInternal)
+	rg.HEAD(InternalUserdataWithIDURI, authMw.AuthRequired(), authMw.RequiredScopes(readScopes("userdata")), r.instanceUserdataExistsInternal)
+
 	rg.GET(InternalMetadataWithIDURI, authMw.AuthRequired(), authMw.RequiredScopes(readScopes("metadata")), r.instanceMetadataGetInternal)
 	rg.GET(InternalUserdataWithIDURI, authMw.AuthRequired(), authMw.RequiredScopes(readScopes("userdata")), r.instanceUserdataGetInternal)
 	rg.DELETE(InternalMetadataWithIDURI, authMw.AuthRequired(), authMw.RequiredScopes(deleteScopes("metadata")), r.instanceMetadataDelete)

pkg/api/v1/router_instance_metadata.go

@@ -2,8 +2,10 @@ package metadataservice
 
 import (
 	"database/sql"
+	"encoding/json"
 	"errors"
 	"net/http"
+	"strconv"
 
 	"github.com/gin-gonic/gin"
 	"github.com/volatiletech/null/v8"
@@ -91,7 +93,6 @@ func (r *Router) instanceMetadataGetInternal(c *gin.Context) {
 
 	if err != nil {
 		invalidUUIDResponse(c, err)
-
 		return
 	}
 
@@ -116,6 +117,40 @@ func (r *Router) instanceMetadataGetInternal(c *gin.Context) {
 	}
 }
 
+// instanceMetadataExistsInternal retrieves the requested instance ID from the
+// path and looks to see if the database has metadata recorded for that ID.
+// If so, it returns a 200. If not, it returns a 404. This can be used by an
+// authenticated external system to determine which instances the metadata
+// service already knows about with minimal network overhead.
+func (r *Router) instanceMetadataExistsInternal(c *gin.Context) {
+	instanceID, err := getUUIDParam(c, "instance-id")
+
+	if err != nil {
+		invalidUUIDResponse(c, err)
+		return
+	}
+
+	metadata, err := models.FindInstanceMetadatum(c.Request.Context(), r.DB, instanceID)
+
+	if err != nil {
+		c.Status(http.StatusNotFound)
+		return
+	}
+
+	// HEAD request responses still set the Content-Length header to what it
+	// would be if we were returning the metadata
+	bytes, err := json.Marshal(metadata.Metadata)
+	if err != nil {
+		r.Logger.Warn("Error during json.Marshal() of metadata")
+		c.Status(http.StatusInternalServerError)
+
+		return
+	}
+
+	c.Writer.Header().Set("Content-Length", strconv.Itoa(len(bytes)))
+	c.Status(http.StatusOK)
+}
+
 func (r *Router) instanceUserdataGet(c *gin.Context) {
 	userdata, err := r.getUserdata(c)
 
@@ -145,7 +180,6 @@ func (r *Router) instanceUserdataGetInternal(c *gin.Context) {
 
 	if err != nil {
 		invalidUUIDResponse(c, err)
-
 		return
 	}
 
@@ -162,6 +196,32 @@ func (r *Router) instanceUserdataGetInternal(c *gin.Context) {
 	c.String(http.StatusOK, string(userdata.Userdata.Bytes))
 }
 
+// instanceUserdataExistsInternal retrieves the requested instance ID from the
+// path and looks to see if the database has userdata recorded for that ID.
+// If so, it returns a 200. If not, it will just return a 404. This can be use
+// by an authenticated external system to determine which instances the userdata
+// service already knows about with minimal network overhead.
+func (r *Router) instanceUserdataExistsInternal(c *gin.Context) {
+	instanceID, err := getUUIDParam(c, "instance-id")
+
+	if err != nil {
+		invalidUUIDResponse(c, err)
+		return
+	}
+
+	userdata, err := models.FindInstanceUserdatum(c.Request.Context(), r.DB, instanceID)
+
+	if err != nil {
+		c.Status(http.StatusNotFound)
+		return
+	}
+
+	// HEAD request responses still set the Content-Length header to what it
+	// would be if we were returning the userdata
+	c.Writer.Header().Set("Content-Length", strconv.Itoa(len(userdata.Userdata.Bytes)))
+	c.Status(http.StatusOK)
+}
+
 // There's a few steps we need to perform when upserting both instance_metadata
 // and instance_userdata:
 // 0. Validate the request body

pkg/api/v1/router_instance_metadata_test.go

@@ -599,6 +599,13 @@ func TestDeleteMetadata(t *testing.T) {
 	}
 }
 
+// metadataString is a helper function that ensures the db fixture string is marshaled
+// in a way that we can properly calculate its length for Content-Length comparisons
+func metadataString(metadata interface{}) string {
+	b, _ := json.Marshal(metadata)
+	return string(b)
+}
+
 func TestGetMetadataInternal(t *testing.T) {
 	router := *testHTTPServer(t)
 
@@ -632,25 +639,25 @@ func TestGetMetadataInternal(t *testing.T) {
 			"Instance A",
 			dbtools.FixtureInstanceA.InstanceID,
 			http.StatusOK,
-			dbtools.FixtureInstanceA.InstanceMetadata.Metadata.String(),
+			metadataString(dbtools.FixtureInstanceA.InstanceMetadata.Metadata),
 		},
 		{
 			"Instance B",
 			dbtools.FixtureInstanceB.InstanceID,
 			http.StatusOK,
-			dbtools.FixtureInstanceB.InstanceMetadata.Metadata.String(),
+			metadataString(dbtools.FixtureInstanceB.InstanceMetadata.Metadata),
 		},
 		{
 			"Instance C",
 			dbtools.FixtureInstanceC.InstanceID,
 			http.StatusOK,
-			dbtools.FixtureInstanceC.InstanceMetadata.Metadata.String(),
+			metadataString(dbtools.FixtureInstanceC.InstanceMetadata.Metadata),
 		},
 		{
 			"Instance D",
 			dbtools.FixtureInstanceD.InstanceID,
 			http.StatusOK,
-			dbtools.FixtureInstanceD.InstanceMetadata.Metadata.String(),
+			metadataString(dbtools.FixtureInstanceD.InstanceMetadata.Metadata),
 		},
 		// Instance E does not have metadata, so we'd expect a 404
 		{
@@ -668,6 +675,28 @@ func TestGetMetadataInternal(t *testing.T) {
 		},
 	}
 
+	// HEAD request tests
+	for _, testcase := range testCases {
+		t.Run(testcase.testName, func(t *testing.T) {
+			w := httptest.NewRecorder()
+
+			req, _ := http.NewRequestWithContext(context.TODO(), http.MethodHead, v1api.GetInternalMetadataByIDPath(testcase.instanceID), nil)
+			router.ServeHTTP(w, req)
+			response := w.Result()
+
+			assert.Equal(t, testcase.expectedStatus, w.Code)
+
+			if w.Code == 200 {
+				// HEAD responses should have an empty body, but set the Content-Length
+				// header to what the response body would otherwise be for a GET request
+				assert.Zero(t, w.Body.Len())
+				assert.Equal(t, int64(len(testcase.expectedBody)), response.ContentLength)
+				response.Body.Close()
+			}
+		})
+	}
+
+	// GET request tests
 	for _, testcase := range testCases {
 		t.Run(testcase.testName, func(t *testing.T) {
 			w := httptest.NewRecorder()

pkg/api/v1/router_instance_userdata_test.go

@@ -455,6 +455,28 @@ func TestGetUserdataInternal(t *testing.T) {
 		},
 	}
 
+	// HEAD request tests
+	for _, testcase := range testCases {
+		t.Run(testcase.testName, func(t *testing.T) {
+			w := httptest.NewRecorder()
+
+			req, _ := http.NewRequestWithContext(context.TODO(), http.MethodHead, v1api.GetInternalUserdataByIDPath(testcase.instanceID), nil)
+			router.ServeHTTP(w, req)
+			response := w.Result()
+
+			assert.Equal(t, testcase.expectedStatus, w.Code)
+
+			if w.Code == 200 {
+				// HEAD responses should have an empty body, but set the Content-Length
+				// header to what the response body would otherwise be for a GET request
+				assert.Zero(t, w.Body.Len())
+				assert.Equal(t, int64(len(testcase.expectedBody)), response.ContentLength)
+				response.Body.Close()
+			}
+		})
+	}
+
+	// GET request tests
 	for _, testcase := range testCases {
 		t.Run(testcase.testName, func(t *testing.T) {
 			w := httptest.NewRecorder()

quickstart.yml

@@ -2,7 +2,7 @@ version: "3.9"
 
 services:
   metadataservice:
-    image: ghcr.io/metal-toolbox/hollow-metadaaservice:v0.0.8
+    image: ghcr.io/metal-toolbox/hollow-metadaaservice:v0.0.11
     depends_on:
       crdb:
         condition: service_healthy
@@ -18,7 +18,7 @@ services:
       - metadataservice
 
   metadataservice-migrate:
-    image: ghcr.io/metal-toolbox/hollow-metadataservice:v0.0.8
+    image: ghcr.io/metal-toolbox/hollow-metadataservice:v0.0.11
     command:
       migrate up
     depends_on: