Refactor and provide JSON file loaders for endpoints and tokens

cmd/kubediscovery/kubediscovery.go

@@ -21,19 +21,23 @@ import (
 )
 
 func main() {
-
-	// Make sure the CA cert for the cluster exists and is readable.
-	// We are expecting a base64 encoded version of the cert PEM as this is how
-	// the cert would most likely be provided via kubernetes secrets.
-	if _, err := os.Stat(kd.CAPath); os.IsNotExist(err) {
-		log.Fatalf("CA does not exist: %s", kd.CAPath)
+	// Make sure we can load critical files, and be nice to the user by
+	// printing descriptive error message when we fail.
+	for desc, path := range map[string]string{
+		"root CA certificate":   kd.CAPath,
+		"token map file":        kd.TokenMapPath,
+		"list of API endpoints": kd.EndpointListPath,
+	} {
+		if _, err := os.Stat(path); os.IsNotExist(err) {
+			log.Fatalf("%s does not exist: %s", desc, path)
+		}
+		// Test read permissions
+		file, err := os.Open(path)
+		if err != nil {
+			log.Fatalf("Unable to open %s (%q [%s])", desc, path, err)
+		}
+		file.Close()
 	}
-	// Test read permissions
-	file, err := os.Open(kd.CAPath)
-	if err != nil {
-		log.Fatalf("ERROR: Unable to read %s", kd.CAPath)
-	}
-	file.Close()
 
 	router := kd.NewRouter()
 	log.Printf("Listening for requests on port 9898.")

pkg/kubediscovery/handlers.go

@@ -14,45 +14,23 @@ package kubediscovery
 
 import (
 	"encoding/base64"
-	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"io/ioutil"
 	"log"
 	"net/http"
-	"os"
 
 	"github.com/square/go-jose"
 )
 
-// TODO: Just using a hardcoded token for now.
-const tempTokenId string = "TOKENID"
-const tempToken string = "EF1BA4F26DDA9FE2"
+const secretPath = "/tmp/secret"
 
 // CAPath is the expected location of our cluster's CA to be distributed to
 // clients looking to connect. Because we expect to use kubernetes secrets
 // for the time being, this file is expected to be a base64 encoded version
 // of the normal cert PEM.
-const CAPath = "/tmp/secret/ca.pem"
-
-// tokenLoader is an interface for abstracting how we validate
-// token IDs and lookup their corresponding token.
-type tokenLoader interface {
-	// Lookup returns the token for a given token ID, or an error if the token ID
-	// does not exist. Both token and it's ID are expected to be hex encoded strings.
-	Lookup(tokenId string) (string, error)
-}
-
-type hardcodedTokenLoader struct {
-}
-
-func (tl *hardcodedTokenLoader) Lookup(tokenId string) (string, error) {
-	if tokenId == tempTokenId {
-		return tempToken, nil
-	}
-	return "", errors.New(fmt.Sprintf("invalid token: %s", tokenId))
-}
+const CAPath = secretPath + "/ca.pem"
 
 // caLoader is an interface for abstracting how we load the CA certificates
 // for the cluster.
@@ -63,42 +41,94 @@ type caLoader interface {
 // fsCALoader is a caLoader for loading the PEM encoded CA from
 // /tmp/secret/ca.pem.
 type fsCALoader struct {
+	certData string
 }
 
 func (cl *fsCALoader) LoadPEM() (string, error) {
-	file, err := os.Open(CAPath)
-	if err != nil {
-		return "", err
+	if cl.certData != "" {
+		data, err := ioutil.ReadFile(CAPath)
+		if err != nil {
+			return "", err
+		}
+
+		cl.certData = base64.StdEncoding.EncodeToString(data)
 	}
 
-	data, err := ioutil.ReadAll(file)
-	if err != nil {
-		return "", err
-	}
+	return cl.certData, nil
+}
 
-	return string(data), nil
+const TokenMapPath = secretPath + "/token-map.json"
+const EndpointListPath = secretPath + "/endpoint-list.json"
+
+// tokenLoader is an interface for abstracting how we validate
+// token IDs and lookup their corresponding token.
+type tokenLoader interface {
+	// Lookup returns the token for a given token ID, or an error if the token ID
+	// does not exist. Both token and it's ID are expected be strings.
+	LoadAndLookup(tokenID string) (string, error)
+}
+
+type jsonFileTokenLoader struct {
+	tokenMap map[string]string
+}
+
+func (tl *jsonFileTokenLoader) LoadAndLookup(tokenID string) (string, error) {
+	if len(tl.tokenMap) == 0 {
+		data, err := ioutil.ReadFile(TokenMapPath)
+		if err != nil {
+			return "", err
+		}
+		if err := json.Unmarshal(data, &tl.tokenMap); err != nil {
+			return "", err
+		}
+	}
+	if val, ok := tl.tokenMap[tokenID]; ok {
+		return val, nil
+	}
+	return "", errors.New(fmt.Sprintf("invalid token: %s", tokenID))
+}
+
+type endpointsLoader interface {
+	LoadList() ([]string, error)
+}
+
+type jsonFileEnpointsLoader struct {
+	endpoints []string
+}
+
+func (el *jsonFileEnpointsLoader) LoadList() ([]string, error) {
+	if len(el.endpoints) == 0 {
+		data, err := ioutil.ReadFile(EndpointListPath)
+		if err != nil {
+			return nil, err
+		}
+		if err := json.Unmarshal(data, &el.endpoints); err != nil {
+			return nil, err
+		}
+	}
+	return el.endpoints, nil
 }
 
 // ClusterInfoHandler implements the http.ServeHTTP method and allows us to
 // mock out portions of the request handler in tests.
 type ClusterInfoHandler struct {
-	tokenLoader tokenLoader
-	caLoader    caLoader
+	tokenLoader     tokenLoader
+	caLoader        caLoader
+	endpointsLoader endpointsLoader
 }
 
 func NewClusterInfoHandler() *ClusterInfoHandler {
-	tl := hardcodedTokenLoader{}
-	cl := fsCALoader{}
 	return &ClusterInfoHandler{
-		tokenLoader: &tl,
-		caLoader:    &cl,
+		tokenLoader:     &jsonFileTokenLoader{},
+		caLoader:        &fsCALoader{},
+		endpointsLoader: &jsonFileEnpointsLoader{},
 	}
 }
 
 func (cih *ClusterInfoHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
-	tokenId := req.FormValue("token-id")
-	log.Printf("Got token ID: %s", tokenId)
-	token, err := cih.tokenLoader.Lookup(tokenId)
+	tokenID := req.FormValue("token-id")
+	log.Printf("Got token ID: %s", tokenID)
+	token, err := cih.tokenLoader.LoadAndLookup(tokenID)
 	if err != nil {
 		log.Printf("Invalid token: %s", err)
 		http.Error(resp, "Forbidden", http.StatusForbidden)
@@ -106,32 +136,42 @@ func (cih *ClusterInfoHandler) ServeHTTP(resp http.ResponseWriter, req *http.Req
 	}
 	log.Printf("Loaded token: %s", token)
 
+	// TODO probably should not leak server-side errors to the client
 	caPEM, err := cih.caLoader.LoadPEM()
-	caB64 := base64.StdEncoding.EncodeToString([]byte(caPEM))
-
 	if err != nil {
-		http.Error(resp, "Error encoding CA", http.StatusInternalServerError)
+		err = fmt.Errorf("Error loading root CA certificate data: %s", err)
+		log.Println(err)
+		http.Error(resp, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	endpoints, err := cih.endpointsLoader.LoadList()
+	if err != nil {
+		err = fmt.Errorf("Error loading list of API endpoints: %s", err)
+		log.Println(err)
+		http.Error(resp, err.Error(), http.StatusInternalServerError)
 		return
 	}
 
 	clusterInfo := ClusterInfo{
-		Type:             "ClusterInfo",
-		Version:          "v1",
-		RootCertificates: caB64,
+		CertificateAuthorities: []string{caPEM},
+		Endpoints:              endpoints,
 	}
 
 	// Instantiate an signer using HMAC-SHA256.
-	hmacTestKey := fromHexBytes(token)
-	signer, err := jose.NewSigner(jose.HS256, hmacTestKey)
+	signer, err := jose.NewSigner(jose.HS256, []byte(token))
 	if err != nil {
-		http.Error(resp, fmt.Sprintf("Error creating JWS signer: %s", err), http.StatusInternalServerError)
+		err = fmt.Errorf("Error creating JWS signer: %s", err)
+		log.Println(err)
+		http.Error(resp, err.Error(), http.StatusInternalServerError)
 		return
 	}
 
 	payload, err := json.Marshal(clusterInfo)
 	if err != nil {
-		http.Error(resp, fmt.Sprintf("Error serializing clusterInfo to JSON: %s", err),
-			http.StatusInternalServerError)
+		err = fmt.Errorf("Error serializing clusterInfo to JSON: %s", err)
+		log.Println(err)
+		http.Error(resp, err.Error(), http.StatusInternalServerError)
 		return
 	}
 
@@ -140,8 +180,9 @@ func (cih *ClusterInfoHandler) ServeHTTP(resp http.ResponseWriter, req *http.Req
 	// indicate a problem in an underlying cryptographic primitive.
 	jws, err := signer.Sign(payload)
 	if err != nil {
-		http.Error(resp, fmt.Sprintf("Error signing clusterInfo to JSON: %s", err),
-			http.StatusInternalServerError)
+		err = fmt.Errorf("Error signing clusterInfo with JWS: %s", err)
+		log.Println(err)
+		http.Error(resp, err.Error(), http.StatusInternalServerError)
 		return
 	}
 
@@ -153,13 +194,3 @@ func (cih *ClusterInfoHandler) ServeHTTP(resp http.ResponseWriter, req *http.Req
 	resp.Write([]byte(serialized))
 
 }
-
-// TODO: Move into test package
-// TODO: Should we use base64 instead?
-func fromHexBytes(base16 string) []byte {
-	val, err := hex.DecodeString(base16)
-	if err != nil {
-		panic(fmt.Sprintf("Invalid test data: %s", err))
-	}
-	return val
-}

pkg/kubediscovery/model.go

@@ -12,10 +12,9 @@ limitations under the License.
 */
 package kubediscovery
 
-// TODO: Sync with kubeadm api type
 type ClusterInfo struct {
-	Type             string
-	Version          string
-	RootCertificates string `json:"rootCertificates"`
-	// TODO: ClusterID, Endpoints
+	// TODO Kind, apiVersion
+	// TODO clusterId, fetchedTime, expiredTime
+	CertificateAuthorities []string `json:"certificateAuthorities,omitempty"`
+	Endpoints              []string `json:"endpoints,omitempty"`
 }