Copy trust store to /tmp to work with readonly fs

Co-authored-by: Sumit Kulhadia <sumit.kulhadia@sap.com>

helper/openssl_certificate_loader.go

@@ -19,28 +19,68 @@ package helper
 import (
 	"fmt"
 	"os"
+	"path/filepath"
 
 	"github.com/paketo-buildpacks/libpak/bard"
+	"github.com/paketo-buildpacks/libpak/sherpa"
+	"golang.org/x/sys/unix"
 
 	"github.com/paketo-buildpacks/libjvm"
 )
 
+var TmpTrustStore = filepath.Join(os.TempDir(), "truststore")
+
 type OpenSSLCertificateLoader struct {
 	CertificateLoader libjvm.CertificateLoader
 	Logger            bard.Logger
 }
 
+func (o OpenSSLCertificateLoader) prepareTempTrustStore(trustStore, tempTrustStore string) (map[string]string, error) {
+	o.Logger.Infof("Using readonly truststore: %s", tempTrustStore)
+
+	trustStoreFile, err := os.Open(trustStore)
+	if err != nil {
+		return nil, fmt.Errorf("unable to open trust store %s\n%w", trustStore, err)
+	}
+	defer trustStoreFile.Close()
+
+	err = sherpa.CopyFile(trustStoreFile, tempTrustStore)
+	if err != nil {
+		return nil, fmt.Errorf("unable to copy dir (%s, %s)\n%w", trustStore, tempTrustStore, err)
+	}
+
+	opts := sherpa.AppendToEnvVar("JAVA_TOOL_OPTIONS", " ", fmt.Sprintf("-Djavax.net.ssl.trustStore=%s", tempTrustStore))
+	o.Logger.Debugf("changed JAVA_TOOL_OPTIONS: '%s'", opts)
+
+	return map[string]string{"JAVA_TOOL_OPTIONS": opts}, nil
+}
+
 func (o OpenSSLCertificateLoader) Execute() (map[string]string, error) {
-	k, ok := os.LookupEnv("BPI_JVM_CACERTS")
+	trustStore, ok := os.LookupEnv("BPI_JVM_CACERTS")
 	if !ok {
 		return nil, fmt.Errorf("$BPI_JVM_CACERTS must be set")
 	}
 
+	trustStoreWriteable := true
+	if unix.Access(trustStore, unix.W_OK) != nil {
+		trustStoreWriteable = false
+	}
+
+	var opts map[string]string
+	if !trustStoreWriteable {
+		tmpOpts, err := o.prepareTempTrustStore(trustStore, TmpTrustStore)
+		if err == nil {
+			trustStore = TmpTrustStore
+			opts = tmpOpts
+		}
+	}
+
 	o.CertificateLoader.Logger = o.Logger.InfoWriter()
 
-	if err := o.CertificateLoader.Load(k, "changeit"); err != nil {
+	if err := o.CertificateLoader.Load(trustStore, "changeit"); err != nil {
 		return nil, fmt.Errorf("unable to load certificates\n%w", err)
 	}
 
-	return nil, nil
+	return opts, nil
+
 }

helper/openssl_certificate_loader_test.go

@@ -17,6 +17,7 @@
 package helper_test
 
 import (
+	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
@@ -79,6 +80,7 @@ func testOpenSSLCertificateLoader(t *testing.T, context spec.G, it spec.S) {
 
 		it.After(func() {
 			Expect(os.Unsetenv("BPI_JVM_CACERTS")).To(Succeed())
+			_ = os.Remove(helper.TmpTrustStore)
 		})
 
 		it("loads additional certificates", func() {
@@ -100,12 +102,37 @@ func testOpenSSLCertificateLoader(t *testing.T, context spec.G, it spec.S) {
 			return
 		}
 
-		it("does not return error when keystore is read-only", func() {
+		it("does use temp keystore if keystore is read-only", func() {
 			Expect(os.Chmod(path, 0555)).To(Succeed())
 
 			o := helper.OpenSSLCertificateLoader{CertificateLoader: cl, Logger: bard.NewLogger(ioutil.Discard)}
 
-			Expect(o.Execute()).To(BeNil())
+			env, err := o.Execute()
+			Expect(err).NotTo(HaveOccurred())
+
+			in, err := os.Open(helper.TmpTrustStore)
+			Expect(err).NotTo(HaveOccurred())
+			defer in.Close()
+
+			ks := keystore.New()
+			err = ks.Load(in, []byte("changeit"))
+			Expect(err).NotTo(HaveOccurred())
+			Expect(ks.Aliases()).To(HaveLen(1))
+
+			Expect(env).To(HaveKeyWithValue("JAVA_TOOL_OPTIONS", fmt.Sprintf("-Djavax.net.ssl.trustStore=%s", helper.TmpTrustStore)))
+		})
+
+		it("does not return error when keystore and /tmp/truststore are read-only", func() {
+			Expect(os.Chmod(path, 0555)).To(Succeed())
+			_, err := os.OpenFile(helper.TmpTrustStore, os.O_CREATE, 0)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(os.Chmod(helper.TmpTrustStore, 0555)).To(Succeed())
+
+			o := helper.OpenSSLCertificateLoader{CertificateLoader: cl, Logger: bard.NewLogger(os.Stdout)}
+
+			env, err := o.Execute()
+			Expect(env).To(BeNil())
+			Expect(err).NotTo(HaveOccurred())
 
 			in, err := os.Open(path)
 			Expect(err).NotTo(HaveOccurred())
@@ -116,6 +143,7 @@ func testOpenSSLCertificateLoader(t *testing.T, context spec.G, it spec.S) {
 			Expect(err).NotTo(HaveOccurred())
 			Expect(ks.Aliases()).To(HaveLen(1))
 		})
+
 	})
 
 }