Certificates and security on Linux clusters

Article
08/22/2024

This article provides information about configuring X.509 certificates on Linux clusters.

Location and format of X.509 certificates on Linux nodes

Service Fabric generally expects X.509 certificates to be present in the /var/lib/sfcerts directory on Linux cluster nodes. This is true of cluster certificates, client certificates, etc. In some cases, you can specify a location other than the var/lib/sfcerts folder for certificates. For example, with Reliable Services built using the Service Fabric Java SDK, you can specify a different location through the configuration package (Settings.xml) for some application-specific certificates. To learn more, see Certificates referenced in the configuration package (Settings.xml).

For Linux clusters, Service Fabric expects certificates to be present as either a .pem file that contains both the certificate and private key or as a .crt file that contains the certificate and a .key file that contains the private key. All files should be in PEM format.

If you install your certificate from Azure Key Vault by using either a Resource Manager template or PowerShell commands, the certificate is installed in the correct format in the /var/lib/sfcerts directory on each node. If you install a certificate through another method, you must make sure that the certificate is correctly installed on cluster nodes.

Certificates referenced in the application manifest

Certificates specified in the application manifest, for example, through the SecretsCertificate or EndpointCertificate elements, must be present in the /var/lib/sfcerts directory. The elements that are used to specify certificates in the application manifest do not take a path attribute, so the certificates must be present in the default directory. These elements do take an optional X509StoreName attribute. The default is "My", which points to the /var/lib/sfcerts directory on Linux nodes. Any other value is undefined on a Linux cluster. We recommend that you omit the X509StoreName attribute for apps that run on Linux clusters.

Certificates referenced in the configuration package (Settings.xml)

For some services, you can configure X.509 certificates in the ConfigPackage (by default, Settings.xml). For example, this is the case when you declare certificates used to secure RPC channels for Reliable Services services built with the Service Fabric .NET Core or Java SDKs. There are two ways to reference certificates in the configuration package. Support varies between the .NET Core and Java SDKs.

Using X509 SecurityCredentialsType

WIth the .NET or Java SDKs, you can specify X509 for the SecurityCredentialsType. This corresponds to the X509Credentials (.NET/Java) type of SecurityCredentials (.NET/Java).

The X509 reference locates the certificate in a certificate store. The following XML shows the parameters used to specify the location of the certificate:

    <Parameter Name="SecurityCredentialsType" Value="X509" />
    <Parameter Name="CertificateStoreLocation" Value="LocalMachine" />
    <Parameter Name="CertificateStoreName" Value="My" />

For a service running on Linux, LocalMachine/My points to the default location for certificates, the /var/lib/sfcerts directory. For Linux, any other combinations of CertificateStoreLocation and CertificateStoreName are undefined.

Always specify LocalMachine for the CertificateStoreLocation parameter. There is no need to specify the CertificateStoreName parameter because it defaults to "My". With an X509 reference, the certificate files must be located in the /var/lib/sfcerts directory on the cluster node.

The following XML shows a TransportSettings section based on this style:

<Section Name="HelloWorldStatefulTransportSettings">
    <Parameter Name="MaxMessageSize" Value="10000000" />
    <Parameter Name="SecurityCredentialsType" Value="X509" />
    <Parameter Name="CertificateFindType" Value="FindByThumbprint" />
    <Parameter Name="CertificateFindValue" Value="4FEF3950642138446CC364A396E1E881DB76B48C" />
    <Parameter Name="CertificateRemoteThumbprints" Value="9FEF3950642138446CC364A396E1E881DB76B483" />
    <Parameter Name="CertificateStoreLocation" Value="LocalMachine" />
    <Parameter Name="CertificateProtectionLevel" Value="EncryptAndSign" />
    <Parameter Name="CertificateRemoteCommonNames" Value="ServiceFabric-Test-Cert" />
</Section>

Using X509_2 SecurityCredentialsType

With the Java SDK, you can specify X509_2 for the SecurityCredentialsType. This corresponds to the X509Credentials2 (Java) type of SecurityCredentials (Java).

With an X509_2 reference, you specify a path parameter, so you can locate the certificate in a directory other than /var/lib/sfcerts. The following XML shows the parameters used to specify the location of the certificate:

     <Parameter Name="SecurityCredentialsType" Value="X509_2" />
     <Parameter Name="CertificatePath" Value="/path/to/cert/BD1C71E248B8C6834C151174DECDBDC02DE1D954.crt" />

The following XML shows a TransportSettings section based on this style.

<!--Section name should always end with "TransportSettings".-->
<!--Here we are using a prefix "HelloWorldStateless".-->
<Section Name="HelloWorldStatelessTransportSettings">
    <Parameter Name="MaxMessageSize" Value="10000000" />
    <Parameter Name="SecurityCredentialsType" Value="X509_2" />
    <Parameter Name="CertificatePath" Value="/path/to/cert/BD1C71E248B8C6834C151174DECDBDC02DE1D954.crt" />
    <Parameter Name="CertificateProtectionLevel" Value="EncryptandSign" />
    <Parameter Name="CertificateRemoteThumbprints" Value="BD1C71E248B8C6834C151174DECDBDC02DE1D954" />
</Section>

Note

The certificate is specified as a .crt file in the preceding XML. This implies that there is also a .key file containing the private key in the same location.

Configure a Reliable Services app to run on Linux clusters

The Service Fabric SDKs allow you to communicate with the Service Fabric runtime APIs to leverage the platform. When you run any application that uses this functionality on secure Linux clusters, you need to configure your application with a certificate that it can use to validate with the Service Fabric runtime. Applications that contain Service Fabric Reliable Service services written using the .NET Core or Java SDKs require this configuration.

To configure an application, add a SecretsCertificate element under the Certificates tag, which is located under the ApplicationManifest tag in the ApplicationManifest.xml file. The following XML shows a certificate referenced by its thumbprint:

   <Certificates>
       <SecretsCertificate X509FindType="FindByThumbprint" X509FindValue="0A00AA0AAAA0AAA00A000000A0AA00A0AAAA00" />
   </Certificates>

You can reference either the cluster certificate or a certificate that you install on each cluster node. On Linux, the certificate files must be present in the /var/lib/sfcerts directory. To learn more, see Location and format of X.509 certificates on Linux nodes.

Share via