Update DCAE TLS enablement documentation

Issue-ID: DCAEGEN2-2062
Signed-off-by: Jack Lucas <jflucas@research.att.com>
Change-Id: I4c385518fcf0749570cf5dab267b1ee0df6de202
diff --git a/docs/sections/tls_enablement.rst b/docs/sections/tls_enablement.rst
index 0e469b8..c42c476 100644
--- a/docs/sections/tls_enablement.rst
+++ b/docs/sections/tls_enablement.rst
@@ -4,41 +4,66 @@
 TLS Support
 ===========
 
-To comply with ONAP security requirement, all services exposing external API required TLS support using AAF generated certificates. DCAE Platform was updated in R3 to enable certificate distribution mechanism for services needing TLS support.
+To comply with ONAP security requirement, all services exposing external API required TLS support using AAF generated certificates. DCAE Platform was updated in R3 to enable certificate distribution mechanism for services needing TLS support. For R6, we have moved from generating certificates manually to retrieving certificates from AAF at deployment time.
 
 Solution overview
 -----------------
-1. Certificate generation:
-    This step is done manually currently using Test AAF instance in POD25. Required namespace,  DCAE identity (dcae@dcae.onap.org), roles and Subject Alternative Names for all components are preset. Using the procedure desribed by AAF (using ``agent.sh``), the certificates are generated. Using the Java keystore file  (``.jks``)  generated from AAF, create the .pem files and load them into tls-init-container under dcaegen2/deployment repository. The image has a script that runs when the image is deployed. The script copies the certificate artifacts into a Kubernetes volume. The container is used as an "init-container" included in the Kubernetes pod for a component that needs to use TLS.
+1. Certificate setup:
+
+    AAF requires setting up certificate details in AAF manually before a certificate is generated.
+    This step is currently done using a test AAF instance in POD25.
+    Required namespace,  DCAE identity (dcae@dcae.onap.org), roles and Subject Alternative Names for all components are set in the test instance.
+    We use a single certificate for all DCAE components, with a long list of Subject Alternative Names (SANs).
 
     Current SAN listing::
 
         bbs-event-processor, bbs-event-processor.onap, bbs-event-processor.onap.svc.cluster.local, config-binding-service, config-binding-service.onap, config-binding-service.onap.svc.cluster.local, dcae-cloudify-manager, dcae-cloudify-manager.onap, dcae-cloudify-manager.onap.svc.cluster.local, dcae-datafile-collector, dcae-datafile-collector.onap, dcae-datafile-collector.onap.svc.cluster.local, dcae-hv-ves-collector, dcae-hv-ves-collector.onap, dcae-hv-ves-collector.onap.svc.cluster.local, dcae-pm-mapper, dcae-pm-mapper.onap, dcae-pm-mapper.onap.svc.cluster.local, dcae-prh, dcae-prh.onap, dcae-prh.onap.svc.cluster.local, dcae-tca-analytics, dcae-tca-analytics.onap, dcae-tca-analytics.onap.svc.cluster.local, dcae-ves-collector, dcae-ves-collector.onap, dcae-ves-collector.onap.svc.cluster.local, deployment-handler, deployment-handler.onap, deployment-handler.onap.svc.cluster.local, holmes-engine-mgmt, holmes-engine-mgmt.onap, holmes-engine-mgmt.onap.svc.cluster.local, holmes-rule-mgmt, holmes-rules-mgmt.onap, holmes-rules-mgmt.onap.svc.cluster.local, inventory, inventory.onap, inventory.onap.svc.cluster.local, policy-handler, policy-handler.onap, policy-handler.onap.svc.cluster.local
 
-2. Plugin and Blueprint:
-    Update blueprint to include new (optional) node property (tls_info) to the type definitions for the Kubernetes component types. The property is a dictionary with two elements:
+2. Certificate generation and retrieval:
+
+   When a DCAE component that needs a TLS certificate is launched, a Kubernetes init container runs before the main
+   component container is launched.  The init container contacts the AAF certificate manager server.  The AAF certificate
+   management server generates a certificate based on the information previously set up in step 1 above and sends the certificate
+   (in several formats) along with keys and passwords to the init container.  The init container renames the files to conform to
+   DCAE naming conventions and creates some additional formats.  It stores the results into a volume that's shared with
+   the main component container.
+
+   DCAE platform components are deployed via ONAP OOM.  The Helm chart for each deployment includes the init container
+   and sets up the shared volume.
+
+   DCAE service components (sometimes called "microservices") are deployed via Cloudify using blueprints.  This is described
+   in more detail in the next section.
+
+3. Plugin and Blueprint:
+    The blueprint for a component that needs a TLS certificate needs to include the node property called "tls_info" in
+    the node properties for the component. The property is a dictionary with two elements:
 
         * A boolean (``use_tls``) that indicates whether the component uses TLS.
         * A string (``cert_directory``) that indicates where the component expects to find certificate artifacts.
 
         Example
+
 .. code-block:: yaml
 
         tls_info:
            cert_directory: '/opt/app/dh/etc/cert'
            use_tls: true
+
 (Note that the ``cert_directory`` value does not include a trailing ``/``.)
 
-For this example the certificates are mounted into /opt/app/dh/etc/cert directory within the conainer.
-
+For this example the certificates are mounted into ``/opt/app/dh/etc/cert`` directory within the container.
 
     During deployment Kubernetes plugin (referenced in blueprint) will check if the ``tls_info`` property is set and ``use_tls`` is set to true, then the plugin will add some elements to the Kubernetes Deployment for the component:
           * A Kubernetes volume (``tls-info``) that will hold the certificate artifacts
           * A Kubernetes initContainer (``tls-init``)
-          * A Kubernetes volumeMount for the initContainer that mounts the ``tls-info`` volume at ``/opt/tls/shared``.
+          * A Kubernetes volumeMount for the initContainer that mounts the ``tls-info`` volume at ``/opt/app/osaaf``.
           * A Kubernetes volumeMount for the main container that mounts the ``tls-info`` volume at the mount point specified in the ``cert_directory`` property.
 
-3. Certificate Artifacts
+Service components that act as HTTPS clients only need access to the root CA certificate used by AAF.  For R6, such
+components should set up a tls_info property as described above.  See below for a note about an alternative approach
+that is available in R6 but is not currently being used.
+
+4. Certificate artifacts
 
     The certificate directory mounted on the container will include the following files:
         * ``cert.jks``: A Java keystore containing the DCAE certificate.
@@ -50,3 +75,39 @@
         * ``cert.pem``: The DCAE certificate concatenated with the intermediate CA certficate from AAF, in PEM form.
         * ``key.pem``: The private key for the DCAE certificate. The key is not encrypted.
         * ``cacert.pem``: The AAF CA certificate, in PEM form.  (Needed by clients that access TLS-protected servers.)
+
+5. Alternative for getting CA certificate only
+
+    The certificates generated by AAF are signed by AAF, not by a recognized certificate authority (CA).  If a component acts
+    as a client and makes an HTTPS request to another component, it will not be able to validate the other component's
+    server certificate because it will not recognize the CA.  Most HTTPS client library software will raise an error
+    and drop the connection.  To prevent this, the client component needs to have a copy of the AAF CA certificate.
+    As noted in section 3 above, one way to do this is to set up the tls_info property as described in section 3 above.
+
+    There are alternatives.  In R6, two versions of the DCAE k8splugin are available: version 1.7.2 and version 2.0.0.
+    They behave differently with respect to setting up the CA certs.
+
+    * k8splugin version 1.7.2 will automatically mount the CA certificate, in PEM format, at ``/opt/dcae/cacert/cacert.pem``.
+      It is not necessary to add anything to the blueprint.  To get the CA certificate in PEM format in a different directory,
+      add a  ``tls_info`` property to the blueprint, set ``use_tls`` to ``false``, and set ``cert_directory`` to the directory
+      where the CA cert is needed.  For example:
+
+      .. code-block:: yaml
+
+            tls_info:
+               cert_directory: '/opt/app/certs'
+               use_tls: false
+
+      For this example, the CA certificate would be mounted at ``/opt/app/certs/cacert.pem``.
+
+      k8splugin version 1.7.2 uses a configmap, rather than an init container, to supply the CA certificate.
+
+    * k8splugin version 2.0.0 will automatically mount the CA certificate, in PEM and JKS formats, in the directory ``/opt/dcae/cacert``.
+      It is not necessary to add anything to the blueprint.  To get the CA certificates in a different directory, add a ``tls_info`` property to the blueprint, set ``use_tls`` to ``false``, and set ``cert_directory`` to the directory
+      where the CA certs are needed.  Whatever directory is used, the following files will be available:
+
+      * ``trust.jks``: A Java truststore containing the AAF CA certificate.  (Needed by clients that access TLS-protected servers.)
+      * ``trust.pass``: A text file with a single line that contains the password for the ``trust.jks`` keystore.
+      * ``cacert.pem``: The AAF CA certificate, in PEM form.  (Needed by clients that access TLS-protected servers.)
+
+      k8splugin version 2.0.0 uses an init container to supply the CA certificates.
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