[OOM-K8S-CERT-EXTERNAL-PROVIDER] Add documentation for k8s external provider

Issue-ID: OOM-2560
Signed-off-by: Jan Malkiewicz <jan.malkiewicz@nokia.com>
Change-Id: I76659e1369c2a6ec43f9d31326ff0c43d6a1ccdc

2 files changed, 139 insertions, 0 deletions

diff --git a/docs/index.rst b/docs/index.rst
index 97bfcac3..6d8e329c 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -12,6 +12,7 @@ OOM Certification Service
 
    sections/introduction.rst
    sections/architecture.rst
+   sections/external-provider.rst
    sections/build.rst
    sections/offeredapis.rst
    sections/usage.rst
diff --git a/docs/sections/external-provider.rst b/docs/sections/external-provider.rst
new file mode 100644
index 00000000..2ae1de9b
--- /dev/null
+++ b/docs/sections/external-provider.rst
@@ -0,0 +1,138 @@
+.. This work is licensed under a Creative Commons Attribution 4.0 International License.
+.. http://creativecommons.org/licenses/by/4.0
+.. Copyright 2020 NOKIA
+
+K8s external provider
+==============================
+
+General information
+------------------------------
+
+Cert Service K8s external provider is a part of certificate distribution infrastructure in ONAP.
+The main functionality of the provider is to forward Certificate Signing Requests (CSRs) created by cert-mananger (https://cert-manager.io) to CertServiceAPI.
+
+Additional information can be found on a dedicated page:  https://wiki.onap.org/display/DW/CertService+and+K8s+Cert-Manager+integration.
+
+
+CMPv2 Issuer
+------------------------------
+
+In order to be able to request a certificate via K8s external provider a *CMPv2Issuer* CRD (Customer Resource Definition) instance has to be created.
+
+It is important to note that the attribute *kind* has to be set to **CMPv2Issuer**, all other attributes can be set as needed.
+
+NOTE: a default instance of CMPv2Issuer is created when installing ONAP via OOM deployment (values can also be adjusted as needed)
+
+Here is an example of a *CMPv2Issuer*:
+
+.. code-block:: yaml
+
+  apiVersion: certmanager.onap.org/v1
+  kind: CMPv2Issuer
+  metadata:
+    name: cmpv2-issuer
+    namespace: onap
+  spec:
+    url: https://oom-cert-service:8443
+    healthEndpoint: actuator/health
+    certEndpoint: v1/certificate
+    caName: RA
+    certSecretRef:
+      name: cmpv2-issuer-secret
+      certRef: cmpv2Issuer-cert.pem
+      keyRef: cmpv2Issuer-key.pem
+      cacertRef: cacert.pem
+
+
+Certificate enrolling
+------------------------------
+
+In order to request a certificate a K8s *Certificate* CRD (Custom Resource Definition) has to be created.
+
+It is important that in the section issuerRef following attributes have correct values:
+  - group: **certmanager.onap.org**
+  - kind: **CMPv2Issuer**
+
+After *Certificate* CRD has been placed cert manager will send a *CSR* (Certificate Sign Request) to CA (Certificate Authority) via K8s external provider.
+Signed certificate as well as trust anchor (CA root certificate) will be stored in the K8s *secret* specified in *Certificate* CRD (see secretName attribute).
+
+By default certificates will be stored in PEM format. It is possible to get certificates also in JKS and P12 format - see example below - more information can be found on official cert manager page.
+
+Here is an example of a *Certificate*:
+
+.. code-block:: yaml
+
+  apiVersion: cert-manager.io/v1
+  kind: Certificate
+  metadata:
+    name: certificate_name
+    namespace: onap
+  spec:
+    # The secret name to store the signed certificate
+    secretName: secret_name
+    # Common Name
+    commonName: certissuer.onap.org
+    subject:
+      organizations:
+        - Linux-Foundation
+      countries:
+        - US
+      localities:
+        - San-Francisco
+      provinces:
+        - California
+      organizationalUnits:
+        - ONAP
+    # DNS SAN
+    dnsNames:
+      - localhost
+      - certissuer.onap.org
+    # The reference to the CMPv2 issuer
+    issuerRef:
+      group: certmanager.onap.org
+      kind: CMPv2Issuer
+      name: cmpv2-issuer
+    # Section keystores is optional and defines in which format certificates will be stored
+    # If this section is omitted than only PEM format will be present in the secret
+    keystores:
+        jks:
+          create: true
+          passwordSecretRef: # Password used to encrypt the keystore
+            name: certservice-key
+            key: key
+        pkcs12:
+          create: true
+          passwordSecretRef: # Password used to encrypt the keystore
+            name: certservice-key
+            key: key
+
+
+Here is an example of generated *secret* containing certificates:
+
+.. code-block:: yaml
+
+    Name:         secret_name
+    Namespace:    onap
+    Labels:       <none>
+    Annotations:  cert-manager.io/alt-names: localhost,certissuer.onap.org
+                  cert-manager.io/certificate-name: certificate_name
+                  cert-manager.io/common-name: certissuer.onap.org
+                  cert-manager.io/ip-sans:
+                  cert-manager.io/issuer-group: certmanager.onap.org
+                  cert-manager.io/issuer-kind: CMPv2Issuer
+                  cert-manager.io/issuer-name: cmpv2-issuer-onap
+                  cert-manager.io/uri-sans:
+
+    Type:  kubernetes.io/tls
+
+    Data
+    ====
+    tls.crt:         1675 bytes  <-- Certificate (PEM)
+    tls.key:         1679 bytes  <-- Private Key (PEM)
+    truststore.jks:  1265 bytes  <-- Trusted anchors (JKS)
+    ca.crt:          1692 bytes  <-- Trusted anchors (PEM)
+    keystore.jks:    3786 bytes  <-- Certificate and Private Key (JKS)
+    keystore.p12:    4047 bytes  <-- Certificate and Private Key (P12)
+
+
+