First draft for declarative combined scans

Author: zzzFelix

docs/user-guide/README.md

@@ -1,3 +1,123 @@
 # Using the secureCodeBox
 
-follwing...
+## Declarative Combines Scans
+### Install Hook
+Installing the Declarative Combined Scan hook will add a ReadOnly Hook to your namespace which looks for matching CascadingRules in the namespace and start subsequent scans accordingly.
+
+```bash
+helm install combined-scans ./hooks/declarative-subsequent-scans
+```
+
+### Verify Hook Installation
+
+Successful installation can be verified by retrieving installed ScanCompletionHooks.
+
+```bash
+$ kubectl get ScanCompletionHooks
+```
+
+The result should contain a hook for declarative subsequent scans.
+
+```bash
+NAME                                          TYPE       IMAGE
+combined-scans-declarative-subsequent-scans   ReadOnly   docker.io/scbexperimental/hook-declarative-subsequent-scans:latest
+```
+
+### Verify CascadingRules
+
+CascadingRules are included in each individual scanner's Helm chart.
+
+```bash
+$ kubectl get CascadingRules
+```
+Output should show these CascadingRules:
+
+```bash
+NAME             STARTS         INVASIVENESS   INTENSIVENESS
+https-tls-scan   sslyze         non-invasive   light
+imaps-tls-scan   sslyze         non-invasive   light
+nikto-http       nikto          non-invasive   medium
+nmap-smb         nmap           non-invasive   light
+pop3s-tls-scan   sslyze         non-invasive   light
+smtps-tls-scan   sslyze         non-invasive   light
+ssh-scan         ssh-scan       non-invasive   light
+zap-http         zap-baseline   non-invasive   medium
+```
+
+### Start Scans
+
+When you start a normal Scan, no CascadingRule will be applied.
+To use CascadingRules the scan must be marked to allow cascading rules.
+This is implemented using kubernetes label selectors, meaning that scans mark the classes of scans which are allowed to be cascaded by the current one.
+
+### Example
+
+```bash
+cat <<EOF | kubectl apply -f -
+apiVersion: "execution.experimental.securecodebox.io/v1"
+kind: Scan
+metadata:
+  name: "example.com"
+spec:
+  scanType: nmap
+  parameters:
+    - -p22,80,443
+    - example.com
+  cascades:
+    matchLabels:
+      securecodebox.io/intensive: light
+EOF
+```
+
+This Scan will used all CascadingRules which are labeled with a "light" intensity.
+
+You can lookup which CascadingRules this selects by running:
+
+```bash
+$ kubectl get CascadingRules -l "securecodebox.io/intensive=light"
+NAME             STARTS     INVASIVENESS   INTENSIVENESS
+https-tls-scan   sslyze     non-invasive   light
+imaps-tls-scan   sslyze     non-invasive   light
+nmap-smb         nmap       non-invasive   light
+pop3s-tls-scan   sslyze     non-invasive   light
+smtps-tls-scan   sslyze     non-invasive   light
+ssh-scan         ssh-scan   non-invasive   light
+```
+
+The label selectors also allow the more powerful [matchExpression](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#set-based-requirement) selectors:
+
+```bash
+cat <<EOF | kubectl apply -f -
+apiVersion: "execution.experimental.securecodebox.io/v1"
+kind: Scan
+metadata:
+  name: "example.com"
+spec:
+  scanType: nmap
+  parameters:
+    - -p22,80,443
+    - example.com
+  cascades:
+    # Using matchExpression instead of matchLabels
+    matchExpression:
+      key: "securecodebox.io/intensive"
+      operator: In
+      # This select both light and medium intensity rules
+      values: [light, medium]
+EOF
+```
+
+This selection can be replicated in kubectl using:
+
+```bash
+kubectl get CascadingRules -l "securecodebox.io/intensive in (light,medium)"
+NAME             STARTS         INVASIVENESS   INTENSIVENESS
+https-tls-scan   sslyze         non-invasive   light
+imaps-tls-scan   sslyze         non-invasive   light
+nikto-http       nikto          non-invasive   medium
+nmap-smb         nmap           non-invasive   light
+pop3s-tls-scan   sslyze         non-invasive   light
+smtps-tls-scan   sslyze         non-invasive   light
+ssh-scan         ssh-scan       non-invasive   light
+zap-http         zap-baseline   non-invasive   medium
+```