terrascan argo-cd instructions

docs/cicd.md

@@ -52,3 +52,129 @@ terrascan:
   script:
     - /go/bin/terrascan scan .
 ```
+
+
+## ArgoCD Application PreSync Hooks
+
+
+Terrascan can be configured as a job during the application sync process using [resource hooks](https://argoproj.github.io/argo-cd/user-guide/resource_hooks). The PreSync resource hook is the best way to evaluate the kubernetes deployment configuration and report any violations through notification. 
+
+
+![picture](img/terrascan-argo-cd-pipeline.png)
+
+See example hooks yaml where one can simply add it to an existing kubernetes configuration.
+
+
+``` YAML
+apiVersion: batch/v1
+kind: Job
+metadata:
+  generateName: terrascan-hook-
+  annotations:
+    argocd.argoproj.io/hook: PreSync
+spec:
+  ttlSecondsAfterFinished: 3600
+  template:
+    spec:
+      volumes:
+      - name: secret-volume
+        secret:
+          secretName: ssh-key-secret    
+      containers:
+      - name: terrascan-argocd
+        image: accurics/terrascan-argocd:latest
+        command: ["/bin/ash", "-c"]
+        args:
+        - >
+          cp /etc/secret-volume/ssh-privatekey /home/terrascan/.ssh/id_rsa &&
+          chmod 400 /home/terrascan/.ssh/id_rsa &&
+          /go/bin/terrascan scan -r git -u git@bitbucket.org:example/argo-cd-nginx-sample.git -i k8s -t k8s | /home/terrascan/bin/notify_slack.sh webhook-tests argo-cd https://hooks.slack.com/services/TXXXXXXXX/XXXXXXXXXXX/0XXXXXXXXXXXXXXXXXX
+        volumeMounts:
+          - name: secret-volume
+            readOnly: true
+            mountPath: "/etc/secret-volume"
+      restartPolicy: Never
+  backoffLimit: 1
+```
+
+As shown, the PreSync requires access to the repository and using the same branch (default) as the Argo CD application pipeline. 
+
+For non-public repositories, the private key needs to be added as a kubernetes secret.
+
+``` CONSOLE
+  kubectl create secret generic ssh-key-secret \
+    --from-file=ssh-privatekey=/path/to/.ssh/id_rsa \
+    --from-file=ssh-publickey=/path/to/.ssh/id_rsa.pub
+```
+
+Configuring the job to delete only after the specified time see `ttlSecondsAfterFinished` will allow users to check for violations in the UI w/o having to use the notification, see example below.
+
+![picture](img/terrascan-argo-cd-resource-hook-logs.png)
+
+Below if a full example on building the terrascan-argo-cd integration container. 
+
+`known_hosts`
+
+```
+github.com,192.30.255.113 ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAq2A7hRGmdnm9tUDbO9IDSwBK6TbQa+PXYPCPy6rbTrTtw7PHkccKrpp0yVhp5HdEIcKr6pLlVDBfOLX9QUsyCOV0wzfjIJNlGEYsdlLJizHhbn2mUjvSAHQqZETYP81eFzLQNnPHt4EVVUh7VfDESU84KezmD5QlWpXLmvU31/yMf+Se8xhHTvKSCZIFImWwoG6mbUoWf9nzpIoaSjB+weqqUUmpaaasXVal72J+UX2B+2RPW3RcT0eOzQgqlJL3RKrTJvdsjE3JEAvGq3lGHSZXy28G3skua2SmVi/w4yCE6gbODqnTWlg7+wC604ydGXA8VJiS5ap43JXiUFFAaQ==
+bitbucket.org,104.192.141.1 ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAubiN81eDcafrgMeLzaFPsw2kNvEcqTKl/VqLat/MaB33pZy0y3rJZtnqwR2qOOvbwKZYKiEO1O6VqNEBxKvJJelCq0dTXWT5pbO2gDXC6h6QDXCaHo6pOHGPUy+YBaGQRGuSusMEASYiWunYN0vCAI8QaXnWMXNMdFP3jHAJH0eDsoiGnLPBlBp4TNm6rYI74nMzgz3B9IikW4WVK+dc8KZJZWYjAuORU3jc1c/NPskD2ASinf8v3xnfXeukU0sJ5N6m5E8VLjObPEO+mN2t/FZTMZLiFqPWc/ALSqnMnnhwrNi2rbfg/rd/IpL8Le3pSBne8+seeFVBoGqzHM9yXw==
+gitlab.com,172.65.251.78 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFSMqzJeV9rUzU4kWitGjeR4PWSa29SPqJ1fVkhtj3Hw9xjLVXVYrU9QlYWrOLXBpQ6KWjbjTDTdDkoohFzgbEY=
+```
+
+`notify_slack.sh` the notification example, for this case we used slack.
+
+``` SH
+#!/bin/ash
+
+function send_slack_notificaton {
+  channel=$1
+  username=$2
+  slack_hook=$3
+
+  curl -X POST --data-urlencode payload="{\"channel\": \"#${channel}\", \"username\": \"${username}\", \"text\": \" \`\`\` $(cat results.out) \`\`\` \", \"icon_emoji\": \":ghost:\"}" ${slack_hook}
+}
+
+if [ -p /dev/stdin ]; then
+  echo "processing terrascan results"
+  while IFS= read line; do
+          echo "${line}" | tr '\\"' ' ' >> results.out
+  done
+
+  cat results.out
+
+  send_slack_notificaton $1 $2 $3
+
+  echo "notification exit code: $?"
+else
+  echo "no response skipping"
+fi
+```
+
+`Dockerfile`
+
+``` SH
+  FROM accurics/terrascan:929e377
+
+  ENTRYPOINT []
+
+  USER root 
+
+  RUN apk add --no-cache openssh curl
+
+  WORKDIR /home/terrascan
+
+  RUN mkdir -p .ssh && mkdir -p bin
+
+  COPY known_hosts .ssh
+
+  COPY notify_slack.sh bin/
+
+  RUN chown -R terrascan:terrascan .ssh && \
+      chown -R terrascan:terrascan bin && \
+      chmod 400 .ssh/known_hosts && \
+      chmod u+x bin/notify_slack.sh
+
+  USER terrascan
+
+  CMD ["ash"]
+```