Use config map for storage engine cache size

docs/server/source/production-deployment-template/node-on-kubernetes.rst

@@ -542,7 +542,7 @@ Step 12: Start a Kubernetes StatefulSet for MongoDB
     - ``mdb-certs``
     - ``ca-auth``
 
-  * **Optional**: You can also change the value for ``STORAGE_ENGINE_CACHE_SIZE``, for more information
+  * **Optional**: You can change the value for ``STORAGE_ENGINE_CACHE_SIZE`` in the ConfigMap ``storage-engine-cache-size``, for more information
     regarding this configuration, please consult the `MongoDB Official
     Documentation <https://docs.mongodb.com/manual/reference/configuration-options/#storage.wiredTiger.engineConfig.cacheSizeGB>`_.
 

k8s/configuration/config-map.yaml

@@ -99,6 +99,11 @@ data:
   # WebSocket API in BigchainDB; can be 'ws' or 'wss' (default).
   bigchaindb-wsserver-advertised-scheme: "wss"
 
+  # Optional: Optimize storage engine(wired tiger)
+  # cache size. e.g. (2048MB, 2GB, 1TB), otherwise
+  # it will use the default cache size; i.e. max((50% RAM - 1GB), 256MB)
+  storage-engine-cache-size: ""
+
 ---
 apiVersion: v1
 kind: ConfigMap

k8s/mongodb/mongo-ss.yaml

@@ -43,10 +43,11 @@ spec:
             configMapKeyRef:
              name: vars
              key: mongodb-backend-port
-        # Optional: Optimize storage engine(wired tiger)
-        # cache size. e.g. (2048MB, 2GB, 1TB)
         - name: STORAGE_ENGINE_CACHE_SIZE
-          value: ""
+          valueFrom:
+            configMapKeyRef:
+             name: vars
+             key: storage-engine-cache-size
         args:
         - --mongodb-port
         - $(MONGODB_PORT)