fix(common): limit default emptydir size for memory emptyDir (#604)

**Description**
Currently emptyDir ramdisks are set to have unlimited size.
This puts a limit to that, sized in accordance to
.values.resources.limits.memory

Yes this means an App consuming all space in an emptyDir can exceed the
limits, but at least it prevents attacks where host OOMs can be
triggered by oversaturating a memory-backed emptyDir

⚒️ Fixes  #602 

**⚙️ Type of change**

- [ ] ⚙️ Feature/App addition
- [x] 🪛 Bugfix
- [ ] ⚠️ Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] 🔃 Refactor of current code

**🧪 How Has This Been Tested?**
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**📃 Notes:**
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**✔️ Checklist:**

- [ ] ⚖️ My code follows the style guidelines of this project
- [ ] 👀 I have performed a self-review of my own code
- [ ] #️⃣ I have commented my code, particularly in hard-to-understand
areas
- [ ] 📄 I have made corresponding changes to the documentation
- [ ] ⚠️ My changes generate no new warnings
- [ ] 🧪 I have added tests to this description that prove my fix is
effective or that my feature works
- [ ] ⬆️ I increased versions for any altered app according to semantic
versioning

**➕ App addition**

If this PR is an app addition please make sure you have done the
following.

- [ ] 🪞 I have opened a PR on
[truecharts/containers](https://github.com/truecharts/containers) adding
the container to TrueCharts mirror repo.
- [ ] 🖼️ I have added an icon in the Chart's root directory called
`icon.png`

---

_Please don't blindly check all the boxes. Read them and only check
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---------

Co-authored-by: Stavros kois <s.kois@outlook.com>
Co-authored-by: Stavros Kois <47820033+stavros-k@users.noreply.github.com>

library/common-test/tests/addons/autoperms_test.yaml

@@ -175,6 +175,7 @@ tests:
             name: tmp
             emptyDir:
               medium: Memory
+              sizeLimit: 8Gi
       - documentIndex: *jobDoc
         contains:
           path: spec.template.spec.containers[0].volumeMounts
@@ -511,6 +512,7 @@ tests:
             name: tmp
             emptyDir:
               medium: Memory
+              sizeLimit: 8Gi
       - documentIndex: *jobDoc
         contains:
           path: spec.template.spec.containers[0].volumeMounts

library/common-test/tests/defaults/defaults-test.yaml

@@ -90,17 +90,21 @@ tests:
               - name: devshm
                 emptyDir:
                   medium: Memory
+                  sizeLimit: 8Gi
               - name: shared
                 emptyDir: {}
               - name: tmp
                 emptyDir:
                   medium: Memory
+                  sizeLimit: 8Gi
               - name: varlogs
                 emptyDir:
                   medium: Memory
+                  sizeLimit: 8Gi
               - name: varrun
                 emptyDir:
                   medium: Memory
+                  sizeLimit: 8Gi
       - documentIndex: *deploymentDoc
         isSubset:
           path: spec.template.spec.containers[0]

library/common-test/tests/pod/volume_emptyDIr_test.yaml

@@ -81,6 +81,7 @@ tests:
             name: emptyDir-vol
             emptyDir:
               medium: Memory
+              sizeLimit: 8Gi
 
   - it: should pass with emptyDir volume with size set
     set:
@@ -107,6 +108,65 @@ tests:
             emptyDir:
               sizeLimit: 3Gi
 
+  - it: should pass with emptyDir volume with medium Memory and size from resource limits
+    set:
+      resources:
+        limits:
+          memory: 500Mi
+      workload:
+        workload-name1:
+          enabled: true
+          primary: true
+          type: Deployment
+          podSpec: {}
+      persistence:
+        emptyDir-vol:
+          enabled: true
+          type: emptyDir
+          medium: Memory
+    asserts:
+      - documentIndex: &deploymentDoc 0
+        isKind:
+          of: Deployment
+      - documentIndex: *deploymentDoc
+        contains:
+          path: spec.template.spec.volumes
+          content:
+            name: emptyDir-vol
+            emptyDir:
+              medium: Memory
+              sizeLimit: 500Mi
+
+  - it: should pass with emptyDir volume with medium Memory and size override
+    set:
+      resources:
+        limits:
+          memory: 500Mi
+      workload:
+        workload-name1:
+          enabled: true
+          primary: true
+          type: Deployment
+          podSpec: {}
+      persistence:
+        emptyDir-vol:
+          enabled: true
+          type: emptyDir
+          medium: Memory
+          size: 1Gi
+    asserts:
+      - documentIndex: &deploymentDoc 0
+        isKind:
+          of: Deployment
+      - documentIndex: *deploymentDoc
+        contains:
+          path: spec.template.spec.volumes
+          content:
+            name: emptyDir-vol
+            emptyDir:
+              medium: Memory
+              sizeLimit: 1Gi
+
 # Failures
   - it: should fail with invalid medium in emptyDir
     set:

library/common/templates/lib/pod/volumes/_emptyDir.tpl

@@ -23,6 +23,8 @@ objectData: The object data to be used to render the volume.
       {{- $formats := "(Suffixed with E/P/T/G/M/K - eg. 1G), (Suffixed with Ei/Pi/Ti/Gi/Mi/Ki - eg. 1Gi), (Plain Integer in bytes - eg. 1024), (Exponent - eg. 134e6)" -}}
       {{- fail (printf "Persistence Expected [size] to have one of the following formats [%s], but got [%s]" $formats $size) -}}
     {{- end -}}
+  {{- else if eq $medium "Memory" -}}
+    {{- $size = $rootCtx.Values.resources.limits.memory -}}
   {{- end -}}
 
   {{- if and $medium (ne $medium "Memory") -}}