CH-288 add support for RWX volumes by filippomc · Pull Request #862 · MetaCell/cloud-harness

filippomc · 2026-08-31T14:35:10Z

Implemented solution

ReadWriteMany support at the application level, and a configurable storage class for every auto-created volume (standard was hardcoded in the templates).

Setting	Default	Meaning
`harness.deployment.volume.writeMany`	`false`	Create and mount the volume as ReadWriteMany
`harness.deployment.volume.storageClass`	`standard`	Storage class of the volume claim, overrides the deployment default
`harness.database.storageClass`	`-` (default)	Storage class of the database volume claim (plain, statefulset and CNPG operator storage); `null` omits it

A ReadWriteMany volume attaches to several nodes, so its pods are not pinned: no podAffinity, no Recreate strategy, and a statefulset keeps mounting the shared PVC instead of provisioning one per replica.
Argo workflows are covered too: volume_requires_affinity resolves ReadWriteMany from the application configuration, so a workflow mounting a writeMany application volume gets no usesvolume affinity, without needing the :rwx marker (still honoured for claims no application declares).
Storage class resolution: usenfs → volume storageClass → harness.deployment.storageClass → standard when the key is absent (values generated before this change render as today).
usenfs is now legacy sugar for writeMany + the nfs provisioner class, and the nfs settings prevail: harness-deployment warns on collision (sets usenfs and storageClass efs-sc: the nfs server storage class prevails).
Database volumes stay ReadWriteOnce by design.

Deployment update required (alert:deployment): the database PVC previously emitted no storageClassName and now emits standard, which is immutable on an existing claim. Clusters whose default class is standard (minikube, kind, GKE) are unaffected (no-op patch); on EKS/AKS set harness.database.storageClass to the cluster class or to null before upgrading a release that already has a database volume, otherwise helm upgrade is rejected. Same for flipping writeMany or the storage class on a live volume: the claim must be recreated and the data is not migrated.

How to test this PR

conda activate ch
cd tools/deployment-cli-tools && pytest tests/test_helm.py     # 41 tests, incl. the 3 new volume ones
cd ../../libraries/cloudharness-common && pytest tests/test_workflow.py

Manually, on an application with harness.deployment.volume:

writeMany: true → the PVC is ReadWriteMany and the Deployment has no strategy: Recreate and no affinity.
storageClass: efs-sc on the volume → storageClassName: efs-sc; harness.deployment.storageClass: null with no volume class → no storageClassName at all.
usenfs: true together with storageClass/writeMany: false → the PVC gets the nfs class and ReadWriteMany, and harness-deployment logs the collision warnings.
harness.database.storageClass → standard by default on the database PVC, null omits it.

Sanity checks:

The pull request is explicitly linked to the relevant issue(s)
The issue is well described: clearly states the problem and the general proposed solution(s)
In this PR it is explicitly stated how to test the current change
The issue seta the scope and the type of issue (bug, story, task, etc.)
The relevant components are indicated in the issue (if any)
All the automated test checks are passing
All the linked issues are included in one Sprint
All the linked issues are in the Review state
All the linked issues are assigned

Breaking changes (select one):

The present changes do not change the preexisting api in any way
This PR and the issue are tagged as a breaking-change and the migration procedure is well described above

Possible deployment updates issues (select one):

There is no reason why deployments based on CloudHarness may break after the current update
This PR and the issue are tagged as alert:deployment because might need to delete stateful sets

Test coverage (select one):

Tests for the relevant cases are included in this pr
The changes included in this pr are out of the current test coverage scope

Documentation (select one):

The documentation has been updated to match the current changes
The changes included in this PR are out of the current documentation scope

Nice to have (if relevant):

Screenshots of the changes
Explanatory video/animated gif

afonsobspinto · 2026-08-31T14:57:00Z

This is going to be useful for neuroglass skeleton ingestion 👍

aranega

@filippomc All looks good :) thanks a lot for the quick implementation!

aranega

I reviewed the delta between the last version and my last acceptance, all looks good :)

+import {
+    WriteFile200ResponseFromJSON,
+    WriteFile200ResponseToJSON,
+    WriteFileRequestFromJSON,
+    WriteFileRequestToJSON,
+} from '../models/index';


+ * Do not edit the class manually.
+ */
+
+import { mapValues } from '../runtime';


+ * Do not edit the class manually.
+ */
+
+import { mapValues } from '../runtime';


@@ -0,0 +1,113 @@
+from datetime import date, datetime  # noqa: F401


@@ -0,0 +1,113 @@
+from datetime import date, datetime  # noqa: F401
+
+from typing import List, Dict  # noqa: F401


@@ -0,0 +1,61 @@
+from datetime import date, datetime  # noqa: F401


@@ -0,0 +1,61 @@
+from datetime import date, datetime  # noqa: F401
+
+from typing import List, Dict  # noqa: F401


+        return response
+
+    @app.before_request
+    def handle_preflight():


+            try:
+                import flask
+                request = flask.request if flask.has_request_context() else None
+            except:


filippomc added 2 commits August 31, 2026 16:29

CH-288 add support for RWX volumes

0c42c85

CH-288 linting fix

4233bca

filippomc requested a review from aranega August 31, 2026 14:35

github-advanced-security Bot found potential problems Aug 31, 2026

View reviewed changes

Comment thread tools/deployment-cli-tools/ch_cli_tools/configurationgenerator.py Fixed

Comment thread tools/deployment-cli-tools/ch_cli_tools/configurationgenerator.py Fixed

CH-288 remove unnecessary configuration level

7d25496

aranega approved these changes Aug 31, 2026

View reviewed changes

CH-288 fix defaults

9bac9d5

aranega approved these changes Aug 31, 2026

View reviewed changes

filippomc added 4 commits August 31, 2026 17:44

CH-288 fix defaults on db

c49cf64

Fix dates marshaling for flask server

25265c7

Refactor flask server utility

8432b02

Regenerate samples application to cover new API

bea9417

github-code-quality Bot found potential problems Sep 1, 2026

View reviewed changes

Fix regression post refactoring

e9f3114

github-code-quality Bot found potential problems Sep 1, 2026

View reviewed changes

Comment thread libraries/cloudharness-common/cloudharness/utils/__init__.py Fixed

filippomc added 2 commits September 1, 2026 14:53

Backward compatibility fix

2c82492

CH-289 rearrange wait-timeouts on test and dev deployments

6d7ad2a

github-code-quality Bot found potential problems Sep 1, 2026

View reviewed changes

filippomc added 4 commits September 1, 2026 15:38

Fix statefulsets not updating after failed roll

e27da91

Fix sample test issue

a9a4ed6

chore: linting fixes

bce0f43

chore: linting fixes

f76e119

filippomc merged commit 861bbec into develop Sep 1, 2026
9 of 11 checks passed

filippomc deleted the feature/CH-288 branch September 1, 2026 17:02

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CH-288 add support for RWX volumes - #862

CH-288 add support for RWX volumes#862
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filippomc commented Aug 31, 2026 •

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		@@ -0,0 +1,113 @@
		from datetime import date, datetime # noqa: F401

		@@ -0,0 +1,113 @@
		from datetime import date, datetime # noqa: F401

		from typing import List, Dict # noqa: F401

		@@ -0,0 +1,61 @@
		from datetime import date, datetime # noqa: F401

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filippomc commented Aug 31, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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filippomc commented Aug 31, 2026 •

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