DND-1418: support S3Proxy 3.x (appVersion 2.7.0 -> 3.3.0)

Bump appVersion to 3.3.0 (latest stable; the chart was several releases behind
on 2.7.0). Validated on kind that every functionally-tested backend starts and
serves on the 3.3.0 image: s3, filesystem, transient, azureblob (azureblob-sdk),
and the multi-backend routing scenario all pass. CI runs the functional legs
against the default image tag, which now equals appVersion 3.3.0.

Also document S3Proxy version compatibility in the chart README: minimum
supported 2.7.0, and the jclouds deprecation path introduced in 3.0.0 (the
jclouds providers still work on 3.x but are deprecated; 3.3.0 is the last
release to bundle jclouds, after which b2 and rackspace-cloudfiles have no SDK
successor).

Chart version 0.1.0 -> 0.2.0 (minor: new app major version supported, no
breaking chart-values changes).

Scope: minimal bump only. Migrating the chart's default providers to their
SDK/NIO2 replacements (aws-s3-sdk, google-cloud-storage-sdk, openstack-swift-sdk)
and end-of-lifing b2/rackspace is tracked as a separate follow-up.

Author: CRThaze

charts/s3proxy/Chart.yaml

@@ -15,10 +15,10 @@ type: application
 # This is the chart version. This version number should be incremented each time you make changes
 # to the chart and its templates, including the app version.
 # Versions are expected to follow Semantic Versioning (https://semver.org/)
-version: 0.1.0
+version: 0.2.0
 
 # This is the version number of the application being deployed. This version number should be
 # incremented each time you make changes to the application. Versions are not expected to
 # follow Semantic Versioning. They should reflect the version the application is using.
 # It is recommended to use it with quotes.
-appVersion: "2.7.0"
+appVersion: "3.3.0"

charts/s3proxy/README.md.gotmpl

@@ -19,6 +19,17 @@
 - Helm 3.2.0+
 - PV provisioner support in the underlying infrastructure (if using filesystem backend with persistence)
 
+## S3Proxy version compatibility
+
+The chart tracks S3Proxy (`andrewgaul/s3proxy`) through `appVersion` (currently `{{ template "chart.appVersion" . }}`); override it with `image.tag`. Minimum supported version is `2.7.0`.
+
+S3Proxy `3.0.0` deprecated the Apache jclouds storage backends (`s3`, `aws-s3`, `azureblob`, `filesystem`, `transient`) in favor of SDK / NIO2 providers, and `3.3.0` is the last release to bundle jclouds. The jclouds providers still function on 3.x but are deprecated upstream:
+
+- `filesystem` / `transient`: default to the non-deprecated `*-nio2` variants (`nio2: true`).
+- `azureblob`: prefer `provider: azureblob-sdk` (the jclouds `azureblob` provider is deprecated and mis-signs against custom endpoints such as Azurite).
+- `s3`, `googleCloudStorage`, `openstackSwift`: SDK providers exist upstream (`aws-s3-sdk`, `google-cloud-storage-sdk`, `openstack-swift-sdk`); migrating the chart defaults to them is tracked separately.
+- `b2`, `rackspaceCloudfiles`: jclouds-only with no SDK successor; they will stop working on S3Proxy releases after `3.3.0`.
+
 ## Installation
 
 ### Install the chart