Template selection by a subset of tags

(fixes issue #583).

Author: holmesb

docs/advanced-setups.md

@@ -178,11 +178,11 @@ For example, setting it to `0` (zero), entirely disables scheduling based on mem
 
 ## Template lookup based on Proxmox tags
 
-Our provider is able to look up templates based on their attached tags, for `ProxmoxMachine` resources, that make use of an tag selector.
+Our provider is able to look up templates based on their attached tags, for `ProxmoxMachine` resources, that make use of a tag selector.
 
 For example, you can set the `TEMPLATE_TAGS="tag1,tag2"` environment variable. Your custom image will then be used when using the [auto-image](https://github.com/ionos-cloud/cluster-api-provider-ionoscloud/blob/main/templates/cluster-template-auto-image.yaml) template.
 
-Please note: Passed tags must be an exact 1:1 match with the tags on the template you want to use.  The matched result must be unique. If multiple templates are found, provisioning will fail.
+Please note: Passed tags will match at least a subset of the tags on the template you want to use. The lookup must result in a unique template. If multiple templates are found, provisioning will fail.
 
 ## Proxmox RBAC with least privileges
 

pkg/proxmox/goproxmox/api_client.go

@@ -173,9 +173,30 @@ func (c *APIClient) FindVMTemplateByTags(ctx context.Context, templateTags []str
 		}
 
 		vmTags := strings.Split(vm.Tags, ";")
+		for i := range vmTags {
+			vmTags[i] = strings.ToLower(strings.TrimSpace(vmTags[i]))
+		}
 		slices.Sort(vmTags)
+		vmTags = slices.Compact(vmTags)
+
+		// Check whether the template’s tags (tagsPresent) contain all the requested tags (tagsWanted)
+		isSuperset := func(tagsPresent, tagsWanted []string) bool {
+			presentIdx, wantedIdx := 0, 0
+			for presentIdx < len(tagsPresent) && wantedIdx < len(tagsWanted) {
+				switch {
+				case tagsPresent[presentIdx] == tagsWanted[wantedIdx]:
+					presentIdx++
+					wantedIdx++
+				case tagsPresent[presentIdx] < tagsWanted[wantedIdx]:
+					presentIdx++
+				default:
+					return false
+				}
+			}
+			return wantedIdx == len(tagsWanted)
+		}
 
-		if slices.Equal(vmTags, uniqueTags) {
+		if isSuperset(vmTags, uniqueTags) {
 			vmTemplates = append(vmTemplates, vm)
 		}
 	}

pkg/proxmox/goproxmox/api_client_test.go

@@ -416,7 +416,7 @@ func TestProxmoxAPIClient_FindVMTemplateByTags(t *testing.T) {
 			http:           []int{200, 200},
 			vmTags:         nil,
 			fails:          true,
-			err:            "VM template not found: found 0 VM templates with tags \"\"",
+			err:            "VM template not found: found 4 VM templates with tags \"\"",
 			vmTemplateNode: "capmox01",
 			vmTemplateID:   201,
 		},
@@ -449,16 +449,16 @@ func TestProxmoxAPIClient_FindVMTemplateByTags(t *testing.T) {
 			vmTemplateID:   202,
 		},
 		{
-			name:           "find-multiple-templates",
+			name:           "find-multiple-templates-any-version",
 			http:           []int{200, 200},
 			vmTags:         []string{"template", "capmox"},
 			fails:          true,
-			err:            "VM template not found: found 0 VM templates with tags \"template;capmox\"",
+			err:            "VM template not found: found 4 VM templates with tags \"template;capmox\"",
 			vmTemplateID:   69,
 			vmTemplateNode: "nice",
 		},
 		{
-			name:           "find-multiple-templates",
+			name:           "find-multiple-templates-v1.29.2",
 			http:           []int{200, 200},
 			vmTags:         []string{"template", "capmox", "v1.29.2"},
 			fails:          true,