Sanitize build IDs to match k8s label value requirements (#138)

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## What was changed
<!-- Describe what has changed in this PR -->
Build IDs are now sanitized in order to match k8s label value
requirements.

## Why?
<!-- Tell your future self why have you made these changes -->
This ensures that the value of the label `temporal.io/build-id` applied
by the controller to k8s resources can match the build ID registered
with Temporal.

## Checklist
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1. Closes <!-- add issue number here -->

N/A

2. How was this tested:
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-->

Unit tests updated

3. Any docs updates needed?
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      or point out where to update docs.temporal.io -->

No

Author: jlegrone

internal/k8s/deployments.go

@@ -117,7 +117,7 @@ func ComputeBuildID(w *temporaliov1alpha1.TemporalWorkerDeployment) string {
 			shortHashSuffix := ResourceNameSeparator + utils.ComputeHash(&w.Spec.Template, nil, true)
 			maxImgLen := MaxBuildIdLen - len(shortHashSuffix)
 			imagePrefix := computeImagePrefix(img, maxImgLen)
-			return imagePrefix + shortHashSuffix
+			return cleanBuildID(imagePrefix + shortHashSuffix)
 		}
 	}
 	return utils.ComputeHash(&w.Spec.Template, nil, false)
@@ -165,6 +165,23 @@ func CleanStringForDNS(s string) string {
 	return re.ReplaceAllString(s, ResourceNameSeparator)
 }
 
+// Build ID is used as a label in k8s, and as the build ID for
+// the worker in Temporal. That means it needs to conform to both
+// system's requirements.
+//
+// https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
+// Valid label value:
+// - must be 63 characters or less (can be empty),
+// - unless empty, must begin and end with an alphanumeric character ([a-z0-9A-Z]),
+// - could contain dashes (-), underscores (_), dots (.), and alphanumerics between.
+//
+// Temporal build IDs only need to be ASCII.
+func cleanBuildID(s string) string {
+	// Keep only letters, numbers, dashes, and dots.
+	re := regexp.MustCompile(`[^a-zA-Z0-9-._]+`)
+	return re.ReplaceAllString(s, ResourceNameSeparator)
+}
+
 // NewDeploymentWithOwnerRef creates a new deployment resource, including owner references
 func NewDeploymentWithOwnerRef(
 	typeMeta *metav1.TypeMeta,

internal/k8s/deployments_test.go

@@ -323,7 +323,7 @@ func TestGenerateBuildID(t *testing.T) {
 				twd := testhelpers.MakeTWDWithImage("", "", namedImg)
 				return twd, nil // only check 1 result, no need to compare
 			},
-			expectedPrefix:  "library/busybox",
+			expectedPrefix:  "library-busybox",
 			expectedHashLen: 4,
 			expectEquality:  false,
 		},
@@ -334,7 +334,7 @@ func TestGenerateBuildID(t *testing.T) {
 				twd := testhelpers.MakeTWDWithImage("", "", illegalCharsImg)
 				return twd, nil // only check 1 result, no need to compare
 			},
-			expectedPrefix:  "this.is.my_weird/image",
+			expectedPrefix:  "this.is.my_weird-image",
 			expectedHashLen: 4,
 			expectEquality:  false,
 		},