From d42566c5c9ebb82b833388a19e5b59c0fc7e422a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gustaf=20R=C3=A4ntil=C3=A4?= <g.rantila@gmail.com>
Date: Wed, 22 Sep 2021 17:40:56 +0200
Subject: [PATCH] Loosen catalog constraints on entity tag string validity.
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Adding `+` and `#` as valid chars, to e.g. allow "c++" and "c#".

Signed-off-by: Gustaf Räntilä <g.rantila@gmail.com>
---
 .changeset/spicy-spies-roll.md                |  5 ++++
 packages/catalog-model/api-report.md          |  1 +
 .../policies/FieldFormatEntityPolicy.ts       |  4 +++
 .../CommonValidatorFunctions.test.ts          | 25 +++++++++++++++++++
 .../validation/CommonValidatorFunctions.ts    | 14 +++++++++++
 .../src/validation/makeValidator.ts           |  2 +-
 6 files changed, 50 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/spicy-spies-roll.md

diff --git a/.changeset/spicy-spies-roll.md b/.changeset/spicy-spies-roll.md
new file mode 100644
index 0000000000..f20e5b8aae
--- /dev/null
+++ b/.changeset/spicy-spies-roll.md
@@ -0,0 +1,5 @@
+---
+'@backstage/catalog-model': patch
+---
+
+Loosen constraints on what's a valid catalog entity tag name (include + and #)
diff --git a/packages/catalog-model/api-report.md b/packages/catalog-model/api-report.md
index 7d734339b3..3f92a671fa 100644
--- a/packages/catalog-model/api-report.md
+++ b/packages/catalog-model/api-report.md
@@ -50,6 +50,7 @@ export class CommonValidatorFunctions {
     isValidSuffix: (value: string) => boolean,
   ): boolean;
   static isValidString(value: unknown): boolean;
+  static isValidTag(value: unknown): boolean;
   static isValidUrl(value: unknown): boolean;
 }
 
diff --git a/packages/catalog-model/src/entity/policies/FieldFormatEntityPolicy.ts b/packages/catalog-model/src/entity/policies/FieldFormatEntityPolicy.ts
index 8655116ec6..b99901b89b 100644
--- a/packages/catalog-model/src/entity/policies/FieldFormatEntityPolicy.ts
+++ b/packages/catalog-model/src/entity/policies/FieldFormatEntityPolicy.ts
@@ -78,6 +78,10 @@ export class FieldFormatEntityPolicy implements EntityPolicy {
             expectation =
               'a string that is sequences of [a-z0-9] separated by [-], at most 63 characters in total';
             break;
+          case 'isValidTag':
+            expectation =
+              'a string that is sequences of [a-z0-9+#] separated by [-], at most 63 characters in total';
+            break;
           case 'isValidAnnotationValue':
             expectation = 'a string';
             break;
diff --git a/packages/catalog-model/src/validation/CommonValidatorFunctions.test.ts b/packages/catalog-model/src/validation/CommonValidatorFunctions.test.ts
index b15ac385b1..88e3f9b002 100644
--- a/packages/catalog-model/src/validation/CommonValidatorFunctions.test.ts
+++ b/packages/catalog-model/src/validation/CommonValidatorFunctions.test.ts
@@ -162,6 +162,31 @@ describe('CommonValidatorFunctions', () => {
     expect(CommonValidatorFunctions.isValidDnsLabel(value)).toBe(result);
   });
 
+  it.each([
+    // These are identical to isValidDnsLabel
+    [null, false],
+    [7, false],
+    ['', false],
+    ['a', true],
+    ['a-b', true],
+    ['-a-b', false],
+    ['a-b-', false],
+    ['a--b', false],
+    ['a_b', false],
+    [`${'a'.repeat(63)}`, true],
+    [`${'a'.repeat(64)}`, false],
+    // Tags can have other characters though
+    ['a+b', true],
+    ['+a+b', true],
+    ['a+b+', true],
+    ['a++b', true],
+    ['c++', true],
+    ['c#', true],
+    ['#c++', true],
+  ])(`isValidTag %p ? %p`, (value, result) => {
+    expect(CommonValidatorFunctions.isValidTag(value)).toBe(result);
+  });
+
   it.each([
     [null, false],
     [7, false],
diff --git a/packages/catalog-model/src/validation/CommonValidatorFunctions.ts b/packages/catalog-model/src/validation/CommonValidatorFunctions.ts
index 5fcd2ee755..d0357660fc 100644
--- a/packages/catalog-model/src/validation/CommonValidatorFunctions.ts
+++ b/packages/catalog-model/src/validation/CommonValidatorFunctions.ts
@@ -95,6 +95,20 @@ export class CommonValidatorFunctions {
     );
   }
 
+  /**
+   * Checks that the value is a valid tag.
+   *
+   * @param value - The value to check
+   */
+  static isValidTag(value: unknown): boolean {
+    return (
+      typeof value === 'string' &&
+      value.length >= 1 &&
+      value.length <= 63 &&
+      /^[a-z0-9+#]+(\-[a-z0-9+#]+)*$/.test(value)
+    );
+  }
+
   /**
    * Checks that the value is a valid URL.
    *
diff --git a/packages/catalog-model/src/validation/makeValidator.ts b/packages/catalog-model/src/validation/makeValidator.ts
index 48eff566f2..bd6dccc419 100644
--- a/packages/catalog-model/src/validation/makeValidator.ts
+++ b/packages/catalog-model/src/validation/makeValidator.ts
@@ -27,7 +27,7 @@ const defaultValidators: Validators = {
   isValidLabelValue: KubernetesValidatorFunctions.isValidLabelValue,
   isValidAnnotationKey: KubernetesValidatorFunctions.isValidAnnotationKey,
   isValidAnnotationValue: KubernetesValidatorFunctions.isValidAnnotationValue,
-  isValidTag: CommonValidatorFunctions.isValidDnsLabel,
+  isValidTag: CommonValidatorFunctions.isValidTag,
 };
 
 /** @public */