Allow empty matchers

ui/app/src/Utils/Filter.elm

@@ -212,7 +212,7 @@ stringContents separator =
             |= keepOne (\char -> True)
         , Parser.keep Parser.oneOrMore (\char -> char /= separator && char /= '\\')
         ]
-        |> Parser.repeat Parser.oneOrMore
+        |> Parser.repeat Parser.zeroOrMore
         |> Parser.map (String.join "")
 
 

ui/app/src/Views/SilenceForm/Types.elm

@@ -155,7 +155,7 @@ parseEndsAt startsAt endsAt =
 validateMatcherForm : MatcherForm -> MatcherForm
 validateMatcherForm { name, value, isRegex } =
     { name = validate stringNotEmpty name
-    , value = validate stringNotEmpty value
+    , value = value
     , isRegex = isRegex
     }
 

ui/app/tests/Filter.elm

@@ -13,6 +13,9 @@ parseMatcher =
         [ test "should parse empty matcher string" <|
             \() ->
                 Expect.equal Nothing (Utils.Filter.parseMatcher "")
+        , test "should parse empty matcher value" <|
+            \() ->
+                Expect.equal (Just (Matcher "alertname" Eq "")) (Utils.Filter.parseMatcher "alertname=\"\"")
         , fuzz (tuple ( string, string )) "should parse random matcher string" <|
             \( key, value ) ->
                 if List.map isNotEmptyTrimmedAlphabetWord [ key, value ] /= [ True, True ] then