Check for redundant regex anchors

docs/changelog.md

@@ -8,6 +8,7 @@
   `# pint rule/set promql/series min-age ...` and
   `# pint rule/set promql/series ignore/label-value ...`
   See [promql/series](/docs/checks/promql/series.md) for details.
+- `promql/regexp` will report redundant use of regex anchors.
 
 ### Changed
 

docs/checks/promql/regexp.md

@@ -26,6 +26,14 @@ Example of a query that wouldn't trigger this warning:
 foo{job=~"bar|baz"}
 ```
 
+Another problem this check will report on is redundant regexp anchors.
+As noted on [Querying Prometheus](https://prometheus.io/docs/prometheus/latest/querying/basics/)
+page Prometheus fully anchors all regex matchers.
+So a query match using `foo=~"bar.*"` will be parsed as `foo=~"^bar.*$"` and
+so any anchors used in the query will be redundant.
+This means that passing `foo=~"^bar.*$"` to the query will be parsed as
+`foo=~"^^bar.*$$"`, so both `^` and `$` should be skipped to avoid it.
+
 ## Configuration
 
 This check doesn't have any configuration options.

docs/checks/promql/series.md

@@ -155,7 +155,7 @@ Example:
   expr: sum(foo) / sum(bar{instance="xxx"})
 ```
 
-# ignore/label-value
+### ignore/label-value
 
 By default pint will report a problem if a rule uses query with a label filter
 and the value of that filter query doesn't match anything.

go.mod

@@ -16,7 +16,7 @@ require (
 	github.com/rogpeppe/go-internal v1.8.1
 	github.com/rs/zerolog v1.26.1
 	github.com/stretchr/testify v1.7.1
-	github.com/urfave/cli/v2 v2.4.8
+	github.com/urfave/cli/v2 v2.5.0
 	golang.org/x/oauth2 v0.0.0-20220411215720-9780585627b5
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b
 )
@@ -25,10 +25,10 @@ require (
 	github.com/agext/levenshtein v1.2.3 // indirect
 	github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137 // indirect
 	github.com/apparentlymart/go-textseg/v13 v13.0.0 // indirect
-	github.com/aws/aws-sdk-go v1.43.43 // indirect
+	github.com/aws/aws-sdk-go v1.44.0 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.1.2 // indirect
-	github.com/cpuguy83/go-md2man/v2 v2.0.1 // indirect
+	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dennwc/varint v1.0.0 // indirect
 	github.com/edsrzf/mmap-go v1.1.0 // indirect
@@ -67,9 +67,9 @@ require (
 	go.uber.org/atomic v1.9.0 // indirect
 	go.uber.org/goleak v1.1.12 // indirect
 	golang.org/x/crypto v0.0.0-20220411220226-7b82a4e95df4 // indirect
-	golang.org/x/net v0.0.0-20220420153159-1850ba15e1be // indirect
+	golang.org/x/net v0.0.0-20220425223048-2871e0cb64e4 // indirect
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
-	golang.org/x/sys v0.0.0-20220412211240-33da011f77ad // indirect
+	golang.org/x/sys v0.0.0-20220422013727-9388b58f7150 // indirect
 	golang.org/x/text v0.3.7 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
 	google.golang.org/protobuf v1.28.0 // indirect

go.sum

@@ -151,8 +151,8 @@ github.com/aws/aws-sdk-go v1.15.11/go.mod h1:mFuSZ37Z9YOHbQEwBWztmVzqXrEkub65tZo
 github.com/aws/aws-sdk-go v1.38.35/go.mod h1:hcU610XS61/+aQV88ixoOzUoG7v3b31pl2zKMmprdro=
 github.com/aws/aws-sdk-go v1.43.11/go.mod h1:y4AeaBuwd2Lk+GepC1E9v0qOiTws0MIWAX4oIKwKHZo=
 github.com/aws/aws-sdk-go v1.43.31/go.mod h1:y4AeaBuwd2Lk+GepC1E9v0qOiTws0MIWAX4oIKwKHZo=
-github.com/aws/aws-sdk-go v1.43.43 h1:1L06qzQvl4aC3Skfh5rV7xVhGHjIZoHcqy16NoyQ1o4=
-github.com/aws/aws-sdk-go v1.43.43/go.mod h1:y4AeaBuwd2Lk+GepC1E9v0qOiTws0MIWAX4oIKwKHZo=
+github.com/aws/aws-sdk-go v1.44.0 h1:jwtHuNqfnJxL4DKHBUVUmQlfueQqBW7oXP6yebZR/R0=
+github.com/aws/aws-sdk-go v1.44.0/go.mod h1:y4AeaBuwd2Lk+GepC1E9v0qOiTws0MIWAX4oIKwKHZo=
 github.com/benbjohnson/clock v1.0.3/go.mod h1:bGMdMPoPVvcYyt1gHDf4J2KE153Yf9BuiUKYMaxlTDM=
 github.com/beorn7/perks v0.0.0-20160804104726-4c0e84591b9a/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=
 github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=
@@ -326,8 +326,8 @@ github.com/coreos/pkg v0.0.0-20160727233714-3ac0863d7acf/go.mod h1:E3G3o1h8I7cfc
 github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f/go.mod h1:E3G3o1h8I7cfcXa63jLwjI0eiQQMgzzUDFVpN/nH/eA=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/cpuguy83/go-md2man/v2 v2.0.0/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
-github.com/cpuguy83/go-md2man/v2 v2.0.1 h1:r/myEWzV9lfsM1tFLgDyu0atFtJ1fXn261LKYj/3DxU=
-github.com/cpuguy83/go-md2man/v2 v2.0.1/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/cpuguy83/go-md2man/v2 v2.0.2 h1:p1EgwI/C7NhT0JmVkwCD2ZBK8j4aeHQX2pMHHBfMQ6w=
+github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/creack/pty v1.1.7/go.mod h1:lj5s0c3V2DBrqTV7llrYr5NG6My20zk30Fl46Y7DoTY=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/creack/pty v1.1.11/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
@@ -1093,8 +1093,8 @@ github.com/urfave/cli v0.0.0-20171014202726-7bc6a0acffa5/go.mod h1:70zkFmudgCuE/
 github.com/urfave/cli v1.20.0/go.mod h1:70zkFmudgCuE/ngEzBv17Jvp/497gISqfk5gWijbERA=
 github.com/urfave/cli v1.22.1/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
 github.com/urfave/cli v1.22.2/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
-github.com/urfave/cli/v2 v2.4.8 h1:9HuvvddU3oEJr1tJlwUVVsk3snVWMuKSpyAO+SzTNuI=
-github.com/urfave/cli/v2 v2.4.8/go.mod h1:oDzoM7pVwz6wHn5ogWgFUU1s4VJayeQS+aEZDqXIEJs=
+github.com/urfave/cli/v2 v2.5.0 h1:2sqblaW62ebcTIEvwb8eRvDfNHeBAeKxfhdynaanhug=
+github.com/urfave/cli/v2 v2.5.0/go.mod h1:oDzoM7pVwz6wHn5ogWgFUU1s4VJayeQS+aEZDqXIEJs=
 github.com/vishvananda/netlink v0.0.0-20181108222139-023a6dafdcdf/go.mod h1:+SR5DhBJrl6ZM7CoCKvpw5BKroDKQ+PJqOg65H/2ktk=
 github.com/vishvananda/netlink v1.1.0/go.mod h1:cTgwzPIzzgDAYoQrMm0EdrjRUBkTqKYppBueQtXaqoE=
 github.com/vishvananda/netlink v1.1.1-0.20201029203352-d40f9887b852/go.mod h1:twkDnbuQxJYemMlGd4JFIcuhgX83tXhKS2B/PRMpOho=
@@ -1344,8 +1344,8 @@ golang.org/x/net v0.0.0-20211216030914-fe4d6282115f/go.mod h1:9nx3DQGgdP8bBQD5qx
 golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/net v0.0.0-20220225172249-27dd8689420f/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/net v0.0.0-20220325170049-de3da57026de/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
-golang.org/x/net v0.0.0-20220420153159-1850ba15e1be h1:yx80W7nvY5ySWpaU8UWaj5o9e23YgO9BRhQol7Lc+JI=
-golang.org/x/net v0.0.0-20220420153159-1850ba15e1be/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
+golang.org/x/net v0.0.0-20220425223048-2871e0cb64e4 h1:HVyaeDAYux4pnY+D/SiwmLOR36ewZ4iGQIIrtnuCjFA=
+golang.org/x/net v0.0.0-20220425223048-2871e0cb64e4/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
@@ -1503,8 +1503,8 @@ golang.org/x/sys v0.0.0-20220128215802-99c3d69c2c27/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220209214540-3681064d5158/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220328115105-d36c6a25d886/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220412211240-33da011f77ad h1:ntjMns5wyP/fN65tdBD4g8J5w8n015+iIIs9rtjXkY0=
-golang.org/x/sys v0.0.0-20220412211240-33da011f77ad/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220422013727-9388b58f7150 h1:xHms4gcpe1YE7A3yIllJXP16CMAGuqwO2lX1mTyyRRc=
+golang.org/x/sys v0.0.0-20220422013727-9388b58f7150/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210220032956-6a3ed077a48d/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=

internal/checks/promql_regexp.go

@@ -37,14 +37,17 @@ func (c RegexpCheck) Check(ctx context.Context, rule parser.Rule, entries []disc
 
 	for _, selector := range getSelectors(expr.Query) {
 		for _, lm := range selector.LabelMatchers {
-			if s := lm.GetRegexString(); s != "" {
+			if re := lm.GetRegexString(); re != "" {
 				var isUseful bool
-				r, _ := syntax.Parse(s, syntax.Perl)
+				var beginText, endText int
+				r, _ := syntax.Parse(re, syntax.Perl)
 				for _, s := range r.Sub {
 					switch s.Op {
 					case syntax.OpBeginText:
+						beginText++
 						continue
 					case syntax.OpEndText:
+						endText++
 						continue
 					case syntax.OpLiteral:
 						continue
@@ -55,20 +58,29 @@ func (c RegexpCheck) Check(ctx context.Context, rule parser.Rule, entries []disc
 					}
 				}
 				if !isUseful {
-					var text string
 					var op labels.MatchType
 					switch lm.Type {
 					case labels.MatchRegexp:
 						op = labels.MatchEqual
 					case labels.MatchNotRegexp:
 						op = labels.MatchNotEqual
 					}
-					text = fmt.Sprintf(`unnecessary regexp match on static string %s, use %s%s%q instead`, lm, lm.Name, op, lm.Value)
 					problems = append(problems, Problem{
 						Fragment: selector.String(),
 						Lines:    expr.Lines(),
 						Reporter: c.Reporter(),
-						Text:     text,
+						Text:     fmt.Sprintf(`unnecessary regexp match on static string %s, use %s%s%q instead`, lm, lm.Name, op, lm.Value),
+						Severity: Bug,
+					})
+				}
+				if beginText > 1 || endText > 1 {
+					problems = append(problems, Problem{
+						Fragment: selector.String(),
+						Lines:    expr.Lines(),
+						Reporter: c.Reporter(),
+						Text: fmt.Sprintf(`prometheus regexp matchers are automatically fully anchored so match for %s will result in %s%s"^%s$", remove regexp anchors ^ and/or $`,
+							lm, lm.Name, lm.Type, lm.Value,
+						),
 						Severity: Bug,
 					})
 				}

internal/checks/promql_regexp_test.go

@@ -90,6 +90,38 @@ func TestRegexpCheck(t *testing.T) {
 				}
 			},
 		},
+		{
+			description: "unnecessary regexp anchor",
+			content:     "- record: foo\n  expr: foo{job=~\"^.+$\"}\n",
+			checker:     newRegexpCheck,
+			problems: func(uri string) []checks.Problem {
+				return []checks.Problem{
+					{
+						Fragment: `foo{job=~"^.+$"}`,
+						Lines:    []int{2},
+						Reporter: checks.RegexpCheckName,
+						Text:     `prometheus regexp matchers are automatically fully anchored so match for job=~"^.+$" will result in job=~"^^.+$$", remove regexp anchors ^ and/or $`,
+						Severity: checks.Bug,
+					},
+				}
+			},
+		},
+		{
+			description: "unnecessary regexp anchor",
+			content:     "- record: foo\n  expr: foo{job=~\"(foo|^.+)$\"}\n",
+			checker:     newRegexpCheck,
+			problems: func(uri string) []checks.Problem {
+				return []checks.Problem{
+					{
+						Fragment: `foo{job=~"(foo|^.+)$"}`,
+						Lines:    []int{2},
+						Reporter: checks.RegexpCheckName,
+						Text:     `prometheus regexp matchers are automatically fully anchored so match for job=~"(foo|^.+)$" will result in job=~"^(foo|^.+)$$", remove regexp anchors ^ and/or $`,
+						Severity: checks.Bug,
+					},
+				}
+			},
+		},
 	}
 	runTests(t, testCases)
 }