Add text regex support for Event watcher

docs/content/en/docs/user-guide/configuration-reference.md

@@ -148,11 +148,13 @@ spec:
 | replacements | [][EventWatcherReplacement](/docs/user-guide/configuration-reference/#eventwatcherreplacement) | List of places where will be replaced when the new event matches. | Yes |
 
 ## EventWatcherReplacement
+One of `yamlField` or `regex` is required.
 
 | Field | Type | Description | Required |
 |-|-|-|-|
 | file | string | The path to the file to be updated. | Yes |
-| yamlField | string | The yaml path to the field to be updated. It requires to start with `$` which represents the root element. e.g. `$.foo.bar[0].baz`. | Yes |
+| yamlField | string | The yaml path to the field to be updated. It requires to start with `$` which represents the root element. e.g. `$.foo.bar[0].baz`. | No |
+| regex | string | The regex string that specify what should be replaced. The only first capturing group enclosed by `()` will be replaced with the new value. e.g. `host.xz/foo/bar:(v[0-9].[0-9].[0-9])` | No |
 
 ## CommitMatcher
 

pkg/app/piped/eventwatcher/BUILD.bazel

@@ -9,6 +9,7 @@ go_library(
         "//pkg/config:go_default_library",
         "//pkg/git:go_default_library",
         "//pkg/model:go_default_library",
+        "//pkg/regexpool:go_default_library",
         "//pkg/yamlprocessor:go_default_library",
         "@org_uber_go_zap//:go_default_library",
     ],

pkg/app/piped/eventwatcher/eventwatcher.go

@@ -24,6 +24,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"regexp/syntax"
 	"strconv"
 	"sync"
 	"time"
@@ -33,6 +34,7 @@ import (
 	"github.com/pipe-cd/pipe/pkg/config"
 	"github.com/pipe-cd/pipe/pkg/git"
 	"github.com/pipe-cd/pipe/pkg/model"
+	"github.com/pipe-cd/pipe/pkg/regexpool"
 	"github.com/pipe-cd/pipe/pkg/yamlprocessor"
 )
 
@@ -239,6 +241,8 @@ func (w *watcher) commitFiles(ctx context.Context, eventCfg config.EventWatcherE
 			// TODO: Empower Event watcher to parse JSON format
 		case r.HCLField != "":
 			// TODO: Empower Event watcher to parse HCL format
+		case r.Regex != "":
+			newContent, upToDate, err = modifyText(path, r.Regex, latestEvent.Data)
 		}
 		if err != nil {
 			return err
@@ -269,7 +273,7 @@ func (w *watcher) commitFiles(ctx context.Context, eventCfg config.EventWatcherE
 // modifyYAML returns a new YAML content as a first returned value if the value of given
 // field was outdated. True as a second returned value means it's already up-to-date.
 func modifyYAML(path, field, newValue string) ([]byte, bool, error) {
-	yml, err := ioutil.ReadFile(path)
+	yml, err := os.ReadFile(path)
 	if err != nil {
 		return nil, false, fmt.Errorf("failed to read file: %w", err)
 	}
@@ -320,3 +324,55 @@ func convertStr(value interface{}) (out string, err error) {
 	}
 	return
 }
+
+// modifyText returns a new text replacing all matches of the given regex with the newValue.
+// The only first capturing group enclosed by `()` will be replaced.
+// True as a second returned value means it's already up-to-date.
+func modifyText(path, regexText, newValue string) ([]byte, bool, error) {
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return nil, false, fmt.Errorf("failed to read file: %w", err)
+	}
+
+	pool := regexpool.DefaultPool()
+	regex, err := pool.Get(regexText)
+	if err != nil {
+		return nil, false, fmt.Errorf("failed to compile regex text (%s): %w", regexText, err)
+	}
+
+	// Extract the first capturing group.
+	firstGroup := ""
+	re, err := syntax.Parse(regexText, syntax.Perl)
+	if err != nil {
+		return nil, false, fmt.Errorf("failed to parse the first capturing group regex: %w", err)
+	}
+	for _, s := range re.Sub {
+		if s.Op == syntax.OpCapture {
+			firstGroup = s.String()
+			break
+		}
+	}
+	if firstGroup == "" {
+		return nil, false, fmt.Errorf("capturing group not found in the given regex")
+	}
+	subRegex, err := pool.Get(firstGroup)
+	if err != nil {
+		return nil, false, fmt.Errorf("failed to compile the first capturing group: %w", err)
+	}
+
+	var touched, outDated bool
+	newText := regex.ReplaceAllFunc(content, func(match []byte) []byte {
+		touched = true
+		outDated = string(subRegex.Find(match)) != newValue
+		// Return text replacing the only first capturing group with the newValue.
+		return subRegex.ReplaceAll(match, []byte(newValue))
+	})
+	if !touched {
+		return nil, false, fmt.Errorf("the content of %s doesn't match %s", path, regexText)
+	}
+	if !outDated {
+		return nil, true, nil
+	}
+
+	return newText, false, nil
+}

pkg/app/piped/eventwatcher/eventwatcher_test.go

@@ -117,3 +117,122 @@ func TestModifyYAML(t *testing.T) {
 		})
 	}
 }
+
+func TestModifyText(t *testing.T) {
+	testcases := []struct {
+		name         string
+		path         string
+		regex        string
+		newValue     string
+		want         []byte
+		wantUpToDate bool
+		wantErr      bool
+	}{
+		{
+			name:         "invalid regex given",
+			path:         "testdata/with-template.yaml",
+			regex:        "[",
+			newValue:     "v0.2.0",
+			want:         nil,
+			wantUpToDate: false,
+			wantErr:      true,
+		},
+		{
+			name:         "no capturing group given",
+			path:         "testdata/with-template.yaml",
+			regex:        "image: gcr.io/pipecd/foo:v[0-9].[0-9].[0-9]",
+			newValue:     "v0.2.0",
+			want:         nil,
+			wantUpToDate: false,
+			wantErr:      true,
+		},
+		{
+			name:         "invalid capturing group given",
+			path:         "testdata/with-template.yaml",
+			regex:        "image: gcr.io/pipecd/foo:([)",
+			newValue:     "v0.2.0",
+			want:         nil,
+			wantUpToDate: false,
+			wantErr:      true,
+		},
+		{
+			name:         "the file doesn't match regex",
+			path:         "testdata/with-template.yaml",
+			regex:        "abcdefg",
+			newValue:     "v0.1.0",
+			want:         nil,
+			wantUpToDate: false,
+			wantErr:      true,
+		},
+		{
+			name:         "the file is up-to-date",
+			path:         "testdata/with-template.yaml",
+			regex:        "image: gcr.io/pipecd/foo:(v[0-9].[0-9].[0-9])",
+			newValue:     "v0.1.0",
+			want:         nil,
+			wantUpToDate: true,
+			wantErr:      false,
+		},
+		{
+			name:     "replace a part of text",
+			path:     "testdata/with-template.yaml",
+			regex:    "image: gcr.io/pipecd/foo:(v[0-9].[0-9].[0-9])",
+			newValue: "v0.2.0",
+			want: []byte(`apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: foo
+spec:
+  template:
+    spec:
+      containers:
+      - name: foo
+        image: gcr.io/pipecd/foo:v0.2.0
+        ports:
+        - containerPort: 9085
+        env:
+        - name: FOO
+          value: {{ .encryptedSecrets.foo }}
+
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: bar
+spec:
+  template:
+    spec:
+      containers:
+      - name: bar
+        image: gcr.io/pipecd/bar:v0.1.0
+        ports:
+        - containerPort: 9085
+        env:
+        - name: BAR
+          value: {{ .encryptedSecrets.bar }}
+`),
+			wantUpToDate: false,
+			wantErr:      false,
+		},
+		{
+			name:     "replace text",
+			path:     "testdata/kustomization.yaml",
+			regex:    "newTag: (v[0-9].[0-9].[0-9])",
+			newValue: "v0.2.0",
+			want: []byte(`images:
+- name: gcr.io/pipecd/foo
+  newTag: v0.2.0
+`),
+			wantUpToDate: false,
+			wantErr:      false,
+		},
+	}
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			got, gotUpToDate, err := modifyText(tc.path, tc.regex, tc.newValue)
+			assert.Equal(t, tc.wantErr, err != nil)
+			assert.Equal(t, tc.want, got)
+			assert.Equal(t, tc.wantUpToDate, gotUpToDate)
+		})
+	}
+}

pkg/app/piped/eventwatcher/testdata/kustomization.yaml

@@ -0,0 +1,3 @@
+images:
+- name: gcr.io/pipecd/foo
+  newTag: v0.1.0

pkg/app/piped/eventwatcher/testdata/with-template.yaml

@@ -0,0 +1,32 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: foo
+spec:
+  template:
+    spec:
+      containers:
+      - name: foo
+        image: gcr.io/pipecd/foo:v0.1.0
+        ports:
+        - containerPort: 9085
+        env:
+        - name: FOO
+          value: {{ .encryptedSecrets.foo }}
+
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: bar
+spec:
+  template:
+    spec:
+      containers:
+      - name: bar
+        image: gcr.io/pipecd/bar:v0.1.0
+        ports:
+        - containerPort: 9085
+        env:
+        - name: BAR
+          value: {{ .encryptedSecrets.bar }}

pkg/config/event_watcher.go

@@ -50,6 +50,10 @@ type EventWatcherReplacement struct {
 	JSONField string `json:"jsonField"`
 	// The HCL path to the field to be updated.
 	HCLField string `json:"HCLField"`
+	// The regex string specifying what should be replaced.
+	// Only the first capturing group enclosed by `()` will be replaced with the new value.
+	// e.g. "host.xz/foo/bar:(v[0-9].[0-9].[0-9])"
+	Regex string `json:"regex"`
 }
 
 // LoadEventWatcher gives back parsed EventWatcher config after merging config files placed under
@@ -172,6 +176,9 @@ func (e *EventWatcherEvent) Validate() error {
 		if r.HCLField != "" {
 			count++
 		}
+		if r.Regex != "" {
+			count++
+		}
 		if count == 0 {
 			return fmt.Errorf("event %q has a replacement with no field", e.Name)
 		}