yqutil: fix to preserve line breaks

.github/workflows/test.yml

@@ -90,6 +90,10 @@ jobs:
       run: make
     - name: Install
       run: sudo make install
+    - name: Verify templates match `limactl edit` format
+      run: |
+        find examples -name '*.yaml' -exec limactl edit --set 'del(.nothing)' {} \;
+        git diff-index --exit-code HEAD
     - name: Uninstall
       run: sudo make uninstall
 

examples/buildkit.yaml

@@ -5,11 +5,11 @@
 # $ export BUILDKIT_HOST=$(limactl list buildkit --format 'unix://{{.Dir}}/sock/buildkitd.sock')
 # $ buildctl debug workers
 message: |
- To run `buildkit` on the host (assumes buildctl is installed), run the following commands:
- -------
- export BUILDKIT_HOST="unix://{{.Dir}}/sock/buildkitd.sock"
- buildctl debug workers
- -------
+  To run `buildkit` on the host (assumes buildctl is installed), run the following commands:
+  -------
+  export BUILDKIT_HOST="unix://{{.Dir}}/sock/buildkitd.sock"
+  buildctl debug workers
+  -------
 images:
 # Try to use release-yyyyMMdd image if available. Note that release-yyyyMMdd will be removed after several months.
 - location: "https://cloud-images.ubuntu.com/releases/24.04/release-20240821/ubuntu-24.04-server-cloudimg-amd64.img"

examples/default.yaml

@@ -264,10 +264,10 @@ containerd:
 # Setting of instructions is supported like this: "qemu64,+ssse3".
 # 🟢 Builtin default: hard-coded arch map with type (see the output of `limactl info | jq .defaultTemplate.cpuType`)
 cpuType:
-  # aarch64: "cortex-a72" # (or "host" when running on aarch64 host)
-  # armv7l: "cortex-a7" # (or "host" when running on armv7l host)
-  # riscv64: "rv64" # (or "host" when running on riscv64 host)
-  # x86_64: "qemu64" # (or "host,-pdpe1gb" when running on x86_64 host)
+# aarch64: "cortex-a72" # (or "host" when running on aarch64 host)
+# armv7l: "cortex-a7" # (or "host" when running on armv7l host)
+# riscv64: "rv64" # (or "host" when running on riscv64 host)
+# x86_64: "qemu64" # (or "host,-pdpe1gb" when running on x86_64 host)
 
 rosetta:
   # Enable Rosetta for Linux (EXPERIMENTAL; will graduate from experimental in Lima v1.0).
@@ -456,8 +456,8 @@ hostResolver:
   # predefined to specify the gateway address to the host.
   # 🟢 Builtin default: null
   hosts:
-    # guest.name: 127.1.1.1
-    # host.name: host.lima.internal
+  # guest.name: 127.1.1.1
+  # host.name: host.lima.internal
 
 # If hostResolver.enabled is false, then the following rules apply for configuring dns:
 # Explicitly set DNS addresses for qemu user-mode networking. By default qemu picks *one*

pkg/yqutil/yqutil.go

@@ -1,6 +1,7 @@
 package yqutil
 
 import (
+	"bufio"
 	"bytes"
 	"fmt"
 	"os"
@@ -15,13 +16,17 @@ import (
 // EvaluateExpression evaluates the yq expression, and returns the modified yaml.
 func EvaluateExpression(expression string, content []byte) ([]byte, error) {
 	logrus.Debugf("Evaluating yq expression: %q", expression)
+	contentModified, err := replaceLineBreaksWithMagicString(content)
+	if err != nil {
+		return nil, err
+	}
 	tmpYAMLFile, err := os.CreateTemp("", "lima-yq-*.yaml")
 	if err != nil {
 		return nil, err
 	}
 	tmpYAMLPath := tmpYAMLFile.Name()
 	defer os.RemoveAll(tmpYAMLPath)
-	_, err = tmpYAMLFile.Write(content)
+	_, err = tmpYAMLFile.Write(contentModified)
 	if err != nil {
 		tmpYAMLFile.Close()
 		return nil, err
@@ -94,3 +99,41 @@ func yamlfmt(content []byte) ([]byte, error) {
 	}
 	return formatter.Format(content)
 }
+
+const yamlfmtLineBreakPlaceholder = "#magic___^_^___line"
+
+type paddinger struct {
+	strings.Builder
+}
+
+func (p *paddinger) adjust(txt string) {
+	var indentSize int
+	for i := 0; i < len(txt) && txt[i] == ' '; i++ { // yaml only allows space to indent.
+		indentSize++
+	}
+	// Grows if the given size is larger than us and always return the max padding.
+	for diff := indentSize - p.Len(); diff > 0; diff-- {
+		p.WriteByte(' ')
+	}
+}
+
+func replaceLineBreaksWithMagicString(content []byte) ([]byte, error) {
+	// hotfix: yq does not support line breaks in the middle of a string.
+	var buf bytes.Buffer
+	reader := bytes.NewReader(content)
+	scanner := bufio.NewScanner(reader)
+	var padding paddinger
+	for scanner.Scan() {
+		txt := scanner.Text()
+		padding.adjust(txt)
+		if strings.TrimSpace(txt) == "" { // line break or empty space line.
+			buf.WriteString(padding.String()) // prepend some padding incase literal multiline strings.
+			buf.WriteString(yamlfmtLineBreakPlaceholder)
+			buf.WriteString("\n")
+		} else {
+			buf.WriteString(txt)
+			buf.WriteString("\n")
+		}
+	}
+	return buf.Bytes(), scanner.Err()
+}

pkg/yqutil/yqutil_test.go

@@ -19,6 +19,7 @@ memory: null
 	expected := `
 # CPUs
 cpus: 2
+
 # Memory size
 memory: 2GiB
 `