feat: Added npm-packages #33

Roemer · 2026-01-22T20:51:37Z

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Copilot

Pull request overview

This PR adds a new npm-packages devcontainer feature that allows users to install npm packages globally. The feature is designed to work after node.js is installed and supports installing multiple packages with optional version specifications in a comma-separated format.

Changes:

Added new npm-packages feature with installer logic and configuration
Extended installer package with InstallGlobalPackage function for npm
Integrated npm-packages into build system, CI workflow, and documentation

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
installer/npm.go	Added InstallGlobalPackage function to install npm packages globally
features/src/npm-packages/installer.go	Main installer logic for parsing and installing comma-separated npm packages
features/src/npm-packages/install.sh	Shell script entry point that invokes the Go installer
features/src/npm-packages/devcontainer-feature.json	Feature metadata and configuration with installsAfter dependency on node
features/src/npm-packages/README.md	Documentation for the npm-packages feature
features/test/npm-packages/scenarios.json	Test scenario configuration
features/test/npm-packages/test-images.json	Test image definitions (Debian 11, 12, Ubuntu 24.04)
features/test/npm-packages/install.sh	Test verification script
build/build.go	Added build, test, and publish tasks for npm-packages
README.md	Added npm-packages to the feature list
.github/workflows/ci.yml	Added npm-packages to the CI matrix

Copilot · 2026-01-23T10:50:51Z

installer/npm.go

+func (npm) InstallGlobalPackage(npmPackage, version string) error {
+	packageWithVersion := npmPackage
+	if version != "" && version != "latest" {
+		packageWithVersion = fmt.Sprintf("%s@%s", npmPackage, version)
+	}


The InstallGlobalPackage function should validate that npmPackage doesn't already contain a version specifier when version is non-empty, or document that npmPackage can be a combined "package@version" string and version parameter should be empty in that case. The current implementation allows invalid combinations like npmPackage="which@3.0.1" and version="4.0.0" which would result in attempting to install "which@3.0.1@4.0.0".

Copilot · 2026-01-23T10:50:51Z

features/src/npm-packages/installer.go

+	parts := strings.Split(*version, ",")
+	var pkgs []string
+	for _, p := range parts {
+		trimmed := strings.TrimSpace(p)
+		if trimmed != "" {
+			pkgs = append(pkgs, trimmed)
+		}
+	}


Missing handling for empty package list. When no packages are specified, the code should print a message like "No packages specified for installation." and return early, consistent with the system-packages feature (features/src/system-packages/installer.go:25-28).

Copilot · 2026-01-23T10:50:51Z

features/src/npm-packages/installer.go

+	flag.Parse()
+
+	if _, err := exec.LookPath("npm"); err != nil {
+		return fmt.Errorf("Could not find npm, make sure to install it first.")


Error message should start with a lowercase letter to be consistent with error message conventions throughout the codebase. All error messages in the installer package start with lowercase (e.g., "failed to install dependencies" in installer/apk.go:15, "failed getting latest version" in installer/npm.go:15). Change "Could not find" to "could not find".

Copilot · 2026-01-23T10:50:51Z

features/test/npm-packages/install.sh

+[[ -f "$(dirname "$0")/functions.sh" ]] && source "$(dirname "$0")/functions.sh"
+
+check_version "$(npm list -g @devcontainers/cli 2>&1)" "@devcontainers/cli"
+check_version "$(npm list -g which@3.0.1 2>&1)" "which@3.0.1"


The test checks for "which@3.0.1" in the npm list output, but npm list may show the package name and version differently depending on the npm version. Consider checking for just "which" to make the test more robust, or verify that npm list consistently outputs the package@version format across all test images.

Suggested change

check_version "$(npm list -g which@3.0.1 2>&1)" "which@3.0.1"

check_version "$(npm list -g which 2>&1)" "which"

Copilot · 2026-01-23T10:50:52Z

features/src/npm-packages/devcontainer-feature.json

+                "@devcontainers/cli,which@3.0.1"
+            ],
+            "default": "",
+            "description": "The packages to install, comma separated"


The description should use "Comma-separated" (with hyphen and capital C) to be consistent with the system-packages feature (features/src/system-packages/devcontainer-feature.json:9). Change "comma separated" to "Comma-separated".

Copilot · 2026-01-23T10:50:52Z

features/src/npm-packages/installer.go

+	version := flag.String("packages", "", "")
+	flag.Parse()
+
+	if _, err := exec.LookPath("npm"); err != nil {
+		return fmt.Errorf("Could not find npm, make sure to install it first.")
+	}
+
+	parts := strings.Split(*version, ",")


The flag variable is named "version" but should be named "packages" to reflect what it actually contains. This is inconsistent with the flag name "-packages" and confusing for maintainability.

Suggested change

version := flag.String("packages", "", "")

flag.Parse()

if _, err := exec.LookPath("npm"); err != nil {

return fmt.Errorf("Could not find npm, make sure to install it first.")

}

parts := strings.Split(*version, ",")

packages := flag.String("packages", "", "")

flag.Parse()

if _, err := exec.LookPath("npm"); err != nil {

return fmt.Errorf("Could not find npm, make sure to install it first.")

}

parts := strings.Split(*packages, ",")

Copilot · 2026-01-23T10:50:52Z

features/src/npm-packages/installer.go

+		}
+	}
+	for _, pkg := range pkgs {
+		fmt.Printf("Installing '%s'", pkg)


Missing newline character at the end of the printf statement. This will cause subsequent output to appear on the same line, making logs harder to read. Add "\n" at the end of the format string.

Suggested change

fmt.Printf("Installing '%s'", pkg)

fmt.Printf("Installing '%s'\n", pkg)

Copilot · 2026-01-23T10:50:53Z

features/src/npm-packages/installer.go

+	for _, pkg := range pkgs {
+		fmt.Printf("Installing '%s'", pkg)
+		if err := installer.Tools.Npm.InstallGlobalPackage(pkg, ""); err != nil {
+			return err
+		}
+	}
+	return nil
+}


The InstallGlobalPackage function expects npmPackage and version as separate parameters, but this code passes packages that may already contain version specifiers (e.g., "which@3.0.1"). While passing an empty string for version makes this work, the API usage is confusing and error-prone. If someone were to accidentally pass a non-empty version parameter when the package string already contains a version, it would result in an invalid package specifier like "which@3.0.1@4.0.0". Consider either: (1) parsing the package string to extract name and version separately before calling InstallGlobalPackage, or (2) modifying InstallGlobalPackage to accept a single combined package@version string.

Suggested change

for _, pkg := range pkgs {

fmt.Printf("Installing '%s'", pkg)

if err := installer.Tools.Npm.InstallGlobalPackage(pkg, ""); err != nil {

return err

}

}

return nil

}

for _, pkgSpec := range pkgs {

name, ver := parseNpmPackageSpec(pkgSpec)

if name == "" {

continue

}

fmt.Printf("Installing '%s'", pkgSpec)

if err := installer.Tools.Npm.InstallGlobalPackage(name, ver); err != nil {

return err

}

}

return nil

}

// parseNpmPackageSpec splits an npm package specifier into name and version.

// Examples:

// "which" -> ("which", "")

// "which@3.0.1" -> ("which", "3.0.1")

// "@scope/pkg" -> ("@scope/pkg", "")

// "@scope/pkg@3.0.1" -> ("@scope/pkg", "3.0.1")

func parseNpmPackageSpec(spec string) (string, string) {

spec = strings.TrimSpace(spec)

if spec == "" {

return "", ""

}

// Find the last '@'. For scoped packages without version (e.g. "@scope/pkg"),

// the only '@' is at index 0, which we treat as "no version".

idx := strings.LastIndex(spec, "@")

if idx <= 0 {

return spec, ""

}

name := spec[:idx]

version := strings.TrimSpace(spec[idx+1:])

if version == "" {

return name, ""

}

return name, version

}

Copilot

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.

Copilot · 2026-01-23T11:15:27Z

features/src/npm-packages/README.md

+```json
+"features": {
+    "ghcr.io/postfinance/devcontainer-features/npm-packages:0.1.0": {
+        "packages": ""


The example usage shows an empty string for the packages option, which would result in no packages being installed. Consider using a more meaningful example, such as the one from the proposals field: "@devcontainers/cli,which@3.0.1". This would better demonstrate the feature's functionality to users.

Suggested change

"packages": ""

"packages": "@devcontainers/cli,which@3.0.1"

Roemer requested a review from Copilot January 23, 2026 10:43

Copilot started reviewing on behalf of Roemer January 23, 2026 10:43 View session

Copilot AI reviewed Jan 23, 2026

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feat: Added npm-packages

58badc2

Roemer force-pushed the feature/npm-packages branch from 4682d2c to 58badc2 Compare January 23, 2026 11:06

Roemer requested a review from Copilot January 23, 2026 11:06

Copilot started reviewing on behalf of Roemer January 23, 2026 11:08 View session

Copilot AI reviewed Jan 23, 2026

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feat: Added npm-packages #33

feat: Added npm-packages #33

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	check_version "$(npm list -g which@3.0.1 2>&1)" "which@3.0.1"
	check_version "$(npm list -g which 2>&1)" "which"

	fmt.Printf("Installing '%s'", pkg)
	fmt.Printf("Installing '%s'\n", pkg)

-	for _, pkg := range pkgs {
-		fmt.Printf("Installing '%s'", pkg)
-		if err := installer.Tools.Npm.InstallGlobalPackage(pkg, ""); err != nil {
-			return err
-		}
-	}
-	return nil
-}
+	for _, pkgSpec := range pkgs {
+		name, ver := parseNpmPackageSpec(pkgSpec)
+		if name == "" {
+			continue
+		}
+		fmt.Printf("Installing '%s'", pkgSpec)
+		if err := installer.Tools.Npm.InstallGlobalPackage(name, ver); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+// parseNpmPackageSpec splits an npm package specifier into name and version.
+// Examples:
+//   "which" -> ("which", "")
+//   "which@3.0.1" -> ("which", "3.0.1")
+//   "@scope/pkg" -> ("@scope/pkg", "")
+//   "@scope/pkg@3.0.1" -> ("@scope/pkg", "3.0.1")
+func parseNpmPackageSpec(spec string) (string, string) {
+	spec = strings.TrimSpace(spec)
+	if spec == "" {
+		return "", ""
+	}
+	// Find the last '@'. For scoped packages without version (e.g. "@scope/pkg"),
+	// the only '@' is at index 0, which we treat as "no version".
+	idx := strings.LastIndex(spec, "@")
+	if idx <= 0 {
+		return spec, ""
+	}
+	name := spec[:idx]
+	version := strings.TrimSpace(spec[idx+1:])
+	if version == "" {
+		return name, ""
+	}
+	return name, version
+}

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