Improved WSL 2 detection and browser resolution

CHANGELOG.md

@@ -6,6 +6,10 @@
 
 - Allow to set timeout for Puppeteer actions by `PUPPETEER_TIMEOUT` env ([#409](https://github.com/marp-team/marp-cli/pull/409))
 
+### Fixed
+
+- Improved WSL 2 detection and browser resolution ([#410](https://github.com/marp-team/marp-cli/pull/410))
+
 ### Changed
 
 - Upgrade Marpit to [v2.2.1](https://github.com/marp-team/marpit/releases/tag/v2.2.1) ([#408](https://github.com/marp-team/marp-cli/pull/408))

src/utils/chrome-finder.ts

@@ -7,9 +7,13 @@ import {
 import { isWSL } from './wsl'
 
 // A lightweight version of Launcher.getFirstInstallation()
-// https://github.com/GoogleChrome/chrome-launcher/blob/master/src/chrome-launcher.ts#L175
+// https://github.com/GoogleChrome/chrome-launcher/blob/30755cde8627b7aad6caff1594c9752f80a39a4d/src/chrome-launcher.ts#L189-L192
 export const findChromeInstallation = () => {
-  const platform = isWSL() ? 'wsl' : process.platform
+  // 'wsl' platform will resolve Chrome from Windows. In WSL 2, Puppeteer cannot
+  // communicate with Chrome spawned in the host OS so should follow the
+  // original platform ('linux') if CLI was executed in WSL 2.
+  const platform = isWSL() === 1 ? 'wsl' : process.platform
+
   const installations = (() => {
     switch (platform) {
       /* istanbul ignore next: CI is not testing against darwin */

src/utils/edge-finder.ts

@@ -14,7 +14,8 @@ export const findAccessiblePath = (paths: string[]): string | undefined =>
   })
 
 const linux = (): string | undefined => {
-  if (isWSL()) {
+  // WSL 1 should find Edge executable from host OS
+  if (isWSL() === 1) {
     const localAppData = resolveWindowsEnvSync('LOCALAPPDATA')
 
     return win32({

src/utils/puppeteer.ts

@@ -50,8 +50,8 @@ export const generatePuppeteerDataDirPath = async (
 ): Promise<string> => {
   const dataDir = await (async () => {
     if (isWSL() && wslHost) {
-      // In WSL environment, Marp CLI will use Chrome on Windows. Thus, we have to
-      // specify Windows path when converting within WSL.
+      // In WSL environment, Marp CLI may use Chrome on Windows. If Chrome has
+      // located in host OS (Windows), we have to specify Windows path.
       if (wslTmp === undefined) wslTmp = await resolveWindowsEnv('TMP')
       if (wslTmp !== undefined) return path.win32.resolve(wslTmp, name)
     }

src/utils/wsl.ts

@@ -33,15 +33,23 @@ export const resolveWindowsEnvSync = (key: string): string | undefined => {
 export const isWSL = (): number => {
   if (isWsl === undefined) {
     if (require('is-wsl')) {
-      isWsl = 1
-
-      try {
-        // https://github.com/microsoft/WSL/issues/423#issuecomment-611086412
-        const release = readFileSync('/proc/sys/kernel/osrelease').toString()
-        if (release.includes('WSL2')) isWsl = 2
-      } catch (e: unknown) {
-        // no ops
-      }
+      // Detect whether WSL version is 2
+      // https://github.com/microsoft/WSL/issues/4555#issuecomment-700213318
+      const isWSL2 = (() => {
+        if (process.env.WSL_DISTRO_NAME && process.env.WSL_INTEROP) return true
+
+        try {
+          const verStr = readFileSync('/proc/version', 'utf8').toLowerCase()
+          if (verStr.includes('microsoft-standard-wsl2')) return true
+
+          const gccMatched = verStr.match(/gcc[^,]+?(\d+)\.\d+\.\d+/)
+          if (gccMatched && Number.parseInt(gccMatched[1], 10) >= 8) return true
+        } catch (e: unknown) {
+          // no ops
+        }
+      })()
+
+      isWsl = isWSL2 ? 2 : 1
     } else {
       isWsl = 0
     }

test/utils/wsl.ts

@@ -82,7 +82,23 @@ describe('#resolveWindowsEnvSync', () => {
 })
 
 describe('#isWSL', () => {
-  afterEach(() => jest.dontMock('is-wsl'))
+  let originalWSLDistroName: string | undefined
+  let originalWSLInterop: string | undefined
+
+  beforeEach(() => {
+    originalWSLDistroName = process.env.WSL_DISTRO_NAME
+    originalWSLInterop = process.env.WSL_INTEROP
+
+    process.env.WSL_DISTRO_NAME = ''
+    process.env.WSL_INTEROP = ''
+  })
+
+  afterEach(() => {
+    process.env.WSL_DISTRO_NAME = originalWSLDistroName
+    process.env.WSL_INTEROP = originalWSLInterop
+
+    jest.dontMock('is-wsl')
+  })
 
   it('returns 0 if is-wsl module returned false', () => {
     jest.doMock('is-wsl', () => false)
@@ -94,7 +110,9 @@ describe('#isWSL', () => {
 
     const readFileSync = jest
       .spyOn(fs, 'readFileSync')
-      .mockImplementation(() => '4.19.128-microsoft-standard')
+      .mockImplementation(
+        () => 'Linux version 4.5.6-12345-Microsoft (gcc version 5.4.0 (GCC) )'
+      )
 
     expect(wsl().isWSL()).toBe(1)
     expect(readFileSync).toHaveBeenCalledTimes(1)
@@ -104,15 +122,55 @@ describe('#isWSL', () => {
     expect(readFileSync).toHaveBeenCalledTimes(1)
   })
 
-  it('returns 2 if running on WSL 2', () => {
+  it('returns 2 if running on WSL 2 (Fast check by environment values)', () => {
     jest.doMock('is-wsl', () => true)
 
-    // https://github.com/microsoft/WSL/issues/423#issuecomment-611086412
-    jest
+    const readFileSync = jest.spyOn(fs, 'readFileSync')
+
+    // WSL 2 has WSL_DISTRO_NAME and WSL_INTEROP
+    process.env.WSL_DISTRO_NAME = 'Ubuntu'
+    process.env.WSL_INTEROP = '/run/WSL/11_interop'
+
+    expect(wsl().isWSL()).toBe(2)
+    expect(readFileSync).not.toHaveBeenCalled()
+  })
+
+  it('returns 2 if running on WSL 2 (Check WSL2 annotation in /proc/version string)', () => {
+    jest.doMock('is-wsl', () => true)
+
+    const readFileSync = jest
+      .spyOn(fs, 'readFileSync')
+      .mockImplementation(() => 'Linux version 4.5.6-Microsoft-Standard-WSL2')
+
+    expect(wsl().isWSL()).toBe(2)
+    expect(readFileSync).toHaveBeenCalledTimes(1)
+  })
+
+  it('returns 2 if running on WSL 2 (Check gcc version in /proc/version string)', () => {
+    jest.doMock('is-wsl', () => true)
+
+    const readFileSync = jest
       .spyOn(fs, 'readFileSync')
-      .mockImplementation(() => '4.19.128-microsoft-WSL2-standard')
+      .mockImplementation(
+        () => 'Linux version 4.5.6-12345-Microsoft (gcc version 8.4.0 (GCC) )'
+      )
 
     expect(wsl().isWSL()).toBe(2)
+    expect(readFileSync).toHaveBeenCalledTimes(1)
+  })
+
+  it('returns 2 if running on WSL 2 (The latest format of /proc/version string)', () => {
+    jest.doMock('is-wsl', () => true)
+
+    const readFileSync = jest
+      .spyOn(fs, 'readFileSync')
+      .mockImplementation(
+        () =>
+          'Linux version 5.10.74.3 (x86_64-msft-linux-gcc (GCC) 9.3.0, GNU ld (GNU Binutils) 2.34.0.20200220)'
+      )
+
+    expect(wsl().isWSL()).toBe(2)
+    expect(readFileSync).toHaveBeenCalledTimes(1)
   })
 })