Add support for sparse checkouts (#1369)

* Add support for sparse checkouts

* sparse-checkout: optionally turn off cone mode

While it _is_ true that cone mode is the default nowadays (mainly for
performance reasons: code mode is much faster than non-cone mode), there
_are_ legitimate use cases where non-cone mode is really useful.

Let's add a flag to optionally disable cone mode.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

* Verify minimum Git version for sparse checkout

The `git sparse-checkout` command is available only since Git version
v2.25.0. The `actions/checkout` Action actually supports older Git
versions than that; As of time of writing, the minimum version is
v2.18.0.

Instead of raising this minimum version even for users who do not
require a sparse checkout, only check for this minimum version
specifically when a sparse checkout was asked for.

Suggested-by: Tingluo Huang <tingluohuang@github.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

* Support sparse checkout/LFS better

Instead of fetching all the LFS objects present in the current revision
in a sparse checkout, whether they are needed inside the sparse cone or
not, let's instead only pull the ones that are actually needed.

To do that, let's avoid running that preemptive `git lfs fetch` call in
case of a sparse checkout.

An alternative that was considered during the development of this patch
(and ultimately rejected) was to use `git lfs pull --include <path>...`,
but it turned out to be too inflexible because it requires exact paths,
not the patterns that are available via the sparse checkout definition,
and that risks running into command-line length limitations.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

---------

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Co-authored-by: Daniel <daniel.fernandez@feverup.com>

src/git-command-manager.ts

@@ -1,5 +1,6 @@
 import * as core from '@actions/core'
 import * as exec from '@actions/exec'
+import * as fs from 'fs'
 import * as fshelper from './fs-helper'
 import * as io from '@actions/io'
 import * as path from 'path'
@@ -16,6 +17,8 @@ export interface IGitCommandManager {
   branchDelete(remote: boolean, branch: string): Promise<void>
   branchExists(remote: boolean, pattern: string): Promise<boolean>
   branchList(remote: boolean): Promise<string[]>
+  sparseCheckout(sparseCheckout: string[]): Promise<void>
+  sparseCheckoutNonConeMode(sparseCheckout: string[]): Promise<void>
   checkout(ref: string, startPoint: string): Promise<void>
   checkoutDetach(): Promise<void>
   config(
@@ -25,7 +28,13 @@ export interface IGitCommandManager {
     add?: boolean
   ): Promise<void>
   configExists(configKey: string, globalConfig?: boolean): Promise<boolean>
-  fetch(refSpec: string[], fetchDepth?: number): Promise<void>
+  fetch(
+    refSpec: string[],
+    options: {
+      filter?: string
+      fetchDepth?: number
+    }
+  ): Promise<void>
   getDefaultBranch(repositoryUrl: string): Promise<string>
   getWorkingDirectory(): string
   init(): Promise<void>
@@ -52,9 +61,14 @@ export interface IGitCommandManager {
 
 export async function createCommandManager(
   workingDirectory: string,
-  lfs: boolean
+  lfs: boolean,
+  doSparseCheckout: boolean
 ): Promise<IGitCommandManager> {
-  return await GitCommandManager.createCommandManager(workingDirectory, lfs)
+  return await GitCommandManager.createCommandManager(
+    workingDirectory,
+    lfs,
+    doSparseCheckout
+  )
 }
 
 class GitCommandManager {
@@ -64,6 +78,7 @@ class GitCommandManager {
   }
   private gitPath = ''
   private lfs = false
+  private doSparseCheckout = false
   private workingDirectory = ''
 
   // Private constructor; use createCommandManager()
@@ -154,6 +169,27 @@ class GitCommandManager {
     return result
   }
 
+  async sparseCheckout(sparseCheckout: string[]): Promise<void> {
+    await this.execGit(['sparse-checkout', 'set', ...sparseCheckout])
+  }
+
+  async sparseCheckoutNonConeMode(sparseCheckout: string[]): Promise<void> {
+    await this.execGit(['config', 'core.sparseCheckout', 'true'])
+    const output = await this.execGit([
+      'rev-parse',
+      '--git-path',
+      'info/sparse-checkout'
+    ])
+    const sparseCheckoutPath = path.join(
+      this.workingDirectory,
+      output.stdout.trimRight()
+    )
+    await fs.promises.appendFile(
+      sparseCheckoutPath,
+      `\n${sparseCheckout.join('\n')}\n`
+    )
+  }
+
   async checkout(ref: string, startPoint: string): Promise<void> {
     const args = ['checkout', '--progress', '--force']
     if (startPoint) {
@@ -202,15 +238,23 @@ class GitCommandManager {
     return output.exitCode === 0
   }
 
-  async fetch(refSpec: string[], fetchDepth?: number): Promise<void> {
+  async fetch(
+    refSpec: string[],
+    options: {filter?: string; fetchDepth?: number}
+  ): Promise<void> {
     const args = ['-c', 'protocol.version=2', 'fetch']
     if (!refSpec.some(x => x === refHelper.tagsRefSpec)) {
       args.push('--no-tags')
     }
 
     args.push('--prune', '--progress', '--no-recurse-submodules')
-    if (fetchDepth && fetchDepth > 0) {
-      args.push(`--depth=${fetchDepth}`)
+
+    if (options.filter) {
+      args.push(`--filter=${options.filter}`)
+    }
+
+    if (options.fetchDepth && options.fetchDepth > 0) {
+      args.push(`--depth=${options.fetchDepth}`)
     } else if (
       fshelper.fileExistsSync(
         path.join(this.workingDirectory, '.git', 'shallow')
@@ -423,10 +467,15 @@ class GitCommandManager {
 
   static async createCommandManager(
     workingDirectory: string,
-    lfs: boolean
+    lfs: boolean,
+    doSparseCheckout: boolean
   ): Promise<GitCommandManager> {
     const result = new GitCommandManager()
-    await result.initializeCommandManager(workingDirectory, lfs)
+    await result.initializeCommandManager(
+      workingDirectory,
+      lfs,
+      doSparseCheckout
+    )
     return result
   }
 
@@ -476,7 +525,8 @@ class GitCommandManager {
 
   private async initializeCommandManager(
     workingDirectory: string,
-    lfs: boolean
+    lfs: boolean,
+    doSparseCheckout: boolean
   ): Promise<void> {
     this.workingDirectory = workingDirectory
 
@@ -539,6 +589,16 @@ class GitCommandManager {
       }
     }
 
+    this.doSparseCheckout = doSparseCheckout
+    if (this.doSparseCheckout) {
+      // The `git sparse-checkout` command was introduced in Git v2.25.0
+      const minimumGitSparseCheckoutVersion = new GitVersion('2.25')
+      if (!gitVersion.checkMinimum(minimumGitSparseCheckoutVersion)) {
+        throw new Error(
+          `Minimum Git version required for sparse checkout is ${minimumGitSparseCheckoutVersion}. Your git ('${this.gitPath}') is ${gitVersion}`
+        )
+      }
+    }
     // Set the user agent
     const gitHttpUserAgent = `git/${gitVersion} (github-actions-checkout)`
     core.debug(`Set git useragent to: ${gitHttpUserAgent}`)