fix(vcs): don't fork a process for every untracked file

This solves an issue where Garden would flood spawned processes with
a huge amount of source files. This could happen, for example, when
library directories (e.g. node_modules) weren't ignored.

garden-service/package.json

@@ -52,6 +52,7 @@
     "fs-extra": "^7.0.1",
     "get-port": "^4.0.0",
     "has-ansi": "^3.0.0",
+    "hasha": "^5.0.0",
     "ignore": "^5.0.4",
     "indent-string": "^3.2.0",
     "inquirer": "^6.2.1",

garden-service/src/vcs/git.ts

@@ -8,7 +8,9 @@
 
 import * as execa from "execa"
 import { join, resolve } from "path"
-import { ensureDir, pathExists } from "fs-extra"
+import { ensureDir, pathExists, stat, createReadStream } from "fs-extra"
+import { PassThrough } from "stream"
+import * as hasha from "hasha"
 
 import { VcsHandler, RemoteSourceParams, VcsFile } from "./vcs"
 import { ConfigurationError, RuntimeError } from "../exceptions"
@@ -115,7 +117,7 @@ export class GitHandler extends VcsHandler {
         // If we can't compute the hash, i.e. the file is gone, we filter it out below
         let hash = ""
         try {
-          hash = (await git("hash-object", resolvedPath))[0]
+          hash = await this.hashObject(resolvedPath) || ""
         } catch (err) {
           // 128 = File no longer exists
           if (err.code !== 128) {
@@ -191,4 +193,15 @@ export class GitHandler extends VcsHandler {
     }
   }
 
+  /**
+   * Replicates the `git hash-object` behavior. See https://stackoverflow.com/a/5290484/3290965
+   */
+  async hashObject(path: string) {
+    const info = await stat(path)
+    const stream = new PassThrough()
+    const output = hasha.fromStream(stream, { algorithm: "sha1" })
+    stream.push(`blob ${info.size}\0`)
+    createReadStream(path).pipe(stream)
+    return output
+  }
 }

garden-service/test/unit/src/vcs/git.ts

@@ -124,6 +124,17 @@ describe("GitHandler", () => {
       ])
     })
   })
+
+  describe("hashObject", () => {
+    it("should return the same result as `git hash-object` for a file", async () => {
+      const path = resolve(tmpPath, "foo.txt")
+      await createFile(path)
+
+      const expected = (await git("hash-object", path))[0]
+
+      expect(await handler.hashObject(path)).to.equal(expected)
+    })
+  })
 })
 
 describe("git", () => {