Install: advanced option to force global libvips #4060

docs/changelog.md

@@ -12,6 +12,9 @@ Requires libvips v8.15.2
   [#4048](https://github.com/lovell/sharp/pull/4048)
   [@ike-gg](https://github.com/ike-gg)
 
+* Install: add advanced option to force use of a globally-installed libvips.
+  [#4060](https://github.com/lovell/sharp/issues/4060)
+
 * Expose `bilinear` resizing kernel (and interpolator).
   [#4061](https://github.com/lovell/sharp/issues/4061)
 

docs/install.md

@@ -103,9 +103,14 @@ and on macOS when running Node.js under Rosetta.
 
 This module will be compiled from source at `npm install` time when:
 
-* a globally-installed libvips is detected (set the `SHARP_IGNORE_GLOBAL_LIBVIPS` environment variable to skip this), or
+* a globally-installed libvips is detected, or
 * when the `npm install --build-from-source` flag is used.
 
+The logic to detect a globally-installed libvips can be skipped by setting the
+`SHARP_IGNORE_GLOBAL_LIBVIPS` (never try to use it) or
+`SHARP_FORCE_GLOBAL_LIBVIPS` (always try to use it, even when missing or outdated)
+environment variables.
+
 Building from source requires:
 
 * C++11 compiler

lib/libvips.js

@@ -162,15 +162,21 @@ const pkgConfigPath = () => {
   }
 };
 
+const skipSearch = (status, reason) => {
+  log(`Detected ${reason}, skipping search for globally-installed libvips`);
+  return status;
+};
+
 const useGlobalLibvips = () => {
   if (Boolean(process.env.SHARP_IGNORE_GLOBAL_LIBVIPS) === true) {
-    log('Detected SHARP_IGNORE_GLOBAL_LIBVIPS, skipping search for globally-installed libvips');
-    return false;
+    return skipSearch(false, 'SHARP_IGNORE_GLOBAL_LIBVIPS');
+  }
+  if (Boolean(process.env.SHARP_FORCE_GLOBAL_LIBVIPS) === true) {
+    return skipSearch(true, 'SHARP_FORCE_GLOBAL_LIBVIPS');
   }
   /* istanbul ignore next */
   if (isRosetta()) {
-    log('Detected Rosetta, skipping search for globally-installed libvips');
-    return false;
+    return skipSearch(false, 'Rosetta');
   }
   const globalVipsVersion = globalLibvipsVersion();
   return !!globalVipsVersion && /* istanbul ignore next */

test/unit/libvips.js

@@ -66,6 +66,14 @@ describe('libvips binaries', function () {
 
       delete process.env.SHARP_IGNORE_GLOBAL_LIBVIPS;
     });
+    it('useGlobalLibvips can be forced via an env var', function () {
+      process.env.SHARP_FORCE_GLOBAL_LIBVIPS = 1;
+
+      const useGlobalLibvips = libvips.useGlobalLibvips();
+      assert.strictEqual(true, useGlobalLibvips);
+
+      delete process.env.SHARP_FORCE_GLOBAL_LIBVIPS;
+    });
   });
 
   describe('Build time platform detection', () => {