Revert "prune all images instead of parsing output"

This reverts commit d42c524a46.

This caused a bug that all app images are getting removed since we remove
all containers on infra update!

src/platform.js

@@ -97,7 +97,28 @@ async function onPlatformReady(infraChanged) {
 
 async function pruneInfraImages() {
     debug('pruneInfraImages: checking existing images');
-    await shell.promises.exec('pruneInfraImages', 'docker image prune -a --force');
+
+    // cannot blindly remove all unused images since redis image may not be used
+    const images = infra.baseImages.concat(Object.keys(infra.images).map(function (addon) { return infra.images[addon]; }));
+
+    for (const image of images) {
+        let output = safe.child_process.execSync(`docker images --digests ${image.repo} --format "{{.ID}} {{.Repository}}:{{.Tag}}@{{.Digest}}"`, { encoding: 'utf8' });
+        if (output === null) {
+            debug(`Failed to list images of ${image}`, safe.error);
+            throw safe.error;
+        }
+
+        let lines = output.trim().split('\n');
+        for (let line of lines) {
+            if (!line) continue;
+            let parts = line.split(' '); // [ ID, Repo:Tag@Digest ]
+            if (image.tag === parts[1]) continue; // keep
+            debug(`pruneInfraImages: removing unused image of ${image.repo}: tag: ${parts[1]} id: ${parts[0]}`);
+
+            let result = safe.child_process.execSync(`docker rmi ${parts[0]}`, { encoding: 'utf8' });
+            if (result === null) debug(`Error removing image ${parts[0]}: ${safe.error.mesage}`);
+        }
+    }
 }
 
 async function createDockerNetwork() {