feat: avoid pulling remote images when cached results are available

Author: themightychris

lib/Lens.js

@@ -110,33 +110,46 @@ class Lens extends Configurable {
         }
     }
 
-    async buildSpecForContainer (inputTree, config) {
-        const { container: containerQuery } = config;
-
-        // check if image exists locally first
-        let imageHash;
+    async getImageHash (containerQuery) {
+        // Try local first (fastest)
         try {
             const inspectOutput = await Studio.execDocker(['inspect', containerQuery]);
             const imageInfo = JSON.parse(inspectOutput)[0];
-            imageHash = imageInfo.Id;
-            logger.info(`found local image: ${containerQuery}@${imageHash}`);
+            logger.info(`found local image: ${containerQuery}@${imageInfo.Id}`);
+            return { hash: imageInfo.Id, isLocal: true };
         } catch (err) {
-            // image doesn't exist locally or can't be inspected, try pulling
-            logger.info(`pulling image: ${containerQuery}`);
-
-            try {
-                await Studio.execDocker(['pull', containerQuery], { $relayStdout: true });
-                const inspectOutput = await Studio.execDocker(['inspect', containerQuery]);
-                const imageInfo = JSON.parse(inspectOutput)[0];
-                imageHash = imageInfo.Id;
-            } catch (err) {
-                throw new Error(`failed to pull container image ${containerQuery}: ${err.message}`);
-            }
+            // Not found locally, try remote manifest
         }
 
-        if (!imageHash) {
-            throw new Error(`failed to get hash for container image ${containerQuery}`);
+        // Try remote manifest (doesn't pull the image)
+        try {
+            logger.info(`querying remote manifest for: ${containerQuery}`);
+            const manifestOutput = await Studio.execDocker(['manifest', 'inspect', containerQuery]);
+            const manifest = JSON.parse(manifestOutput);
+
+            // Extract digest from manifest
+            // For multi-arch images, manifest.config.digest contains the config digest
+            // For single-arch images, we may need to look at the digest field
+            const digest = manifest.config?.digest || manifest.digest;
+
+            if (!digest) {
+                throw new Error('No digest found in manifest');
+            }
+
+            // Ensure the digest is in the format sha256:...
+            const imageHash = digest.startsWith('sha256:') ? digest : `sha256:${digest}`;
+            logger.info(`found remote image hash: ${containerQuery}@${imageHash}`);
+            return { hash: imageHash, isLocal: false };
+        } catch (err) {
+            throw new Error(`failed to get hash for container image ${containerQuery}: ${err.message}`);
         }
+    }
+
+    async buildSpecForContainer (inputTree, config) {
+        const { container: containerQuery } = config;
+
+        // Get image hash without pulling
+        const { hash: imageHash, isLocal } = await this.getImageHash(containerQuery);
 
         // build spec
         const data = {
@@ -152,7 +165,8 @@ class Lens extends Configurable {
         return {
             ...await SpecObject.write(this.workspace.getRepo(), 'lens', data),
             data,
-            type: 'container'
+            type: 'container',
+            imageIsLocal: isLocal
         };
     }
 
@@ -317,6 +331,26 @@ class Lens extends Configurable {
         }
         const [, sha256Hash] = containerMatch;
 
+        // Ensure image is available locally
+        try {
+            await Studio.execDocker(['inspect', sha256Hash]);
+        } catch (err) {
+            // Image not found locally, need to pull it
+            // Extract the original container query from spec to pull by name:tag
+            const containerQueryMatch = spec.container.match(/^(.+)@sha256:[a-f0-9]{64}$/);
+            if (containerQueryMatch) {
+                const containerQuery = containerQueryMatch[1];
+                logger.info(`pulling required image: ${containerQuery}`);
+                try {
+                    await Studio.execDocker(['pull', containerQuery], { $relayStdout: true });
+                } catch (pullErr) {
+                    throw new Error(`failed to pull container image ${containerQuery}: ${pullErr.message}`);
+                }
+            } else {
+                throw new Error(`cannot extract container query from spec.container: ${spec.container}`);
+            }
+        }
+
         // create and start container
         const persistentDebugContainer = process.env.HOLO_DEBUG_PERSIST_CONTAINER;
         let containerId;