René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Build context scan feels slow when directory contains large file tree","articleBody":"Environment: IntelliJ IDEA 2020.2 EAP Build #IU-202.5103.13 with bundled Docker plugin 202.5103.13. Docker plugin must use docker-java, connection to Docker Desktop for Windows via npipe. Cannot find out the exact version of docker-java that is used.\r\n\r\nGiven the following minimal project setup:\r\n`node_modules` with +67k files\r\n`Dockerfile` with single line `FROM hello-world` \r\n`.dockerignore` with single line `node_modules`\r\n\r\nThen, run `docker build .` in the root directory.\r\n\r\nExpected behaviour: The image is built instantly, because build context contains only the Dockerfile (large node_modules directory is ignored), and there are almost no instructions in the Dockerfile itself.\r\n\r\nObserved behaviour: For +30 seconds, the screen shows \"Building image...\" , and after that only one file is added to the build context archive.\r\n\r\nI assume, the build traverses all +67k files in the node_modules directory, only to find none of them have to be included. This would be very inefficient. When there are no exceptions, that allow a file below node_modules, it might skip the whole directory.\r\n\r\nUpdate:\r\nUnit test in `docker-java-core`, `testdir` has the large folder as child, `.dockerignore` absent:\r\n```java\r\n@Test\r\n    public void can_parse_dockerfile() throws IOException {\r\n        File dockerFile = new File(\".\\\\testdir\\\\Dockerfile\");\r\n        File baseDirectory = new File(\".\\\\testdir\");\r\n        Dockerfile dockerfile = new Dockerfile(dockerFile, baseDirectory);\r\n        Stopwatch stopwatch = Stopwatch.createStarted();\r\n        Dockerfile.ScannedResult parse = dockerfile.parse();\r\n        System.out.println(\"Parse took \" + stopwatch.elapsed(TimeUnit.MILLISECONDS) + \"ms\");\r\n        System.out.println(parse.filesToAdd.size() + \" files added\");\r\n    }\r\n```\r\nOutput:\r\n\u003e Parse took 28008ms\r\n\u003e 4 files added","author":{"url":"https://github.com/swiedenfeld","@type":"Person","name":"swiedenfeld"},"datePublished":"2020-06-07T20:43:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":7},"url":"https://github.com/1409/docker-java/issues/1409"}