jetbrains.jdk: add updateScript and a test

The update script uses the `jbr/release` file in IDEA Ultimate’s
current release tarball to resolve the latest JBR version JetBrains
is currently using in their IDEs.

pkgs/development/compilers/jetbrains-jdk/default.nix

@@ -37,29 +37,26 @@ let
     "x86_64-linux" = "x64";
   }.${stdenv.hostPlatform.system} or (throw "Unsupported system: ${stdenv.hostPlatform.system}");
   cpu = stdenv.hostPlatform.parsed.cpu.name;
+
+  versionInfo = lib.importJSON ./version-info.json;
+
 in
 jdk.overrideAttrs (oldAttrs: rec {
   pname = "jetbrains-jdk" + lib.optionalString withJcef "-jcef";
-  javaVersion = "21.0.4";
-  build = "598.4";
-  # To get the new tag:
-  # git clone https://github.com/jetbrains/jetbrainsruntime
-  # cd jetbrainsruntime
-  # git checkout jbr-release-${javaVersion}b${build}
-  # git log --simplify-by-decoration --decorate=short --pretty=short | grep "jbr-" --color=never | cut -d "(" -f2 | cut -d ")" -f1 | awk '{print $2}' | sort -t "-" -k 2 -g | tail -n 1 | tr -d ","
-  openjdkTag = "jbr-21.0.4+8";
+  inherit (versionInfo)
+    javaVersion
+    build
+    openjdkTag
+    SOURCE_DATE_EPOCH;
   version = "${javaVersion}-b${build}";
 
   src = fetchFromGitHub {
     owner = "JetBrains";
     repo = "JetBrainsRuntime";
-    rev = "jb${version}";
-    hash = "sha256-YF5Z1A4qmD9Z4TE6f2i8wv9ZD+NqHGY5Q0oIVQiC3Bg=";
+    inherit (versionInfo) rev hash;
   };
 
   BOOT_JDK = jdk.home;
-  # run `git log -1 --pretty=%ct` in jdk repo for new value on update
-  SOURCE_DATE_EPOCH = 1726275531;
 
   patches = [ ];
 
@@ -162,5 +159,6 @@ jdk.overrideAttrs (oldAttrs: rec {
       };
       jcef = nixosTests.jetbrains-jdk;
     };
+    updateScript = [ ./update.py jetbrains.idea-ultimate.src jetbrains.idea-ultimate.version ];
   };
 })

pkgs/development/compilers/jetbrains-jdk/update.py

@@ -0,0 +1,102 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i python3
+#!nix-shell -p nix-prefetch-github
+#!nix-shell -p "python3.withPackages(p: with p; [ python-dotenv ])"
+#
+# Usage: ./update <idea-ultimate tarball> <idea version>
+#
+# The first argument is a path to an IntelliJ IDEA Ultimate tarball and the second argument is version, like 2023.3.1
+# of that tarball. You can get a path to one with `nix-build -A jetbrains.idea-ultimate.src`.
+#
+# The tarball contains a file with JBR version information at <prefix>/jbr/release. From that file we resolve the
+# Git tag and a few other bits of metadata of the JBR version used by that version of IDEA, and with that we can
+# pre-fetch the source and get the hash.
+#
+import json
+import os.path
+import re
+import subprocess
+import sys
+import tarfile
+from datetime import datetime
+from io import TextIOWrapper
+from json.decoder import JSONDecodeError
+from pathlib import PurePath
+
+import dotenv.parser
+
+# Size of the tarfile buffer
+BUFFER_SIZE = 4 * 1024 * 1024
+
+# Regular expression for extracting different components from an `IMPLEMENTOR_VERSION` line, like:
+#     JBR-17.0.10+1-1087.23-jcef
+#         └┬────┘ ╿ └┬────┘
+#          │      │  │
+#          │      │  │
+#          │      │  ┕ build
+#          │      ┕ javaBuild
+#          ┕ javaVersion
+#
+VERSION_LINE = re.compile(r"""JBR-(?P<javaVersion>[0-9.]+)\+(?P<javaBuild>\d+)-(?P<build>\d+\.\d+)(-\w+)?""")
+
+
+def extract_jbr_release(intellij_tarball: str) -> dict[str, str]:
+    """Extracts jbr/release from the source tarball and returns a dict with the contents of that file."""
+
+    with tarfile.open(name=intellij_tarball, mode="r", bufsize=BUFFER_SIZE) as src:
+        member = next(member for member in src if PurePath(member.name).match("*/jbr/release"))
+
+        with src.extractfile(member) as release:
+            return {b.key: b.value for b in dotenv.parser.parse_stream(TextIOWrapper(release))}
+
+
+def prefetch(rev: str) -> str:
+    argv = ["nix-prefetch-github", "--meta", "--rev", tag, "JetBrains", "JetBrainsRuntime"]
+    prefetched = json.loads(subprocess.check_output(argv).decode("utf-8"))
+    src = prefetched["src"]
+    meta = prefetched["meta"]
+    commit_timestamp = datetime.fromisoformat(f"{meta['commitDate']}T{meta['commitTimeOfDay']}Z")
+    return dict(
+        hash=src["hash"],
+        SOURCE_DATE_EPOCH=int(commit_timestamp.timestamp()),
+    )
+
+
+if __name__ == "__main__":
+    idea_tarball = sys.argv[1]
+    idea_version = sys.argv[2]
+    version_info_file = os.path.join(os.path.dirname(os.path.realpath(__file__)), "version-info.json")
+
+    try:
+        with open(version_info_file, mode="rb") as input:
+            version_info = json.load(input)
+    except (FileNotFoundError, JSONDecodeError):
+        version_info = dict()
+
+    if version_info.get("ideaVersion") == idea_version:
+        print(f"Up to date at {version_info['rev']} for IntelliJ IDEA {idea_version}.", file=sys.stderr)
+        sys.exit(0)
+
+    print(f"Updating JBR release to match IDEA {idea_version}…", file=sys.stderr)
+
+    release = extract_jbr_release(idea_tarball)
+
+    version_info = {"ideaVersion": idea_version}
+
+    version_info |= VERSION_LINE.fullmatch(release["IMPLEMENTOR_VERSION"]).groupdict()
+
+    java_version = version_info["javaVersion"]
+    java_build = version_info["javaBuild"]
+    build = version_info["build"]
+    tag = f"jb{java_version}-b{build}"
+
+    version_info["openjdkTag"] = f"jbr-{java_version}+{java_build}"
+
+    version_info["rev"] = tag
+    version_info |= prefetch(tag)
+
+    with open(version_info_file, "w") as out:
+        json.dump(version_info, out, indent=4)
+        out.write("\n")
+
+    print(f"JBR updated to {tag}", file=sys.stderr)

pkgs/development/compilers/jetbrains-jdk/version-info.json

@@ -0,0 +1,10 @@
+{
+    "ideaVersion": "2024.2.1",
+    "javaVersion": "21.0.3",
+    "javaBuild": "13",
+    "build": "509.11",
+    "openjdkTag": "jbr-21.0.3+13",
+    "rev": "jb21.0.3-b509.11",
+    "hash": "sha256-zTstmrH4KteR40BVDRfxOrl8aUQ26acE+ywscBd8sw8=",
+    "SOURCE_DATE_EPOCH": 1723453663
+}