[CI] Add a helper script to aid Maven release (#7470)

* [CI] Add a helper script to aid Maven release

* Move script to dev/ [skip ci]

* Update command [skip ci]

dev/prepare_jvm_release.py

@@ -0,0 +1,83 @@
+import os
+import sys
+import errno
+import subprocess
+import glob
+import shutil
+from contextlib import contextmanager
+
+def normpath(path):
+    """Normalize UNIX path to a native path."""
+    normalized = os.path.join(*path.split("/"))
+    if os.path.isabs(path):
+        return os.path.abspath("/") + normalized
+    else:
+        return normalized
+
+def cp(source, target):
+    source = normpath(source)
+    target = normpath(target)
+    print("cp {0} {1}".format(source, target))
+    shutil.copy(source, target)
+
+def maybe_makedirs(path):
+    path = normpath(path)
+    print("mkdir -p " + path)
+    try:
+        os.makedirs(path)
+    except OSError as e:
+        if e.errno != errno.EEXIST:
+            raise
+
+@contextmanager
+def cd(path):
+    path = normpath(path)
+    cwd = os.getcwd()
+    os.chdir(path)
+    print("cd " + path)
+    try:
+        yield path
+    finally:
+        os.chdir(cwd)
+
+def run(command, **kwargs):
+    print(command)
+    subprocess.check_call(command, shell=True, **kwargs)
+
+def main():
+    with cd("jvm-packages/"):
+        print("====copying pure-Python tracker====")
+        for use_cuda in [True, False]:
+            xgboost4j = "xgboost4j-gpu" if use_cuda else "xgboost4j"
+            cp("../python-package/xgboost/tracker.py", f"{xgboost4j}/src/main/resources")
+
+        print("====copying resources for testing====")
+        with cd("../demo/CLI/regression"):
+            run(f"{sys.executable} mapfeat.py")
+            run(f"{sys.executable} mknfold.py machine.txt 1")
+        for use_cuda in [True, False]:
+            xgboost4j = "xgboost4j-gpu" if use_cuda else "xgboost4j"
+            xgboost4j_spark = "xgboost4j-spark-gpu" if use_cuda else "xgboost4j-spark"
+            maybe_makedirs(f"{xgboost4j}/src/test/resources")
+            maybe_makedirs(f"{xgboost4j_spark}/src/test/resources")
+            for file in glob.glob("../demo/data/agaricus.*"):
+                cp(file, f"{xgboost4j}/src/test/resources")
+                cp(file, f"{xgboost4j_spark}/src/test/resources")
+            for file in glob.glob("../demo/CLI/regression/machine.txt.t*"):
+                cp(file, f"{xgboost4j_spark}/src/test/resources")
+
+        print("====Creating directories to hold native binaries====")
+        for os, arch in [("linux", "x86_64"), ("windows", "x86_64"), ("macos", "x86_64")]:
+            output_dir = f"xgboost4j/src/main/resources/lib/{os}/{arch}"
+            maybe_makedirs(output_dir)
+        for os, arch in [("linux", "x86_64")]:
+            output_dir = f"xgboost4j-gpu/src/main/resources/lib/{os}/{arch}"
+            maybe_makedirs(output_dir)
+    print("====Next Steps====")
+    print("1. Obtain Linux and Windows binaries from the CI server")
+    print("2. Put them in xgboost4j(-gpu)/src/main/resources/lib/[os]/[arch]")
+    print("3. Now on a Mac machine, run:")
+    print("   GPG_TTY=$(tty) mvn deploy -Prelease -DskipTests")
+
+if __name__ == "__main__":
+    main()