puppet: Pull in pinned puppet modules.

Using puppet modules from the puppet forge judiciously will allow us
to simplify the configuration somewhat; this specifically pulls in the
stdlib module, which we were already using parts of.

scripts/lib/puppet_cache.py

@@ -0,0 +1,77 @@
+import hashlib
+import json
+import os
+import shutil
+import subprocess
+
+import yaml
+
+from .zulip_tools import parse_os_release, run
+
+ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+ZULIP_SRV_PATH = "/srv"
+
+PUPPET_MODULES_CACHE_PATH = os.path.join(ZULIP_SRV_PATH, "zulip-puppet-cache")
+PUPPET_DEPS_FILE_PATH = os.path.join(ZULIP_PATH, "puppet/deps.yaml")
+PUPPET_THIRDPARTY = os.path.join(PUPPET_MODULES_CACHE_PATH, "current")
+
+
+def generate_sha1sum_puppet_modules() -> str:
+    data = {}
+    with open(PUPPET_DEPS_FILE_PATH, "r") as fb:
+        data["deps.yaml"] = fb.read().strip()
+    data["puppet-version"] = subprocess.check_output(
+        # This is 10x faster than `puppet --version`
+        ["ruby", "-r", "puppet/version", "-e", "puts Puppet.version"],
+        universal_newlines=True,
+    ).strip()
+
+    sha1sum = hashlib.sha1()
+    sha1sum.update(json.dumps(data, sort_keys=True).encode("utf-8"))
+    return sha1sum.hexdigest()
+
+
+def setup_puppet_modules() -> None:
+    sha1sum = generate_sha1sum_puppet_modules()
+    target_path = os.path.join(PUPPET_MODULES_CACHE_PATH, sha1sum)
+    success_stamp = os.path.join(target_path, ".success-stamp")
+    # Check if a cached version already exists
+    if not os.path.exists(success_stamp):
+        do_puppet_module_install(target_path, success_stamp)
+
+    if os.path.islink(PUPPET_THIRDPARTY):
+        os.remove(PUPPET_THIRDPARTY)
+    elif os.path.isdir(PUPPET_THIRDPARTY):
+        shutil.rmtree(PUPPET_THIRDPARTY)
+    os.symlink(target_path, PUPPET_THIRDPARTY)
+
+
+def do_puppet_module_install(
+    target_path: str,
+    success_stamp: str,
+) -> None:
+    # This is to suppress Puppet warnings with ruby 2.7.
+    distro_info = parse_os_release()
+    puppet_env = os.environ.copy()
+    if (distro_info["ID"], distro_info["VERSION_ID"]) in [("ubuntu", "20.04")]:
+        puppet_env["RUBYOPT"] = "-W0"
+
+    os.makedirs(target_path, exist_ok=True)
+    with open(PUPPET_DEPS_FILE_PATH, "r") as yaml_file:
+        deps = yaml.safe_load(yaml_file)
+        for module, version in deps.items():
+            run(
+                [
+                    "puppet",
+                    "module",
+                    "--modulepath",
+                    target_path,
+                    "install",
+                    module,
+                    "--version",
+                    version,
+                ],
+                env=puppet_env,
+            )
+    with open(success_stamp, "w"):
+        pass