fix: Set browser User-Agent for Jenkins requests

Jenkins servers behind a WAF/CDN such as Cloudflare reject the default
python-requests/python-jenkins User-Agent as suspected bot traffic,
causing commands like "lftools jenkins get-credentials" to fail with a
bot-detection challenge.

Set a browser-like User-Agent on the underlying requests session after
creating the python-jenkins client. The value defaults to a Firefox UA
and can be overridden via the LFTOOLS_JENKINS_USER_AGENT environment
variable.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Change-Id: Id76e2348d330aff12fdfa1ecea77daf306954242
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>

Author: askb

lftools/jenkins/__init__.py

@@ -41,6 +41,12 @@ def jjb_ini() -> str | None:
 
 JJB_INI: str | None = jjb_ini()
 
+# Some Jenkins servers sit behind a WAF/CDN (e.g. Cloudflare) that blocks the
+# default python-requests/python-jenkins User-Agent as suspected bot traffic.
+# Sending a browser-like User-Agent avoids these bot-detection challenges.
+# The value can be overridden via the LFTOOLS_JENKINS_USER_AGENT env variable.
+DEFAULT_USER_AGENT: str = "Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0"
+
 
 class Jenkins:
     """lftools Jenkins object."""
@@ -70,4 +76,17 @@ def __init__(
 
         self.server: jenkins.Jenkins = jenkins.Jenkins(server, username=user, password=password)  # type: ignore
 
+        # Override the default User-Agent so requests are not flagged as bot
+        # traffic by WAF/CDN layers (e.g. Cloudflare) in front of Jenkins.
+        # Use `or DEFAULT_USER_AGENT` so an empty env value still applies a
+        # browser-like UA rather than falling back to the requests default.
+        user_agent: str = os.environ.get("LFTOOLS_JENKINS_USER_AGENT") or DEFAULT_USER_AGENT
+        # `_session` is a python-jenkins internal; guard against it being
+        # renamed/removed in a future release so init never hard-fails.
+        session = getattr(self.server, "_session", None)
+        if session is not None:
+            session.headers["User-Agent"] = user_agent
+        else:
+            log.debug("python-jenkins session unavailable; skipping User-Agent override.")
+
         self.url: str = server