From 5bb8fc139481bd6464ab9ec070d24b44bfa41433 Mon Sep 17 00:00:00 2001
From: Andrei Stepanov <astepano@redhat.com>
Date: Oct 25 2021 14:26:19 +0000
Subject: Merge #404 `add support for TEST_SSHD_USEDNS_NO`


---

diff --git a/README.md b/README.md
index 0c37b8c..5f00184 100644
--- a/README.md
+++ b/README.md
@@ -208,5 +208,12 @@ all:
 If the number of hostaliases does not match the number of subjects, you will get
 an error.
 
+## TEST_SSHD_USEDNS_NO
+
+Some EL7 systems have `sshd` configured with `UseDNS yes` by default.  This will
+cause terrible performance with `ssh` and especially with Ansible.  You can use
+`--sshd-usedns-no` or set `TEST_SSHD_USEDNS_NO=True` to configure the VM to use
+`UseDNS no` instead.
+
 [1]: https://fedoraproject.org/wiki/CI/Metadata
 [2]: http://fmf.readthedocs.io/
diff --git a/inventory/standard-inventory-qcow2 b/inventory/standard-inventory-qcow2
index 77a5758..2120723 100755
--- a/inventory/standard-inventory-qcow2
+++ b/inventory/standard-inventory-qcow2
@@ -65,6 +65,17 @@ AUTH_KEY = ("AAAAB3NzaC1yc2EAAAADAQABAAABAQDUOtNJdBEXyKxBB898rdT54ULjMGuO6v4jLX"
 DEF_USER = "root"
 DEF_PASSWD = "foobar"
 DEF_HOST = "127.0.0.3"
+# configure sshd to use UseDNS no to fix broken EL7 systems
+BOOTCMD_SSHD_USEDNS_NO = """bootcmd:
+  - |
+    if grep -q '^UseDNS' /etc/ssh/sshd_config; then
+      sed 's/^UseDNS.*$/UseDNS no/' -i /etc/ssh/sshd_config
+    elif grep -q '^#UseDNS' /etc/ssh/sshd_config; then
+      sed 's/^#UseDNS.*$/UseDNS no/' -i /etc/ssh/sshd_config
+    else
+      echo "UseDNS no" >> /etc/ssh/sshd_config
+    fi
+"""
 USER_DATA = """#cloud-config
 users:
   - default
@@ -485,6 +496,8 @@ def inv_host(opts, image, hostalias):
     userdata = os.path.join(directory, "user-data")
     with open(userdata, 'w') as f:
         f.write(USER_DATA)
+        if opts.sshd_usedns_no:
+            f.write(BOOTCMD_SSHD_USEDNS_NO)
     # Create our cloud init so we can log in
     cloudinit = os.path.join(directory, "cloud-init.iso")
     subprocess.check_call(["/usr/bin/genisoimage", "-input-charset", "utf-8",
@@ -654,6 +667,13 @@ def help_hostalias():
     --use-basename, then you do not have to use --hostalias for every subject.
     """
 
+
+def help_sshd_usedns_no():
+    return """On some EL7 systems, sshd uses 'UseDNS yes' by default.  This can
+    create a very bad performance problem with ssh and Ansible.  You can use
+    --sshd-usedns-no to configure the VM to use 'UseDNS no' instead."""
+
+
 def main():
     global logger
     global diagnose
@@ -683,6 +703,7 @@ def main():
     parser.add_argument('--host', help="Full path to qcow2 disk image")
     parser.add_argument("--use-basename", default=bool(distutils.util.strtobool(os.environ.get("TEST_USE_BASENAME", "False"))), action="store_true", help=help_hostalias())
     parser.add_argument("--hostalias", default=shlex.split(os.environ.get("TEST_HOSTALIASES", "")), action="append", help=help_hostalias())
+    parser.add_argument("--sshd-usedns-no", default=bool(distutils.util.strtobool(os.environ.get("TEST_SSHD_USEDNS_NO", "False"))), action="store_true", help=help_sshd_usedns_no())
     parser.add_argument("subjects", nargs="*", default=shlex.split(os.environ.get("TEST_SUBJECTS", "")))
     opts = parser.parse_args()
     # Send logs to common logfile for all default provisioners.