ansible: increase MaxStartups for jenkins-workspace

This is necessary when many workers running tests try to access the
temp repo to download binaries simultaneously.

PR-URL: #1515
Reviewed-By: Refael Ackermann <[email protected]>
Reviewed-By: Rod Vagg <[email protected]>

Author: joaocgreis

ansible/roles/jenkins-workspace/handlers/main.yml

@@ -0,0 +1,8 @@
+---
+
+#
+# generic handlers for jenkins-workspace stuff
+#
+
+- name: restart sshd
+  service: name="{{ sshd_service_name }}" state=restarted

ansible/roles/jenkins-workspace/tasks/main.yml

@@ -80,3 +80,10 @@
     owner: "binary_tmp"
     group: "binary_tmp"
     mode: 0755
+
+- name: Increase the maximum number of connections trying to authenticate
+  notify: restart sshd
+  lineinfile:
+    line: "MaxStartups 100:30:150"
+    dest: "{{ ssh_config }}"
+    regexp: "MaxStartups"

ansible/roles/jenkins-workspace/vars/main.yml

@@ -0,0 +1,13 @@
+---
+
+#
+# variables for jenkins-workspace
+#
+
+ssh_config: /etc/ssh/sshd_config
+
+sshd_service_map: {
+  'ubuntu1604': 'ssh',
+}
+
+sshd_service_name: "{{ sshd_service_map[os]|default(sshd_service_map[os|stripversion])|default('sshd') }}"