Set ulimits for gerrit

We set core size to 0 and number of files to twice the setting of
core.packedGitOpenFiles. Make gerrit_packed_git_open_files a role
variable so we can jinja the 2x transformation.

Change-Id: I05dbfe1f091e7014c47b0f1ba79f99b51d1a6c30

playbooks/roles/gerrit/defaults/main.yaml

@@ -4,6 +4,7 @@ gerrit_home_dir: /home/gerrit2
 gerrit_site_dir: "{{ gerrit_home_dir }}/review_site"
 gerrit_run_compose_up: false
 gerrit_run_init: false
+gerrit_packed_git_open_files: 4096
 gerrit_container_image: docker.io/opendevorg/gerrit:2.13
 gerrit_container_volumes:
   - /home/gerrit2/review_site/cache:/var/gerrit/cache

playbooks/roles/gerrit/templates/docker-compose.yaml.j2

@@ -13,6 +13,9 @@ services:
     environment:
       JAVA_OPTIONS: "-Xmx{{ gerrit_heap_limit }}"
 {% endif %}
+    ulimits:
+      core: 0
+      nofile: {{ gerrit_packed_git_open_files * 2 }}
   # Utility "service" to allow us to run ad-hoc commands
   shell:
     image: {{ gerrit_container_image }}

playbooks/roles/gerrit/templates/gerrit.config

@@ -40,7 +40,7 @@
 {% endif %}
 [gc]
 [core]
-	packedGitOpenFiles = 4096
+	packedGitOpenFiles = {{ gerrit_packed_git_open_files }}
 	packedGitLimit = 400m
 	packedGitWindowSize = 16k
 [sshd]