Add support for haproxy map files

HAProxy supports the use of map files for selecting backends, or
a number of other functions. See [1] and [2].

This patch adds the key `maps` for each service definition allowing
fragments of a complete map to be defined across all the services,
with each service contributing some elements to the overall map file.

The service enabled/disabled and state flags are observed to add and
remove entries from the map file, and individual map entries can also
be marked as present/absent to make inclusion conditional.

[1] https://www.haproxy.com/blog/introduction-to-haproxy-maps/
[2] https://www.haproxy.com/documentation/hapee/latest/configuration/map-files/syntax/

Change-Id: I755c18a4d33ee69c42d68a50daa63614a2b2feb7

defaults/main.yml

@@ -90,6 +90,48 @@ haproxy_service_configs: []
 #       haproxy_service_enabled: True
 #       haproxy_default_backend: other_backend
 
+# HAProxy maps (unrelated keys are omitted but are required as the previous service example)
+# Example:
+# haproxy_service_configs:
+#   - service:
+#       state: present                         # state 'absent' will remove map entries defined in this service
+#       haproxy_service_enabled: true          # haproxy_service_enabled 'false' will remove map entries defined in this service
+#       haproxy_service_name: "one"
+#       haproxy_maps:
+#         - 'use_backend %[req.hdr(host),lower,map(/etc/haproxy/route.map)]'
+#       haproxy_map_entries:
+#         - name: 'route'                      # this service contributes entries to the map called 'route'
+#           order: 10                         # prefix the name of the map fragment wih this string to control ordering of the assembled map
+#           entries:
+#             - compute.example.com nova-api
+#             - dashboard.example.com horizon
+#   - service:                                # this service has no map definitions
+#       haproxy_service_name: "two"
+#   - service:
+#       haproxy_service_name: "three"
+#       haproxy_map_entries:
+#         - name: 'route'                     # this service contributes to the map called 'route'
+#           entries:
+#             - s3.example.com radosgw
+#             - sso.example.com keycloak
+#         - name: 'rate'                      # and also to the map called 'rate'
+#           state: present                    # individual map entries can be removed with state 'absent'
+#           entries:
+#             - /api/foo 20
+#             - /api/bar 40
+#
+# Results:
+#
+# /etc/haproxy/route.map
+#    s3.example.com radosgw
+#    sso.example.com keycloak
+#    compute.example.com nova-api
+#    dashboard.example.com horizon
+#
+# /etc/haproxy/rate.map
+#    /api/foo 20
+#    /api/bar 40
+
 galera_monitoring_user: monitoring
 haproxy_bind_on_non_local: False
 

handlers/main.yml

@@ -25,6 +25,15 @@
   listen:
     - cert installed
 
+- name: regenerate maps
+  vars:
+    all_changed_results: "{{ (map_create.results + map_delete.results) | select('changed') }}"
+  assemble:
+    src: "/etc/haproxy/map.conf.d/{{ item }}"
+    dest: "/etc/haproxy/{{ item }}.map"
+  notify: Reload haproxy
+  with_items: "{{ all_changed_results | map(attribute='item') | flatten | selectattr('name', 'defined') | map(attribute='name') | unique }}"
+
 - name: Regenerate haproxy configuration
   assemble:
     src: "/etc/haproxy/conf.d"

releasenotes/notes/haproxy-maps-787084d7f161c27e.yaml

@@ -0,0 +1,11 @@
+---
+features:
+  - |
+    A new key `haproxy_map_entries` is now able to be configured for each
+    haproxy service definition to allow arbitrary entries to be placed in
+    any number of haproxy map files which may then be referenced in other
+    directives in the haproxy config file such as ``use_backend`` or
+    ``http-request``. The complete map files are constructed from the
+    fragments defined across all the service definitions and are assembled
+    into a complete map file in alphanumeric sort order, or optionally with
+    a user defined ordering.

tasks/haproxy_service_config.yml

@@ -13,6 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+
+###########################################################################
+# Service frontends and backends assembled from fragments into haproxy.conf
+###########################################################################
+
 - name: Create haproxy service config files
   template:
     src: service.j2
@@ -41,3 +46,44 @@
       (item.service.state is defined and item.service.state == 'absent')
   tags:
     - haproxy-service-config
+
+###########################################################################
+# Map files assembled from fragments from each service into <map-name>.map
+###########################################################################
+
+- name: Create haproxy map fragment directories
+  file:
+    state: directory
+    path: "/etc/haproxy/map.conf.d/{{ item }}"
+  with_items: "{{ haproxy_service_configs | selectattr('service.haproxy_map_entries', 'defined') | map(attribute='service.haproxy_map_entries') | flatten | map(attribute='name') | unique }}"
+
+# create map entries when the service is enabled and an existing map fragment is not absent
+- name: Create haproxy map files
+  vars:
+    map_file: "/etc/haproxy/map.conf.d/{{ item.1.name }}/{{ item.1.order | default('00') }}-{{ item.0.service.haproxy_service_name }}.map"
+  template:
+    src: map.j2
+    dest: "{{ map_file }}"
+  with_subelements:
+    - "{{ haproxy_service_configs | selectattr('service.haproxy_map_entries', 'defined') }}"
+    - service.haproxy_map_entries
+  when:
+    - (item.0.service.haproxy_service_enabled | default(True)) | bool
+    - item.1.state | default('present') != 'absent'
+  notify: regenerate maps
+  register: map_create
+
+# remove map entries when the service is not enabled, the service is absent or the map is absent
+- name: Delete unused map entries
+  file:
+    state: absent
+    path: "/etc/haproxy/map.conf.d/{{ item.1.name }}/{{ item.1.order | default('00') }}-{{ item.0.service.haproxy_service_name }}.map"
+  when:
+    - (item.0.service.haproxy_service_enabled | default('True')) | bool is falsy or
+      (item.0.service.state is defined and item.0.service.state == 'absent') or
+      (item.1.state | default('present') == 'absent')
+  with_subelements:
+    - "{{ haproxy_service_configs | selectattr('service.haproxy_map_entries', 'defined') }}"
+    - service.haproxy_map_entries
+  notify: regenerate maps
+  register: map_delete

templates/map.j2

@@ -0,0 +1,3 @@
+{% for m in item.1.entries %}
+{{ m }}
+{% endfor %}

templates/service.j2

@@ -79,6 +79,9 @@ frontend {{ item.service.haproxy_service_name }}-front-{{ loop.index }}
 {%     endif %}
 {%   endfor %}
 {% endif %}
+{% for entry in item.service.haproxy_maps | default([])  %}
+    {{ entry }}
+{% endfor %}
 {% if (item.service.haproxy_ssl | default(false) | bool) and request_option == 'http' and (loop.index == 1 or vip_address in extra_lb_tls_vip_addresses or (item.service.haproxy_ssl_all_vips | default(false) | bool and vip_address not in extra_lb_vip_addresses)) %}
     http-request add-header X-Forwarded-Proto https
 {% endif %}