Add ability to use exporter without id propertyv1.1.0

The id property of the exporter is used for checking the default values
specified in `prometheus_target_exporter_defaults` variable.
However when both the `host` and the `path` fields are specified
manually in the `prometheus_target_exporter` list this id is never
looked up.
The way the templating was handled however, still resulted in an error
when leaving out the id field.
The templating code was now rewritten to allow for the following
exporter configuraion to run:

prometheus_target_exporter:
- { host: exporter_without_id, path: /opt/simple_target4.yml }

Signed-off-by: Colin Wilk <colin.wilk@tum.de>

5 files changed, 19 insertions, 6 deletions

diff --git a/README.md b/README.md
index f3d285c..0cfe278 100644
--- a/README.md
+++ b/README.md
@@ -254,6 +254,8 @@ Multiple exporters
     - role: kliwniloc.prometheus_target # deploy targets
       prometheus_target_exporter:
         - id: node_exporter # deploy node_exporter with default host
+        # deploy an exporter that is not specified in prometheus_target_exporter_defaults
+        - { host: exporter_without_id, path: /opt/simple_target4.yml }
         # deploy blackbox_exporter with multiple hosts
         - { id: blackbox_exporter, host: node1.example.org }
         - { id: blackbox_exporter, host: node2.example.org }
diff --git a/meta/argument_specs.yml b/meta/argument_specs.yml
index 270bf68..502c640 100644
--- a/meta/argument_specs.yml
+++ b/meta/argument_specs.yml
@@ -71,7 +71,7 @@ argument_specs:
         options:
           id:
             type: str
-            required: true
+            required: false
           path:
             type: str
             required: false
diff --git a/molecule/default/converge.yml b/molecule/default/converge.yml
index e96fb81..9346988 100644
--- a/molecule/default/converge.yml
+++ b/molecule/default/converge.yml
@@ -17,6 +17,7 @@
         - /opt/simple_target1.yml
         - /opt/simple_target2.yml
         - /opt/simple_target3.yml
+        - /opt/simple_target4.yml
 
   vars:
     prometheus_target_host: prometheus
@@ -34,6 +35,7 @@
         - id: node_exporter
         - { id: blackbox_exporter, host: test1 }
         - { id: blackbox_exporter, host: test2 }
+        - { host: exporter_without_id, path: /opt/simple_target4.yml }
     - role: kliwniloc.prometheus_target
       prometheus_target_exporter:
         - id: blackbox_exporter
diff --git a/molecule/default/tests/test_check_prometheus_targets.py b/molecule/default/tests/test_check_prometheus_targets.py
index 9ce1056..ddf3a22 100644
--- a/molecule/default/tests/test_check_prometheus_targets.py
+++ b/molecule/default/tests/test_check_prometheus_targets.py
@@ -7,10 +7,12 @@ def test_check_hosts_added_simple(host):
     t1 = host.file('/opt/simple_target1.yml')
     t2 = host.file('/opt/simple_target2.yml')
     t3 = host.file('/opt/simple_target3.yml')
+    t4 = host.file('/opt/simple_target4.yml')
 
     assert t1.exists
     assert t2.exists
     assert t3.exists
+    assert t4.exists
 
     assert t1.content_string == \
         '    - application\n'
@@ -23,6 +25,9 @@ def test_check_hosts_added_simple(host):
     assert t3.content_string == \
         '    - application_AA\n'
 
+    assert t4.content_string == \
+        '    - exporter_without_id\n'
+
 """
 Test prefix functionality
 """
diff --git a/tasks/lineinfile.yml b/tasks/lineinfile.yml
index d7f0793..0367be9 100644
--- a/tasks/lineinfile.yml
+++ b/tasks/lineinfile.yml
@@ -1,12 +1,16 @@
 ---
 - name: Make sure targets are deployed
   ansible.builtin.lineinfile:
-    path: '{{ (item.path_prefix
-           | default(prometheus_target_exporter_defaults[item.id].path_prefix)
-           | default(prometheus_target_exporter_target_prefix)) ~
-           item.path | default(prometheus_target_exporter_defaults[item.id].path) }}'
+    path: '{{ (
+           item.path_prefix if item.path_prefix is defined else
+           (prometheus_target_exporter_defaults[item.id].path_prefix
+           | default(prometheus_target_exporter_target_prefix))
+           if item.id is defined)
+           ~
+           (item.path if item.path is defined
+           else prometheus_target_exporter_defaults[item.id].path if item.id is defined) | mandatory }}'
     line: '{{ prometheus_target_strategy_lineinfile_prefix ~
-           (item.host | default(prometheus_target_exporter_defaults[item.id].host)) ~
+           (item.host if item.host is defined else prometheus_target_exporter_defaults[item.id].host) | mandatory ~
            prometheus_target_strategy_lineinfile_suffix }}'
     state: present
   become: true