Strip empty lines from Sensu configuration files

While it is true that the generated configuration files should not be
modified manually, they might still get inspected from time to time.
And in those cases, having a nice, readable configuration file can
make a significant difference in usability.

But because we do not want to bundle all our template conditional
logic into one continuous block that looks like a core dump, we
implemented the cleanup by using Jinja's trim modifiers to code
blocks.

This way we can almost have a cake and eat it too: the template is
readable from developer's perspective and the generated configuration
is concise and clean.

roles/agent/templates/agent.yml.j2

@@ -9,18 +9,18 @@
 {% if not agent_config or "backend-url" not in agent_config %}
 backend-url:
 {{ agent_backend_urls | to_nice_yaml }}
-{% endif %}
+{% endif -%}
 
 {% if agent_trusted_ca_file is defined and
       not (agent_config and "trusted-ca-file" in agent_config) %}
 trusted-ca-file: /etc/sensu/sensu-agent-trusted-ca.crt
-{% endif %}
+{% endif -%}
 
 {% if agent_trusted_ca_file is defined or agent_config and
       ("trusted-ca-file" in agent_config and
        not "insecure-skip-tls-verify" in agent_config) %}
 insecure-skip-tls-verify: false
-{% endif %}
+{% endif -%}
 
 {% if agent_config %}
 {{ agent_config | to_nice_yaml }}

roles/backend/templates/backend.yml.j2

@@ -5,119 +5,119 @@
 
 {% if not backend_config or "state-dir" not in backend_config %}
 state-dir: "/var/lib/sensu/sensu-backend"
-{% endif %}
+{% endif -%}
 
 {% set secure_etcd = etcd_trusted_ca_file is defined or etcd_cert_file is defined or
         etcd_key_file is defined or etcd_peer_cert_file is defined or
         etcd_peer_key_file is defined %}
 {% if secure_etcd and
       (not backend_config or "etcd-listen-client-urls" not in backend_config) %}
 etcd-listen-client-urls: "https://localhost:2379"
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or "etcd-listen-peer-urls" not in backend_config) %}
 etcd-listen-peer-urls: "https://localhost:2380"
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or "etcd-initial-cluster" not in backend_config) %}
 etcd-initial-cluster: "default=https://localhost:2380"
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or
        "etcd-initial-advertise-peer-urls" not in backend_config) %}
 etcd-initial-advertise-peer-urls: "https://localhost:2380"
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or "etcd-cert-file" not in backend_config) %}
 etcd-cert-file: "/etc/sensu/etcd-client.crt"
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or "etcd-key-file" not in backend_config) %}
 etcd-key-file: "/etc/sensu/etcd-client.key"
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or "etcd-client-cert-auth" not in backend_config) %}
 etcd-client-cert-auth: true
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or "etcd-trusted-ca-file" not in backend_config) %}
 etcd-trusted-ca-file: "/etc/sensu/etcd-client-ca.crt"
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or "etcd-peer-cert-file" not in backend_config) %}
 etcd-peer-cert-file: "/etc/sensu/etcd-peer.crt"
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or "etcd-peer-key-file" not in backend_config) %}
 etcd-peer-key-file: "/etc/sensu/etcd-peer.key"
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or
        "etcd-peer-client-cert-auth" not in backend_config) %}
 etcd-peer-client-cert-auth: true
-{% endif %}
+{% endif -%}
 
 {% if secure_etcd and
       (not backend_config or
        "etcd-peer-trusted-ca-file" not in backend_config) %}
 etcd-peer-trusted-ca-file: "/etc/sensu/etcd-peer-ca.crt"
-{% endif %}
+{% endif -%}
 
 {% set secure_api = api_cert_file is defined or api_key_file is defined or
         api_trusted_ca_file is defined %}
 {% if secure_api and
       (not backend_config or "cert-file" not in backend_config) %}
 cert-file: "/etc/sensu/api.crt"
-{% endif %}
+{% endif -%}
 
 {% if secure_api and
       (not backend_config or "key-file" not in backend_config) %}
 key-file: "/etc/sensu/api.key"
-{% endif %}
+{% endif -%}
 
 {% if secure_api and
       (not backend_config or
        "insecure-skip-tls-verify" not in backend_config) %}
 insecure-skip-tls-verify: false
-{% endif %}
+{% endif -%}
 
 {% if secure_api and
       (not backend_config or "trusted-ca-file" not in backend_config) %}
 trusted-ca-file: "/etc/sensu/api-ca.crt"
-{% endif %}
+{% endif -%}
 
 {% if secure_api and
       (not backend_config or
        "insecure-skip-tls-verify" not in backend_config) %}
 insecure-skip-tls-verify: false
-{% endif %}
+{% endif -%}
 
 {% if secure_api and
       (not backend_config or "api-url" not in backend_config) %}
 api-url: "https://localhost:8080"
-{% endif %}
+{% endif -%}
 
 {% set secure_dashboard = dashboard_cert_file is defined or
         dashboard_key_file is defined %}
 {% if secure_dashboard and
       (not backend_config or "dashboard-cert-file" not in backend_config) %}
 dashboard-cert-file: "/etc/sensu/dashboard.crt"
-{% endif %}
+{% endif -%}
 
 {% if secure_dashboard and
       (not backend_config or "dashboard-key-file" not in backend_config) %}
 dashboard-key-file: "/etc/sensu/dashboard.key"
-{% endif %}
+{% endif -%}
 
 {% if backend_config %}
 {{ backend_config | to_nice_yaml }}