Merge pull request #5 from centic9/fix_ansible_2_1_and_make_idempotent

Support Ansible < 2.3 and make it idempotent

tasks/main.yml

@@ -1,6 +1,11 @@
 ---
- - name: Download Dynatrace OneAgent using token id
-   block:
+ - name: Check if Dynatrace OneAgent is already installed
+   stat:
+     path: /opt/dynatrace/oneagent/agent/lib64/liboneagentos.so
+   register: agent_installed
+
+# only in Ansible >= 2.3.0: - name: Download Dynatrace OneAgent using token id
+ - block:
     - fail:
        msg: "The 'dynatrace_oneagent_cluster_subdomain' variable has not been set, it must point to the subdomain of your Dynatrace cluster. Please consult the documentation."
       when: (dynatrace_oneagent_cluster_subdomain is undefined) or (dynatrace_oneagent_cluster_subdomain is none) or (dynatrace_oneagent_cluster_subdomain | trim == "")
@@ -20,19 +25,20 @@
        url: "https://{{ dynatrace_oneagent_cluster_subdomain }}/e/{{ dynatrace_oneagent_environment_id }}/installer/agent/unix/latest/{{ dynatrace_oneagent_tenant_token }}"
        dest: "/tmp/dynatrace-oneagent.sh"
       when: ("live.dynatrace.com" != dynatrace_oneagent_cluster_subdomain) and ("live.ruxit.com" != dynatrace_oneagent_cluster_subdomain)
-   when: (oneagent_installer_script_url is undefined) or (oneagent_installer_script_url is none) or (oneagent_installer_script_url | trim == "")
+   when: agent_installed == False and ((oneagent_installer_script_url is undefined) or (oneagent_installer_script_url is none) or (oneagent_installer_script_url | trim == ""))
 
- - name: Download Dynatrace OneAgent using installer script url
-   block:
+# only in Ansible >= 2.3.0: - name: Download Dynatrace OneAgent using installer script url
+ - block:
    - fail:
       msg: "The 'oneagent_installer_script_url' variable has not been set, it must contain the Dynatrace OneAgent Installer Script URL. Please consult the documentation."
      when: (oneagent_installer_script_url is undefined) or (oneagent_installer_script_url is none) or (oneagent_installer_script_url | trim == "")
    - name: "Download Dynatrace OneAgent"
      get_url:
       url: "{{ oneagent_installer_script_url }}"
       dest: "/tmp/dynatrace-oneagent.sh"    
-   when: (oneagent_installer_script_url is defined) and (oneagent_installer_script_url is not none)
-    
+   when: agent_installed.stat.exists == False and (oneagent_installer_script_url is defined) and (oneagent_installer_script_url is not none)
+
  - name: "Install Dynatrace OneAgent"
    shell: "sh /tmp/dynatrace-oneagent.sh"
    become: yes
+   when: ansible_architecture != "armv7l" and agent_installed.stat.exists == False