One thing that I do frequently with an Ansible role is check to see if software is already installed and at the desired version. I do this for several related reasons:<\/p>\n
I’m thinking particularly of software that needs to be unpacked, configured, compiled, and installed (rather than .rpm or .deb packages). In this example, I’ll be installing the fictional widgetizer<\/em> software.<\/p>\n First I add a couple variables to the Next I add a task to see if the installed binary already exists:<\/p>\n Then, if widgetizer<\/em> is installed, I check which version is installed:<\/p>\n 2 things to note in the above:<\/p>\n Now I can check the registered variables to determine if widgetizer<\/em> needs to be installed or upgraded:<\/p>\n However, when I ran my playbook I received an error:<\/p>\n The key piece of information to note in that error message is:<\/p>\n We’ve supplied There are at least 2 ways to fix this:<\/p>\n After making either of those changes, the playbook runs successfully and correctly includes or ignores the Before copying source code, configuring, compiling, and installing a software package via Ansible, first check to see if the target package is already installed and at the target version. This post includes Ansible tasks to perform those checks and covers a couple common pitfalls along the way.<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[439],"tags":[423,469],"class_list":["post-2403","post","type-post","status-publish","format-standard","hentry","category-ansible","tag-ansible","tag-jinja2"],"_links":{"self":[{"href":"https:\/\/osric.com\/chris\/accidental-developer\/wp-json\/wp\/v2\/posts\/2403","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/osric.com\/chris\/accidental-developer\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/osric.com\/chris\/accidental-developer\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/osric.com\/chris\/accidental-developer\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/osric.com\/chris\/accidental-developer\/wp-json\/wp\/v2\/comments?post=2403"}],"version-history":[{"count":7,"href":"https:\/\/osric.com\/chris\/accidental-developer\/wp-json\/wp\/v2\/posts\/2403\/revisions"}],"predecessor-version":[{"id":2413,"href":"https:\/\/osric.com\/chris\/accidental-developer\/wp-json\/wp\/v2\/posts\/2403\/revisions\/2413"}],"wp:attachment":[{"href":"https:\/\/osric.com\/chris\/accidental-developer\/wp-json\/wp\/v2\/media?parent=2403"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/osric.com\/chris\/accidental-developer\/wp-json\/wp\/v2\/categories?post=2403"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/osric.com\/chris\/accidental-developer\/wp-json\/wp\/v2\/tags?post=2403"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}defaults\/main.yml<\/code> file for the role:<\/p>\n---\r\npath_to_widgetizer: \/usr\/local\/bin\/widgetizer\r\nwidgetizer_target_version: 1.2\r\n...<\/code><\/pre>\n- name: check for existing widgetizer install\r\n stat:\r\n path: \"{{ path_to_widgetizer }}\"\r\n register: result_a\r\n tags: widgetizer<\/code><\/pre>\n- name: check widgetizer version\r\n command: \"{{ path_to_widgetizer }} --version\"\r\n register: result_b\r\n when: \"result_a.stat.exists\"\r\n changed_when: False\r\n failed_when: False\r\n tags: widgetizer<\/code><\/pre>\n\n
changed: true<\/code>, so specify changed_when: False<\/code> to prevent this.<\/li>\nfailed_when: false<\/code> to prevent this. (I could also specify ignore_errors: true<\/code>, which would report the error but would not prevent the rest of the playbook from running.)<\/li>\n<\/ul>\n- name: install\/upgrade widgetizer, if needed\r\n include: tasks\/install.yml\r\n when: \"not result_a.stat.exists or widgetizer_target_version is not defined or widgetizer_target_version not in result_b.stdout\"\r\n tags: widgetizer<\/code><\/pre>\n$ ansible-playbook -i hosts site.yaml --limit localhost --tags widgetizer\r\n\r\n...\r\n\r\nfatal: [localhost]: FAILED! => {\"failed\": true, \"msg\": \"The conditional check 'not result_a.stat.exists or widgetizer_target_version is not defined or widgetizer_target_version not in result_b.stdout' failed. The error was: Unexpected templating type error occurred on ({% if not result_a.stat.exists or widgetizer_target_version is not defined or widgetizer_target_version not in result_b.stdout %} True {% else %} False {% endif %}): coercing to Unicode: need string or buffer, float found\\n\\nThe error appears to have been in '\/home\/chris\/projectz\/roles\/widgetizer\/tasks\/install.yml': line 3, column 3, but may\\nbe elsewhere in the file depending on the exact syntax problem.\\n\\nThe offending line appears to be:\\n\\n\\n- name: copy widgetizer source\\n ^ here\\n\"}<\/code><\/pre>\nneed string or buffer, float found<\/code><\/pre>\nwidgetizer_target_version<\/code> as 1.2<\/code> (a floating point number), but Python\/jinja2 wants a string to search for in result_b.stdout<\/code>.<\/p>\n\n
widgetizer_target_version<\/code> as a string in the variable definition, e.g. widgetizer_target_version: \"1.2\"<\/code><\/li>\nwidgetizer_target_version<\/code> to a string in the when<\/code> statement, e.g. widgetizer_target_version|string not in result_b.stdout<\/code><\/li>\n<\/ul>\ninstall.yml<\/code> file as appropriate.<\/p>\n","protected":false},"excerpt":{"rendered":"