dest: destination of templated file in remote hosts. using for loops for configs of reverse proxies like HAProxy or Nginx; using variables is useful to share the same templates for prod/stg/dev environments; Important points As I explained template module is very convenient, but as long as it modifies original files at execution of Ansible, there is a possibility of miss configurations. Ansible provides a very useful module named template, which give you the ability to use a template where you can make use of available variables, use conditions to generate specific case data, use filters, statements and comments to provide more information to the template user. The "fatal" loop task loses data that one should reasonably expect to find in the register variable. First, add the following line to your ansible.cfg:--- [defaults] jinja2_extensions = jinja2.ext.do,jinja2.ext.i18n Ask Question Asked 4 years, 7 months ago. In most cases, Jinja2 template files are used for creating files or replacing configuration files on servers. If you iterate over huge dictionary Ansible’s output is real mess. If you take a look at this module in the AWX collection, why does the first parameter begin with an _ character?. Author: Tim Fairweather. _terms. The variables are all optional, so I needed a way to handle this. You can use the cat command to examine the output and verify where the models exist in … This option will expose the following information. Now we write a simple playbook that will call on a Jinja template we will write. [gituser@ip RTR-TEMPLATE]$ ansible-playbook site.yml PLAY ... After the template line is 'with_items:'; with_items is an iterator (it acts like a for loop where the variable 'item' will be set to equal one of with_items elements on each iteration). I'm using for in template file {% for vhost in item %} server = {{vhost}} {% endfor %} With items use with_items in file yml ansible. If the result of any attempt has “all systems go” in its stdout, the task succeeds. Using ‘for’ loop structure inside Ansible template One of the main program expression we usually use is the ‘for’ loop. Im just trying to get my head around the example in the docs. repeating a polling step until a certain result is reached. I have also used ansible facts to get the IPv4 address from the managed node and place it in the vsftpd.conf just for reference purpose. Note: You can use Jinja2 loops and conditionals in Ansible templates, but not in Ansible Playbooks. src: source of the template file which is ./templates by default. It can be a relative and absolute path. The item from the previous iteration of the loop. Sometimes, though, just expanding pre-defined variables is not good enough. with_items is replaced by loop and the flatten filter. We get an output that is not what we expect. Jinja templates in Ansible can be very powerful. So what I want to do is: In a template I want to loop over all the objects in the array and output the values of each "mount" key. Tim has spent the bulk of his career in the solution architecture space, problem solving and designing solutions to meet very specific needs. These examples show how to convert many common with_ style loops to loop and filters. ansible Nested loops Example. Ansible will look for jinja2 template files in your project directory or in a directory named templates under your project directory. #we can further add more parameters as follows owner: user_name group: user_group mode: u+rw,g-wx,o-rwx Active 1 year, 8 months ago. To see the results of individual retries, run the play with -vv. For example: When you use register with a loop, the data structure placed in the variable will contain a results attribute that is a list of all responses from the module. The template files will usually have the.j2 extension, which denotes the Jinja2 templating engine used. (1 indexed), The current iteration of the loop. Before you look at loops in Ansible, I hope you have followed other chapters in this Ansible tutorial series. However, by default Ansible sets the loop variable item for each loop. We use this information to set up host aggregates. To control the time (in seconds) between the execution of each item in a task loop, use the pause directive with loop_control: To keep track of where you are in a loop, use the index_var directive with loop_control. And so on. Templating is extremely useful when creating custom configuration files for multiple servers but unique for each of them. When available, passing the list to a parameter is better than looping over the task. With the introduction of Ansible Collections, we gained a lot more control over the content we use in our Ansible playbooks. If until is not defined, the value for the retries parameter is forced to 1. Now for the j2 template itself varloop.j2: In this j2 template we are attempting the following: looping over the list of colours and attempting to run a nested loop inside, that counts the number of people who’s favourite is the colour of the current loop iteration, listing all of the things that are of the colour of the current loop iteration. — http://jinja.pocoo.org/docs/2.9/templates/#assignments. included tasks/roles can overwrite variables from basically anywhere. Loop dictionary in ansible template. I try it like this: (% for mounts in {{ ansible_mounts }} %) Mountpoint: {{ ansible_mounts.mount }} (% endfor %) But it does not work. When looping over complex data structures, the console output of your task can be enormous. Template files bear the .j2 extension, implying that Jinja2 templating is in use. This is for making console output more readable, not protecting sensitive data. Viewed 41k times 13. with_indexed_items is replaced by loop, the flatten filter and loop_control.index_var. They can also be a leading contributor to hair loss. Hi all, I think I'm just being dumb here, but I cant find anything that explicitly answers my question. In some ways it comes down to documentation, a mixing of languages (YAML, Python, Jinja2), and variables. Hosts is our inventory file and is simply our localhost that we are running Ansible on. This can result in a great amount of verbosity if the item is a dictionary or is otherwise long. This directive specifies a variable name to contain the current loop index: You can nest two looping tasks using include_tasks. This also applies to loops. Mainly the ability to have a variable’s value accessible outside of the loop that is currently being run. For example: Check the module documentation to see if you can pass a list to any particular module’s parameter(s). Notice in our output after running Ansible with our updated template file, the numbers are properly counted. You can specify the name of the variable for each loop using loop_var with loop_control: If Ansible detects that the current loop is using a variable which has already been defined, it will raise an error to fail the task. Knowing the basics of YAML is also appreciated. In computer programming, this is called a loop. Active 3 years, 10 months ago. Iterating over a simple loop. (0 indexed), The number of iterations from the end of the loop (1 indexed), The number of iterations from the end of the loop (0 indexed). See the output here: In our example we see that because we can’t call the variable outside of the inner loop, the counting didn’t work. We have specified an array called ‘ packages ‘ that contains a list of packages that need to be installed. It's really important to know how Jinja2 works if you want to create powerful templates for your playbooks. Hope this helps you out in your template writing. SUMMARY late template expansion turns the lack of variable scopes into a problem under certain conditions. The playbook is called varloop.yml: The playbook simply uses the variable file we specified and calls the template module in a task to build a file called output.txt from a j2 template. The benefit of using the template module, rather than the copy module, is that the Ansible template module can … Ansible Jinja Warrior - Mastering "Loop Variable Scope" Average Reading Time: ~6 minutes 0 Comments. with_sequence is replaced by loop and the range function, and potentially the format filter. If there is sensitive data in loop, set no_log: yes on the task to prevent disclosure. In developing the j2 (the Jinja2 templating language) logic to do things like calculate bandwidth figures, we ran into some limitations. For example, when looping through the output of the "show ip bgp sum", we want to use just an IP of the peer as an input in another task. In the next example, I’ll be using the template module to print all the items present in a list using the for the loop. In my case each iteration produced about 3k output, and it pushed full jenkins output way over 2Mb for my project. Let’s create a templates directory to keep thing cleaner and more organized: [elliot@control plays]$ mkdir templates [elliot@control plays]$ cd templates/ The template module also copies a file to a remote server, but it allows you to use Jinja2 to render a template to a file dynamically. Have a question? As you can see we have 2 dictionary variables defined. Common Ansible loops include changing ownership on several files and/or directories with the file module, creating multiple users with the user module, and The loop keyword requires a list as input, but the lookup keyword returns a string of comma-separated values by default. Multiple loop keywords were provided, which were prefixed with with_, followed by the name of an Ansible look-up plug-in (an advanced feature not covered in detail in this course). This config file has a heading for each machine type, and then a series of variables. These include lineinfile and blockinfile, among others. Ansible 2.5 introduced a new Jinja2 function named query that always returns a list, offering a simpler interface and more predictable output from lookup plugins when using the loop keyword. (1 indexed) loop.length: The number of items in the sequence Two different examples for different files: /etc/hosts and workers.properties: /etc/hosts We want to generate the following snip… © Copyright 2019 Red Hat, Inc. Author: Tim Fairweather. As of Ansible 2.8 you can get extended loop information using the extended option to loop control. Jinja2 can be a pain, but ultimately a very powerful tool. You can force lookup to return a list to loop by using wantlist=True, or you can use query instead. The loop syntax is usually best expressed using filters instead of more complex use of query or lookup. (1 indexed) loop.length: The number of items in the sequence Two different examples for different files: /etc/hosts and workers.properties: /etc/hosts We want to generate the following snip… A quick modification to your /etc/ansible.cfg file and a small change to your template, and we can get this working. You should know the concept of Ansible playbooks, aware of the ad-hoc commands and know the basic terminology associated with Ansible like list, dictionaries etc. The loop keyword is equivalent to with_list, and is the best choice for simple loops. Notice how the for loop in Jinja2 mimics the syntax of Python’s for loop; again don’t forget to end the loop with {% endfor %}. We are looking to improve loop syntax - watch this page and the changelog for updates. As of Ansible 2.8 you can get the name of the value provided to loop_control.loop_var using the ansible_loop_var variable. ansible_hostnameis just another regular variable expansion. Viewed 1k times 1. This block allows us to use the update function to update an element in a dictionary variable. Undefined during the first iteration. Ansible has a number of modules that can be used to modify existing files. In 2.0 you are able to use with_ loops and task includes (but not playbook includes), this adds the ability to loop over the set of tasks in one shot. In Ansible loops you can use the conditional statement when to control the looping based on the nature of variables or system facts. In our example we see that because we can’t call the variable outside of the inner loop, the counting didn’t work. One containing a list of people with their favourite colours, and a second one containing a list of colours with things that happen to be of those colours. SUMMARY. The benefit of using the template module, rather than the copy module, is that the Ansible template module can use the Jinja2 templating language.Jinja2. A significant part of this initiative was to dynamically create configuration templates for routers, based on variable input. That might sound confusing to the new Ansible user, so I'll break it down a bit through an example. Along with marketing and website responsibilities, Tim’s focus at Arctiq is in the following key areas: jinja2_extensions = jinja2.ext.do,jinja2.ext.i18n, Arctiq, 41 Britain Street, Suite 302, Toronto, ON, M5A 1R7, Canada, Microservices - Anthos, GKE, Openshift, Kubernetes, Docker, CI/CD, Foundations - Red Hat Enterprise Linux, VMware, Cloud (GCP, AWS, Azure), Integrated Security - Satellite, image hardening, custom provisioning, DevOps Consulting - Team and culture improvements, workflow and process improvements. Accessing Ansible Variables with Jinja2 Loops 03 January 2018. We could either use what Ansible package delivered or resort to things like distributing Ansible modules in roles (which we consider an ugly hack around Ansible's limitations). Apart from that, you can perform conditional statements such as loops and if-else statements, and transform the data using filters and so much more. While using loops in Ansible, by default, output contains the entire content of the item being processed. Why? First, I’ll describe the issue in detail (feel free to follow along on your own Ansible install).