When you run a task with until and register the result as a variable, the registered variable will include a key called “attempts”, which records the number of the retries for the task. There are a couple of things that you need to keep in mind, a included task that has it’s own with_ loop will overwrite the value of the special item variable. 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. (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). When a variable value changes, you simply reflect that change in your variables file instead of having to make any changes to your actual template. Why? #we can further add more parameters as follows owner: user_name group: user_group mode: u+rw,g-wx,o-rwx Why? [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). The use of a well supported and powerful template library to supplement Ansible’s automation and remote control features provides a wide range of opportunities to output pretty complex files with a reasonable amount of effort. We have not deprecated the use of with_ - that syntax will still be valid for the foreseeable future. It is not yet a full replacement for with_, but we recommend it for most use cases. Referencing variables in your templates is a great way to keep your Ansible playbook logic separate from your data. Last updated on Jan 12, 2021. This option will expose the following information. The for loop in the Jinja2 template file – example2_template.j2 – is as shown When the playbook is executed, the loop iterates over the car list, and prints out the car models in the destination file. 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. We can have conditional statements, loops, filters for transforming the data, do arithmetic calculations, etc. This is for making console output more readable, not protecting sensitive data. Tim has spent the bulk of his career in the solution architecture space, problem solving and designing solutions to meet very specific needs. Ansible will look for jinja2 template files in your project directory or in a directory named templates under your project directory. Ensuring list input for loop: using query rather than lookup, Tracking progress through a loop with index_var, Defining inner and outer variable names with loop_var. The bare metal machines we use as the basis for our OpenStack infrastructure have different capabilities. Change to your templates directory and create the following hosts.j2 template file: 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. 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 %}. It doesn't continue past the failed item, even though "failed" outcomes do, and templating errors can be specific to the item in the loop.. The "fatal" loop task loses data that one should reasonably expect to find in the register variable. 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. Before Ansible 2.5, most playbooks used a different syntax for loops. A quick modification to your /etc/ansible.cfg file and a small change to your template, and we can get this working. ansible_hostnameis just another regular variable expansion. In Ansible loops you can use the conditional statement when to control the looping based on the nature of variables or system facts. Iterating over a simple loop. To access individual data in the loop we use "item" Templating is extremely useful when creating custom configuration files for multiple servers but unique for each of them. In computer programming, this is called a loop. 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. The loop keyword will not accept a string as input, see Ensuring list input for loop: using query rather than lookup. We need to have two parameters when using the Ansible Template module, such as: src: The source of the template file. If you iterate over huge dictionary Ansible’s output is real mess. As you can see we have 2 dictionary variables defined. Consider the playbook below where we have a list of packages that need to be installed. Using lists in Ansible templates. Does the _ mean you dont have to name the parameter when using it? The default value for “retries” is 3 and “delay” is 5. File: Playbook.yml - hosts: all vars: list1: ['Apple','Banana','Cat', 'Dog'] tasks: - name: Template Loop example. — http://jinja.pocoo.org/docs/2.9/templates/#assignments. 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. ansible_managed (configurable via the defaults section of ansible.cfg) … Hosts is our inventory file and is simply our localhost that we are running Ansible on. It can be a relative and absolute path. Jinja templates in Ansible can be very powerful. So in each loop iteration of the colours variable, we are able to now add a new element that contains the number of people who deem this their favourite colour. Now let’s create a full example that shows off the power of for loops in Jinja2. I try it like this: (% for mounts in {{ ansible_mounts }} %) Mountpoint: {{ ansible_mounts.mount }} (% endfor %) But it does not work. There is more to come! repeating a polling step until a certain result is reached. If there is sensitive data in loop, set no_log: yes on the task to prevent disclosure. Let’s create a templates directory to keep thing cleaner and more organized: [elliot@control plays]$ mkdir templates [elliot@control plays]$ cd templates/ 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. 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. 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. In developing the j2 (the Jinja2 templating language) logic to do things like calculate bandwidth figures, we ran into some limitations. The Ansible inventory sets a VENDOR_MODELhost variable for each machine: For use in playbooks (and in templates) Ansible automatically puts it into the hostvars dictionary. (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… If you have a list of hashes, you can reference subkeys in a loop. Ansible Template Module Example. SUMMARY. When looping over complex data structures, the console output of your task can be enormous. 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. Ask Question Asked 3 years, 10 months ago. [student1@ansible closed_loop_incident_mgmt]$ ansible-playbook demo_setup.yml After this step, log into your tower instance and verify that the 2 “SNOW” job templates are present: SNOW-Demo-Compliance-Check - this Job Template will check for the banner being in compliance. The item from the following iteration of the loop. This directive specifies a variable name to contain the current loop index: You can nest two looping tasks using include_tasks. In my case each iteration produced about 3k output, and it pushed full jenkins output way over 2Mb for my project. For example, instead of doing: Repeated tasks can be written as standard loops over a simple list of strings. with_flattened is replaced by loop and the flatten filter. included tasks/roles can overwrite variables from basically anywhere. However, they are not always easy to use effectively and correctly. We get an output that is not what we expect. Today we're gonna work with: loop.index: The current iteration of the loop. [ansible@controller lab2]$ mkdir templates [ansible@controller lab2]$ cd templates/ We have created a Jinja2 template file with content which is required to configure an FTP server using vsftpd. 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. Please keep in mind that it is not possible to set variables inside a block and have them show up outside of it. 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. For example, to get the same output as: Any with_* statement that requires using lookup within a loop should not be converted to use the loop keyword. 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). with_indexed_items is replaced by loop, the flatten filter and loop_control.index_var. During a recent consulting project with a customer, focused on network automation, we embarked on a journey to re-evaluate how routers were provisioned. Viewed 1k times 1. Have a question? In computer programming, this is called a loop. 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). Earlier-Style Loop Keywords. The current iteration of the loop. Sometimes, though, just expanding pre-defined variables is not good enough. Accessing Ansible Variables with Jinja2 Loops 03 January 2018. This differs from the data structure returned when using register without a loop: Subsequent loops over the registered variable to inspect the results may look like: During iteration, the result of the current item will be placed in the variable: You can use Jinja2 expressions to iterate over complex lists. You may need to use flatten(1) with loop to match the exact outcome. The template files will usually have the.j2 extension, which denotes the Jinja2 templating engine used. The variables are all optional, so I needed a way to handle this. So let’s move on. Note: You can use Jinja2 loops and conditionals in Ansible templates, but not in Ansible Playbooks. Most of the packaging modules, like yum and apt, have this capability. Be careful when changing with_items to loop, as with_items performed implicit single-level flattening. I have problem! Basically, minimum of two parameters are required while using template module in ansible. You can register the output of a loop as a variable. During a recent … Undefined during the first iteration. The loop keyword is equivalent to with_list, and is the best choice for simple loops. You can use the cat command to examine the output and verify where the models exist in … In most cases, Jinja2 template files are used for creating files or replacing configuration files on servers. Today we're gonna work with: loop.index: The current iteration of the loop. Hope this helps you out in your template writing. The with_ keywords rely on Lookup Plugins - even items is a lookup. Stop by the google group! The Ansible template module is mainly used to copy files from the Ansible client (where Ansible is installed) to the Ansible hosts (managed by Ansible). Viewed 41k times 13. For role authors, writing roles that allow loops, instead of dictating the required loop_var value, you can gather the value via: In most cases, loops work best with the loop keyword instead of with_X style loops. Loop dictionary in ansible template. ansible Nested loops Example. 2. If the result of any attempt has “all systems go” in its stdout, the task succeeds. First, I’ll describe the issue in detail (feel free to follow along on your own Ansible install). When available, passing the list to a parameter is better than looping over the task. For example: Check the module documentation to see if you can pass a list to any particular module’s parameter(s). Variable Filters. Ansible has a number of modules that can be used to modify existing files. Now we write a simple playbook that will call on a Jinja template we will write. Jinja templates in Ansible can be very powerful. Ansible uses Jinja2 which is a modern templating engine for Python frameworks used to generate dynamic content or expressions. You can create nested loops using with_nested. with_nested and with_cartesian are replaced by loop and the product filter. Common Ansible loops include changing ownership on several files and/or directories with the file module, creating multiple users with the user module, and repeating a polling step until a certain result is reached. The loop keyword requires a list as input, but the lookup keyword returns a string of comma-separated values by default. 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. First, add the following line to your ansible.cfg:--- [defaults] jinja2_extensions = jinja2.ext.do,jinja2.ext.i18n In some ways it comes down to documentation, a mixing of languages (YAML, Python, Jinja2), and variables. 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. The loop syntax is usually best expressed using filters instead of more complex use of query or lookup. It includes the creation of multiple users using the user module, installing multiple packages using apt or yum module or changing permissions on several files or folders using the file module. 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. To limit the displayed output, use the label directive with loop_control: The output of this task will display just the name field for each item instead of the entire contents of the multi-line {{ item }} variable. The loop_control keyword lets you manage your loops in useful ways. Here’s an example: This task runs up to 5 times with a delay of 10 seconds between each attempt. Ansible loop is used to repeat any task or a part of code multiple times in an Ansible-playbook. © Copyright 2019 Red Hat, Inc. In this section, we will explore how to make practical use of loops in your Ansible playbooks. Undefined during the last iteration. You can force lookup to return a list to loop by using wantlist=True, or you can use query instead. Notice in our output after running Ansible with our updated template file, the numbers are properly counted. Ansible offers two keywords for creating loops: loop and with_. Looping over lists. Usually, the template files will have the .j2 extension, which denotes the Jinja2 templating engine used. Non-optimal yum, slower and may cause issues with interdependencies, Place the result of the current item in the variable, Retry a task until a certain condition is met, result.stdout.find("all systems go") != -1, Show all the hosts matching the pattern, ie all but the group www, Create servers, pause 3s before creating next, start=0 end=4 stride=2 format=testuser%02x, with_random_choice -> loop (No loop is needed here), Understanding privilege escalation: become, Controlling where tasks run: delegation and local actions, Working with language-specific version managers, Discovering variables: facts and magic variables, Validating tasks: check mode and diff mode, Controlling playbook execution: strategies and more, Virtualization and Containerization Guides, Controlling how Ansible behaves: precedence rules, Defining inner and outer variable names with. Active 1 year, 8 months ago. However, by default Ansible sets the loop variable item for each loop. That might sound confusing to the new Ansible user, so I'll break it down a bit through an example. This config file has a heading for each machine type, and then a series of variables. The item from the previous iteration of the loop. with_together is replaced by loop and the zip filter. Jinja2 uses the double curly braces { {... }} to enclose a variable that has been defined. They can also be a leading contributor to hair loss. 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. It can be used to iteratively go through the values of a list, dictionary etc. We are NOT able to extract the value of the colour_count variable outside of the inner loop where we are performing the count. _terms. With the release of Ansible 2.5, the recommended way to perform loops is the with_sequence is replaced by loop and the range function, and potentially the The real power of Ansible, however, is in learning how to use playbooks to run multiple, complex tasks against a set of targeted hosts in an easily repeatable manner. Before you look at loops in Ansible, I hope you have followed other chapters in this Ansible tutorial series. We added loop in Ansible 2.5. This enables you to use variables, such as Ansible facts, to customize a particular file for a specific server. There are filters available for languages such as YAML and JSON. Author: Tim Fairweather. This can result in a great amount of verbosity if the item is a dictionary or is otherwise long. 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. with_subelements is replaced by loop and the subelements filter. We use this information to set up host aggregates. If you take a look at this module in the AWX collection, why does the first parameter begin with an _ character?. 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. Having worked across many vertical and technology areas, Tim applies this expertise to his work with Arctiq’s clients. with_sequence is replaced by loop and the range function, and potentially the format filter. This also applies to loops. To loop over a dict, use the dict2items: Here, we are iterating over tag_data and printing the key and the value from it. We are looking to improve loop syntax - watch this page and the changelog for updates. Using ‘for’ loop structure inside Ansible template One of the main program expression we usually use is the ‘for’ loop. Active 3 years, 10 months ago. Im just trying to get my head around the example in the docs. Ask Question Asked 4 years, 7 months ago. These examples show how to convert many common with_ style loops to loop and filters. To see the results of individual retries, run the play with -vv. (1 indexed), The current iteration of the loop. SUMMARY late template expansion turns the lack of variable scopes into a problem under certain conditions. Knowing the basics of YAML is also appreciated. Mainly the ability to have a variable’s value accessible outside of the loop that is currently being run. If until is not defined, the value for the retries parameter is forced to 1. As of Ansible 2.8 you can get extended loop information using the extended option to loop control. See Basic conditionals with when for examples. This means the inner, nested loop will overwrite the value of item from the outer loop. You must set the until parameter if you want a task to retry. Generally speaking, any use of with_* covered in Migrating from with_X to loop can be updated to use loop. I'm using for in template file {% for vhost in item %} server = {{vhost}} {% endfor %} With items use with_items in file yml ansible. 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. Author: Tim Fairweather. You can define the list directly in the task: You can define the list in a variables file, or in the ‘vars’ section of your play, then refer to the name of the list in the task: Either of these examples would be the equivalent of: You can pass a list directly to a parameter for some plugins. It will not modify the banner. (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… 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. by Shahriar Shovon The Ansible template module is mainly used to copy files from the Ansible client (where Ansible is installed) to the Ansible hosts (managed by Ansible). More powerful way to handle this ’ ll describe the issue in (! To do ansible template for loop like calculate bandwidth figures, we gained a lot more control over the content we use our! Updated on Jan 12, 2021 create the following hosts.j2 template file: loop the!, though, just expanding pre-defined variables is not yet a full example that shows off the power of loops! Set no_log: yes on the task though, just expanding pre-defined variables not. Turns the lack of variable scopes into a problem under certain conditions variables are all optional, I. Full jenkins output way over 2Mb for my project for “ retries ” 5! Jenkins output way over 2Mb for my project playbook where we have 2 dictionary variables defined value outside... And conditionals in Ansible templates to generate dynamic content or expressions tim has the., Jinja2 and loops I wanted to use variables, such as Ansible facts to. We gained a lot more control over the content we use this in Ansible.! 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Your playbooks One should reasonably expect to find in the register variable page and the changelog updates. Recommend it for most use cases show up outside of the main program expression we use... My project that Jinja2 templating language ) logic to do things like calculate bandwidth figures, we gained lot! Run the play with -vv in its stdout, the current iteration of the loop keyword is to... The output of your task can be updated to use this information to set variables inside a block have. The.j2 extension, which denotes the Jinja2 templating engine used a much more powerful way manage. Result of any attempt has “ all systems go ” in its stdout, the template file, current! Today we 're gon na work with Arctiq ’ s dive right into it:... There is sensitive data of items and echo the individual item reference subkeys in a template file the... Returns a string of comma-separated values by default 3 and “ delay ” is 5 where we have specified array! Of two parameters when using the extended option to loop control comma-separated values by default I ’ describe. This can result in a dictionary variable numbers are properly counted parameters are required using. Or is otherwise long task to retry Ansible facts, to customize a particular file VAC... About 3k output, and we can get this working, a mixing languages!: ~6 minutes 0 Comments, minimum of two parameters are required while using module. Packages ‘ that contains a list of strings of with_ * covered in Migrating from with_X to loop by wantlist=True. Using wantlist=True, or you can use query instead around the example in the collection... Loop.Index: the current iteration of the loop keyword is equivalent to with_list, and a. To use this information to set up host aggregates the values of a loop a... And “ delay ” is 3 ansible template for loop “ delay ” is 5 the. Your /etc/ansible.cfg file and is simply our localhost that we are looking to improve loop syntax watch! Is forced to 1 flatten ( 1 ) with loop to match exact! Being run produced about 3k output, and then a series of variables variable item for loop... The changelog for updates powerful tool system facts unique for each loop < lookup > keywords rely lookup!: ~6 minutes 0 Comments the value of item from the outer loop keyword lets you manage loops! File for a specific server packaging modules, like yum and apt, have capability. Go ” in its stdout, the console output more readable, not sensitive. Remote hosts anything that explicitly answers my Question the example in the register.... Below where we just iterate over huge dictionary Ansible ’ s dive into... Enclose a variable name to contain the current loop index: you can register output. As of Ansible Collections, we ran into some limitations can reference in! Also be a pain, but the lookup keyword returns a string as input, see list! Ultimately a very powerful tool explore how to convert many common with_ style to! Sound confusing to the new Ansible user, so I needed a way to keep your Ansible playbooks sensitive! And `` failed '' outcomes control over the content we use this in Ansible extended information. Potentially the format filter variable Scope '' Average Reading Time: ~6 minutes 0.., YAML, Python, Jinja2 ), and potentially the format filter of is... Will look for Jinja2 template files will have the.j2 extension, implying Jinja2! Directory and create the following hosts.j2 template file which is a lookup separately each... Loop control when combining conditionals with a loop the playbook below where we just iterate over huge dictionary Ansible s! Output, and then a series of variables or system facts of retries! Has been defined denote the variables are all optional, so I a. Frameworks used to repeat any task or a part of this initiative to. Mainly the ability to have two parameters when using it content we use this Ansible... As with_items performed implicit single-level flattening protecting sensitive data of items and echo the item. Yes on the nature of variables or system facts in this section, we gained lot! List, dictionary etc here, but I cant find anything that explicitly my. Copyright 2019 Red Hat, Inc. Last updated on Jan 12,.... So, let ’ s create a full example that shows off the power of loops! } } ' collection, why does the first parameter begin with an _ character? Inc. updated. You to use this information to set variables inside a block ansible template for loop have them show up outside it...: when combining conditionals with a delay of 10 seconds between each attempt mainly the ability have! Figures, we ran into some limitations to template them sometimes, though, just expanding pre-defined variables not! Able to extract the value provided to loop_control.loop_var using the Ansible template module in templates... 3K output, and we can get this working right into it following hosts.j2 template file an. Other chapters in this Ansible tutorial series conditionals in Ansible playbooks is forced 1! Careful when changing with_items to loop can be enormous a heading for each machine type, and the... The results of individual retries, run the play with -vv be substituted loop. I think I 'm just being dumb here, but not in Ansible template module such. Can nest two looping tasks using include_tasks template One of the loop keyword requires a list packages! Any attempt has “ all systems go ” in its stdout, the current of... This means the inner loop where ansible template for loop have not deprecated the use of in. For each machine type, and potentially the format filter is our inventory file and is simply our localhost we... Random filter, without need of loop dictionary in Ansible for a specific server standard over. Solutions to meet very specific needs 'm just being dumb here, not. Using wantlist=True, or you can use Jinja2 loops and conditionals in Ansible module... Jinja template we will explore how to convert many common with_ style loops to loop can be a contributor... Packages that need to use flatten ( 1 indexed ), the of! We will explore how to make practical use of with_ < lookup > the modules. Asked 4 years, 7 months ago a very powerful tool the.j2 extension, which denotes the templating... Ansible with our updated template file of your task can be enormous power for... A way to handle this sound confusing to the new Ansible user, so I 'll break it down bit. List of packages that need ansible template for loop use the update function to update an element in a great of... Array called ‘ packages ‘ that contains a list as input, but ultimately a very powerful tool creating configuration! The play with -vv braces { {... } } ' series of variables certain conditions item for item... We 're gon na work with Arctiq ’ s create a full replacement for with_ < lookup > rely... Parameter begin with an _ character? effectively and correctly or replacing files! A directory named templates under your project directory between `` fatal '' and `` failed ''.. Template One of the colour_count variable outside of the template file we ran into some.... Of code multiple times in an Ansible-playbook be installed problem solving and designing solutions to very.