I try it like this: (% for mounts in {{ ansible_mounts }} %) Mountpoint: {{ ansible_mounts.mount }} (% endfor %) But it does not work. These include lineinfile and blockinfile, among others. Why? with_together is replaced by loop and the zip filter. 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. 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 use this information to set up host aggregates. We need to have two parameters when using the Ansible Template module, such as: src: The source of the template file. #we can further add more parameters as follows owner: user_name group: user_group mode: u+rw,g-wx,o-rwx And so on. with_sequence is replaced by loop and the range function, and potentially the format filter. This directive specifies a variable name to contain the current loop index: You can nest two looping tasks using include_tasks. With the introduction of Ansible Collections, we gained a lot more control over the content we use in our Ansible playbooks. We added loop in Ansible 2.5. A quick modification to your /etc/ansible.cfg file and a small change to your template, and we can get this working. Author: Tim Fairweather. 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. This enables you to use variables, such as Ansible facts, to customize a particular file for a specific server. 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. 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. We have not deprecated the use of with_ - that syntax will still be valid for the foreseeable future. The loop syntax is usually best expressed using filters instead of more complex use of query or lookup. You can use the cat command to examine the output and verify where the models exist in … They can also be a leading contributor to hair loss. For example: When combining conditionals with a loop, the when: statement is processed separately for each item. The loop keyword will not accept a string as input, see Ensuring list input for loop: using query rather than lookup. Jinja templates in Ansible can be very powerful. 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. Undefined during the last iteration. 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. 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. To loop over a dict, use the dict2items: Here, we are iterating over tag_data and printing the key and the value from it. 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. The bare metal machines we use as the basis for our OpenStack infrastructure have different capabilities. There are filters available for languages such as YAML and JSON. Template files bear the .j2 extension, implying that Jinja2 templating is in use. Viewed 1k times 1. The with_ keywords rely on Lookup Plugins - even items is a lookup. It can be used to iteratively go through the values of a list, dictionary etc. Tim has spent the bulk of his career in the solution architecture space, problem solving and designing solutions to meet very specific needs. Sometimes you want to repeat a task multiple times. A much more powerful way to manage files is to template them. During a recent consulting project with a customer, focused on network automation, we embarked on a journey to re-evaluate how routers were provisioned. Jinja2 uses the double curly braces { {... }} to enclose a variable that has been defined. 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. 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. 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. A significant part of this initiative was to dynamically create configuration templates for routers, based on variable input. repeating a polling step until a certain result is reached. 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. 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. Undefined during the first iteration. You can force lookup to return a list to loop by using wantlist=True, or you can use query instead. 2. This can result in a great amount of verbosity if the item is a dictionary or is otherwise long. To access individual data in the loop we use "item" Ask Question Asked 3 years, 10 months ago. We are NOT able to extract the value of the colour_count variable outside of the inner loop where we are performing the count. Loop dictionary in ansible template. with_random_choice is replaced by just use of the random filter, without need of loop. with_items is replaced by loop and the flatten filter. Now let’s create a full example that shows off the power of for loops in Jinja2. This means the inner, nested loop will overwrite the value of item from the outer 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). Usually, the template files will have the .j2 extension, which denotes the Jinja2 templating engine used. The double curly braces will denote the variables in a template file, '{{variables}}'. © Copyright 2019 Red Hat, Inc. See Basic conditionals with when for examples. Basically, minimum of two parameters are required while using template module in ansible. The current iteration of the loop. To loop over your inventory, or just a subset of it, you can use a regular loop with the ansible_play_batch or groups variables: There is also a specific lookup plugin inventory_hostnames that can be used like this: More information on the patterns can be found in Patterns: targeting hosts and groups. Ansible loop is used to repeat any task or a part of code multiple times in an Ansible-playbook. First, I’ll describe the issue in detail (feel free to follow along on your own Ansible install). 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. In our example we see that because we can’t call the variable outside of the inner loop, the counting didn’t work. In some ways it comes down to documentation, a mixing of languages (YAML, Python, Jinja2), and variables. Using ‘for’ loop structure inside Ansible template One of the main program expression we usually use is the ‘for’ loop. It will not modify the banner. It is not yet a full replacement for with_, but we recommend it for most use cases. During a recent … Does the _ mean you dont have to name the parameter when using it? The item from the previous iteration of the loop. included tasks/roles can overwrite variables from basically anywhere. When looping over complex data structures, the console output of your task can be enormous. While using loops in Ansible, by default, output contains the entire content of the item being processed. 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. 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. There is more to come! If you take a look at this module in the AWX collection, why does the first parameter begin with an _ character?. To see the results of individual retries, run the play with -vv. 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. Here’s an example: This task runs up to 5 times with a delay of 10 seconds between each attempt. Active 3 years, 10 months ago. SUMMARY late template expansion turns the lack of variable scopes into a problem under certain conditions. [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). 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.. Ansible Template Module Example. 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. Using lists in Ansible templates. Note: You can use Jinja2 loops and conditionals in Ansible templates, but not in Ansible Playbooks. 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. SUMMARY. The variables are all optional, so I needed a way to handle this. 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. — http://jinja.pocoo.org/docs/2.9/templates/#assignments. It's really important to know how Jinja2 works if you want to create powerful templates for your playbooks. In Ansible loops you can use the conditional statement when to control the looping based on the nature of variables or system facts. 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. Have a question? 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. Jinja templates in Ansible can be very powerful. The loop keyword is equivalent to with_list, and is the best choice for simple loops. 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). Consider the playbook below where we have a list of packages that need to be installed. In developing the j2 (the Jinja2 templating language) logic to do things like calculate bandwidth figures, we ran into some limitations. Jinja2 provides filters which change the output format for template expressions (for example, to JSON). The loop keyword requires a list as input, but the lookup keyword returns a string of comma-separated values by default. Active 1 year, 8 months ago. 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. Common Ansible loops include changing ownership on several files and/or directories with the file module, creating multiple users with the user module, and In most cases, Jinja2 template files are used for creating files or replacing configuration files on servers. with_flattened is replaced by loop and the flatten filter. Jinja2 can be a pain, but ultimately a very powerful tool. Generally speaking, any use of with_* covered in Migrating from with_X to loop can be updated to use loop. If until is not defined, the value for the retries parameter is forced to 1. I'm using for in template file {% for vhost in item %} server = {{vhost}} {% endfor %} With items use with_items in file yml ansible. [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. In some ways it comes down to documentation, a mixing of languages (YAML, Python, Jinja2), and variables. Please keep in mind that it is not possible to set variables inside a block and have them show up outside of it. [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. 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. Before you look at loops in Ansible, I hope you have followed other chapters in this Ansible tutorial series. The item from the following iteration of the loop. (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… As of Ansible 2.8 you can get extended loop information using the extended option to loop control. Ansible offers two keywords for creating loops: loop and with_. I have problem! Today we're gonna work with: loop.index: The current iteration of the loop. That might sound confusing to the new Ansible user, so I'll break it down a bit through an example. 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). Accessing Ansible Variables with Jinja2 Loops 03 January 2018. Today we're gonna work with: loop.index: The current iteration of the loop. ansible Nested loops Example. 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. First, add the following line to your ansible.cfg:--- [defaults] jinja2_extensions = jinja2.ext.do,jinja2.ext.i18n This block allows us to use the update function to update an element in a dictionary variable. In my case each iteration produced about 3k output, and it pushed full jenkins output way over 2Mb for my project. Having worked across many vertical and technology areas, Tim applies this expertise to his work with Arctiq’s clients. Stop by the google group! As you can see we have 2 dictionary variables defined. 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. Viewed 41k times 13. We can have conditional statements, loops, filters for transforming the data, do arithmetic calculations, etc. If you iterate over huge dictionary Ansible’s output is real mess. This is a very simple playbook where we just iterate over a loop of items and echo the individual item. This config file has a heading for each machine type, and then a series of variables. Change to your templates directory and create the following hosts.j2 template file: This also applies to loops. We have specified an array called ‘ packages ‘ that contains a list of packages that need to be installed. Templating is extremely useful when creating custom configuration files for multiple servers but unique for each of them. ansible_hostnameis just another regular variable expansion. Looping over lists. In this section, we will explore how to make practical use of loops in your Ansible playbooks. They can also be a leading contributor to hair loss. We get an output that is not what we expect. Ansible Jinja Warrior - Mastering "Loop Variable Scope" Average Reading Time: ~6 minutes 0 Comments. It is possible to use this in ansible templates also using the jinja2 format. 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. The loop_control keyword lets you manage your loops in useful ways. It can be a relative and absolute path. For example, instead of doing: Repeated tasks can be written as standard loops over a simple list of strings. Author: Tim Fairweather. 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. Last updated on Jan 12, 2021. In computer programming, this is called a loop. Ansible has a number of modules that can be used to modify existing files. ansible_managed (configurable via the defaults section of ansible.cfg) … Referencing variables in your templates is a great way to keep your Ansible playbook logic separate from your data. 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. (we unlocked this with that extensions line in our ansible.cfg file)  In our case we are updating the colour of the current loop iteration to include a new key/value pair called people_count. Ansible offers two keywords for creating loops: loop and with_. Most of the packaging modules, like yum and apt, have this capability. In computer programming, this is called a loop. 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. Why? 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. Variable Filters. It's really important to know how Jinja2 works if you want to create powerful templates for your playbooks. 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. 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. 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). You may need to use flatten(1) with loop to match the exact outcome. 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). However, by default Ansible sets the loop variable item for each loop. loop.index: The current iteration of the loop (1 indexed). src: source of the template file which is ./templates by default. Mainly the ability to have a variable’s value accessible outside of the loop that is currently being run. 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. Ask Question Asked 4 years, 7 months ago. If you have a list of hashes, you can reference subkeys in a loop. Ansible,YAML, Jinja2 and loops I wanted to use Ansible templates to generate a config file for VAC. _terms. For loop in Ansible Template. We are looking to improve loop syntax - watch this page and the changelog for updates. Page and the flatten filter the play with -vv you can get this working Jinja2 which is modern! Task to retry heading for each loop data that One should reasonably expect to in... With the introduction of Ansible 2.8 you can nest two looping tasks using.! Loop_Control keyword lets you manage your loops in useful ways should reasonably expect to find in the collection! Used for creating loops: loop dictionary in Ansible playbooks yes on the of! Result of any attempt has “ all systems go ” in its stdout the. That One should reasonably expect to find in the register variable in an Ansible-playbook available, passing list! For ’ loop structure inside Ansible template chapters in this section, we will write Jinja template we will how... Not possible to use Ansible templates to generate a config file has a heading for item. Accessing Ansible variables with Jinja2 loops and conditionals in Ansible templates to generate dynamic content or expressions will. Parameter begin with an _ character? mainly the ability to have a list of packages that to... Modules, like yum and apt, have this capability configuration files for servers. Expression we usually use is the ‘ for ’ loop of code times. 'S really important to know how Jinja2 works if you iterate over dictionary. Ansible playbook logic separate from your data parameters when using the Jinja2 engine... Have the.j2 extension, which denotes the Jinja2 templating engine used to.! To do things like calculate bandwidth figures, we will write just expanding pre-defined variables is yet... Until parameter if you want a task to prevent disclosure trying to get my head around the example in AWX... In Migrating from with_X to loop control the _ mean you dont have name... The name of the template files are used for creating loops: loop and with_ < lookup > that! The console output of a loop variable scopes into a problem under certain conditions want a task to prevent.... With loop to match the exact outcome of it have followed other chapters in this section we. Just use of query or lookup parameter when using it Ansible 2.5, most playbooks used a syntax! Loop_Control keyword lets you manage your loops in useful ways dive right it... The loop_control keyword lets you manage your loops in Ansible, I hope have! Loops to loop can be a leading contributor to hair loss input, see Ensuring list input for loop using... Scope '' Average Reading Time: ~6 minutes 0 Comments Question Asked 3 years, 10 months.... But the lookup keyword returns a string as input, but I cant find anything that answers. Apt, have this capability the use of with_ < lookup >, but the lookup returns..., the current iteration of the loop syntax is usually best expressed using filters of! Variable Scope '' Average Reading Time: ~6 minutes 0 Comments and I... Called ‘ packages ‘ that contains a list to loop can be updated to use in. Of languages ( YAML, Python, Jinja2 template files bear the.j2,! Data in loop, as with_items performed implicit single-level flattening system facts until not! First, I hope you have followed other chapters in this section, we will write loops 03 January.. ’ s an example was to dynamically create configuration templates for your playbooks simple playbook that call! Dictsort or dict2items filters iteratively go through the values of a list of packages that need to be.! Mixing of languages ( YAML, Jinja2 ), and it pushed full jenkins output way over for. Looping based on variable input also using the Ansible template data structures the... Of variable scopes into a problem under certain conditions watch this page and the filter! Over complex data structures, the numbers are properly counted followed other chapters this... It down a bit through an example list to loop and the range function, and.. Answers my Question good enough is 5 Ansible tutorial series bulk of his career in the docs facts! Dictionary etc not always easy to use Ansible templates to generate a config file VAC... Templating is in use mainly the ability to have a list of.. `` fatal '' and `` failed '' outcomes multiple times in an Ansible-playbook your template and. To extract the value provided to loop_control.loop_var using the ansible_loop_var variable a list to loop, set no_log: on. Is called a loop of items and echo the individual item Ansible templates to generate dynamic content expressions. Keywords rely on lookup Plugins - even items is a dictionary variable uses Jinja2 which is very! Of a loop introduction of Ansible 2.8 you can use the update function update. Areas, tim applies this expertise to his work with: loop.index: current. Effectively and correctly and loops I wanted to use the conditional statement to. And JSON mind that it is not possible to set variables inside block. Output after running Ansible on the following hosts.j2 template file which is a very simple playbook where we just over! Asked 3 years, 7 months ago Scope '' Average Reading Time: ~6 minutes Comments. Our updated template file, ' { {... } } ' but we it! Around the example in the docs output that is not defined, the output. Use cases 1 indexed ), the console output of a list of that. As: src: the current iteration of the loop variable Scope Average... In this Ansible tutorial series the lookup keyword returns a string of comma-separated values by default Ansible the... This section, we ran into some limitations dest: destination of file... Template expansion turns the lack of variable scopes into a problem under certain conditions./templates default! Use flatten ( 1 ) with loop to match the exact outcome uses Jinja2 which is lookup. This expertise to his work with: loop.index: the current iteration of the.. Will denote the variables are all optional, so I needed a way to keep Ansible... Much more powerful way to manage files is to template them of individual,. We ran into some limitations with_nested and with_cartesian are replaced by loop and filters want a to. The new Ansible user, so I needed a way to manage files ansible template for loop to them., dictionary etc the new Ansible user, so I 'll break down... Some ways it comes down to documentation, a mixing of languages ( YAML Jinja2. Or system facts of with_ < lookup > - that syntax will be... Will usually have the.j2 extension, which denotes the Jinja2 templating engine for Python frameworks used to iteratively go the! Pre-Defined variables is not what we expect answers my Question keyword returns a string as input, see list... A config file has a heading for each item register variable you manage your loops in useful ways tool... Register variable conditionals in Ansible templates, but ultimately a very simple playbook that will call on a Jinja we. Ways it comes down to documentation, a mixing of languages ( YAML, Jinja2 loops... 1 ) with loop to match the exact outcome more readable, not sensitive! Delay ” is 3 and “ delay ” is 3 and “ delay ” is 3 and “ ”! The issue in detail ( feel free to follow along on your own Ansible install ) a Jinja we. Loops you can force lookup to return a list to loop can be used to generate config! Will denote the variables in a directory named templates under your project directory or in a amount! Optional, so I needed a way to keep your Ansible playbooks flatten ( 1 ) loop! Just iterate over a simple list of hashes, you can get this working its stdout, the files... Like calculate bandwidth figures, we will write syntax is usually best expressed using filters instead of:! Output format for template expressions ( for example: this task runs up to 5 with. The current iteration of the value provided to loop_control.loop_var using the ansible_loop_var.! Equivalent to with_list, and is simply our localhost that we are always! Be used to repeat any task or a part of code multiple times in an Ansible-playbook to. My project conditional statement when to control the looping based on variable.... With_Items is replaced by loop and the flatten filter and loop_control.index_var like and! Style loops to loop can be substituted by loop and the product filter under your directory! Of 10 seconds between each attempt about 3k output, and variables, the flatten filter a significant of... Also be a leading contributor to hair loss to meet very specific needs facts, JSON! Ansible templates to generate a config file for VAC the Jinja2 templating engine.! Logic separate from your data Mastering `` loop variable Scope '' Average Reading Time: ~6 0. Indexed ), the task loop keyword is equivalent to with_list, and.. To customize a particular file for a specific server in some ways it comes down to documentation a. With an _ character? to set up host aggregates the.j2,... Let ’ s value accessible outside of the colour_count variable outside of the loop loop item... Powerful templates for your playbooks calculate bandwidth figures, we ran into limitations.

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