Ansible's "synchronize" module is used to synchronize the contents of two directories. It is particularly useful when you need to keep files in two locations identical, for example when you want to keep a local and remote directory in sync.

The basic syntax for using the "synchronize" module is:

In this example, Ansible will compare the contents of the "src" directory with the "dest" directory and copy any missing files from "src" to "dest". If a file exists in both directories but has a different content, Ansible will replace the file in "dest" with the version from "src". If a file exists in "dest" but not in "src", it will not be deleted.

You can also specify additional options to control the behavior of the synchronization. For example, you can use the "delete" option to delete files in "dest" that do not exist in "src":

- name: Synchronize directories (including deletions)

You can also use the "synchronize" module to transfer files between hosts using SSH. By default, Ansible will use the "rsync" command to transfer the files, but you can also specify other methods such as "scp" or "sftp".

Here is an example of using "synchronize" to transfer a file from a local host to a remote host using SSH:

In this example, we are using the "mode: push" option to push the file from the local host to the remote host. We are also using the "compress: yes" option to compress the file during transfer. The "rsync_opts" option is used to specify additional options to the "rsync" command, in this case "--archive" and "--compress".

The "delegate_to" option is used to specify that the task should be executed on the local host instead of the remote host. This is necessary because the "synchronize" module requires access to both the source and destination files, so it cannot be run directly on the remote host.

Overall, the "synchronize" module is a powerful tool for keeping directories and files in sync, both locally and remotely. It is particularly useful in scenarios where you need to keep multiple hosts or locations identical, such as in a distributed system or a development environment.

Synchronize is a wrapper around rsync to make common tasks in your playbooks quick and easy.

Ansible Synchronize Module

To unarchive a file using Ansible, you can use the unarchive module. Here is an example playbook:

In this example, src is the path to the archive file you want to unarchive, and dest is the path where you want to extract the archive. The remote_src option is set to yes to indicate that the source archive is located on the remote host.

You can run this playbook by saving it to a file (e.g. unarchive.yml) and then executing the following command:

Replace your_host with the name of the host where you want to unarchive the file. Make sure that you have SSH access to the host and that Ansible is installed on your local machine.

Unarchive a specific file or directory from the archive :

If you want to unarchive a specific file or directory from the archive, you can use the copy option in the unarchive module. Here is an example playbook that unarchives a specific file:

In this example, copy is set to your_file.txt, which means that only the your_file.txt file will be extracted from the archive.

If you want to extract the archive to a specific owner or group, you can use the owner and group options. Here is an example playbook:

In this example, owner is set to your_user, and group is set to your_group, which means that the extracted files will be owned by the your_user user and the your_group group.

You can also specify the file permissions for the extracted files using the mode option. Here is an example playbook:

In this example, mode is set to "0755", which means that the extracted files will have the permissions -rwxr-xr-x.

These are just a few examples of how you can use the unarchive module in Ansible to extract files from an archive. The unarchive module provides many more options and features that you can use to customize the extraction process to meet your specific needs. 

Ansible archive module is an ansible way of compressing the file and creating an archive. Just like the tar and gz commands working together if you are a Linux guy you would easily get this analogy.

How to unarchive a file using Ansible?

Ansible Galaxy is a platform for sharing, finding, and collaborating on Ansible content, which includes roles, modules, plugins, and collections.

Collections are a new type of content in Ansible Galaxy that was introduced in Ansible 2.10. They are a way to package and distribute reusable Ansible content, such as roles, modules, and plugins, as a single unit. Collections can be installed and used independently of Ansible, and they can also be installed as dependencies of other collections.

Collections are organized into namespaces, which are like top-level directories. Each namespace can contain multiple collections. The namespace and collection name form a unique identifier for a collection, which is used when installing and referencing it.

Collections can be uploaded to Ansible Galaxy using the ansible-galaxy collection publish command, or they can be added to a repository on GitHub or another source control system and published using a CI/CD pipeline.

To install a collection from Ansible Galaxy, you can use the ansible-galaxy collection install command, followed by the namespace and collection name. For example, to install the community.general collection, you would run:

ansible-galaxy collection install community.general

Once a collection is installed, you can use its content in your playbooks and roles by referencing its modules, roles, and plugins using the namespace and collection name. For example, to use the yum module from the community.general collection, you would use the following syntax:

- name: Install Apache using the community.general.yum module

Collections can be browsed and searched on the Ansible Galaxy website, where you can find collections created by the Ansible community, as well as official collections maintained by Red Hat. Collections can also be installed directly from a URL, a file, or a directory, which makes it easy to distribute and use private collections.

Collections can include multiple versions, and you can specify which version to install when using the ansible-galaxy collection install command. You can also specify collection dependencies in your playbook or role metadata, which will automatically install the required collections when running ansible-galaxy collection install.

Collections can include documentation, examples, and tests, which make it easier to understand how to use and contribute to a collection. Collections can also be versioned and tagged, which enables you to keep track of changes and updates to a collection over time.

Overall, Ansible Galaxy collections provide a powerful and flexible way to package, distribute, and use Ansible content, which helps to simplify automation and increase collaboration and reuse within the Ansible community.

Ansible Galaxy is a galaxy website where users can share roles and a command-line tool for installing, creating, and managing roles.

Ansible Galaxy

The Ansible reboot module is used to reboot a remote server. This module initiates a system reboot on the target machine and waits for the machine to come back online before returning control to the user.

Here is an example playbook that uses the reboot module:

In this example, we are rebooting a server with the hostname webserver. The reboot_timeout parameter specifies the amount of time (in seconds) to wait for the server to come back online before timing out.

It is important to note that using the reboot module can potentially cause downtime on your servers, so it should be used with caution. It is recommended that you perform a dry-run of your playbook before running it in production to ensure that it will not cause any unexpected downtime.

Using "pre_tasks" and "post_tasks" options in your playbook :

If you need to perform certain tasks before or after a server reboot, you can use the pre_tasks and post_tasks options in your playbook. For example:

In this example, we are stopping the Nginx web server before rebooting the server, and then starting it again after the server has come back online.

Note that the reboot module is only available for certain operating systems and requires root or administrator privileges to execute. Additionally, some systems may require additional configuration or kernel settings to allow the reboot to be executed by Ansible.

In summary, the Ansible reboot module is used to initiate a system reboot on a remote server. It waits for the server to come back online before returning control to the user. The module is only available for certain operating systems and requires root or administrator privileges to execute. It is important to use caution when using the reboot module, as it can potentially cause downtime on your servers. You can use the pre_tasks and post_tasks options in your playbook to perform certain tasks before or after the server reboot. Proper planning and communication are important to ensure that the reboot does not interrupt ongoing operations

The ansible reboot module is part of ansible-core and included in all Ansible installations.

Ansible Reboot Module

ansible_become_exe is an Ansible variable that specifies the path to the executable that is used to escalate privileges when using the become feature in Ansible.

The become feature in Ansible allows you to run tasks with escalated privileges, such as running commands as the root user on a remote server. The ansible_become_exe variable specifies the path to the executable that is used to escalate privileges.

The default value of ansible_become_exe is sudo, which means that Ansible will use the sudo command to escalate privileges. However, you can set this variable to any executable that can be used to escalate privileges, such as su or pbrun, depending on the requirements of your environment.

Here is an example of how to set the ansible_become_exe variable in an Ansible playbook:

- name: Run task with escalated privileges

In this example, the ansible_become_exe variable is set to su, which means that Ansible will use the su command to escalate privileges when running the service task.

It's worth noting that the ansible_become_exe variable is just one of several variables that are used to configure the become feature in Ansible. Here are some other variables that are commonly used with become:

1. ansible_become: This variable specifies whether to escalate privileges or not. It can be set to true or false.

2. ansible_become_method: This variable specifies the method used to escalate privileges. The default value is sudo, but you can also use su or other methods depending on your environment.

3. ansible_become_user: This variable specifies the user account to use when escalating privileges. The default value is root.

When using become in Ansible, it's important to ensure that you have the appropriate permissions to escalate privileges on the remote system. You should also be careful when running tasks with escalated privileges, as they can potentially cause unintended consequences if not executed properly.

Another thing to keep in mind when using become in Ansible is that it can have an impact on the performance of your playbooks. Running tasks with escalated privileges can be slower than running them without privileges, especially if there are a large number of tasks to execute.

To improve the performance of your playbooks, you can use the become_flags variable to pass additional arguments to the privilege escalation command. For example, you can use the -n flag with sudo to skip reading the sudoers file, which can improve performance in some cases:

In this example, the become_flags variable is set to -n, which tells sudo to skip reading the sudoers file. This can improve performance when running the service task with escalated privileges.

Overall, the become feature in Ansible is a powerful tool that allows you to run tasks with escalated privileges on remote systems. By using variables like ansible_become_exe, ansible_become_method, ansible_become_user, and become_flags, you can customize the privilege escalation process to meet the requirements of your environment and improve the performance of your playbooks.

In this blog, I will discuss what is become_exe in ansible and how to use it in your Ansible playbook. 

What is become_exe in Ansible and how to use it?

In certain scenarios, you may want to control the number of hosts on which your playbook tasks should be executed. This can be useful when you have a large number of hosts in your inventory, but you want to limit the execution to a specific subset of hosts at a time.

To achieve this, you can follow these steps:

1. Create a dynamic inventory script: Ansible supports dynamic inventory scripts that provide a dynamic view of your infrastructure. These scripts can retrieve host information from various sources like files, APIs, databases, or external services. In this case, you would create a custom dynamic inventory script that also retrieves the host count.

2. Implement logic to fetch the host count: Within the dynamic inventory script, you need to implement the logic to fetch the host count dynamically. The source of the host count can be any data store or calculation based on your infrastructure. For example, you may retrieve the host count from a file, query an API, or perform a database query. This logic should return the host count as part of the inventory structure.

3. Specify the maximum number of hosts for playbook execution: Once you have the dynamic inventory script in place and it includes the host count field, you can run your playbook with the --limit option. The --limit option allows you to restrict the execution to a subset of hosts based on a pattern or expression. In this case, you would use a pattern that limits the execution to a certain number of hosts, using the host count retrieved from the inventory.

4. Adjust playbook configuration if needed: Depending on your requirements, you may need to modify your playbook to handle the desired number of hosts. For example, you can use the serial keyword in your playbook to control the number of hosts on which tasks are executed simultaneously. This allows you to limit the concurrency and ensure that tasks are executed on a subset of hosts at a time.

By combining these steps, you can effectively limit the execution of an Ansible playbook based on the number of hosts in your inventory. This gives you flexibility and control over task execution when dealing with a large number of hosts.

Limit the execution of an Ansible playbook in code snippet:

To limit the execution of an Ansible playbook based on the number of hosts in the inventory, you can make use of Ansible's --limit option along with a dynamic inventory script that provides the host count.

Step 1. Create a dynamic inventory script: Ansible supports various dynamic inventory scripts, such as the one for AWS EC2, OpenStack, etc. In this case, we can create a custom script to retrieve the host count. The script should output a JSON representation of the inventory, including a host count field.

Here's an example code of a dynamic inventory script (inventory.py) that retrieves the host count from a source (e.g., a file, API, or database):

    # Retrieve host count from the source and store it in a variable

    host_count = 42  # Replace with your own logic to get the host count

    # Generate the inventory JSON structure

        "host_count": host_count  # Add the host count field

Make sure to replace the logic in get_inventory() to fetch the host count from your source.

Step 2. Make the script executable: Run the following command to make the script executable:

Step 3. Run the playbook with the --limit option: Now, when executing your playbook, you can use the --limit option to limit the execution based on the host count. Specify the maximum number of hosts you want to target.

For example, to limit the playbook execution to a maximum of 5 hosts:

ansible-playbook -i inventory.py playbook.yml --limit 'all:&lt;5'

The all:&lt;5 filter in --limit will match all hosts and limit the execution to a maximum of 5.

Adjust the 5 to your desired host count threshold.

Step 4. Updating dynamic inventory script: Update the dynamic inventory script to generate the inventory based on the desired logic or source. In the provided example, the host count is hardcoded as 42. Replace this logic with your own implementation to retrieve the host count dynamically.

The inventory structure generated by the script should include a "host_count" field, as shown in the example. This field will be used to limit the playbook execution.

Step 5. Designing your Ansible playbook: Make sure your playbook is designed to handle the desired number of hosts. For example, if you want to execute tasks only on a specific number of hosts, you can use the serial keyword in your playbook. The serial keyword controls how many hosts Ansible will run the tasks on simultaneously.

Here's an example playbook (playbook.yml) that demonstrates the usage of serial to limit the execution to a certain number of hosts:

  serial: 5  # Limit execution to 5 hosts at a time

        msg: "This task will be executed on a maximum of 5 hosts at a time."

In this playbook, the serial parameter is set to 5, which means Ansible will execute the tasks on a maximum of 5 hosts concurrently. Adjust the 5 to your desired host count threshold.

Step 6. Execute the playbook: Execute the playbook with the --limit option as explained in step 3. Ansible will use the dynamic inventory script to retrieve the host count and limit the execution based on the specified number.

By combining the dynamic inventory script, the host count field, and the --limit option with the serial parameter in your playbook, you can restrict the execution of Ansible tasks based on the number of hosts in your inventory.

In conclusion, by utilizing a dynamic inventory script, retrieving the host count, and using the --limit option in Ansible playbooks, you can effectively limit the execution of tasks based on the number of hosts in your inventory. This approach provides flexibility and control over task execution, especially when dealing with a large number of hosts.

Limit Ansible playbook execution based on host count using dynamic inventory script and --limit option with desired number.

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configuration-management

Trending Blogposts on configuration-management

Ansible Synchronize Module

How to unarchive a file using Ansible?

Ansible Galaxy

Ansible Reboot Module

What is become_exe in Ansible and how to use it?

Limit Ansible Playbook Execution

Popular Discussions on configuration-management