Скачать или смотреть Evaluating YAML Keys with Jinja in Ansible Templates

Learn how to evaluate YAML keys and their values using Jinja in Ansible templates for Kubernetes secrets. This guide provides step-by-step instructions and examples.
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Evaluating YAML Keys with Jinja in Ansible Templates: A Complete Guide

When working with Kubernetes secrets in Ansible, especially when handling sensitive data such as password keys, understanding how to evaluate YAML keys using Jinja can be crucial. In this guide, we’ll address a specific challenge: how to effectively modify your secret manifest to resolve encrypted values while using Jinja in Ansible templates.

The Challenge

Say you have a Kubernetes secrets manifest in the form of a secret.j2 file that contains password keys that need to be dynamically populated with values from an Ansible Vault encrypted string stored in a dev.yml file. Below is how your dev.yml file might look:

[[See Video to Reveal this Text or Code Snippet]]

You are passing "dev" as a runtime parameter (namespace=dev) to your playbook and have structured your stringData section in the secret.j2 file like this:

[[See Video to Reveal this Text or Code Snippet]]

The output when templating secret.j2 into secret.yml would look something like the following:

[[See Video to Reveal this Text or Code Snippet]]

Your objective is to set the dbpassword key directly to the decrypted value from dev.yml while generating the secret.yml using Jinja.

The Solution

Great news! You can achieve this using the lookup plugin for variables. This method allows you to access dynamically generated variable names. Here’s how you can modify the dbpassword entry in your secret.j2 file:

[[See Video to Reveal this Text or Code Snippet]]

Example Setup

Update secret.j2 Template

Your complete secret.j2 template should now look like this:

[[See Video to Reveal this Text or Code Snippet]]

Ansible Playbook Configuration

In your Ansible playbook, use the following setup:

[[See Video to Reveal this Text or Code Snippet]]

Resulting Output

After running the playbook, the generated secret.yml will correctly reflect the values:

[[See Video to Reveal this Text or Code Snippet]]

Additional Options

If you no longer require enclosed Jinja syntax and just need plain text values in your generated secret.yml, you can simplify your secret.j2 further:

[[See Video to Reveal this Text or Code Snippet]]

With this setup, the output would directly show passwords without the extra Jinja syntax:

[[See Video to Reveal this Text or Code Snippet]]

Working with Encrypted Files

If your passwords are stored in an encrypted file, make sure they are correctly referenced in your playbook:

[[See Video to Reveal this Text or Code Snippet]]

Running this code after encrypting your dev.yml file with ansible-vault will still yield the expected results.

Conclusion

By leveraging the Jinja lookup function, you can dynamically resolve YAML keys in Ansible templates for Kubernetes secrets. This approach not only improves the readability of your templates but also helps in managing sensitive information effectively. Happy coding!