Using ASCII Templates for Dynamic Container Configuration

  • Published on Aug 19, 2025
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INSYS icom routers support running Linux Containers (LXC) to host edge applications. These containers can mount a persistent folder /data/etc/, commonly used to store .ini files, Lua scripts, or similar configuration assets required by the containerized application.

With the new "Container Configuration" ASCII template type, you can:

  • Manage environment-specific container configurations (e.g. development, staging, production)

  • Inject router-specific parameters using Custom Fields or inline String parameters

  • Deploy consistent and scalable configurations across multiple devices

This template type behaves similarly to existing ASCII templates, but specifically targets container configuration files.

How It Works

The container configuration template results in a file placed in /data/etc/ inside the container. The container then reads and applies the configuration as designed by your application logic (e.g. on startup or upon file change).

Supported formats within the template:

  • .ini-style key-value pairs

  • Embedded Lua scripting

  • Parameter placeholders ({{parameter_name}}) for inline or Custom Field-based substitution

Note: Only String-type inline parameters are supported for now. All referenced Custom Fields must be populated before deployment.

Step-by-Step Guide

1. Create a Container Configuration Template

  1. Navigate to Inventory → ASCII Templates

  2. Click + or choose "Add" from the "Select action" menu

  3. In the popup, select "Container Configuration" as the template type

  4. Enter a unique name for the template

  5. Specify the container designator. You can find the container designator by visiting the WebUI of your router.

    Important!

    This must exactly match the container’s designator on all target routers. Mismatches will cause deployment failure.

  6. Define the target file name (e.g. config.ini) to be written into the container

  7. Enter the desired content using .ini or Lua syntax, with optional placeholders for parameters

2. Handle Template Parameters

  • Use inline placeholders like {{env}}, {{mode}}, etc.

  • Define which values are inline parameters (String type) and which are Custom Fields

  • Ensure that:

    • Inline parameters will be provided per device before deployment

    • All referenced Custom Fields are set for each router

3. Save and Deploy

  1. Click "Save"

  2. While still in the editor, optionally choose "Apply to router" from the "Select action" menu
    Alternatively, apply later from the ASCII Templates list.

  3. Select the target router(s) or router group(s) and click "Continue"

4. Provide Parameter Values

You’ll see a preview table with one row per target router, including:

  • Rendered configuration file

  • Required parameter fields

💡 Tip: Download the sample Excel file, populate all required values, and re-upload it. This ensures consistency across large deployments.

5. Finalize the Update Job

  1. Click "Continue"

  2. Provide a name for the Update Job or use the pre-filled suggestion

  3. Choose to deploy the configuration "Immediately" or "Later"

  4. Track deployment status under Update → Update Jobs

Best Practices

  • Template Naming: Use clear names like prod_app_config, dev_app_config, etc.

  • Parameter Strategy: Use Custom Fields for device metadata (e.g. location, customer_id) and inline parameters for context-dependent values

  • Container Designator Consistency: Enforce naming standards across routers

  • Testing: Validate your rendered configuration on one test device before scaling out

Known Limitations

  • Only String parameters are supported for inline placeholders

  • Mismatches in container designator or missing parameter values will cause Update Job failure

  • No validation is done on the content format—ensure your application accepts the resulting file