feat(template): add read_file() function

[jdx]

Summary

• Add a new template function read_file(path) that reads file contents relative to config_root
• Files are read relative to the directory containing the mise.toml file, not the current working directory
• Returns raw file contents as a string that can be processed with filters

Use Case

This allows configuration files to dynamically include content from external files during template rendering. For example:

• Reading version numbers from a VERSION file
• Including configuration from separate files
• Loading environment-specific settings

Example Usage

[env]
VERSION = "{{ read_file(path='VERSION') | trim }}"
CONFIG = "{{ read_file(path='config/production.txt') | trim }}"

Test Plan

• Added unit test for the new function
• Added comprehensive e2e tests covering:
  • Basic file reading
  • Relative paths
  • Multi-line content
  • Path resolution relative to config_root (not CWD)
  • Nested configurations with their own relative paths

🤖 Generated with Claude Code

[Copilot]

Pull Request Overview

This PR adds a new template function read_file() that allows reading file contents during template rendering in mise configuration files. The function reads files relative to the directory containing the mise.toml file, enabling dynamic inclusion of external content.

Key changes:

• Added tera_read_file() function that reads file contents and returns them as a string
• Modified get_tera() to register the new function alongside the existing exec function
• Added comprehensive test coverage for various use cases including relative paths and nested configurations

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/tera.rs	Implements the read_file() template function and registers it with the Tera engine
e2e/env/test_env_template_read_file	Comprehensive end-to-end tests covering various read_file scenarios
docs/templates.md	Documents the new read_file function with usage examples

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[Copilot]

The read_file function allows reading arbitrary files from the filesystem without any path validation or security checks. Consider adding validation to prevent directory traversal attacks (e.g., paths containing ../ or absolute paths) and restrict file access to only files within the configuration directory tree.

[Copilot]

When no directory context is provided, the function uses the path as-is, which could allow reading files from anywhere on the filesystem. Consider either requiring a base directory or defaulting to a safe directory like the current working directory to prevent unintended file access.

Suggested change

	// Use path as-is if no directory context
	PathBuf::from(path_str)
	// Default to current working directory if no directory context
	match std::env::current_dir() {
	Ok(cwd) => cwd.join(path_str),
	Err(e) => {
	return Err(format!("Failed to get current directory: {}", e).into());
	}
	}

[github-actions]

Hyperfine Performance

mise x -- echo

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.9.17 x -- echo	20.1 ± 0.5	19.3	25.0	1.00
mise x -- echo	20.6 ± 0.7	19.5	25.3	1.03 ± 0.04

mise env

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.9.17 env	19.6 ± 0.6	18.7	23.3	1.00
mise env	19.8 ± 0.5	18.9	23.6	1.01 ± 0.04

mise hook-env

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.9.17 hook-env	19.1 ± 0.4	18.4	21.1	1.00
mise hook-env	19.5 ± 0.6	18.5	21.9	1.02 ± 0.04

mise ls

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.9.17 ls	17.0 ± 0.4	16.3	18.7	1.00
mise ls	18.0 ± 0.9	16.5	22.1	1.06 ± 0.06

xtasks/test/perf

Command	mise-2025.9.17	mise	Variance
install (cached)	173ms	✅ 106ms	+63%
ls (cached)	65ms	64ms	+1%
bin-paths (cached)	72ms	71ms	+1%
task-ls (cached)	484ms	492ms	-1%

✅ Performance improvement: install cached is 63%