Skip writing files if they haven't' changed

[CLHatch]

Pull request

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Summary by Sourcery

Avoid rewriting docker-compose and env files when their contents have not changed.

Bug Fixes:

• Prevent unnecessary rewrites of docker-compose.yml by generating output in a temporary file and only copying when contents differ.
• Prevent unnecessary rewrites of .env and app-specific .env files by comparing temporary updates to existing files before copying.

[sourcery-ai]

Reviewer's Guide

This PR updates the YAML merge and env update scripts to write composed/updated output to temporary files first and only overwrite the target files when the content has actually changed, avoiding unnecessary writes while preserving existing logging and error handling behavior.

Sequence diagram for updated docker_compose_yml_merge_behavior

sequenceDiagram
    participant yml_merge_script
    participant docker_compose
    participant filesystem

    yml_merge_script->>filesystem: mktemp MKTEMP_COMPOSE_YML
    Note over yml_merge_script,filesystem: If mktemp fails, fatal and exit

    yml_merge_script->>docker_compose: run config with COMPOSE_FILE
    docker_compose-->>yml_merge_script: write output to MKTEMP_COMPOSE_YML (or error)

    alt docker_compose_config_failed
        yml_merge_script->>filesystem: rm -f MKTEMP_COMPOSE_YML
        yml_merge_script-->>yml_merge_script: error and return nonzero
    else docker_compose_config_succeeded
        yml_merge_script->>filesystem: check if docker-compose.yml exists
        yml_merge_script->>filesystem: cmp -s MKTEMP_COMPOSE_YML docker-compose.yml
        alt files_differ_or_target_missing
            yml_merge_script->>filesystem: cp -f MKTEMP_COMPOSE_YML docker-compose.yml
            Note over yml_merge_script,filesystem: If cp fails, fatal and exit
        else files_identical
            Note over yml_merge_script,filesystem: Skip overwriting docker-compose.yml
        end
        yml_merge_script->>filesystem: rm -f MKTEMP_COMPOSE_YML
        yml_merge_script-->>yml_merge_script: log merge complete and unset_needs_yml_merge
    end

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Sequence diagram for updated_env_update_file_write_behavior

sequenceDiagram
    participant env_update_script
    participant filesystem

    Note over env_update_script: Main .env update
    env_update_script->>filesystem: mktemp MKTEMP_ENV_UPDATED
    env_update_script->>filesystem: write UPDATED_ENV_LINES to MKTEMP_ENV_UPDATED
    Note over env_update_script,filesystem: If write fails, fatal and exit

    env_update_script->>filesystem: check if COMPOSE_ENV exists
    env_update_script->>filesystem: cmp -s MKTEMP_ENV_UPDATED COMPOSE_ENV
    alt compose_env_missing_or_differs
        env_update_script->>filesystem: RunAndLog cp -f MKTEMP_ENV_UPDATED COMPOSE_ENV
        Note over env_update_script,filesystem: If cp fails, fatal and exit
    else compose_env_identical
        Note over env_update_script,filesystem: Skip overwriting COMPOSE_ENV
    end
    env_update_script->>filesystem: RunAndLog rm -f MKTEMP_ENV_UPDATED

    Note over env_update_script: Per_app_env_update
    env_update_script->>filesystem: mktemp MKTEMP_APP_ENV_UPDATED
    env_update_script->>filesystem: write UPDATED_APP_ENV_LINES to MKTEMP_APP_ENV_UPDATED
    Note over env_update_script,filesystem: If write fails, fatal and exit

    env_update_script->>filesystem: check if APP_ENV_FILE exists
    env_update_script->>filesystem: cmp -s MKTEMP_APP_ENV_UPDATED APP_ENV_FILE
    alt app_env_missing_or_differs
        env_update_script->>filesystem: RunAndLog cp -f MKTEMP_APP_ENV_UPDATED APP_ENV_FILE
        Note over env_update_script,filesystem: If cp fails, fatal and exit
    else app_env_identical
        Note over env_update_script,filesystem: Skip overwriting APP_ENV_FILE
    end
    env_update_script->>filesystem: RunAndLog rm -f MKTEMP_APP_ENV_UPDATED

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File-Level Changes

Change	Details	Files
Generate docker-compose.yml via a temporary file and copy it over only when content differs from the existing file.	Create a temporary compose output file using mktemp before running docker compose config Write docker compose config output to the temporary file instead of directly to docker-compose.yml On failure, remove the temporary file and report the failing command using the temporary path If docker-compose.yml is missing or differs from the temporary file, copy the temporary file to docker-compose.yml Always remove the temporary compose file after processing	scripts/yml_merge.sh
Avoid rewriting .env and per-app .env files when there are no content changes by comparing temporary updates to existing files.	After writing updated .env content to a temporary file, compare it to the existing .env and only cp -f when the files differ or the target does not exist Apply the same compare-before-copy logic for per-app .env.app. files Suppress cmp errors by redirecting stderr to /dev/null during comparison Retain existing RunAndLog wrappers and fatal error handling around cp operations	scripts/env_update.sh

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[sourcery-ai]

Hey - I've left some high level feedback:

• Several cmp and cp invocations use unquoted paths (e.g., ${COMPOSE_FOLDER}/docker-compose.yml, ${COMPOSE_ENV}, ${APP_ENV_FILE}); consider quoting these variables to avoid issues with spaces or special characters in paths.
• The new temporary file handling (mktemp/rm -f) is duplicated and manually cleaned up in multiple places; consider wrapping this pattern in a small helper or using a trap to ensure consistent cleanup on all exit paths.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- Several `cmp` and `cp` invocations use unquoted paths (e.g., `${COMPOSE_FOLDER}/docker-compose.yml`, `${COMPOSE_ENV}`, `${APP_ENV_FILE}`); consider quoting these variables to avoid issues with spaces or special characters in paths.
- The new temporary file handling (`mktemp`/`rm -f`) is duplicated and manually cleaned up in multiple places; consider wrapping this pattern in a small helper or using a `trap` to ensure consistent cleanup on all exit paths.

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