Enhance Docker Compose With Run-merged.sh

Nov 9, 2025 by Admin 42 views

Introduction: The Need for Seamless Docker Container Management

Hey guys, let's talk about something super important for anyone using Docker: how run-merged.sh works and how we can make it even better. Right now, there's a bit of a gap between how run-merged.sh behaves and what you get with docker compose up stage-2. This can lead to some unexpected behavior, especially when you're running containers in the background. The goal here is to make things more intuitive and user-friendly, so you spend less time troubleshooting and more time building awesome stuff. We're aiming for a setup where the default behavior of run-merged.sh mirrors the experience you get with docker compose, making the whole process smoother and more predictable. This means containers that stay up and running as you'd expect, whether you're working in the foreground or detached mode. Let's dive into the details, and I'll walk you through the proposed changes, the benefits, and how you can get the most out of it.

Current Challenges with run-merged.sh

Currently, run-merged.sh is pretty handy when you're working in the foreground. You run it, and you see the logs, everything's cool. But things get a bit tricky when you detach it (using -d). The container might just exit immediately because the entrypoint often starts an interactive shell. This can be frustrating because you expect the container to keep running in the background, but it disappears. The problem lies in how the shell is initiated and how TTY/STDIN are handled. When you use docker compose up stage-2, the template sets tty: true and stdin_open: true. This keeps the container alive even in detached mode. To solve this, we're adjusting run-merged.sh to behave more like docker compose, so the container sticks around, making your workflow smoother and less prone to unexpected exits. This means less debugging and more time focused on your projects. Imagine a world where your containers behave consistently, no matter how you start them! That's what we're aiming for here.

The Proposed Solution: Aligning Defaults and Introducing --shell

Goals and Desired Behavior for run-merged.sh

Here’s the deal: We want run-merged.sh to be predictable and easy to use. The main goal is to align its behavior with docker compose up stage-2. This ensures that, by default, your containers stay running, whether you're watching the logs in the foreground or letting them run in the background. Specifically:

Foreground Mode: When you run run-merged.sh without any extra flags, it should act like it's been given the -it flags (equivalent to compose’s tty: true + stdin_open: true). This means it blocks and allocates a TTY/STDIN, letting you interact with the container. You see the logs and the container runs as expected.
Detached Mode (-d): Even when running in detached mode, we want to keep the -it flags (or -t and -i separately). This prevents the container from immediately exiting if the entrypoint drops into an interactive shell. The container stays alive, doing its thing in the background.

Explicit Shell Mode

We're also adding a --shell flag. This will let you jump directly into an interactive shell, similar to using docker run -it. If you provide a custom command after --, that command will take precedence. This gives you flexibility. You get to choose when you want to interact directly with the shell.

CLI/UX Improvements for run-merged.sh

We’ll keep all the existing flags you know and love, like -d/--detach, -n/--name, -p/--publish, -v/--volume, and --gpus. Here’s what we're adding and adjusting:

--shell: This is the big one. It forces an interactive shell (by default, /bin/bash -l). If you provide a command after --, that command runs instead of the default shell.
--no-tty: This flag lets you disable TTY/STDIN allocation. This is for those rare cases where you don't need or want a TTY.
Optional Fine-Tuning: We could also include --stdin-open/--no-stdin-open and --tty/--no-tty for even more granular control, mirroring compose's settings.

How Defaults and Env Vars Will Work

We will keep and extend the existing keys within merged.env. Think of things like RUN_DETACH='0', RUN_TTY='1', RUN_DEVICE_TYPE='gpu', and RUN_PORTS=.... We'll also add new keys:

RUN_STDIN_OPEN='1': Controls whether to pass -i to docker run. The default will be 1, matching compose.
RUN_KEEP_TTY_IN_DETACH='1': This keeps -t/-i even when -d is used. The default will also be 1. This ensures your containers stay alive when detached.
RUN_EXTRA_ARGS: This is for advanced cases, but users won't need to add -it here to prevent background exits anymore.

Implementation and Migration

Step-by-Step Implementation of run-merged.sh

Parse and Normalize New Env Vars: We'll start by parsing the new environment variables. For example:

STDIN_OPEN=$(normalize_bool "${RUN_STDIN_OPEN:-1}")
KEEP_TTY_IN_DETACH=$(normalize_bool "${RUN_KEEP_TTY_IN_DETACH:-1}")

Build the Docker Run Command with Compose-Like Logic: We'll build the docker run command using the TTY/STDIN logic:

cmd=( docker run )
if [[ "$DETACH" == "1" ]]; then
  cmd+=( -d )
  if [[ "$KEEP_TTY_IN_DETACH" == "1" ]]; then
    [[ "$TTY" == "1" ]] && cmd+=( -t )
    [[ "$STDIN_OPEN" == "1" ]] && cmd+=( -i )
  fi
else
  [[ "$TTY" == "1" ]] && cmd+=( -t )
  [[ "$STDIN_OPEN" == "1" ]] && cmd+=( -i )
fi

Add the --shell Flag: We'll add a --shell flag to launch an interactive shell:

SHELL_MODE=0
--shell) SHELL_MODE=1; shift ;;
if [[ $SHELL_MODE -eq 1 && ${#POSITIONAL[@]} -eq 0 ]]; then
  POSITIONAL=( "/bin/bash" "-l" )
fi

Optional Fine-Grained Controls: We might implement --no-tty, --tty, --stdin-open/--no-stdin-open for even more detailed control.
Update usage(): The usage() text will explicitly state that the default behavior is compose-like and that you should use --shell for an interactive shell.

Ensuring Compatibility and Smooth Migration

Backward Compatibility: The changes are designed to be fully backward-compatible. Existing flags and merged.env settings will continue to work as expected.
Safer Defaults: The new defaults will prevent many users from running into the