feat(install): add port conflict detection before starting services

[logicalangel]

Summary

Adds automatic port conflict detection during installation to prevent the infinite Docker restart loop described in #10.

Problem

When another service already occupies port 8000 (the default UVICORN_PORT), docker compose up starts PasarGuard with network_mode: host, which causes:

[Errno 98] error while attempting to bind on address ('0.0.0.0', 8000): address already in use

This leads to an infinite restart loop since there is no pre-flight port check.

Solution

After the .env file is written and before up_pasarguard() starts the containers, the script now:

1. Reads the configured UVICORN_PORT from .env (defaults to 8000)
2. Checks if that port is already in use via the existing is_port_in_use() utility
3. If a conflict is detected, warns the user and prompts for an alternative port
4. Validates the new port (1-65535 range, not already in use)
5. Updates both UVICORN_PORT and ALLOWED_ORIGINS in .env

Changes

• pasarguard.sh: Added ~39 lines of port conflict detection logic in install_command(), placed between install_completion and up_pasarguard calls.

Testing

• Verified the detection logic uses the existing is_port_in_use() function (ss → netstat → lsof fallback chain)
• The prompt loop validates port range and re-checks availability before accepting

Closes #10

Summary by CodeRabbit

• New Features
  • The installation process now intelligently detects if the configured port is already in use and interactively prompts you to select an available alternative. The system validates your port selection and automatically updates the configuration with the new port.

[coderabbitai]

Walkthrough

The installation script now detects port conflicts before deployment. During setup, it checks if the configured UVICORN_PORT is in use, prompts the user to select an alternative if occupied, and updates the environment file with the new port selection.

Changes

Cohort / File(s)	Summary
Port Conflict Detection pasarguard.sh	Added port availability check during install_command() that validates the configured port, interactively prompts for an alternative if occupied, validates user input (integer 1-65535 range), and updates $ENV_FILE with the selected port, including replacing old port references in ALLOWED_ORIGINS.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 A script so wise, now checks the door,
Before the app tries port once more,
If 8000's taken, fear not, my friend,
Pick another—our conflicts end! 🔌

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main change: adding port conflict detection before services start during installation.
Linked Issues check	✅ Passed	All requirements from issue #10 are met: port availability checking, user prompting for alternatives, port validation (1-65535), .env file updates, and ALLOWED_ORIGINS updates.
Out of Scope Changes check	✅ Passed	All changes are directly related to implementing port conflict detection as specified in issue #10; no unrelated modifications detected.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

pasarguard.sh (1)

3746-3785: Port conflict detection logic looks solid and addresses the issue requirements.

The implementation correctly:

• Reads UVICORN_PORT from .env with a sensible default of 8000
• Uses the existing is_port_in_use() utility for detection
• Validates port range and availability in a prompt loop
• Updates both UVICORN_PORT and ALLOWED_ORIGINS in the .env file

One minor improvement per the static analysis hint:

🔧 Add `-r` flag to `read` command

The read command on line 3760 should include the -r flag to prevent backslash interpretation. While users are unlikely to enter backslashes in port numbers, it's a shell scripting best practice.

 while true; do
-    read -p "Enter a different port for PasarGuard (1-65535) or 'q' to abort: " new_port
+    read -rp "Enter a different port for PasarGuard (1-65535) or 'q' to abort: " new_port
     if [[ "$new_port" == "q" || "$new_port" == "Q" ]]; then

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@pasarguard.sh` around lines 3746 - 3785, The read invocation inside the port
prompt loop should use the -r flag to prevent backslash interpretation; update
the read command that assigns to new_port (inside the while true loop that
validates ports) to use read -r so user input is read raw; no other logic
changes needed—this affects the read that prompts "Enter a different port for
PasarGuard..." in the block that checks is_port_in_use and later calls
set_or_uncomment_env_var and up_pasarguard.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@pasarguard.sh`:
- Around line 3746-3785: The read invocation inside the port prompt loop should
use the -r flag to prevent backslash interpretation; update the read command
that assigns to new_port (inside the while true loop that validates ports) to
use read -r so user input is read raw; no other logic changes needed—this
affects the read that prompts "Enter a different port for PasarGuard..." in the
block that checks is_port_in_use and later calls set_or_uncomment_env_var and
up_pasarguard.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: a827e407-bb3c-4261-89d5-fc325c123701

📥 Commits

Reviewing files that changed from the base of the PR and between 8fb1929 and 86cbfe2.

📒 Files selected for processing (1)

• pasarguard.sh