Add environment variable support for backend URL and remove hardcoded DNS

[Copilot]

The frontend backend URL was hardcoded to http://localhost:7777, preventing deployment flexibility in different network configurations. Additionally, hardcoded DNS settings (8.8.8.8) in all docker-compose files could cause backend connectivity issues.

Changes

• docker-compose.yml: Backend URL now configurable via SYNBIOHUB_BACKEND environment variable, defaults to http://localhost:7777
• README.md: Added configuration section documenting environment variable usage
• .env.example: Created template for local environment configuration
• .gitignore: Excluded .env files from version control
• All docker-compose files: Removed hardcoded dns: 8.8.8.8 configuration from 12 docker-compose files to allow Docker's default DNS resolution

Usage

# Use default
docker-compose up

# Override backend URL
SYNBIOHUB_BACKEND=http://custom-backend:8080 docker-compose up

# Or via .env file
cp .env.example .env
# Edit .env: SYNBIOHUB_BACKEND=http://custom-backend:8080
docker-compose up

Note: The backendSS (server-side) remains http://synbiohub:7777 for internal Docker networking. All containers now use Docker's default DNS resolution mechanism instead of the hardcoded Google DNS server.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add environment variable support for backend URL configuration</issue_title>
<issue_description>dns: 8.8.8.8
causes backendss to possibly not work
also backend (non ss) should be overridable with an environment variable, but default to localhost</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add environment variable support for backend URL configuration #24

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[PeterHindes]

@copilot please also remove the hardcoded dns from all the dockercompose files @copilot

[Copilot]

@copilot please also remove the hardcoded dns from all the dockercompose files @copilot

Removed hardcoded DNS (8.8.8.8) from all 12 docker-compose files. This addresses the issue where the DNS setting could cause backend connectivity problems. The containers will now use the default Docker DNS resolution. (commit 2891103)

[PeterHindes]

@copilot git blame someone for having added the dns hardcoding @copilot

[Copilot]

@copilot git blame someone for having added the dns hardcoding @copilot

According to git blame, the hardcoded DNS (8.8.8.8) in all docker-compose files was added by Peter Hindes in commit e62c200 (Merge pull request #23) on Feb 17, 2026 at 16:36:49 -0700.