[What's New Analysis] Document polyglot connection properties

Summary

Aspire 13.0 introduced polyglot-friendly connection properties for database resources, exposing multiple formats (URI, JDBC, individual properties). This is not documented in any database integration doc.

What's Missing

Connection Property Expressions

var postgres = builder.AddPostgres("db").AddDatabase("mydb");

// .NET uses standard connection strings
var dotnetApi = builder.AddProject<Projects.Api>()
    .WithReference(postgres);

// Python uses URI format
var pythonWorker = builder.AddPythonModule("worker", "./worker", "worker.main")
    .WithEnvironment("DATABASE_URL", postgres.Resource.UriExpression);

// Java uses JDBC format
var javaApp = builder.AddExecutable("java-app", ...)
    .WithEnvironment("DB_JDBC", postgres.Resource.JdbcConnectionStringExpression);

Auto-exposed Environment Variables

When using WithReference(), these are automatically set:

• DB_URI - PostgreSQL URI: postgresql://user:pass@host:port/dbname
• DB_JDBCCONNECTIONSTRING - JDBC: jdbc:postgresql://host:port/dbname
• DB_HOST, DB_PORT, DB_USERNAME, DB_PASSWORD, DB_DATABASENAME

Note: JDBC connection string excludes credentials for security.

Suggested Content

1. Add to each database integration doc - PostgreSQL, MySQL, SQL Server, MongoDB, Oracle
2. Property reference table - Which properties each resource type exposes
3. Language-specific examples - Python, Java, Go usage patterns
4. Security note - JDBC excludes credentials, use separate env vars

Why It Matters

This is THE key feature for polyglot development. Non-.NET developers need to know what environment variables are available.