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Networking

WSLC networking behaviour and how Purview.Containers models it.

Verified behaviour

Mode (ContainerNetworkingMode) Effect Port mappings
null (default) Docker NetworkMode: "none" — no network, no IP ❌ CreateContainer throws 0x80070057
None same as null ❌
Bridged container gets 172.17.0.x on the session bridge; host→container mapped ports work ✅
  • Host bind address is IPv4 loopback only (HostIp: 127.0.0.1). IPv6 ::1 does not connect to the mapped port.
  • Clients must use 127.0.0.1, not localhost. localhost resolves to ::1 first on .NET; most clients (Npgsql, StackExchange.Redis) fall back to IPv4, but Microsoft.Data.SqlClient hangs on ::1 without falling back, so the SQL Server module's connection strings use 127.0.0.1,{port} explicitly.
  • Containers in the same session can reach each other by IP (Bridged) — wget http://<ip>:8080/ works.
  • No name/DNS resolution between containers. wget http://<hostname>:8080/ and http://<container-name>:8080/ fail with "bad address"; /etc/hosts contains only localhost + the container's own IP <short-id>.
  • There are no managed network objects (no network create/connect in Microsoft.WSL.Containers, unlike the CLI).

Library design

  1. Default NetworkingMode = Bridged for containers that bind ports (or, by default, for all containers to be useful). This is baked into ContainerBuilder defaults.
  2. GetMappedPublicPort(containerPort) reads Inspect().Ports["<port>/tcp"][0].HostPort.
  3. GetNetworkIp() reads Inspect().NetworkSettings.Networks.bridge.IPAddress (Bridged only).
  4. TCP/HTTP wait strategies connect to 127.0.0.1:<hostPort> (IPv4 only).
  5. Multi-container environments are deliberately deferred. Because there is no native DNS/alias, a future ContainerEnvironmentBuilder would wire containers together by passing each other's IPs (from GetNetworkIp()) into configuration/env. The core API must not preclude this (it doesn't — GetNetworkIp + environment are enough).

What NOT to model

  • Do not invent Docker-style Network objects; the underlying semantics are just "bridged with IPs".
  • Do not claim container-name resolution works; it does not.