feat: add Docker container column in drill-down view

CHANGELOG.md

@@ -0,0 +1,10 @@
+# Changelog
+
+## feat/docker-container-column
+
+Drilling into Docker processes now reveals which containers own each connection (#12).
+A new "Container" column appears showing container name, image, and port mapping
+(e.g., `nginx (nginx:latest) 8080→80`) — powered by the Docker Engine API with
+async resolution and port-keyed caching. The column is fully sortable and degrades
+gracefully when Docker is unavailable. New `internal/docker` package with `Resolver`
+interface and comprehensive test coverage across model, resolver, UI, and integration layers.

docs/plans/2026-02-11-docker-container-column-design.md

@@ -0,0 +1,178 @@
+# Docker Container Column
+
+## Summary
+
+When drilling into a Docker process (`com.docker.backend`, `dockerd`, `docker-proxy`, `containerd`), show an extra "Container" column in the connections table. Column displays: `name (image) hostPort→containerPort`.
+
+## Decisions
+
+- **Display**: Extra column in connections table (not a sub-grouping or separate view)
+- **Visibility**: Docker processes only; non-Docker views unchanged
+- **Data source**: Docker Engine API via `github.com/docker/docker/client`
+- **Column content**: `containerName (image:tag) hostPort→containerPort`
+- **Scope**: Drill-down only; containers do NOT appear as top-level process entries
+
+## Architecture
+
+### New package: `internal/docker/`
+
+**resolver.go**:
+- `ContainerResolver` interface: `Resolve(ctx) → map[int]ContainerInfo, error`
+- `ContainerInfo`: `Name`, `Image`, `ID` (short), `Ports []PortMapping`
+- `PortMapping`: `HostPort int`, `ContainerPort int`, `Protocol string`
+- Impl connects via default Docker socket
+- Calls `client.ContainerList(ctx, types.ContainerListOptions{})` for running containers
+- Iterates `NetworkSettings.Ports` → builds `hostPort → ContainerInfo` map
+- Graceful degradation: Docker unavailable → empty map, no error
+
+### Model changes (`internal/model/network.go`)
+
+```go
+type ContainerInfo struct {
+    Name  string
+    Image string
+    ID    string
+}
+
+type PortMapping struct {
+    HostPort      int
+    ContainerPort int
+    Protocol      string
+}
+```
+
+Add to `Connection`:
+```go
+Container    *ContainerInfo // nil for non-Docker
+PortMapping  *PortMapping   // nil if no mapping found
+```
+
+### UI changes
+
+**Detection** (`internal/ui/update.go`):
+- `isDockerProcess(name string) bool` — matches known Docker process names
+- On drill-down into Docker process, set flag `m.dockerView = true`
+
+**Messages** (`internal/ui/messages.go`):
+- `DockerResolveMsg` — triggers async Docker API call
+- `DockerResolvedMsg` — carries `map[int]ContainerInfo`
+
+**Model** (`internal/ui/model.go`):
+- Add `dockerCache map[int]docker.ContainerInfo`
+- Add `dockerView bool` (true when viewing Docker process connections)
+
+**View** (`internal/ui/view_table.go`):
+- When `dockerView`, add "Container" column after "State"
+- Format: `name (image) hostPort→containerPort`
+- Max width ~35 chars, truncate with `...`
+
+**Sort** (`internal/ui/view_sort.go`):
+- Add `SortContainer` to `SortColumn` enum
+- Sortable when `dockerView` is true
+
+### Data flow
+
+```
+Tick → Collect connections → snapshot
+     → if Docker process in snapshot:
+         fire DockerResolveMsg (async cmd)
+     → DockerResolvedMsg received:
+         store in m.dockerCache
+     → View renders:
+         for each connection, lookup localPort in dockerCache
+         populate Container column
+```
+
+Cache refreshed every tick. Single async call, same pattern as NetIO.
+
+## Files to create/modify
+
+| File | Action |
+|------|--------|
+| `internal/docker/resolver.go` | **Create** — ContainerResolver interface + impl |
+| `internal/docker/resolver_test.go` | **Create** — tests with mock Docker client |
+| `internal/model/network.go` | **Modify** — add ContainerInfo, PortMapping types |
+| `internal/ui/model.go` | **Modify** — add dockerCache, dockerView fields |
+| `internal/ui/messages.go` | **Modify** — add Docker messages |
+| `internal/ui/update.go` | **Modify** — handle Docker messages, detect Docker process |
+| `internal/ui/view_table.go` | **Modify** — render Container column |
+| `internal/ui/view_sort.go` | **Modify** — add SortContainer |
+| `internal/ui/keys.go` | No change (sort mode keys already generic) |
+| `go.mod` | **Modify** — add `github.com/docker/docker` dep |
+
+## Tests
+
+### `internal/docker/resolver_test.go` (new)
+
+**Mock strategy**: Define `ContainerResolver` interface; tests use a mock impl (same pattern as `mockCollector` in `internal/ui/mock_collector_test.go`).
+
+| Test | Description |
+|------|-------------|
+| `TestResolve_RunningContainers` | Mock returns 2 containers with port bindings → verify port→ContainerInfo map has correct entries |
+| `TestResolve_NoContainers` | Mock returns empty list → verify empty map, no error |
+| `TestResolve_ContainerWithoutPorts` | Container running but no published ports → excluded from map |
+| `TestResolve_MultiplePortsOneContainer` | Container publishes ports 80,443 → both map to same ContainerInfo |
+| `TestResolve_OverlappingPorts` | Two containers claim same host port → last-write-wins (document behavior) |
+| `TestResolve_DockerUnavailable` | Mock returns connection error → empty map, nil error (graceful degradation) |
+| `TestResolve_ContextCancelled` | Cancelled context → returns context error |
+| `TestContainerInfo_Format` | `ContainerInfo.Format()` returns `"name (image) hostPort→containerPort"` |
+| `TestContainerInfo_FormatTruncation` | Long names truncated to max width with `…` |
+
+### `internal/ui/update_test.go` (additions)
+
+| Test | Description |
+|------|-------------|
+| `TestIsDockerProcess_KnownNames` | `"com.docker.backend"`, `"dockerd"`, `"docker-proxy"`, `"containerd"` → true |
+| `TestIsDockerProcess_NonDocker` | `"Chrome"`, `"nginx"`, `"docker-cli"` → false |
+| `TestIsDockerProcess_CaseInsensitive` | `"Docker-Proxy"` → true (if we decide case-insensitive) |
+| `TestDrillIntoDocker_SetsDockerView` | Enter on Docker process → `m.dockerView == true` |
+| `TestDrillIntoNonDocker_DockerViewFalse` | Enter on regular process → `m.dockerView == false` |
+| `TestPopFromDockerView_ClearsDockerView` | Esc from Docker connections → `m.dockerView == false` |
+| `TestDockerResolvedMsg_PopulatesCache` | Receive `DockerResolvedMsg` with data → `m.dockerCache` populated |
+| `TestDockerResolvedMsg_EmptyResult` | Receive empty `DockerResolvedMsg` → cache empty, no error |
+| `TestDockerResolvedMsg_ReplacesOldCache` | Second `DockerResolvedMsg` overwrites previous cache |
+
+### `internal/ui/view_table_test.go` (additions or new)
+
+| Test | Description |
+|------|-------------|
+| `TestRenderConnections_DockerView_HasContainerColumn` | Docker view renders "Container" header in table |
+| `TestRenderConnections_NonDockerView_NoContainerColumn` | Regular view does NOT render "Container" header |
+| `TestRenderConnections_DockerView_MatchedPort` | Connection on port 8080 + cache has port 8080 → shows `"nginx (nginx:latest) 8080→80"` |
+| `TestRenderConnections_DockerView_UnmatchedPort` | Connection on port 9999 + cache has no entry → Container column empty |
+| `TestRenderConnections_DockerView_EmptyCache` | Docker view with empty cache → all Container columns empty |
+
+### `internal/ui/view_sort_test.go` (additions)
+
+| Test | Description |
+|------|-------------|
+| `TestSortContainer_Ascending` | Sort by Container column ascending → alphabetical by container name |
+| `TestSortContainer_Descending` | Sort descending → reverse alphabetical |
+| `TestSortContainer_EmptyValues` | Connections without container info sort to bottom (ascending) or top (descending) |
+| `TestSortContainer_OnlyInDockerView` | `SortContainer` not in column list for non-Docker views |
+
+### `internal/model/network_test.go` (additions)
+
+| Test | Description |
+|------|-------------|
+| `TestContainerInfo_Struct` | Verify struct fields populate correctly |
+| `TestPortMapping_Struct` | Verify PortMapping fields |
+| `TestConnection_WithContainer` | Connection with non-nil Container field |
+| `TestConnection_WithoutContainer` | Connection with nil Container (backwards compat) |
+
+### `internal/ui/mock_collector_test.go` (additions)
+
+| Test | Description |
+|------|-------------|
+| `mockDockerResolver` | New mock implementing `ContainerResolver` interface — returns configurable `map[int]ContainerInfo` |
+
+### Integration-style tests
+
+| Test | Description |
+|------|-------------|
+| `TestDockerDrillDownFlow` | Full flow: create model with Docker snapshot → drill in → receive DockerResolvedMsg → verify view renders container column with data |
+| `TestDockerDrillDownFlow_NoDocker` | Same flow but resolver returns empty → container column shows empty values, no errors |
+
+## Open questions
+
+None — all design decisions resolved.

go.mod

@@ -1,37 +1,56 @@
 module github.com/kostyay/netmon
 
-go 1.25.5
+go 1.25.7
 
 require (
 	github.com/charmbracelet/bubbles v0.21.0
 	github.com/charmbracelet/bubbletea v1.3.10
 	github.com/charmbracelet/lipgloss v1.1.0
+	github.com/docker/docker v28.5.2+incompatible
 	github.com/shirou/gopsutil/v3 v3.24.5
 	github.com/spf13/cobra v1.10.2
 	golang.org/x/term v0.39.0
 	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
+	github.com/Microsoft/go-winio v0.6.2 // indirect
 	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/charmbracelet/colorprofile v0.4.1 // indirect
 	github.com/charmbracelet/x/ansi v0.11.4 // indirect
 	github.com/charmbracelet/x/cellbuf v0.0.14 // indirect
 	github.com/charmbracelet/x/term v0.2.2 // indirect
 	github.com/clipperhouse/displaywidth v0.7.0 // indirect
 	github.com/clipperhouse/stringish v0.1.1 // indirect
 	github.com/clipperhouse/uax29/v2 v2.3.1 // indirect
+	github.com/containerd/errdefs v1.0.0 // indirect
+	github.com/containerd/errdefs/pkg v0.3.0 // indirect
+	github.com/containerd/log v0.1.0 // indirect
+	github.com/distribution/reference v0.6.0 // indirect
+	github.com/docker/go-connections v0.6.0 // indirect
+	github.com/docker/go-units v0.5.0 // indirect
 	github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-ole/go-ole v1.3.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/lucasb-eyer/go-colorful v1.3.0 // indirect
 	github.com/lufia/plan9stats v0.0.0-20251013123823-9fd1530e3ec3 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mattn/go-localereader v0.0.1 // indirect
 	github.com/mattn/go-runewidth v0.0.19 // indirect
+	github.com/moby/docker-image-spec v1.3.1 // indirect
+	github.com/moby/sys/atomicwriter v0.1.0 // indirect
+	github.com/moby/term v0.5.2 // indirect
+	github.com/morikuni/aec v1.1.0 // indirect
 	github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
 	github.com/muesli/termenv v0.16.0 // indirect
+	github.com/opencontainers/go-digest v1.0.0 // indirect
+	github.com/opencontainers/image-spec v1.1.1 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/shoenig/go-m1cpu v0.1.7 // indirect
@@ -40,6 +59,14 @@ require (
 	github.com/tklauser/numcpus v0.11.0 // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
 	github.com/yusufpapurcu/wmi v1.2.4 // indirect
+	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.65.0 // indirect
+	go.opentelemetry.io/otel v1.40.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.40.0 // indirect
+	go.opentelemetry.io/otel/metric v1.40.0 // indirect
+	go.opentelemetry.io/otel/trace v1.40.0 // indirect
 	golang.org/x/sys v0.40.0 // indirect
 	golang.org/x/text v0.33.0 // indirect
+	golang.org/x/time v0.14.0 // indirect
+	gotest.tools/v3 v3.5.2 // indirect
 )