Pools, CLI, versioning, Debian packaging, HTTPS fix

- Replaced flat `backends: [...]` list on frontends with an ordered `pools:`
  list; each pool has a name and a map of backends with per-pool weights (0–100,
  default 100). Pools express priority: first pool with a healthy backend wins.
- Removed global backend weight (was on the backend, now lives in the pool).
- Config validation enforces non-empty pools, non-empty pool names, weight
  range, and consistent address families across all pools of a frontend.

- Added `PoolBackendInfo { name, weight }` and changed `PoolInfo.backends` from
  `repeated string` to `repeated PoolBackendInfo` so weights are visible over
  the API.

- Full interactive shell with readline, tab completion, and `?` inline help.
- Command tree parser (Walk) handles fixed keywords and dynamic slot nodes;
  prefix matching with exact-match priority.
- Commands: `show version/frontends/frontend/backends/backend/healthchecks/
  healthcheck`, `set backend <name> pause|resume`, `quit`/`exit`.
- `show frontend` output is hierarchical (pools → backends) with per-backend
  weights and `[disabled]` notation; pool section uses fixed-width formatting
  so ANSI color codes don't corrupt tabwriter alignment.
- `-color` flag (default true) wraps static field labels in dark-blue ANSI;
  works correctly with tabwriter because all labels carry identical-length
  escape sequences.

- `cmd/version.go` package holds `version`, `commit`, `date` vars set at build
  time via `-ldflags -X`.
- `make build` / `make build-amd64` / `make build-arm64` all inject
  `VERSION=0.1.1`, `COMMIT_HASH` (from `git rev-parse --short HEAD`), and
  `DATE` (UTC ISO-8601).
- `maglevc` prints version on interactive startup and exposes `show version`.
- `maglevd` logs version/commit/date at startup; `-version` flag prints and exits.

- `doHTTPProbe` was building a `https://` target URL even though TLS was already
  applied to the connection inside `inNetns`. `http.Transport` then wrapped the
  connection in a second TLS layer, producing "http: server gave HTTP response
  to HTTPS client". Fixed by always using `http://` in the target URL.
- Added `TestHTTPSProbe` using `httptest.NewTLSServer` to cover the full path.

- New `docs/user-guide.md`: maglevd flags/signals, maglevc commands, shell
  completion, and command-tree parser walkthrough.
- New `docs/healthchecks.md`: state machine, rise/fall model, probe intervals,
  all transition events with log examples.
- Updated `docs/config-guide.md`: pools design, removed global weight from
  backends, updated all examples.
- Updated `README.md`: packaging table, build paths, corrected binary locations
  (`/usr/sbin/maglevd`), config filename (`.yaml`).

- `debian/` directory contains `control.in`, `maglevd.service`, `default.maglev`,
  `maglev.yaml` (example config), `conffiles`, `postinst`, `prerm`.
- `debian/build-deb.sh` stages a package tree and calls `dpkg-deb`; emits
  `build/vpp-maglev_<version>~<commit>_<arch>.deb`.
- Cross-compiles for amd64 and arm64 in one `make pkg-deb` invocation.
- `maglevd` installed to `/usr/sbin/`, `maglevc` to `/usr/bin/`.
- Service reads `MAGLEV_CONFIG` from `/etc/default/maglev`
  (default: `/etc/maglev/maglev.yaml`).
- Man pages `maglevd(8)` and `maglevc(1)` live in `docs/` and are gzip'd into
  the package.
- All build output goes to `build/<arch>/`; `build/` is gitignored.

cmd/maglevc/commands.go

@@ -10,6 +10,7 @@ import (
 	"text/tabwriter"
 	"time"
 
+	buildinfo "git.ipng.ch/ipng/vpp-maglev/cmd"
 	"git.ipng.ch/ipng/vpp-maglev/internal/grpcapi"
 )
 
@@ -24,6 +25,9 @@ func buildTree() *Node {
 	quit := &Node{Word: "quit", Help: "exit the shell", Run: runQuit}
 	exit := &Node{Word: "exit", Help: "exit the shell", Run: runQuit}
 
+	// show version
+	showVersion := &Node{Word: "version", Help: "show build version", Run: runShowVersion}
+
 	// show frontends
 	showFrontends := &Node{Word: "frontends", Help: "list all frontends", Run: runShowFrontends}
 	// show frontend <name>
@@ -70,6 +74,7 @@ func buildTree() *Node {
 	}
 
 	show.Children = []*Node{
+		showVersion,
 		showFrontends, showFrontend,
 		showBackends, showBackend,
 		showHealthChecks, showHealthCheck,
@@ -125,6 +130,12 @@ func dynHealthChecks(ctx context.Context, client grpcapi.MaglevClient) []string
 
 // ---- run functions ---------------------------------------------------------
 
+func runShowVersion(_ context.Context, _ grpcapi.MaglevClient, _ []string) error {
+	fmt.Printf("maglevc %s (commit %s, built %s)\n",
+		buildinfo.Version(), buildinfo.Commit(), buildinfo.Date())
+	return nil
+}
+
 func runQuit(_ context.Context, _ grpcapi.MaglevClient, _ []string) error {
 	return errQuit
 }
@@ -152,22 +163,53 @@ func runShowFrontend(ctx context.Context, client grpcapi.MaglevClient, args []st
 	if err != nil {
 		return err
 	}
+
 	w := tabwriter.NewWriter(os.Stdout, 0, 0, 2, ' ', 0)
-	fmt.Fprintf(w, "name\t%s\n", info.Name)
-	fmt.Fprintf(w, "address\t%s\n", info.Address)
-	fmt.Fprintf(w, "protocol\t%s\n", info.Protocol)
-	fmt.Fprintf(w, "port\t%d\n", info.Port)
-	for i, b := range info.BackendNames {
-		if i == 0 {
-			fmt.Fprintf(w, "backends\t%s\n", b)
-		} else {
-			fmt.Fprintf(w, "\t%s\n", b)
+	fmt.Fprintf(w, "%s\t%s\n", label("name"), info.Name)
+	fmt.Fprintf(w, "%s\t%s\n", label("address"), info.Address)
+	fmt.Fprintf(w, "%s\t%s\n", label("protocol"), info.Protocol)
+	fmt.Fprintf(w, "%s\t%d\n", label("port"), info.Port)
+	if info.Description != "" {
+		fmt.Fprintf(w, "%s\t%s\n", label("description"), info.Description)
+	}
+	if len(info.Pools) > 0 {
+		fmt.Fprintf(w, "%s\n", label("pools"))
+	}
+	if err := w.Flush(); err != nil {
+		return err
+	}
+
+	// Pool section uses direct Printf with fixed-width padding so that ANSI
+	// escape codes in labels don't confuse tabwriter's byte-based alignment.
+	// "backends" is always the widest pool label (8 chars); all pool labels
+	// are right-padded to that width, giving a 2+8+2 = 12-char visual indent.
+	const poolLblWidth = len("backends")
+	const poolIndent = "  "
+	const poolSep = "  "
+	contIndent := strings.Repeat(" ", len(poolIndent)+poolLblWidth+len(poolSep))
+
+	for _, pool := range info.Pools {
+		namePad := strings.Repeat(" ", poolLblWidth-len("name"))
+		fmt.Printf("%s%s%s%s%s\n", poolIndent, label("name"), namePad, poolSep, pool.Name)
+		for i, pb := range pool.Backends {
+			beInfo, beErr := client.GetBackend(ctx, &grpcapi.GetBackendRequest{Name: pb.Name})
+			suffix := ""
+			if beErr == nil && !beInfo.Enabled {
+				suffix = "  [disabled]"
+			}
+			weightStr := ""
+			if pb.Weight != 100 {
+				weightStr = fmt.Sprintf("  %s %d", label("weight"), pb.Weight)
+			}
+			if i == 0 {
+				bePad := strings.Repeat(" ", poolLblWidth-len("backends"))
+				fmt.Printf("%s%s%s%s%s%s%s\n", poolIndent, label("backends"), bePad, poolSep, pb.Name, weightStr, suffix)
+			} else {
+				fmt.Printf("%s%s%s%s\n", contIndent, pb.Name, weightStr, suffix)
+			}
 		}
 	}
-	if info.Description != "" {
-		fmt.Fprintf(w, "description\t%s\n", info.Description)
-	}
-	return w.Flush()
+	return nil
 }
 
 func runShowBackends(ctx context.Context, client grpcapi.MaglevClient, _ []string) error {
@@ -194,25 +236,24 @@ func runShowBackend(ctx context.Context, client grpcapi.MaglevClient, args []str
 		return err
 	}
 	w := tabwriter.NewWriter(os.Stdout, 0, 0, 2, ' ', 0)
-	fmt.Fprintf(w, "name\t%s\n", info.Name)
-	fmt.Fprintf(w, "address\t%s\n", info.Address)
+	fmt.Fprintf(w, "%s\t%s\n", label("name"), info.Name)
+	fmt.Fprintf(w, "%s\t%s\n", label("address"), info.Address)
 	stateDur := ""
 	if len(info.Transitions) > 0 {
 		since := time.Since(time.Unix(0, info.Transitions[0].AtUnixNs))
 		stateDur = " for " + formatDuration(since)
 	}
-	fmt.Fprintf(w, "state\t%s%s\n", info.State, stateDur)
-	fmt.Fprintf(w, "enabled\t%v\n", info.Enabled)
-	fmt.Fprintf(w, "weight\t%d\n", info.Weight)
-	fmt.Fprintf(w, "healthcheck\t%s\n", info.Healthcheck)
+	fmt.Fprintf(w, "%s\t%s%s\n", label("state"), info.State, stateDur)
+	fmt.Fprintf(w, "%s\t%v\n", label("enabled"), info.Enabled)
+	fmt.Fprintf(w, "%s\t%s\n", label("healthcheck"), info.Healthcheck)
 	for i, t := range info.Transitions {
 		ts := time.Unix(0, t.AtUnixNs)
-		label := ""
+		lbl := ""
 		if i == 0 {
-			label = "transitions"
+			lbl = label("transitions")
 		}
 		fmt.Fprintf(w, "%s\t%s → %s\t%s\t%s\n",
-			label,
+			lbl,
 			t.From, t.To,
 			ts.Format("2006-01-02 15:04:05.000"),
 			formatAgo(time.Since(ts)),
@@ -245,41 +286,41 @@ func runShowHealthCheck(ctx context.Context, client grpcapi.MaglevClient, args [
 		return err
 	}
 	w := tabwriter.NewWriter(os.Stdout, 0, 0, 2, ' ', 0)
-	fmt.Fprintf(w, "name\t%s\n", info.Name)
-	fmt.Fprintf(w, "type\t%s\n", info.Type)
+	fmt.Fprintf(w, "%s\t%s\n", label("name"), info.Name)
+	fmt.Fprintf(w, "%s\t%s\n", label("type"), info.Type)
 	if info.Port > 0 {
-		fmt.Fprintf(w, "port\t%d\n", info.Port)
+		fmt.Fprintf(w, "%s\t%d\n", label("port"), info.Port)
 	}
-	fmt.Fprintf(w, "interval\t%s\n", time.Duration(info.IntervalNs))
+	fmt.Fprintf(w, "%s\t%s\n", label("interval"), time.Duration(info.IntervalNs))
 	if info.FastIntervalNs > 0 {
-		fmt.Fprintf(w, "fast-interval\t%s\n", time.Duration(info.FastIntervalNs))
+		fmt.Fprintf(w, "%s\t%s\n", label("fast-interval"), time.Duration(info.FastIntervalNs))
 	}
 	if info.DownIntervalNs > 0 {
-		fmt.Fprintf(w, "down-interval\t%s\n", time.Duration(info.DownIntervalNs))
+		fmt.Fprintf(w, "%s\t%s\n", label("down-interval"), time.Duration(info.DownIntervalNs))
 	}
-	fmt.Fprintf(w, "timeout\t%s\n", time.Duration(info.TimeoutNs))
-	fmt.Fprintf(w, "rise\t%d\n", info.Rise)
-	fmt.Fprintf(w, "fall\t%d\n", info.Fall)
+	fmt.Fprintf(w, "%s\t%s\n", label("timeout"), time.Duration(info.TimeoutNs))
+	fmt.Fprintf(w, "%s\t%d\n", label("rise"), info.Rise)
+	fmt.Fprintf(w, "%s\t%d\n", label("fall"), info.Fall)
 	if info.ProbeIpv4Src != "" {
-		fmt.Fprintf(w, "probe-ipv4-src\t%s\n", info.ProbeIpv4Src)
+		fmt.Fprintf(w, "%s\t%s\n", label("probe-ipv4-src"), info.ProbeIpv4Src)
 	}
 	if info.ProbeIpv6Src != "" {
-		fmt.Fprintf(w, "probe-ipv6-src\t%s\n", info.ProbeIpv6Src)
+		fmt.Fprintf(w, "%s\t%s\n", label("probe-ipv6-src"), info.ProbeIpv6Src)
 	}
 	if h := info.Http; h != nil {
-		fmt.Fprintf(w, "http.path\t%s\n", h.Path)
+		fmt.Fprintf(w, "%s\t%s\n", label("http.path"), h.Path)
 		if h.Host != "" {
-			fmt.Fprintf(w, "http.host\t%s\n", h.Host)
+			fmt.Fprintf(w, "%s\t%s\n", label("http.host"), h.Host)
 		}
-		fmt.Fprintf(w, "http.response-code\t%d-%d\n", h.ResponseCodeMin, h.ResponseCodeMax)
+		fmt.Fprintf(w, "%s\t%d-%d\n", label("http.response-code"), h.ResponseCodeMin, h.ResponseCodeMax)
 		if h.ResponseRegexp != "" {
-			fmt.Fprintf(w, "http.response-regexp\t%s\n", h.ResponseRegexp)
+			fmt.Fprintf(w, "%s\t%s\n", label("http.response-regexp"), h.ResponseRegexp)
 		}
 	}
 	if t := info.Tcp; t != nil {
-		fmt.Fprintf(w, "tcp.ssl\t%v\n", t.Ssl)
+		fmt.Fprintf(w, "%s\t%v\n", label("tcp.ssl"), t.Ssl)
 		if t.ServerName != "" {
-			fmt.Fprintf(w, "tcp.server-name\t%s\n", t.ServerName)
+			fmt.Fprintf(w, "%s\t%s\n", label("tcp.server-name"), t.ServerName)
 		}
 	}
 	return w.Flush()