ovnmon: list DB tables

The list command has one subcommand per table
Each subcommand has an argument completer based on the possible fields.
That way we can limit the number of fields we show

Also, paging is supported out of the box

Signed-off-by: Adrian Moreno <[email protected]>

Author: amorenoz

cmd/ovnmon/ovnmon.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"flag"
+	"fmt"
 	"log"
 	"os"
 
@@ -23,6 +24,14 @@ var (
 type ormSignal struct{}
 
 func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, "%s [FLAGS] [COMMAND] \n", os.Args[0])
+		fmt.Fprintf(os.Stderr, "FLAGS:\n")
+		flag.PrintDefaults()
+		fmt.Fprintf(os.Stderr, "COMMAND:\n")
+		fmt.Fprintf(os.Stderr, "\tIf provided, it will run the command and exit. If not, it will enter interactive mode\n")
+		fmt.Fprintf(os.Stderr, "\tFor a full description of available commands use the command 'help'")
+	}
 	flag.Parse()
 
 	var addr string
@@ -41,7 +50,7 @@ func main() {
 		log.Fatal(err)
 	}
 
-	shell := newOvnShell(*auto)
+	shell := newOvnShell(*auto, dbModel)
 	config := goovn.Config{
 		Db:          goovn.DBNB,
 		Addr:        addr,
@@ -53,5 +62,5 @@ func main() {
 		panic(err)
 	}
 	defer orm.Close()
-	shell.Run(orm)
+	shell.Run(orm, flag.Args()...)
 }

cmd/ovnmon/shell.go

@@ -1,6 +1,10 @@
 package main
 
 import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"strings"
 	"sync"
 
 	goovn "github.com/ebay/go-ovn"
@@ -12,6 +16,7 @@ type OvnShell struct {
 	mutex   *sync.RWMutex
 	monitor bool
 	orm     goovn.ORMClient
+	dbModel *goovn.DBModel
 }
 
 func (s *OvnShell) Monitor(monitor bool) {
@@ -40,7 +45,7 @@ func (s *OvnShell) OnDeleted(m goovn.Model) {
 	}
 }
 
-func (s *OvnShell) Run(orm goovn.ORMClient) {
+func (s *OvnShell) Run(orm goovn.ORMClient, args ...string) {
 	s.orm = orm
 	shell := ishell.New()
 	shell.Set("ovnShell", s)
@@ -85,12 +90,87 @@ func (s *OvnShell) Run(orm goovn.ORMClient) {
 			}
 		},
 	})
+
+	// List Command
+	// Add a subcommand per table
+	listCmd := ishell.Cmd{
+		Name: "list",
+		Help: "List the content of a specific table",
+	}
+
+	// To generate the completer for each subcommand we store all the possible fields per table
+	tableFields := make(map[string][]string)
+	for tname, mtype := range s.dbModel.GetTypes() {
+		fields := []string{}
+		for i := 0; i < mtype.Elem().NumField(); i++ {
+			fields = append(fields, mtype.Elem().Field(i).Name)
+		}
+		tableFields[tname] = fields
+	}
+
+	for name := range s.dbModel.GetTypes() {
+		// Trick to be able to use name inside closures
+		tableName := name
+		subTableCmd := ishell.Cmd{
+			Name: name,
+			Help: fmt.Sprintf("%s [Field1 Field2 ...]", name),
+			LongHelp: fmt.Sprintf(
+				"List the content of Table %s", name) +
+				fmt.Sprintf("\n\n%s [Field1 Field2 ...]", name) +
+				"\n\t[Field1 Field2 ...]: List of fields to show (default: all fields will be shown)" +
+				fmt.Sprintf("\n\t\tPossible Fields: %s", strings.Join(tableFields[name], ", ")),
+			Func: func(c *ishell.Context) {
+				ovnShell := c.Get("ovnShell")
+				if ovnShell == nil {
+					c.Println("Error: No context")
+				}
+				// Use a buffer to store the generated output table
+				buffer := bytes.Buffer{}
+				mtype := ovnShell.(*OvnShell).dbModel.GetTypes()[c.Cmd.Name]
+				printer, err := NewStructPrinter(&buffer, mtype.Elem(), c.Args...)
+				if err != nil {
+					c.Println(err)
+					return
+				}
+
+				// call ORM.List()
+				valueList := reflect.New(reflect.SliceOf(mtype.Elem()))
+				orm := ovnShell.(*OvnShell).orm
+				err = orm.List(valueList.Interface())
+				if err != nil {
+					if err == goovn.ErrorNotFound {
+						return
+					}
+					c.Println(err)
+					return
+				}
+
+				// Render the result table
+				printer.Append(reflect.Indirect(valueList).Interface())
+				printer.Render()
+				// Print the result table through shell so it can be paged
+				c.ShowPaged(buffer.String())
+			},
+			Completer: func(args []string) []string {
+				return tableFields[tableName]
+			},
+		}
+		listCmd.AddCmd(&subTableCmd)
+	}
+	shell.AddCmd(&listCmd)
+
+	// If we have arguments, just run them and exit
+	if len(args) > 0 {
+		shell.Process(args...)
+		return
+	}
 	shell.Run()
 }
 
-func newOvnShell(auto bool) *OvnShell {
+func newOvnShell(auto bool, dbmodel *goovn.DBModel) *OvnShell {
 	return &OvnShell{
 		mutex:   new(sync.RWMutex),
 		monitor: auto,
+		dbModel: dbmodel,
 	}
 }

cmd/ovnmon/tables.go

@@ -0,0 +1,80 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"reflect"
+
+	"github.com/olekukonko/tablewriter"
+)
+
+// StructPrinter is a wrapper around tablewriter that
+// uses the struct's field names as columns
+type StructPrinter struct {
+	cols  []string
+	table *tablewriter.Table
+}
+
+// Append adds a list of objects to be printed
+func (sp *StructPrinter) Append(objList interface{}) error {
+	objListVal := reflect.ValueOf(objList)
+	if objListVal.Type().Kind() != reflect.Slice {
+		return fmt.Errorf("Append expects a slice of objects. Instead go %s", objListVal.Type())
+	}
+
+	data := make([][]string, 0, objListVal.Len())
+	for i := 0; i < objListVal.Len(); i++ {
+		objVal := objListVal.Index(i)
+		objData := make([]string, 0, len(sp.cols))
+		for _, col := range sp.cols {
+			field := objVal.FieldByName(col)
+			if !field.IsValid() {
+				continue
+			}
+			objData = append(objData, fmt.Sprintf("%v", field.Interface()))
+		}
+		data = append(data, objData)
+	}
+	sp.table.AppendBulk(data)
+	return nil
+}
+
+// Render prints the table content
+func (sp *StructPrinter) Render() {
+	sp.table.Render()
+}
+
+// NewStructPrinter generates a StructPrinter based on a Writer for a given reflect.Type
+// Optionally, a list of field selectors can be given. If so, only those columns
+// will be printed.
+func NewStructPrinter(writer io.Writer, stype reflect.Type, fieldSel ...string) (*StructPrinter, error) {
+	var cols []string
+	table := tablewriter.NewWriter(writer)
+
+	if len(fieldSel) > 0 {
+		for _, sel := range fieldSel {
+			found := false
+			for i := 0; i < stype.NumField(); i++ {
+				if stype.Field(i).Name == sel {
+					found = true
+					break
+				}
+			}
+			if !found {
+				return nil, fmt.Errorf("Field %s not found in Type %s", sel, stype.Name())
+			}
+		}
+		cols = fieldSel
+		cols = fieldSel
+	} else {
+		for i := 0; i < stype.NumField(); i++ {
+			field := stype.Field(i).Name
+			cols = append(cols, field)
+		}
+	}
+	table.SetHeader(cols)
+	return &StructPrinter{
+		cols:  cols,
+		table: table,
+	}, nil
+}

go.mod

@@ -3,14 +3,18 @@ module github.com/amorenoz/ovnmodel
 go 1.15
 
 require (
+	github.com/abiosoft/readline v0.0.0-20180607040430-155bce2042db // indirect
 	github.com/cenk/hub v1.0.1 // indirect
 	github.com/ebay/go-ovn v0.0.0-00010101000000-000000000000
 	github.com/ebay/libovsdb v0.2.0
 	github.com/fatih/color v1.10.0
+	github.com/flynn-archive/go-shlex v0.0.0-20150515145356-3f9db97f8568 // indirect
 	github.com/k0kubun/pp v2.4.0+incompatible
+	github.com/olekukonko/tablewriter v0.0.5
+	gopkg.in/abiosoft/ishell.v2 v2.0.0
 )
 
 replace (
-	github.com/ebay/go-ovn => github.com/amorenoz/go-ovn v0.1.1-0.20210305093751-39f4443b448d
+	github.com/ebay/go-ovn => github.com/amorenoz/go-ovn v0.1.1-0.20210309183059-6707d7ad0208
 	github.com/ebay/libovsdb => github.com/amorenoz/libovsdb v0.2.1-0.20210305093614-80f588f3e2db
 )

go.sum

@@ -8,6 +8,8 @@ github.com/amorenoz/go-ovn v0.1.1-0.20210305093751-39f4443b448d h1:p7AjjLYdIZSQ+
 github.com/amorenoz/go-ovn v0.1.1-0.20210305093751-39f4443b448d/go.mod h1:ozqnCmbSPuoGRJvZxDEOVAXd/F/Lyr27976cmLL9wl8=
 github.com/amorenoz/go-ovn v0.1.1-0.20210309175803-fc72470a0885 h1:3FssF6nKW0245obz/fP5+s94EBZFe9abi7/DJkrSVKU=
 github.com/amorenoz/go-ovn v0.1.1-0.20210309175803-fc72470a0885/go.mod h1:ozqnCmbSPuoGRJvZxDEOVAXd/F/Lyr27976cmLL9wl8=
+github.com/amorenoz/go-ovn v0.1.1-0.20210309183059-6707d7ad0208 h1:jxI537Jk7qoxd7y3ae6JvLuSF1YUpHv1O6vWUwTF5/o=
+github.com/amorenoz/go-ovn v0.1.1-0.20210309183059-6707d7ad0208/go.mod h1:ozqnCmbSPuoGRJvZxDEOVAXd/F/Lyr27976cmLL9wl8=
 github.com/amorenoz/libovsdb v0.2.1-0.20210223160324-916daff1677b h1:48XQjWRAc+C1vS5dab7fJfAHlhdGjZFVfLiyAbhBJS8=
 github.com/amorenoz/libovsdb v0.2.1-0.20210223160324-916daff1677b/go.mod h1:PTzqmBaVTOgGqKH05sIO2B6tauEwb5X000PvIKwLGd4=
 github.com/amorenoz/libovsdb v0.2.1-0.20210305093614-80f588f3e2db h1:7ilcb1RL51pKspczGOknPjeRmAJpbbDqBjOIOE/fqqw=
@@ -32,6 +34,10 @@ github.com/mattn/go-colorable v0.1.8 h1:c1ghPdyEDarC70ftn0y+A/Ee++9zz8ljHG1b13eJ
 github.com/mattn/go-colorable v0.1.8/go.mod h1:u6P/XSegPjTcexA+o6vUJrdnUu04hMope9wVRipJSqc=
 github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHXY=
 github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
+github.com/mattn/go-runewidth v0.0.9 h1:Lm995f3rfxdpd6TSmuVCHVb/QhupuXlYr8sCI/QdE+0=
+github.com/mattn/go-runewidth v0.0.9/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=
+github.com/olekukonko/tablewriter v0.0.5 h1:P2Ga83D34wi1o9J6Wh1mRuqd4mF/x/lgBS7N7AbDhec=
+github.com/olekukonko/tablewriter v0.0.5/go.mod h1:hPp6KlRPjbx+hW8ykQs1w3UBbZlj6HuIJcUGPhkA7kY=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=