incorporated comments No. 4

clab/general.go

@@ -3,14 +3,13 @@ package clab
 import (
 	"bufio"
 	"bytes"
-	"errors"
 	"fmt"
 	"io"
 	"os"
 	"strings"
 
-	"github.com/cloudflare/cfssl/log"
 	"github.com/srl-labs/containerlab/types"
+	"github.com/srl-labs/containerlab/utils"
 )
 
 const (
@@ -19,9 +18,16 @@ const (
 )
 
 func AppendHostsFileEntries(containers []types.GenericContainer, labname string) error {
+	filename := "/etc/hosts"
 	if labname == "" {
 		return fmt.Errorf("missing lab name")
 	}
+	if !utils.FileExists(filename) {
+		err := utils.CreateFile(filename, "127.0.0.1\tlocalhost")
+		if err != nil {
+			return err
+		}
+	}
 	// lets make sure we do not have remaining of a non destroyed run in the hosts file
 	err := DeleteEntriesFromHostsFile(labname)
 	if err != nil {
@@ -31,10 +37,13 @@ func AppendHostsFileEntries(containers []types.GenericContainer, labname string)
 	if len(data) == 0 {
 		return nil
 	}
-	f, err := os.OpenFile("/etc/hosts", os.O_APPEND|os.O_WRONLY, os.ModeAppend)
+	var f *os.File
+
+	f, err = os.OpenFile("/etc/hosts", os.O_APPEND|os.O_WRONLY, os.ModeAppend)
 	if err != nil {
 		return err
 	}
+
 	defer f.Close()
 	_, err = f.Write(data)
 	if err != nil {
@@ -78,12 +87,7 @@ func DeleteEntriesFromHostsFile(labname string) error {
 	}
 	f, err := os.OpenFile("/etc/hosts", os.O_RDWR, 0644) // skipcq: GSC-G302
 	if err != nil {
-		if errors.Is(err, os.ErrNotExist) {
-			log.Info("/etc/hosts does not exist")
-			return nil
-		} else {
-			return err
-		}
+		return err
 	}
 	defer f.Close()
 	reader := bufio.NewReader(f)

tests/01-smoke/01-basic-flow.robot

@@ -15,6 +15,12 @@ ${n2-ipv4}        172.20.20.100/24
 ${n2-ipv6}        2001:172:20:20::100/64
 
 *** Test Cases ***
+Verify number of Hosts entries before deploy
+    ${rc}    ${output} =    Run And Return Rc And Output
+    ...    cat /etc/hosts | wc -l
+    Log    ${output}
+    Set Suite Variable  ${HostsFileLines}   ${output}
+
 Deploy ${lab-name} lab
     Log    ${CURDIR}
     ${rc}    ${output} =    Run And Return Rc And Output
@@ -110,7 +116,7 @@ Verify l1 environment has MYVAR variable set
 Verify Hosts entries exist
     [Documentation]     Verification that the expected /etc/hosts entries are created. We are also checking for the HEADER and FOOTER values here, which also contain the lab name.
     ${rc}    ${output} =    Run And Return Rc And Output
-    ...    cat /etc/hosts | grep "2-linux-nodes" | wc -l
+    ...    cat /etc/hosts | grep "${lab-name}" | wc -l
     Log    ${output}
     Should Be Equal As Integers    ${rc}    0
     Should Contain    ${output}    6
@@ -124,10 +130,16 @@ Destroy ${lab-name} lab
 Verify Hosts entries are gone
     [Documentation]     Verification that the previously created /etc/hosts entries are properly removed. (Again including HEADER and FOOTER).
     ${rc}    ${output} =    Run And Return Rc And Output
-    ...    cat /etc/hosts | grep "2-linux-nodes" | wc -l
+    ...    cat /etc/hosts | grep "${lab-name}" | wc -l
     Log    ${output}
     Should Be Equal As Integers    ${rc}    0
     Should Contain    ${output}    0
+
+Verify Hosts file has same number of lines
+    ${rc}    ${output} =    Run And Return Rc And Output
+    ...    cat /etc/hosts | wc -l
+    Log    ${output}
+    Should Be Equal As Integers    ${HostsFileLines}    ${output}
 
 *** Keywords ***
 Setup