adding no_proxy env variable by default to each clab node

clab/config.go

@@ -220,6 +220,53 @@ func (c *CLab) createNodeCfg(nodeName string, nodeDef *types.NodeDefinition, idx
 	// Merge EnvVarFiles content and the existing env variable
 	nodeCfg.Env = utils.MergeStringMaps(envFileContent, nodeCfg.Env)
 
+	// Default set of no_proxy entries
+	noProxyDefaults := []string{"localhost", "127.0.0.1", "::1", "*.local"}
+
+	// check if either of the no_proxy variables exists
+	noProxyLower, existsLower := nodeCfg.Env["no_proxy"]
+	noProxyUpper, existsUpper := nodeCfg.Env["NO_PROXY"]
+	noProxy := ""
+    if existsLower {
+		noProxy = noProxyLower
+        for _, defaultValue := range noProxyDefaults {
+			if !strings.Contains(noProxy, defaultValue) {
+				noProxy=noProxy + "," + defaultValue
+			}
+		}
+    } else if existsUpper {
+		noProxy = noProxyUpper
+		for _, defaultValue := range noProxyDefaults {
+			if !strings.Contains(noProxy, defaultValue) {
+				noProxy=noProxy + "," + defaultValue
+			}
+		}
+	} else {
+		noProxy = strings.Join(noProxyDefaults, ",")
+	}
+
+	// add all clab nodes to the no_proxy variable, if they have a static IP assigned, add this as well
+	var noProxyList []string
+    for key := range c.Config.Topology.Nodes {
+        noProxyList = append(noProxyList, key)
+        ipv4address := c.Config.Topology.Nodes[key].GetMgmtIPv4()
+		if ipv4address != "" {
+			noProxyList = append(noProxyList, ipv4address)
+		}
+		ipv6address := c.Config.Topology.Nodes[key].GetMgmtIPv6()
+		if ipv6address != "" {
+			noProxyList = append(noProxyList, ipv6address)
+		}
+    }
+
+	// sort for better readability
+	sort.Strings(noProxyList)
+
+	noProxy = noProxy + "," + strings.Join(noProxyList, ",")
+
+    nodeCfg.Env["no_proxy"] = noProxy
+	nodeCfg.Env["NO_PROXY"] = noProxy
+
 	log.Debugf("node config: %+v", nodeCfg)
 
 	// process startup-config