added user configuration for containers (#224)

* added user configuration

* documented cmd option

clab/config.go

@@ -64,7 +64,8 @@ type NodeConfig struct {
 	MgmtIPv4 string   `yaml:"mgmt_ipv4,omitempty"` // user-defined IPv4 address in the management network
 	MgmtIPv6 string   `yaml:"mgmt_ipv6,omitempty"` // user-defined IPv6 address in the management network
 
-	Env map[string]string `yaml:"env,omitempty"` // environment variables
+	Env  map[string]string `yaml:"env,omitempty"`  // environment variables
+	User string            `yaml:"user,omitempty"` // linux user used in a container
 }
 
 // Topology represents a lab topology
@@ -325,6 +326,20 @@ func (c *cLab) positionInitialization(nodeCfg *NodeConfig, kind string) string {
 	return c.Config.Topology.Defaults.Position
 }
 
+func (c *cLab) userInit(nodeCfg *NodeConfig, kind string) string {
+	switch {
+	case nodeCfg.User != "":
+		return nodeCfg.User
+
+	case c.Config.Topology.Kinds[kind].User != "":
+		return c.Config.Topology.Kinds[kind].User
+
+	case c.Config.Topology.Defaults.User != "":
+		return c.Config.Topology.Defaults.User
+	}
+	return ""
+}
+
 // NewNode initializes a new node object
 func (c *cLab) NewNode(nodeName string, nodeCfg NodeConfig, idx int) error {
 	// initialize a new node
@@ -361,6 +376,8 @@ func (c *cLab) NewNode(nodeName string, nodeCfg NodeConfig, idx int) error {
 	// initialize passed env variables which will be merged with kind specific ones
 	envs := c.envInit(&nodeCfg, node.Kind)
 
+	user := c.userInit(&nodeCfg, node.Kind)
+
 	switch node.Kind {
 	case "ceos":
 		// initialize the global parameters with defaults, can be overwritten later
@@ -383,7 +400,7 @@ func (c *cLab) NewNode(nodeName string, nodeCfg NodeConfig, idx int) error {
 			"MGMT_INTF":                           "eth0"}
 		node.Env = mergeStringMaps(kindEnv, envs)
 
-		node.User = "root"
+		node.User = user
 		node.Group = c.groupInitialization(&nodeCfg, node.Kind)
 		node.NodeType = nodeCfg.Type
 
@@ -431,10 +448,11 @@ func (c *cLab) NewNode(nodeName string, nodeCfg NodeConfig, idx int) error {
 
 		// initialize specifc container information
 		node.Cmd = "sudo bash -c /opt/srlinux/bin/sr_linux"
+
 		kindEnv := map[string]string{"SRLINUX": "1"}
 		node.Env = mergeStringMaps(kindEnv, envs)
 
-		node.User = "root"
+		node.User = user
 
 		node.Sysctls = make(map[string]string)
 		node.Sysctls["net.ipv4.ip_forward"] = "0"
@@ -468,6 +486,7 @@ func (c *cLab) NewNode(nodeName string, nodeCfg NodeConfig, idx int) error {
 		node.NodeType = c.typeInit(&nodeCfg, node.Kind)
 		node.Position = c.positionInitialization(&nodeCfg, node.Kind)
 		node.Cmd = c.cmdInit(&nodeCfg, node.Kind)
+		node.User = user
 
 		node.Sysctls = make(map[string]string)
 		node.Sysctls["net.ipv6.conf.all.disable_ipv6"] = "0"

clab/config_test.go

@@ -213,3 +213,51 @@ func TestEnvInit(t *testing.T) {
 		})
 	}
 }
+
+func TestUserInit(t *testing.T) {
+	tests := map[string]struct {
+		got  string
+		node string
+		want string
+	}{
+		"user_defined_at_node_level": {
+			got:  "test_data/topo1.yml",
+			node: "node2",
+			want: "custom",
+		},
+		"user_defined_at_kind_level": {
+			got:  "test_data/topo2.yml",
+			node: "node2",
+			want: "customkind",
+		},
+		"user_defined_at_defaults_level": {
+			got:  "test_data/topo3.yml",
+			node: "node1",
+			want: "customglobal",
+		},
+		"user_defined_at_node_and_kind_and_default_level": {
+			got:  "test_data/topo4.yml",
+			node: "node1",
+			want: "customnode",
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			opts := []ClabOption{
+				WithTopoFile(tc.got),
+			}
+			c := NewContainerLab(opts...)
+			if err := c.ParseTopology(); err != nil {
+				t.Fatal(err)
+			}
+
+			nodeCfg := c.Config.Topology.Nodes[tc.node]
+			kind := strings.ToLower(c.kindInitialization(&nodeCfg))
+			user := c.userInit(&nodeCfg, kind)
+			if user != tc.want {
+				t.Fatalf("wanted %q got %q", tc.want, user)
+			}
+		})
+	}
+}

clab/test_data/topo1.yml

@@ -13,3 +13,4 @@ topology:
     node2:
       kind: srl
       license: node1.lic
+      user: custom

clab/test_data/topo2.yml

@@ -6,6 +6,7 @@ topology:
       type: ixrd2
       env:
         env1: val1
+      user: customkind
   nodes:
     node1:
       kind: srl

clab/test_data/topo3.yml

@@ -7,6 +7,7 @@ topology:
     type: ixrd2
     env:
       env1: val1
+    user: customglobal
   nodes:
     node1:
       kind: srl

clab/test_data/topo4.yml

@@ -8,6 +8,7 @@ topology:
       env1: global
       env2: global
       env3: global
+    user: customglobal
   kinds:
     srl:
       license: kind.lic
@@ -16,6 +17,7 @@ topology:
       env:
         env2: kind
         env4: kind
+      user: customkind
   nodes:
     node1:
       kind: srl
@@ -26,3 +28,4 @@ topology:
       env:
         env1: node
         env5: node
+      user: customnode

docs/manual/nodes.md

@@ -19,6 +19,10 @@ topology:
       - 80:8080
       - 55555:43555/udp
       - 55554:43554/tcp
+      user: test
+      env:
+        ENV1: VAL1
+      cmd: /bin/bash script.sh
 ```
 
 ### kind
@@ -107,4 +111,34 @@ topology:
     node1:
       env:
         ENV1: 1 # ENV1=1 will be set for node1
+```
+
+### user
+To set a user which will be used to run a containerized process use the `user` configuration option. Can be defined at `node`, `kind` and `global` levels.
+
+```yaml
+topology:
+  defaults:
+    user: alice # alice user will be used for all nodes unless set on kind or node levels
+  kinds:
+    srl:
+      user: bob # bob user will be used for nodes of kind srl unless it is set on node level
+  nodes:
+    node1:
+      user: clab # clab user will be used for node1
+```
+
+### cmd
+It is possible to set/override the command of the container image with `cmd` configuration option. It accepts the "shell" form and can be set on all levels.
+
+```yaml
+topology:
+  defaults:
+    cmd: bash cmd.sh
+  kinds:
+    srl:
+      cmd: bash cmd2.sh
+  nodes:
+    node1:
+      cmd: bash cmd3.sh
 ```