adding env-files to kind and node topology definition

clab/config.go

@@ -260,9 +260,17 @@ func (c *CLab) createNodeCfg(nodeName string, nodeDef *types.NodeDefinition, idx
 		// Extras
 		Extras: c.Config.Topology.GetNodeExtras(nodeName),
 	}
+	var err error
+
+	// Load content of the EnvVarFiles
+	envFileContent, err := utils.LoadEnvVarFiles(c.TopoFile.dir, c.Config.Topology.GetNodeEnvFiles(nodeName))
+	if err != nil {
+		return nil, err
+	}
+	// Merge EnvVarFiles content and the existing env variable
+	nodeCfg.Env = utils.MergeStringMaps(envFileContent, nodeCfg.Env)
 
 	log.Debugf("node config: %+v", nodeCfg)
-	var err error
 	// initialize config
 	p, err := c.Config.Topology.GetNodeStartupConfig(nodeCfg.ShortName)
 	if err != nil {

clab/config_test.go

@@ -470,3 +470,54 @@ func TestVerifyRootNetnsInterfaceUniqueness(t *testing.T) {
 	t.Logf("error: %v", err)
 
 }
+
+func TestEnvFileInit(t *testing.T) {
+	tests := map[string]struct {
+		got  string
+		node string
+		want map[string]string
+	}{
+		"env-file_defined_at_node_and_default_1": {
+			got:  "test_data/topo10.yml",
+			node: "node1",
+			want: map[string]string{
+				"env1":     "val1",
+				"env2":     "val2",
+				"ENVFILE1": "SOMEOTHERDATA",
+				"ENVFILE2": "THISANDTHAT",
+			},
+		},
+		"env-file_defined_at_node_and_default_2": {
+			got:  "test_data/topo10.yml",
+			node: "node2",
+			want: map[string]string{
+				"ENVFILE1": "SOMEENVVARDATA",
+				"ENVFILE2": "THISANDTHAT",
+			},
+		},
+	}
+
+	teardownTestCase := setupTestCase(t)
+	defer teardownTestCase(t)
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			opts := []ClabOption{
+				WithTopoFile(tc.got, ""),
+			}
+			c, err := NewContainerLab(opts...)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			env := c.Nodes[tc.node].Config().Env
+			// check all the want key/values are there
+			for k, v := range tc.want {
+				//check keys defined in tc.want exist and values are equal
+				if val, exists := env[k]; !(exists && val == v) {
+					t.Fatalf("wanted %q to be contained in env, but got %q", tc.want, env)
+				}
+			}
+		})
+	}
+}

clab/test_data/envfile1

@@ -0,0 +1 @@
+ENVFILE1=SOMEENVVARDATA

clab/test_data/envfile2

@@ -0,0 +1,2 @@
+ENVFILE1=SOMEOTHERDATA
+ENVFILE2=THISANDTHAT

clab/test_data/topo10.yml

@@ -0,0 +1,20 @@
+name: topo10
+topology:
+  defaults:
+    env-files:
+      - envfile2
+  nodes:
+    node1:
+      kind: linux
+      env:
+        env1: val1
+        env2: val2
+      mgmt_ipv4: 172.100.100.11
+    node2:
+      kind: linux
+      mgmt_ipv4: 172.100.100.12
+      labels:
+        node-label: value
+      env-files:
+        - envfile1
+

docs/manual/nodes.md

@@ -202,6 +202,30 @@ topology:
 
 You can also specify a magic ENV VAR - `__IMPORT_ENVS: true` - which will import all environment variables defined in your shell to the relevant topology level.
 
+### env-files
+To add environment variables defined in a file use the `env-files` property that can be defined at `defaults`, `kind` and `node` levels.
+
+The variable defined in the files are merged across all of them wtit more specific definitions overwriting less specific. Node level is the most specific one.
+
+Files can either be specified with their absolute path or a relative path. The base path for the relative path resolution is the directory that holds the topology definition file.
+
+```yaml
+topology:
+  defaults:
+    env-files:
+      - envfiles/defaults
+      - /home/user/clab/default-env
+  kinds:
+    srl:
+      env-files:
+        - envfiles/common
+        - ~/spines
+  nodes:
+    node1:
+      env-files:
+        - /home/user/somefile
+```
+
 ### 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.
 

types/node_definition.go

@@ -37,6 +37,8 @@ type NodeDefinition struct {
 	Publish []string `yaml:"publish,omitempty"`
 	// environment variables
 	Env map[string]string `yaml:"env,omitempty"`
+	// external file containing environment variables
+	EnvFiles []string `yaml:"env-files,omitempty"`
 	// linux user used in a container
 	User string `yaml:"user,omitempty"`
 	// container labels
@@ -186,6 +188,13 @@ func (n *NodeDefinition) GetEnv() map[string]string {
 	return n.Env
 }
 
+func (n *NodeDefinition) GetEnvFiles() []string {
+	if n == nil {
+		return nil
+	}
+	return n.EnvFiles
+}
+
 func (n *NodeDefinition) GetUser() string {
 	if n == nil {
 		return ""

types/topology.go

@@ -105,6 +105,16 @@ func (t *Topology) GetNodeEnv(name string) map[string]string {
 	return nil
 }
 
+func (t *Topology) GetNodeEnvFiles(name string) []string {
+	if ndef, ok := t.Nodes[name]; ok {
+		return utils.MergeStringSlices(
+			utils.MergeStringSlices(t.GetDefaults().GetEnvFiles(),
+				t.GetKind(t.GetNodeKind(name)).GetEnvFiles()),
+			ndef.GetEnvFiles())
+	}
+	return nil
+}
+
 func (t *Topology) GetNodePublish(name string) []string {
 	if ndef, ok := t.Nodes[name]; ok {
 		if len(ndef.GetPublish()) > 0 {

utils/env.go

@@ -8,6 +8,8 @@ import (
 	"fmt"
 	"os"
 	"reflect"
+
+	"github.com/joho/godotenv"
 )
 
 // convertEnvs convert env variables passed as a map to a list of them
@@ -87,6 +89,29 @@ func StringInSlice(slice []string, val string) (int, bool) {
 	return -1, false
 }
 
+// LoadEnvVarFiles load EnvVars from the given files, resolving relative paths
+func LoadEnvVarFiles(basefolder string, files []string) (map[string]string, error) {
+	resolvedPaths := []string{}
+	// resolve given paths, relative (to topology definition file)
+	for _, file := range files {
+		resolved := ResolvePath(file, basefolder)
+		if !FileExists(resolved) {
+			return nil, fmt.Errorf("env-file %s not found (path resolved to %s)", file, resolved)
+		}
+		resolvedPaths = append(resolvedPaths, resolved)
+	}
+
+	if len(resolvedPaths) == 0 {
+		return map[string]string{}, nil
+	}
+
+	result, err := godotenv.Read(resolvedPaths...)
+	if err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
 // MergeStringSlices merges string slices with duplicates removed
 func MergeStringSlices(ss ...[]string) []string {
 	res := make([]string, 0)

utils/file.go

@@ -5,6 +5,7 @@
 package utils
 
 import (
+	"bufio"
 	"errors"
 	"fmt"
 	"io"
@@ -147,6 +148,26 @@ func ReadFileContent(file string) ([]byte, error) {
 	return b, err
 }
 
+func ReadFileLines(file string) ([]string, error) {
+	// check file exists
+	if !FileExists(file) {
+		return nil, fmt.Errorf("%w: %s", errFileNotExist, file)
+	}
+	content, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+
+	scanner := bufio.NewScanner(content)
+	scanner.Split(bufio.ScanLines)
+	var result []string
+
+	for scanner.Scan() {
+		result = append(result, scanner.Text())
+	}
+	return result, nil
+}
+
 // ExpandHome expands `~` char in the path to home path of a current user in provided path p.
 func ExpandHome(p string) string {
 	userPath, _ := os.UserHomeDir()