Merge pull request #586 from jbemmel/jvb-keep-modified-startup-config

make node's existing config take preference over startup-config + `enforce-startup-config` flag

clab/config.go

@@ -240,6 +240,8 @@ func (c *CLab) createNodeCfg(nodeName string, nodeDef *types.NodeDefinition, idx
 	if err != nil {
 		return nil, err
 	}
+	nodeCfg.EnforceStartupConfig = c.Config.Topology.GetNodeEnforceStartupConfig(nodeCfg.ShortName)
+
 	// initialize license field
 	nodeCfg.License, err = c.Config.Topology.GetNodeLicense(nodeCfg.ShortName)
 	if err != nil {

docs/manual/kinds/ceos.md

@@ -109,7 +109,7 @@ cEOS nodes have a dedicated [`config`](../conf-artifacts.md#identifying-a-lab-di
 used as a startup config instead.
 
 #### Default node configuration
-When a node is defined without `config` statement present, containerlab will generate an empty config from [this template](https://github.com/srl-labs/containerlab/blob/master/nodes/ceos/ceos.cfg) and copy it to the config directory of the node.
+When a node is defined without `startup-config` statement present, containerlab will generate an empty config from [this template](https://github.com/srl-labs/containerlab/blob/master/nodes/ceos/ceos.cfg) and copy it to the config directory of the node.
 
 ```yaml
 # example of a topo file that does not define a custom config
@@ -138,7 +138,7 @@ topology:
       startup-config: myconfig.conf
 ```
 
-When a config file is passed via `startup-config` parameter, it will override any configuration that may have left upon lab destroy.
+When a config file is passed via `startup-config` parameter it will be used during an initial lab deployment. However, a config file that might be in the lab directory of a node takes precedence over the startup-config[^3].
 
 With such topology file containerlab is instructed to take a file `myconfig.conf` from the current working directory, copy it to the lab directory for that specific node under the `/flash/startup-config` name and mount that dir to the container. This will result in this config to act as a startup config for the node.
 
@@ -247,3 +247,4 @@ Consult your distribution's documentation for details regarding configuring cgro
 
 [^1]: https://eos.arista.com/ceos-lab-topo/
 [^2]: do not remove the template variables from the `Management0` interface, otherwise the nodes will not apply the IP address from docker IPAM service.
+[^3]: if startup config needs to be enforced, either deploy a lab with `--reconfigure` flag, or use [`enforce-startup-config`](../nodes.md#enforce-startup-config) setting.

docs/manual/nodes.md

@@ -60,6 +60,11 @@ Some containerized NOSes require a license to operate or can leverage a license
 ### startup-config
 For some kinds it's possible to pass a path to a config file that a node will use on start instead of a bare config. Check documentation for a specific kind to see if `startup-config` element is supported.
 
+Note, that if a config file exists in the lab directory for a given node, then it will take preference over the startup config passed with this setting. If it is desired to discard the previously saved config and use the startup config instead, use the `enforce-startup-config` setting or deploy a lab with the [`reconfigure`](../cmd/deploy.md#reconfigure) flag.
+
+### enforce-startup-config
+By default, containerlab will use the config file that is available in the lab directory for a given node even if the `startup config` parameter points to another file. To make a node to boot with the config set with `startup-config` parameter no matter what, set the `enforce-startup-config` to `true`.
+
 ### binds
 In order to expose host files to the containerized nodes a user can leverage the bind mount capability.
 

nodes/srl/srl.go

@@ -226,6 +226,7 @@ func createSRLFiles(nodeCfg *types.NodeConfig) error {
 	utils.CreateDirectory(path.Join(nodeCfg.LabDir, "config"), 0777)
 	dst = filepath.Join(nodeCfg.LabDir, "config", "config.json")
 	if nodeCfg.StartupConfig != "" {
+		log.Debugf("GenerateConfig reading startup-config %s", nodeCfg.StartupConfig )
 		c, err := os.ReadFile(nodeCfg.StartupConfig)
 		if err != nil {
 			return err

types/node_definition.go

@@ -11,15 +11,16 @@ const (
 
 // NodeDefinition represents a configuration a given node can have in the lab definition file
 type NodeDefinition struct {
-	Kind          string            `yaml:"kind,omitempty"`
-	Group         string            `yaml:"group,omitempty"`
-	Type          string            `yaml:"type,omitempty"`
-	StartupConfig string            `yaml:"startup-config,omitempty"`
-	Config        *ConfigDispatcher `yaml:"config,omitempty"`
-	Image         string            `yaml:"image,omitempty"`
-	License       string            `yaml:"license,omitempty"`
-	Position      string            `yaml:"position,omitempty"`
-	Cmd           string            `yaml:"cmd,omitempty"`
+	Kind                 string            `yaml:"kind,omitempty"`
+	Group                string            `yaml:"group,omitempty"`
+	Type                 string            `yaml:"type,omitempty"`
+	StartupConfig        string            `yaml:"startup-config,omitempty"`
+	EnforceStartupConfig bool              `yaml:"enforce-startup-config,omitempty"`
+	Config               *ConfigDispatcher `yaml:"config,omitempty"`
+	Image                string            `yaml:"image,omitempty"`
+	License              string            `yaml:"license,omitempty"`
+	Position             string            `yaml:"position,omitempty"`
+	Cmd                  string            `yaml:"cmd,omitempty"`
 	// list of bind mount compatible strings
 	Binds []string `yaml:"binds,omitempty"`
 	// list of port bindings
@@ -77,6 +78,13 @@ func (n *NodeDefinition) GetStartupConfig() string {
 	return n.StartupConfig
 }
 
+func (n *NodeDefinition) GetEnforceStartupConfig() bool {
+	if n == nil {
+		return false
+	}
+	return n.EnforceStartupConfig
+}
+
 func (n *NodeDefinition) GetConfigDispatcher() *ConfigDispatcher {
 	if n == nil {
 		return nil

types/topology.go

@@ -171,6 +171,19 @@ func (t *Topology) GetNodeStartupConfig(name string) (string, error) {
 	return cfg, nil
 }
 
+func (t *Topology) GetNodeEnforceStartupConfig(name string) bool {
+	if ndef, ok := t.Nodes[name]; ok {
+		if ndef.GetEnforceStartupConfig() {
+			return true
+		}
+		if t.GetKind(t.GetNodeKind(name)).GetEnforceStartupConfig() {
+			return true
+		}
+		return t.GetDefaults().GetEnforceStartupConfig()
+	}
+	return false
+}
+
 func (t *Topology) GetNodeLicense(name string) (string, error) {
 	var license string
 	if ndef, ok := t.Nodes[name]; ok {

types/types.go

@@ -53,29 +53,30 @@ type MgmtNet struct {
 
 // NodeConfig is a struct that contains the information of a container element
 type NodeConfig struct {
-	ShortName        string // name of the Node inside topology YAML
-	LongName         string // containerlab-prefixed unique container name
-	Fqdn             string
-	LabDir           string // LabDir is a directory related to the node, it contains config items and/or other persistent state
-	Index            int
-	Group            string
-	Kind             string
-	StartupConfig    string // path to config template file that is used for startup config generation
-	ResStartupConfig string // path to config file that is actually mounted to the container and is a result of templation
-	Config           *ConfigDispatcher
-	ResConfig        string // path to config file that is actually mounted to the container and is a result of templation
-	NodeType         string
-	Position         string
-	License          string
-	Image            string
-	Sysctls          map[string]string
-	User             string
-	Entrypoint       string
-	Cmd              string
-	Env              map[string]string
-	Binds            []string    // Bind mounts strings (src:dest:options)
-	PortBindings     nat.PortMap // PortBindings define the bindings between the container ports and host ports
-	PortSet          nat.PortSet // PortSet define the ports that should be exposed on a container
+	ShortName            string // name of the Node inside topology YAML
+	LongName             string // containerlab-prefixed unique container name
+	Fqdn                 string
+	LabDir               string // LabDir is a directory related to the node, it contains config items and/or other persistent state
+	Index                int
+	Group                string
+	Kind                 string
+	StartupConfig        string // path to config template file that is used for startup config generation
+	EnforceStartupConfig bool   // when set to true will enforce the use of startup-config, even when config is present in the lab directory
+	ResStartupConfig     string // path to config file that is actually mounted to the container and is a result of templation
+	Config               *ConfigDispatcher
+	ResConfig            string // path to config file that is actually mounted to the container and is a result of templation
+	NodeType             string
+	Position             string
+	License              string
+	Image                string
+	Sysctls              map[string]string
+	User                 string
+	Entrypoint           string
+	Cmd                  string
+	Env                  map[string]string
+	Binds                []string    // Bind mounts strings (src:dest:options)
+	PortBindings         nat.PortMap // PortBindings define the bindings between the container ports and host ports
+	PortSet              nat.PortSet // PortSet define the ports that should be exposed on a container
 	// container networking mode. if set to `host` the host networking will be used for this node, else bridged network
 	NetworkMode          string
 	MgmtNet              string // name of the docker network this node is connected to with its first interface
@@ -105,12 +106,15 @@ type NodeConfig struct {
 // GenerateConfig generates configuration for the nodes
 // out of the templ based on the node configuration and saves the result to dst
 func (node *NodeConfig) GenerateConfig(dst, templ string) error {
-	// if startup config is not set, and the config file is already present in the node dir
-	// we do not regenerate the config, since we will take what was saved from the previous run
-	// in other words, the startup config set by a user takes preference and will trigger config generation
-	if utils.FileExists(dst) && (node.StartupConfig == "") {
-		log.Debugf("config file '%s' for node '%s' already exists and will not be generated", dst, node.ShortName)
+
+	// If the config file is already present in the node dir
+	// we do not regenerate the config unless EnforceStartupConfig is explicitly set to true and startup-config points to a file
+	// this will persist the changes that users make to a running config when booted from some startup config
+	if utils.FileExists(dst) && (node.StartupConfig == "" || !node.EnforceStartupConfig) {
+		log.Infof("config file '%s' for node '%s' already exists and will not be generated/reset", dst, node.ShortName)
 		return nil
+	} else if node.EnforceStartupConfig {
+		log.Infof("Startup config for '%s' node enforced: '%s'", node.ShortName, dst)
 	}
 	log.Debugf("generating config for node %s from file %s", node.ShortName, node.StartupConfig)
 	tpl, err := template.New(filepath.Base(node.StartupConfig)).Parse(templ)