Where does mender-client save the incoming download?

dat-tran-matternet · October 7, 2021, 9:09pm

Where does mender-client save the incoming download? My rootfs is read-only; only the data partition is read-write. I’m assuming it writes somewhere to the data partition? If so, where?

thanks

dellgreen · October 7, 2021, 9:48pm

I’m pretty certain it streams it and overwrites the non-active partition as it streams, hence not requiring any intermediate storage requirements.

dat-tran-matternet · October 7, 2021, 10:00pm

Thanks for your reply. I can understand that with the rootfs update but what about custom update module like firmware to microcontrollers in the system?

For example I’m writing a update module to program my stm32 micro. Where is the argument FILES pointing to?

set -e

STATE="$1"
FILES="$2"

BLE_RESET=112
BLE_MODE=113
BLE_DEV=/dev/ttyS2

dellgreen · October 7, 2021, 10:40pm

Sorry i dont use update modules myself, so don’t have first hand experience of using them, however a quick bit of github detective work looks like the modules working directory is relative to the mender datastore, of which the datastore is on the data partition by default but is configurable.

github.com

mendersoftware/mender/blob/master/conf/paths.go#L43

    
      
          	DefaultConfFile         = path.Join(GetConfDirPath(), "mender.conf")
          	DefaultFallbackConfFile = path.Join(GetStateDirPath(), "mender.conf")
          )
          
          
var (
          	// device specific paths
          	DefaultArtifactInfoFile  = path.Join(GetConfDirPath(), "artifact_info")
          	DefaultArtScriptsPath    = path.Join(GetStateDirPath(), "scripts")
          	DefaultRootfsScriptsPath = path.Join(GetConfDirPath(), "scripts")
          	DefaultModulesPath       = path.Join(GetDataDirPath(), "modules", "v3")
          	DefaultModulesWorkPath   = path.Join(GetStateDirPath(), "modules", "v3")
          )
          
          
func GetDataDirPath() string {
          	return DefaultPathDataDir
          }
          
          
func GetStateDirPath() string {
          	return DefaultDataStore
          }

github.com

mendersoftware/mender/blob/master/cli/cli.go#L407

    
      
          
          
	// Handle config flags
          	config, err := conf.LoadConfig(
          		runOptions.config, runOptions.fallbackConfig)
          	if err != nil {
          		return nil, err
          	}
          
          
	// Make sure that paths that are not configurable via the config file is conconsistent with --data flag
          	config.ArtifactScriptsPath = path.Join(runOptions.dataStore, "scripts")
          	config.ModulesWorkPath = path.Join(runOptions.dataStore, "modules", "v3")
          
          
	// Checks if the DeviceTypeFile is defined in config file.
          	if config.MenderConfigFromFile.DeviceTypeFile != "" {
          		// Sets the config.DeviceTypeFile to the value in config file.
          		config.DeviceTypeFile = config.MenderConfigFromFile.DeviceTypeFile
          
          
	} else {
          		// If --data flag is not used then dataStore is /var/lib/mender
          		config.MenderConfigFromFile.DeviceTypeFile = path.Join(
          			runOptions.dataStore, "device_type")

dat-tran-matternet · October 7, 2021, 10:54pm

That’s great news. Thank you!

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Where does mender-client save the incoming download?

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