modify a namemapping implies a cygnus restart?

[AlvaroVega]

Some questions to clarify:

• Cygnus need be restarted after modify a namemapping?
• If cygnus namemapping is in a file volume, cygnus container needs be restarted?
• How apply this over kubernetes pods?

[AlvaroVega]

maybe related with permissions file: https://forums.docker.com/t/modify-a-file-which-mount-as-a-data-volume-but-it-didnt-change-in-container/2813

[AlvaroVega]

NM doc:
https://github.com/telefonicaid/fiware-cygnus/blob/master/doc/cygnus-ngsi/flume_extensions_catalogue/ngsi_name_mappings_interceptor.md
https://fiware-cygnus.readthedocs.io/en/latest/cygnus-ngsi/installation_and_administration_guide/name_mappings/index.html

NM are read each 30 seconds:

fiware-cygnus/cygnus-ngsi/src/main/java/com/telefonica/iot/cygnus/interceptors/NGSINameMappingsInterceptor.java

Lines 72 to 73 in 624329a

	// Create and start a periodical name mappings reader
	periodicalNameMappingsReader = new PeriodicalNameMappingsReader(30000);

fiware-cygnus/cygnus-ngsi/src/main/java/com/telefonica/iot/cygnus/interceptors/NGSINameMappingsInterceptor.java

Lines 180 to 234 in 624329a

	/**
	* Class in charge or periodically reading the NGSINameMappingsInterceptor
	* configuration file.
	*/
	private class PeriodicalNameMappingsReader extends Thread {
	private final CygnusLogger logger = new CygnusLogger(PeriodicalNameMappingsReader.class);
	private final int interval;
	private long lastModified;
	private boolean stop;
	PeriodicalNameMappingsReader(int interval) {
	this.interval = interval;
	this.lastModified = 0;
	this.stop = false;
	} // PeriodicalNameMappingsReader
	@Override
	public void run() {
	while (!stop) {
	// Check if the configuration has changed
	File groupingRulesFile = new File(nameMappingsConfFile);
	long modified = groupingRulesFile.lastModified();
	if (lastModified != 0 && modified == lastModified) {
	logger.debug("[nmi] The configuration has not changed");
	try {
	Thread.sleep(interval);
	} catch (InterruptedException e) {
	logger.error(
	"[nmi] There was a problem with the checking interval. Details: " + e.getMessage());
	} // try catch
	continue;
	} // if
	// Reload the name mappings
	lastModified = modified;
	loadNameMappings();
	// Sleep the configured interval of time
	try {
	Thread.sleep(interval);
	} catch (InterruptedException e) {
	logger.error("There was a problem with the checking interval. Details: " + e.getMessage());
	} // try catch
	} // while
	} // run
	public void signalForStop() {
	this.stop = true;
	} // signalForStop
	} // PeriodicalNameMappingsReader

[AlvaroVega]

Cygnus is able to read a namemmapping file modified without restart in a docker:

time=2022-02-07T14:34:28.988Z | lvl=DEBUG | corr=N/A | trans=N/A | srv=N/A | subsrv=N/A | comp=cygnus-ngsi | op=loadNameMappings | msg=com.telefonica.iot.cygnus.interceptors.NGSINameMappingsInterceptor[242] : [nmi] Reading name mappings, Json read: { "serviceMappings": [ { "originalService": "smartcity", "newService": "smartcityXXXXX", "servicePathMappings": [ { "originalServicePath": "", "newServicePath": "", "entityMappings": [ { "originalEntityId": "", "originalEntityType": "", "newEntityId": "", "newEntityType": "", "attributeMappings": [ { "originalAttributeName": "", "originalAttributeType": "", "newAttributeName": "", "newAttributeType": "" } ] } ] } ] } ]}
time=2022-02-07T14:34:28.992Z | lvl=DEBUG | corr=N/A | trans=N/A | srv=N/A | subsrv=N/A | comp=cygnus-ngsi | op=loadNameMappings | msg=com.telefonica.iot.cygnus.interceptors.NGSINameMappingsInterceptor[270] : [nmi] Reading attribute mappings, Json parsed
time=2022-02-07T14:34:28.992Z | lvl=DEBUG | corr=N/A | trans=N/A | srv=N/A | subsrv=N/A | comp=cygnus-ngsi | op=loadNameMappings | msg=com.telefonica.iot.cygnus.interceptors.NGSINameMappingsInterceptor[284] : [nmi] Reading name mappings, Json purged
time=2022-02-07T14:34:28.992Z | lvl=DEBUG | corr=N/A | trans=N/A | srv=N/A | subsrv=N/A | comp=cygnus-ngsi | op=loadNameMappings | msg=com.telefonica.iot.cygnus.interceptors.NGSINameMappingsInterceptor[294] : [nmi] Reading name mappings, regular expressions pre-compiled

ls -la name_mappings_mysql.conf
-rw-r--r-- 1 avega avega 881 Feb 7 15:34 name_mappings_mysql.conf

[AlvaroVega]

Given a cygnus configured with a NM in a volume like:
volumes:
- ${PATH_CYGNUS_CONF}/name_mappings_mysql.conf:/opt/apache-flume/conf/name_mappings_mysql.conf

After change NM file ${PATH_CYGNUS_CONF}/name_mappings_mysql.conf from

{
   "serviceMappings": [
      {
         "originalService": "smartcity",
         "newService": "smartcityXXXXX",
         "servicePathMappings": []
      }
   ]
}

to

{
   "serviceMappings": [
      {
         "originalService": "smartcity",
         "newService": "smartcityXXXXX",
         "servicePathMappings": []
      }
   ]
}

No restart iot-cygnus container is needed, cygnus reads NM each 30 seconds and after then applies the new NM.

[AlvaroVega]

But the importat detail is modify NM file (or any cygnus config file) without changing i-node (i.e. vim editor does it: moby/moby#15793 (comment))
Recommended editor is Nano.

[AlvaroVega]

#2136