is it possible to change the TTL property of Redis cache during the runtime if the same property has been changed in app config server? is there a way to automate the process to refresh the Redis instance properties during runtime on the event of config server change?
If you want to get the latest property in Config Server, it is recommended to do it through the client polling method, which can be found at
https://learn.microsoft.com/en-us/azure/spring-apps/how-to-config-server#config-server-refresh
Regarding the load to Redis instances, you may need to write some code to send out the event.
Related
I am using secondary indexes with Redis thanks to Spring Data Redis #Indexed annotations. My entry has a TTL.
This has a side effect of keeping the indexes after the expiration of the main entry. This is expected, and Spring can listen to keyspace expiry events to remove those indexes once the main TTL is done.
However, enabling the listening to keyspace expiry events with Spring, I face the following error at startup:
ERR unknown command 'CONFIG'
This is how I configured the listener:
#EnableRedisRepositories(enableKeyspaceEvents = EnableKeyspaceEvents.ON_STARTUP)
What can I do to make this work?
This problem is linked to the fact that the Redis cluster is managed, and as such remote clients can't call CONFIG on it. When enabling the Spring keyspace event listener, it tries to configure Redis to emit keyspace expiry events, by setting the notify-keyspace-events config key to "Ex".
The workaround to this is:
Configure your MemoryStore on GCP, adding the notify-keyspace-events key with "Ex" as value.
Use #EnableRedisRepositories(enableKeyspaceEvents = EnableKeyspaceEvents.ON_STARTUP, keyspaceNotificationsConfigParameter = "") for your client configuration. The explicitely empty String prevents Spring from trying to override the remote configuration.
I am using springcloud config server to refresh my application properties at the runtime on scheduled basis in production environment. My schedule runs biweekly without any issues.
My application is running on Kubernetes cloud on multiple pods. Pods tends to crash or restart at any moment. What happens in case of pod crash/restart it fetches the latest property file from Config Server and repository at application startup rather waiting for next scheduled refresh cycle.
This lead to inconsistencies across the pods configuration and application behavior.
What I am looking for a strategy to avoid property refresh at the app startup and "Spring cloud config" client to only refresh based on refresh cycle.
Any suggestions to solve above would be greatly appreciate.
You want to use old properties even your application gets restarted so you need to keep old properties detail somewhere. You can not do that in your application as property detail is coming from config server so its better to set refresh rate for config server also how frequent it should pull config detail from git or whatever is your source.
If you set refresh-rate to two week of config server it will contain old property detail only and does not matter how frequent your application restarted it will get old properties from config-server.
I am storing application.properties file in my config server. And my client applications are refering config server to download the property files.
Scenario 1:
When i change the value of property server.port in my config server. Can i reflect the changes in my client applicaiton without restarting the application.
You can use #RefreshScope beans for this purpose, this is not ideal but as close as you can get in config server, this is a pretty advanced thing after all.
So beans marked with this annotations will cause spring to clear the internal cache of the beans / configuration classes upon EnvironmentChangeEvent, then the instance of the bean will be created next time you'll try to call this bean.
To trigger such an event when the config server changes you can either explicitly call the actuator's refresh enpoint or develop your own solution that might be based on some messaging system so that the config server will be a producer of a "change" message and the consumer will be your application.
Now I can't say for sure whether it will work in particular with server.port, I've personally never seen a need to change this property, but for your custom beans this method will do the job.
Here is a good tutorial about this topic
I am new to Spring Config Server/Client technologies.
I am using a spring config server to hold some config values.
Config clients will connect to the server and get the values.
If i change some of the config values at the config server, then currently I have to refresh the clients to load the config details from config server again by invoking "/refresh" on each client.
Is there anyway the clients will be notified by the config server and they will then reload the configuration again ?
Yes there is a way.
The solution is to use the Spring Cloud Bus. Using this module, you would link multiple clients to the server using a message broker. The only message broker implementation currently supported by this module is AMQP. Once the clients are connected to the server, invoking the endpoint on the server /bus/refresh will automatically broadcast the configuration changes to all the subscribed clients. This therefore means it is possible to reload configuration changes for any number of clients with one single refresh request which originates at the server.
I am setting up an application connecting to mongoDB with high availability.
I have studied the documentation and setup the replica set successfully through
spring.data.mongodb.uri=mongodb://user:secret#mongo1.example.com:12345,mongo2.example.com:23456/test
As the application property file is fixed, the application is required to restart if I change the spring.data.mongodb.uri.
What if I have a new replica member in mongo, should I need to restart my application with the update in application property?
Or, is it fair enough to use the old configuration? Mongo driver will automatically connect to the new replica member for me with the old configuration.
If you are loading properties from the file you need to restart the application once the property is updated.
Otherwise, you need to use some global property management apps like consul which when the properties are changed it will reload the properties value in the application(#RefreshScope).
In your case, once the property is changed you need to disconnect and reconnect to the mongodb by code.