The LivenessState of an application tells whether the internal state is valid. If Liveness is broken, this means that the application itself is in a failed state and cannot recover from it.
I would like to know what are the things that Spring Boot checks to decide the Liveness state.
Quoting from the official documentation of Spring Boot Features
The internal state of Spring Boot applications is mostly represented
by the Spring ApplicationContext. If the application context has
started successfully, Spring Boot assumes that the application is in a
valid state. An application is considered live as soon as the context
has been refreshed.
In general, the "Liveness" state should not be based on external
checks, such as Health checks. If it did, a failing external system (a
database, a Web API, an external cache) would trigger massive restarts
and cascading failures across the platform.
Related
My spring boot application is running when I check service status of it. It shows active and logs are updating as well when I tail them. But any how the rest endpoint is not accessible. Looks like context is not up, How to give priority to context.
I am planning to use Spring Data JPA along with Spring Boot with MySQL server. What are the challenges, considerations and best practices when considering running multiple instances of Spring Boot applications connecting to the DB.
As I understand from my knowledge, Hibernate should be considered when it completely owns the DB which is good in case of building monolith applications, but in case of running multiple instances (Microservices), how will each instance manage, update the state. Please guide me.
Hibernate can be used for Microservices when there is no local state maintained in any of the service in the application. The state could be using a hibernate second-level cache. When you want to go for a second-level cache make sure it is centralized and available for all the services in the application.
In fact this is a shared database pattern and using this pattern in Microservices architecture is absolutely fine. This is discussed in Microservices architecture patterns https://microservices.io/patterns/data/shared-database.html
I've just been playing around with Spring Boot and developed a small Spring Cloud Streams app which basically acts as a destination for incoming messages through a queue.
However, I wanted to expose a health check endpoint so that I can verify if the service is up and running.
Until now, spring.main.web-application-type has been none. However, tu run actuator I must have that on.
I want to think that having the previously mentioned property to none didn't make the service exposed to the outside world and now that it has been enabled I must check and prevent some kind of accesses?
Are there any security concerns I must check now?
After reading up on the Spring Boot Actuator features, specifically the health endpoint, I've found it quite useful for implementing docker container health checks for some of my services.
However some of my services are not webapps, and it seems like overkill to enable HTTP just to allow the container to check the app is up and running. Looking through the options, actuator seems to support HTTP endpoints, JMX, and SSH/Telnet, though that last one apparently requires you to be running a JDK, and is going away in boot 2.0.
Are there any established ways of doing container healthchecks for non-web spring boot apps?
I have used only Spring framework and deployed as spring boot application It just opens and runs as a java application , Why do a companies with only spring framework runs on app server they can run on JAVA application as usual ? why do they need App server? What all can an app server does ?
Application servers are usually designed to host multiple applications, and manage a set of services that are used by all these applications. These services might include transaction management, timers and task management, HTTP request routing, a message broker (for inter-process communication, among other things), user management, etc. There's usually a graphical or command-line management console, or both.
The Spring framework is usually used to build a single, mostly-self-contained application. Spring does provide common services like transaction management, although they typically require a deal more developer understanding than is the case with, say, a JEE appserver.
There are all sorts of application containers and frameworks, offering different kinds of services in different ways. Often there is no killer reason to pick one over the other, and they are to some extent interchangeable. Spring Boot seems to be rising in popularity right now, because (perhaps) of its better fit to the microservices-type development models that are currently popular.