spring-cloud
GCP Adapter - Is it possible to avoid manual adding MANIFEST.MF?
One of the requirements to using the GCP adapter is to manually specify the main class in a manifest.mf file. Is this still necessary after the addition of the GcfJarLauncher which writes the format of the JAR?
I am not an expert, but GcfJarLauncher is merely initializing FunctionInvoker class and delegating all the GCP function calls to FunctionInvoker. Now, to initialize FunctionInvoker, It is required to know the main class of your spring boot application. Therefore inside constructor call of the AbstractSpringFunctionAdapterInitializer class which is parent of FunctionInvoker, it determines the main class by calling FunctionClassUtils.getStartClass(). There, we actually try to find out the main class to bootstrap the application. There are several ways to specify the main class. one of them is manifest.mf as you specified. Others are like mentioning system property.
So to answer your question, it is optional. you can use other methods as well. Look at this code for more details.
