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Java docker container with embedded or standalone tomcat?

Currently I have a tomcat webserver that is hosting multiple .war microservices (if it matters: spring-boot applications). When upgrading an application, I'm using the tomcat parallel deployment feature by adding a myapp##005.war, myapp##006.war, etc to have zero downtime deployment.
I'd like to dockerize the applications. But what suits best for java applications webservice applications?
Is it better to package a war file directly into the container, so that each redeployment would require a new docker container? Or should the tomcat run as a container without applications, and mount the war files from a shared host system folder (and thus provide redeployment without dockerimage recreation)?
I could think of the following 3 possibilities:
run each war file as a jar instead with embedded tomcat, each as own docker container? Then each app is decoupled, but I cannot use the parallel deployment feature anymore as I have to kill the jar before another can take its place. If this would be the best approach, then the question is: how could I get zero downtime deployment though with docker containers?
run each war file as standalone tomcat, each as own docker container? Each app then would be decoupled and could also make use of parallel deployment. But I'd have to launch an explicit tomcat webserver for each application in every docker container here, which might have negative impacts on the host system performance?
run a standalone tomcat as docker, and place all *.war files in a shared folder for deployment? Here I could still use the parallel deployment feature. But isn't this against the idea of docker? Shouldn't the war application be packed inside the container? Performance and resource requirements would probably best here, as this requires only a single tomcat.
Which approach suits for java miroservices?

Deployment using a single Jar for each Docker container is definitely the best approach. As you mentioned, low coupling is something you want from a microservice. Rolling deployments/canary releases etc can easily be done with container orchestration tools like Docker Swarm and Kubernetes.
If you want to play around with these concepts, Docker Swarm is fairly easy:
In your compose file:
version: '3'
services:
example:
build: .
image: example-image:1.0
ports:
- 8080:8080
networks:
- mynet
deploy:
replicas: 6
update_config:
parallelism: 2
delay: 10s
restart_policy:
condition: on-failure
The deploy part in you compose file is all Docker Swarm needs.
replicas tells you that 6 instances of your application will be deployed in the swarm
parallelism will tell you that 2 instances will be updated at the same time (instead of 6)
Between updates there will be a 10 second grace period (delay)
Lot's of other things you can do. Take a look at the documentation.
If you update your service, there will be no downtime, as Docker Swarm will serve all requests through the 4 containers that will still be running.
I don't recommend Docker Swarm in a production environment, but it's a great way to play around with the concepts of container orchestration.
Kubernetes learning curve is quite steep. If you're in the cloud, AWS for example, services like EKS, Fargate etc can take a lot of that complexity away for you.

How to deploy both Spring boot and angular project separately on apache tomcat

I have created Spring boot application and Angular project (Angular 1) separately. In my local i am using npm to server the client app and it calls my back end app services. I am using Embedded tomcat in spring boot application.
Now i want to host my application in server. How do i do that?
Can i have embedded tomcat and build as jar or should i have to install standalone tomcat in the server and deploy my application as war?
How to configure my client code for example, in godaddy i have given ip xx.xx.xx.xx to www.xyz.com. The ip address is my production cloud server. How to redirect to angular application and that application calls server exposed apis.
I cannot have single application that has client code. I should do with two different application only. Please help me deploying this in best way. If embedded tomcat doesnt help then i can install standalone tomcat in server and and build my app as war and deploy it.

The current best practice would be to embed the servlet container (Tomcat, Jetty, other) into the artifact and build a fat JAR. The main advantage is a simplified deployment process: it's enough to push the far JAR into environment and execute it. Unlike the usual servlet container with WAR deployment model the embedded approach doesn't have to deal with additional configuration layers e.g. thread pools or data sources shared between different WARs.
One example of how to build a far JAR with embedded servlet container is spring-boot-starter-web dependency with spring-boot-maven-plugin:repackage goal. In this setup to build a fat JAR it's enough to run mvn clean package repackage.
If you are developing locally your web client code most likely will face issues with the same-origin policy. You most likely will need a CORS filter, however it's provided by Tomcat.

How do I run a spark application on a tomcat server

After a day of googling, I'm still lost.
I've created a Spark web-application that runs on the embedded Jetty server, but I want to run my web-application on a Tomcat server.
I'm using Maven to build my web-application and can't find any good resources on using Spark on Tomcat with Maven.
How can I create a Maven project with Spark and run it on a Tomcat server?

You'll need to implement EmbeddedServer interface in order to do it. Currently, it only supports Jetty by default. So, fork it and submit a PR to the author.

how to configure Embedded Tomcat virtual host for Spring Boot Application?

i have a multiple domains on my centos vps (domains running on apache http server via virtual host configurations). and also same vps, i want to add my new domain but that domain will route my spring boot application (application is a jar file also inside embedded tomcat ). i couldn't find any configuration for embedded tomcat specific domains and ports.
standalone Tomcat i can make configuration via server.xml file like this image
also this short tutorial shows configuration for stadalone tomcat Tomcat Virtual Host Configuration
But how can i do that configuration for embedded Tomcat ? Any suggestion ?

With Spring Boot embedded Tomcat, you are hosting only one application per servlet container. So I don't believe that Tomcat's concept of Virtual Hosts make sense at all.
If you have to host your app on shared Tomcat instance, just build WAR without embedded container.

It depends. 2 ways to deploy your project.jar as you want to :
First way : You can use the "apache web server" and his own "mod_proxy" in order to serve as many Spring webapps you want to, each on a specific port configured with "php-fpm" and with a proxy defined to route requests from/to your namebased VirtualHost configuration.
Nowadays, with Spring Boot 2.5, all you have to do is to set the property server.port in your application.properties file, and use it accordingly with mod_proxy directives.
If you are using profile, you can either set one port to dev or prod or test or whatever properties file you need.
Another way to proceed : you can use the apache web server "mod_jk" bridge module to configure multiple load-balancers for your Virtualhosts too.
Choose your path, young Jedi ;)
This response is certainly not for the OP, 7 years later, but for other people whom are using any web search engine like Google. They will come here and see "something is impossible". It is not true.

Using JavaMelody on a regular (non webApp) JVM

My system is divided to 2 or 3 servers architecture, and only one server has a webApp
Since we use javaMelody to monitor the webApp server, is there a way to use on a regular, no-
webApp JVM, and if so, how can we access the data

I would say include your application into a webapp (a war file for example) then deploy it in a server like Tomcat or Jetty. By the way, Tomcat or Jetty can be embedded.
Otherwise, there is currently no way to do this.