Introduce jib

[KengoTODA]

https://cloud.google.com/run/docs/tips/java

remaining TODO:

• remove nginx.conf
• remove docker-compose.yml
• deploy to heroku via jib command
• remove system.properties and Procfile
• update README.md

[KengoTODA]

before (920edd0 with jlink):

2022-05-25 23:40:17.218 INFO 1 --- [ main] j.s.javadocky.JavadockyApplication : Started JavadockyApplication in 2.62 seconds (JVM running for 4.175)

the size of the container is 122MB according to docker image ls.

after (5570749 with jib):

2022-05-25 23:43:37.354 INFO 1 --- [ main] j.s.javadocky.JavadockyApplication : Started JavadockyApplication in 2.228 seconds (JVM running for 7.404)

the size of the container is 384MB according to docker image ls.

try the jib with AppCDS later.

[KengoTODA]

docker with AppCDS (2b0569e)

2022-05-26 05:04:32.577 INFO 1 --- [ main] j.s.javadocky.JavadockyApplication : Started JavadockyApplication in 1.865 seconds (JVM running for 2.858)

the size of the container is 442MB according to docker image ls.

[KengoTODA]

jlink and AppCDS (902c5a0)

2022-05-26 06:05:53.685 INFO 1 --- [ main] j.s.javadocky.JavadockyApplication : Started JavadockyApplication in 1.438 seconds (JVM running for 2.443)

The size of the container is 164MB according to docker image ls. But when we launch the container, there is a warning reported: "OpenJDK 64-Bit Server VM warning: Sharing is only supported for boot loader classes because bootstrap classpath has been appended"