So jenkins can execute build jobs that require docker and php.
note that you should use this image by sharing the host's docker daemon, for docker-in-docker allegedly is a bad practice, with the option
for more info: http://jpetazzo.github.io/2015/09/03/do-not-use-docker-in-docker-for-ci/
In addition, you can set up default configuration for jenkins, aws connection and github connection, by (1) uncommenting the corresponding parts in dockerfile and (2) putting your configuration/ssh_key files in the specified directory.
Aws configuration files are like, for example
# config/.aws/config [default] output = json region = ap-northeast-1 [profile xxx] output = json region = ap-northeast-1 # config/.aws/credentials [default] aws_access_key_id = xxx aws_secret_access_key = xxx [xxx] aws_access_key_id = xxx aws_secret_access_key = xxx