Intro

Application server is a server type that will let us run applications inside docker containers.

Unused port is automaticaly assigned to each container to route HTTP traffic.

Nginx is listening on ports 80 and 443.

In the example below, organisation has 6 apps and 1 appserver instance

app server instance

Design decisions

Docker

One appserver instance runs multiple apps, each app has its own docker container

Multiple appserver instances inside same organisation will run, the exact same set of apps

Application state

Each application is stateless. We consider that you must NOT use your application server's disk to store app state

Instead, you can use databases, file servers and services like AWS S3

Please check guides on mongodb and mysql to understand how cmdcenter manages databases

Stateless approcoah also helps to horizontaly scale your apps, by adding or removing appserver instances at will.

Create new instance

Assuming that:

cmdcenter.py create instance --pubip aaa.aaa.aaa.aaa --privip bbb.bbb.bbb.bbb --desc "note" appserver --org myorg

Running this command will add new entry into instances.json file in myorg/servers/appserver folder

Instances file

instances.json contains list of every appserver instance available in current organisation


[
    {
        "publicIP": "aaa.aaa.aaa.aaa", 
        "description": "note", 
        "role": "default", 
        "name": "appserver_o6hbh", 
        "privateIP": "bbb.bbb.bbb.bbb"
    }
]

each instance has following fields:

Field Meaning
publicIP Public IP address of this server
privateIP IP address of this server on the private network
name unique instance name
role always default
description optional text to describe this instance

Credentials file

Instances are automatically configured to use sshkeys as ssh auth mecanism.

However, users still require passwords to perform system administrator operations

Assuming that your organisation name is: myorg, username and password of sudo capable user is stored in myorg/servers/appserver/access.ini file:

[sudouser]
username=randomsudousername
password=RaNd0mP@5SW0rD

Apply configuration (1/2)

First configuration step connects as root and creates sudo capable user using access.ini configuration.

Usualy you only run this command once, or/and everytime you add new appserver instance to your organisation.

cmdcenter.py setup server --step 1 appserver --org myorg

Apply configuration (2/2)

Second configuration step connects as sudo capable user and installs minimum viable software:

It also copies configutation files

cmdcenter.py setup server --step 2 appserver --org myorg

Show servers

You can use following command to show servers in your organisation

cmdcenter.py show servers --org myorg

Here is a list of server groups i found in "myorg" organisation:

appserver
  appserver_5davo :: default :: appserver 01
    publicIP  : aaa.aaa.aaa.aaa
    privateIP : bbb.bbb.bbb.bbb

mysql5server
  mysql5server_3mqdG :: default :: main mysql5server
    publicIP  : ccc.ccc.ccc.ccc
    privateIP : ddd.ddd.ddd.ddd

mongo3server
  mongo3server_lEdlj :: default :: main mongo3server
    publicIP  : eee.eee.eee.eee
    privateIP : fff.fff.fff.fff

SSH

You can SSH to any server appserver instance.

Here is a command to lisy your SSH options for myorg organisation

cmdcenter.py ssh appserver --org myorg

USAGE: cmdcenter.py ssh SERVERGROUP USERNAME HOSTNAME

Here is a list of servers you can SSH:

  cmdcenter.py ssh appserver randomsudousername aaa.aaa.aaa.aaa --org myorg
  cmdcenter.py ssh appserver root aaa.aaa.aaa.aaa --org myorg

  cmdcenter.py ssh mysql5server randomsudousername ccc.ccc.ccc.ccc --org myorg
  cmdcenter.py ssh mysql5server root ccc.ccc.ccc.ccc --org myorg

  cmdcenter.py ssh mongo3server randomsudousername eee.eee.eee.eee --org myorg
  cmdcenter.py ssh mongo3server root eee.eee.eee.eee --org myorg

Then, simply pick an instance and user to SSH

cmdcenter.py ssh appserver root aaa.aaa.aaa.aaa --org myorg

You do not need to enter passwords, these are automatically picked up from your access.ini config files in combination with ssh keys.