Application Scripts

CloudShell Colony supports running custom scripts as part of your application's lifecycle. There are 3 types of configurations that colony support – initialization, start and healthcheck. 

Reference to an application script should be added to your application YAML file under the Configuration section. 

configuration:
  initialization:
    script: acme-dashboard-install.sh
  start:
    script: my-script.sh

  healthcheck:
    wait_for_ports: ALL
    timeout: 180

You can reference three types of shell scripts that are executed in different stages of the application deployment and configuration process:

initialization:

configuration:
  initialization:
    script: init.sh

start:

configuration:
  start:
    script: start.sh

  start:

    command: >
      dotnet /home/ubuntu/web/bin/Debug/netcoreapp2.0/publish/DSLibrary.dll

healthcheck:

Healthcheck is a mandatory process that can be implemented in two ways - using the out-of-the-box healtcheck and/or a custom script. The out-of-the-box method is specified using the wait-for-ports element. The flavors can be used together. 

configuration:
  healthcheck:
    wait_for_ports: ALL
    timeout: 100

configuration:
  healthcheck:
    script: my-custom-healthcheck.sh
    timeout: 1000

  
#!/bin/bash

ip=$1
hostname=$ip:$PORT

for (( ; ; ))
do
    sleep 1
    if [[ $(wget -q --spider -T1 -t1 ${hostname} && echo $?) == "0" ]] ; then
        echo 'connected to' ${hostname}
        exit 0
    else
        echo 'cannot connect to' ${hostname}
    fi
done
exit 1

healthcheck:
  script: my-healtcheck-script.sh
  timeout: 1001

All script file references should be placed in the space's blueprint repository, right next to the application's YAML file. For example:

As an example, let's review the WordPress application (Wordpress.yaml file) in CloudShell Colony's sample blueprint repository. The application uses a clean Ubuntu Linux image. Therefore, to install WordPress we need to run additional scripts after the instance is up. The scripts are included in the /wordpress folder, and we declare them in the wordpress.yaml file as follows:

configuration:
  initialization:
    script: wordpress.sh
  start:
    script: wordpress-start.sh;

The wordpress.yaml file includes the following scripts:

• wordpress.sh: This is an initialization script, which takes the clean Ubuntu installation and installs everything needed to run WordPress. The script consists of the following steps:
  1. Update the Linux package manager.
  2. Install Apache web server.
  3. Install PHP and the required PHP modules in order to run WordPress.
  4. Download the latest version of Wordpress and install it.
  5. Configure the database access by modifying the wp-config.php files.
• wordpress-start.sh: This script runs only after the Initialization script completes. It usually starts or restarts an application process. In this example, this script restarts the Apache Web Server.

NOTE: CloudShell Colony does not expect the Start script to complete. It is expecting that the Start script might be the running application process.

Best Practices for Writing Application Scripts

To support you in creating reusable applications and to provide you with a self-service experience, CloudShell Colony includes some important features such as Local DNS service and user input parameters. To learn more about these features, see Working with Parameters and Best Practices for Writing Application Scripts.