Creating a LAMP Stack
LAMP stacks contain a group of software consisting of:
Linux OS
Apache web server
mySQL Database
PHP
Templates
The following templates shows how an instance can be configured using a bash script to install Apache, mySQL, and PHP. The bash script is executed during the VM’s cloud-init phase.
Note: During the cloud-init phase, root executes any user-scripts.
> During the execution of the scripts, we will be ‘holding’ some of the packages to stop them being upgraded during the apt-get upgrade step. This is because the upgrade requires a user response for the packages. These can be upgraded by the user after VM configuration is complete by running the upgrade command.
Using OS::Heat::SoftwareConfig
The heat resource OS::Heat::SoftwareConfig has been used to define the user script.
OS::Heat::SoftwareConfig
heat_template_version: 2018-03-02
parameters:
key_name:
type: string
default: <key-pair-name>
description: Key Pair to use in order to SSH into the instance.
image_id:
type: string
default: <image-id>
description: The image for the instance
flavor_id:
type: string
default: <flavor-id>
description: The flavor for the instance
security_group_id:
type: string
default: <security-group-id>
resources:
test_script:
type: OS::Heat::SoftwareConfig
properties:
group: ungrouped
config: |
#!/bin/bash -v
apt-get update
apt-mark hold libpam-krb5 libpam-modules libpam-modules-bin libpam-runtime libpam-systemd libpam0g
apt-get -y upgrade
apt-mark unhold libpam-krb5 libpam-modules libpam-modules-bin libpam-runtime libpam-systemd libpam0g
# mysql-server is installed at this stage (can install after VM creation)
apt-get install -y apache2 php libapache2-mod-php php-mysql php-gd mysql-server
test_VM:
type: OS::Nova::Server
properties:
image: {get_param: image_id}
flavor: {get_param: flavor_id}
key_name: {get_param: key_name}
networks:
- network: Internal
security_groups:
- {get_param: security_group_id}
user_data_format: SOFTWARE_CONFIG
user_data: {get_resource: test_script}
Using OS::Nova::Server
The bash script can be placed alternatively in the user_data property of the OS::Nova::Server resource.
heat_template_version: <template-version>
parameters:
<define parameters>
resources:
VM:
type: OS::Nova::Server
properties:
image: {get_param: image_id}
flavor: {get_param: flavor_id}
key_name: {get_param: key_name}
networks:
- network: <network-name>
security_groups:
- {get_param: security_group_id}
user_data: |
#!/bin/bash -v
apt-get update
apt-mark hold libpam-krb5 libpam-modules libpam-modules-bin libpam-runtime libpam-systemd libpam0g
apt-get -y upgrade
apt-mark unhold libpam-krb5 libpam-modules libpam-modules-bin libpam-runtime libpam-systemd libpam0g
# mysql-server is installed at this stage (can install after VM creation)
apt-get install -y apache2 php libapache2-mod-php php-mysql php-gd mysql-server
When a Bash Script becomes too long or complex, the get_file function can be used to retrieve and execute the bash script:
heat_template_version: <template-version>
parameters:
<define parameters>
resources:
VM:
type: OS::Nova::Server
properties:
image: {get_param: image_id}
flavor: {get_param: flavor_id}
key_name: {get_param: key_name}
networks:
- network: <network-name>
security_groups:
- {get_param: security_group_id}
user_data_format: RAW
user_data: {get_file: bash-script.sh}
- > Note: user_data_format is required for defining how the user_data should be formatted for the server.
without this parameter when defining a bash script this way, cloud init returns errors in the log and cannot run the script.
The function str_replace can be used in order to set variable values in the bash script based on parameters or resources in the stack.
Example from Openstack: https://docs.openstack.org/heat/rocky/template_guide/software_deployment.html
heat_template_version: <template-version>
parameters:
<define parameters>
resources:
VM:
type: OS::Nova::Server
properties:
image: {get_param: image_id}
flavor: {get_param: flavor_id}
key_name: {get_param: key_name}
networks:
- network: <network-name>
security_groups:
- {get_param: security_group_id}
user_data:
str_replace:
template: |
#!/bin/bash
# ...
params:
$FOO: {get_param: foo}
- > Note: If a stack-update is performed and any changes have been made to the stack update,
then the server will be deleted and replaced.
> If you are using the above bash scripts to install mysql-server as well as the other components of the stack, it is best to also run mysql_secure_installation as well. To automate mysql_secure_installation steps, please see the page Installing and setting up MySQL database in a Stack
References:
https://docs.openstack.org/heat/rocky/template_guide/software_deployment.html