Every AWS EC2 instance will have a *Group* tag that corresponds to a group of machines that need to be deployed/targetted to as a group of servers.
Every AWS EC2 instance will have a *Group* tag that corresponds to a group of
machines that need to be deployed/targetted to as a group of servers.
**Example:**
*`Group`: `edxapp_stage`
*`Group`: `edxapp_prod`
*`Group`: `edxapp_some_other_environment`
Additional tags can be added to AWS resources in the stack but they should not be made necessary deployment or configuration.
Additional tags can be added to AWS resources in the stack but they should not
be made necessary deployment or configuration.
## Ansible
Ansible is a configuration management tool that edX is evaluating to replace the puppet environment
that is currently being used for edX servers.
Ansible is a configuration management tool that edX is evaluating to replace
the puppet environment that is currently being used for edX servers.
http://ansible.cc/docs
_Note: Because the directory structure changes in v1.2 we are using the dev version instead of the official v1.1 release._
_Note: Because the directory structure changes in v1.2 we are using the dev
version instead of the official v1.1 release._
* __Hosts__ - The ec2.py inventory script generates an inventory file where hosts are assigned to groups. Individual hosts can be targeted by the "Name" tag or the instance ID. I don't think there will be a reason to set host specific variables.
* __Groups__ - A Group name is an identifier that corresponds to a group of roles plus an identifier for the environment. Example: _edxapp_stage_, _edxapp_prod_, _xserver_stage_, etc. For the purpose of targetting servers for deployment groups are created automatically by the `ec2.py` inventory sript since these group names will map to the _Group_ AWS tag.
* __Roles__ - A role will map to a single function/service that runs on server.
* __Hosts__ - The ec2.py inventory script generates an inventory file where
hosts are assigned to groups. Individual hosts can be targeted by the "Name"
tag or the instance ID. I don't think there will be a reason to set host
specific variables.
* __Groups__ - A Group name is an identifier that corresponds to a group of
roles plus an identifier for the environment. Example: *edxapp_stage*,
*edxapp_prod*, *xserver_stage*, etc. For the purpose of targetting servers
for deployment groups are created automatically by the `ec2.py` inventory
sript since these group names will map to the _Group_ AWS tag.
* __Roles__ - A role will map to a single function/service that runs on
server.
## Organization
...
...
@@ -32,52 +43,62 @@ The directory structure should follow Ansible best practices.
http://ansible.cc/docs/bestpractices.html
* At the top level there are yml files for every group where a group name is an identifier that corresponds to a set of roles plus an environment.
* At the top level there are yml files for every group where a group name is an
identifier that corresponds to a set of roles plus an environment.
* The standard environments are _stage_ and _production_.
* Additional environments can be named as well, below an example is given called _custom_.
* Additional environments can be named as well, below an example is given
called _custom_.
### Variables
* The ansible.cfg that is checked into the playbook directory has hash merging turned on, this allows
us to to merge secure and custom data into the default variable definitions for every role.
* For example, `vars/lms_vars.yml` (variables needed for the lms role) sets the `env_config` which has keys that can be overridden by `vars/secure/edxapp_stage_vars.yml` for setting passwords and hostnames.
* If needed, additional configuration can be layered, in the example `vars/secure/custom_vars.yml` changes some paramters that are set in `vars/secure/edxapp_stage_vars.yml`.
* The ansible.cfg that is checked into the playbook directory has hash merging
turned on, this allows us to to merge secure and custom data into the default
variable definitions for every role.
* For example, `vars/lms_vars.yml` (variables needed for the lms role) sets the
`env_config` which has keys that can be overridden by
`vars/secure/edxapp_stage_vars.yml` for setting passwords and hostnames.
* If needed, additional configuration can be layered, in the example
`vars/secure/custom_vars.yml` changes some paramters that are set in
`vars/secure/edxapp_stage_vars.yml`.
_The secure/ directories are checked into the public repo for now as an example, these will need to be moved to a private repo or maintained outside of github_
__TODO__: _The secure/ directories are checked into the public repo for now as an
example, these will need to be moved to a private repo or maintained outside of
github._
### Users and Groups
There are two classes of users, admins and environment users.
* The *admin_users* hash will be added to every server and will be put into a group that has admin bits.
* The *env_users* hash are the class of users that can be optionally included in one of the group-environment playbooks.
* The *admin_users* hash will be added to every server and will be put into a
group that has admin bits.
* The *env_users* hash are the class of users that can be optionally included
in one of the group-environment playbooks.
Example users are in the vars/secure directory:
Example users are in the `vars/secure` directory:
*`/vars/secure/edxapp_stage_users.yml` <-- *env_users* for the edxapp staging environment
*`/vars/secure/users.yml` <-- *admin_users* will be realized on every server
*[*env_users* for staging environment](/vars/secure/edxapp_stage_users.yml)
*[*admin_users* will be realized on every server](/vars/secure/users.yml)
```
edxapp_prod.yml <-- [ example production environment playbook ]
edxapp_stage.yml <-- [ example stage environment playbook ]
edxapp_custom.yml <-- [ example custom environment playbook ]
├── files <-- [ edX cloudformation templates ]
│ └── examples <-- [ example cloudformation templates ]
├── group_vars <-- [ var files that correspond to ansible group names (mapped to AWS tags) ]
├── keys <-- [ public keys ]
├── roles <-- [ edX services ]
│ ├── common <-- [ tasks that are run for all roles ]
│ │ └── tasks
│ └── lms
│ ├── tasks <-- [ tasks that are run to setup an LMS ]
│ └── templates
└── vars <-- [ public variable definitions ]
└── secure <-- [ secure variables (example) ]
```
```
edxapp_prod.yml <-- example production environment playbook
edxapp_stage.yml <-- example stage environment playbook
edxapp_custom.yml <-- example custom environment playbook
├── files <-- edX cloudformation templates
│ └── examples <-- example cloudformation templates
├── group_vars <-- var files that correspond to ansible group names (mapped to AWS tags)
├── keys <-- public keys
├── roles <-- edX services
│ ├── common <-- tasks that are run for all roles
│ │ └── tasks
│ └── lms
│ ├── tasks <-- tasks that are run to setup an LMS
