AWS deployment scripts for Cadasta platform v1

There are three steps to this, accessible via the make-base-ami, create-deployment and deploy scripts in the scripts directory. However, it is also possible to use the same Ansible playbooks used for setup on AWS in Vagrant for debugging purposes. See the section Using Vagrant below.

Generating AMIs

An Ansible playbook driven by the make-base-ami script is used to set up the base "fixed" parts of the installation (i.e. operating system package installation, etc.), using an EC2 instance to generate an Amazon Machine Image for later deployment.

The rationale for this is that there are a lot of operating system dependencies that need to be installed, and these are likely to change far less frequently than the platform code itself. Breaking the deployment into two steps (OS package installation and project code installation and configuration) means that the most frequent actions should be relatively quick.

The AMIs generated by this process are registered in a machine-images.csv file since they are AWS region-specific. The easiest way to do a deployment in a new region is simply to copy the deployment AMI from an existing region using the AWS console or command line and then to add an appropriate line to the machine-images.csv file.

The make-base-ami script takes the following parameters:

1. The name of an AWS configuration profile to use for accessing credentials to connect to AWS. (Set one of these up using the aws configure command.)

2. The path to a private key file used for connecting to the sandbox EC2 instance used for generating the AMI. (You'll need to use the cadasta-utility key pair for this. Just ask me [Ian] and I can give it to you. If I've left or been eaten by a grue, just destroy and recreate the cadasta-utility key pair and save the PEM file somewhere.)

So, if you have an AWS profile called cadasta that has permissions to manipulate AWS entities belonging to the Cadasta account, you can create a fresh base AMI like this:

./scripts/make-base-ami cadasta ~/.ssh/cadasta-utility.pem

The base AMI is built from the standard Ubuntu 14.04 LTS AMI for the region being used and contains all of the operating system and "external" software packages needed to support the Cadasta platform code. The base AMI should not need to be changed for code changes to the Cadasta platform unless package dependencies change.

Creating a deployment

The create-deployment script is a quick and simple thing to generate a configuration file for a new deployment. These files are JSON and live in the deployments directory.

When you run create-deployment, you'll need to provide:

• A unique alphanumeric deployment name.
• An endpoint URL for the platform front page (by default this is foo.cadasta.org for a deployment foo).
• An endpoint URL for the ONA instance (by default this is foo-survey.cadasta.org for a deployment foo).
• An AWS EC2 instance type to use for running all the plaform processes.
• An AWS RDS instance type to use for running the Postgres database.

There are some other things you can change in the deployment file (notably the amount of storage allocated for the RDS instance, which defaults to 10 Gb), but most of the defaults should be good.

Deploying

Once you've created a deployment with create-deployment, you can deploy it to AWS using the deploy script, which you invoke with an AWS profile name, a path to an SSH key file and a deployment name, for example:

./scripts/deploy cadasta ~/.ssh/cadasta-utility.pem uat

The deploy script works in two stages:

1. First, it uses AWS CloudFormation to set up all the AWS resources needed (EC2 instance, RDS instance, S3 bucket, networking infrastructure). For a deployment foo, the CloudFormation stack that's created is called foo-stack. The deploy script will not allow you to overwrite an existing stack of the same name! If you want to do a fresh deployment, delete the stack from the AWS CloudFormation console. If you want to do a redeployment, use the redeploy script (not yet written).

2. The EC2 instance created as part of the CloudFormation stack is provisioned using an Ansible playbook that installs all the platform-specific code, sets up database infrastructure, and sets up an Apache+nginx configuration suitable for serving both the main platform and ONA from the same EC2 instance.

This all takes a little while, but once the deployment process is complete, you can look in the JSON deployment file for your deployment to find the public IP address of the EC2 instance, and can then set up DNS entries to point from (for example) foo.cadasta.org and foo-survey.cadasta.org to that IP address. (This will be automated soon.)

AWS prerequisites

The AMI setup steps make use of some pre-existing AWS entities I defined for utility purposes. If these get deleted by accident, you'll need to recreate them to be able to use these scripts:

• A VPC subnet called ami-builders on the default VPC for the Cadasta AWS account. Doesn't matter what CIDR (I used 172.31.64.0/20).
• A VPC security group called cadasta-utility with an inbound rule permitting SSH connections.
• A key pair called cadasta-utility (you'll need the PEM file for this).

Using Vagrant

As well as making AMIs and deploying to an AWS EC2 instance, you can also run all the Ansible provisioning steps within Vagrant, which is handy for debugging.

To bring up a VM provisioned with the base image, go to playbooks/make-base-ami and do vagrant up --provision. Eventually, you'll end up with a running VM containing all the base prerequisites for the Cadasta platform. You can save this as a Vagrant box for use later by doing

vagrant package --output /big/cadasta/cadasta-deploy.box
vagrant box add --name cadasta-base /big/cadasta/cadasta-deploy.box

Once you've done this, you can test the deployment playbook in playbooks/deploy. First do vagrant up --no-provision to get the VM running, then do the following to allow the VM access to your local Postgres server (since we're not going to run Postgres on the VM, you need a Postgres server locally):

vagrant ssh -- -R127.0.0.1:5432:/var/run/postgresql/.s.PGSQL.5432

Leave that SSH session active, and you can now do a vagrant provision.

There's some URL rewriting trickery in the nginx setup to make the main platform site appear at http://localhost:7000/ once everything is up and running.