server/

FOREST continuous deployment pipeline

The scripts contained in this directory are used by AWS CodeDeploy and CodePipeline services to deploy FOREST to https://forest.informaticslab.co.uk. The appspec.yml contained in the top level directory of the repository tells CodeDeploy which scripts to run at which point in the deployment life cycle.

launch-config.sh

This script is not run directly but instead is manually copied and pasted into the user data section of a new launch configuration. Launch configuration user data sections are immutable after creation, so this is a very convenient piece of text to keep around.

appspec.yml

There are is one gotcha with this file, in the files section, source refers to the repository and destination refers to the directory on the EC2 instance that the CodeDeploy agent uses to clone the repository

files:
    source: /
    destination: /path/on/ec2/instance

There is very little documentation elsewhere on the internet at present to explain the true meaning and usage of that section

Health check error code

As bokeh apps return a 302 redirect code instead of 200 on navigation to /, the EC2 application load balancer target group health check has been modified to expect a 302 to signify a healthy FOREST instance

House keeping

FOREST uses a SQL database to power it's menu system. This database needs to be kept up to date with the latest contents of S3. To sync the database a cron job is installed when an EC2 instance is provisioned.

The cronjob runs a docker container, inside which a Python script runs to update the database. The container is run with the --rm flag to automatically remove the container when the task finishes. This prevents name conflicts that would arise if docker run --name forest-cron ... were repeatedly invoked.

Admittedly this periodic updating is not ideal but it is the simplest way to ensure consistency between the contents of our S3 buckets and the buttons in the menu system.