kayako/drone-nomad repository overview

⁠drone-nomad

A Drone plugin to facilitate Nomad job deployment. This is an experiment, do not use it for anything you consider important.

⁠Components

The plugin relies on a Lambda function (see ./homeless/lambda_handler.py) to proxy calls to Nomad API.

It can also make changes in the jobspec before triggering the deployment so it is possible to have a partial job specification in git repository and rest of the information in DynamoDB.

⁠Partial Job Specification

To work with partial job specifications the plugin tries to fetch the delta from DynamoDb table.

The DynamoDb table must have a primary key on (job, environment) where job is the Job ID and environment is the target environment which will receive the delta. The patch is expected to be on attribute overrides.

Overrides are written in a specific format which provides control over list of objects and can target objects based on conditions. Generally the delta is applied as recursive dictionary merge but two special formats can be used to control merge behaviour:

• Attribute.*: Apply the patch on every element in the list
• @cond(attr [=|!=] val): Apply patch only to the element which satisfies the condition. Only = and != operators are supported.

Given a JSON object:

{
    "Name": "user",
    "Projects": [
        {
            "Name": "drone-nomad",
            "Language": "python"
        },
        {
            "Name": "caddy",
            "Language": "go"
        }
    ]
}

Following override will add a new attribute Owner to every project:

{
    "Projects.*": {
        "Owner": "user"
    }
}

And following attribute will add the same attribute but only to the project with name drone-nomad

{
    "Projects.*": {
        "@cond(Name = drone-nomad)": {
            "Owner": "user"
        }
    }
}

⁠Revision Tracking

Some tasks may require information about their own or some other task's active revision. The plugin automatically tries to propagate the active revision information in two ways:

1. By updating REVISION meta variable on each updated task
2. By putting the latest revision in Consul KV under path prefix _config/services/<job_name>/<group_name>/<task_name>/active_tag for each updated task

⁠Plugin Configuration

Following environment variables can be used to configure the plugin:

⁠Example

pipeline:
  deploy:
    image: kayako/drone-nomad
    ci_role: ci-server
    dynamodb_table: drone_nomad_overrides
    lambda_func: DeployFunc
    region: us-east-1
    secrets: [ account_number_production, account_number_staging, account_number_develop ]

Trigger a deployment for this pipeline using drone CLI or github deployment API with remaining parameters:

# with drone cli
drone deploy --param 'container_tag=abcd' \
             --param 'dc=nvirginia:pod_1' \
             --param 'only_plan=true' \
             --param 'target_job=project' \
             --param 'target_task=task_name' \
             project 1 staging

# with github deployment API
curl -s -X POST -H 'Accept: application/vnd.github.ant-man-preview+json' \
    -d '{
      "ref": "staging",
      "environment": "staging",
      "description": "Deploying to staging using github API",
      "payload": "{\"container_tag\":\"abcd\",\"dc\":\"nvirginia:pod_1\",\"only_plan\":true,\"target_job\":\"project\",\"target_task\":\"task_name\"}"
    }' https://api.github.com/repos/octocat/octocat/deployments