Blue/Green Deployment

class shpkpr.deployment.BlueGreenDeployment(marathon_client, marathon_lb_client, timeout, app_definitions, **kw)

BluegreenDeployment implements a blue-green deployment strategy for web-facing applications on Marathon.

It builds on the primitives provided by Marathon to provide zero-downtime deployments for HTTP services exposed to the web via Marathon-LB.

execute(force=False)

Execute a bluegreen deployment.

The mechanics of a bluegreen deploy mean that we have to deploy each application in turn (instead of the all-at-once approach used for standard deployments).

NOTE: We could maybe be smarter here in future e.g. perhaps don’t tear down old stacks until _all_ new stacks are running so we can roll back partially successful invocations.

Blue/Green default template

shpkpr includes a set of default templates which are used when a custom template is not supplied by the user at runtime. The default template used for blue/green deployments is included below for reference purposes.

See also

Standard default template

Default template for standard deployments (from which this one extends).

{#
    Built-In Blue-Green deployment Template

    This file contains the default template used by shpkpr when performing a
    blue-green deployment if no custom template is provided. The goal of
    this template is to provide a comprehensive application definition that
    works in a wide variety of usecases.

    This template contains only those sections (blocks) which need to be
    changed/overridden from the standard deployment template.

    This template makes some assumptions about your application (in addition to
    those made by the standard template from which this extends):

    - It exposes exactly one TCP port.
    - It has a domain/hostname.
    - It exposes a healthcheck endpoint.

    Several values are required to deploy an application using this template (in
    addition to those required by the standard template):

    - DOCKER_EXPOSED_PORT: Port number within the container that should be
      exposed to the host.
    - MARATHON_HEALTH_CHECK_PATH: The path of an HTTP endpoint exposed by the
      application for healthcheck purposes.
    - HAPROXY_VHOST: The hostname(s) that that will be proxied to the
      application (comma separated if multiple).
#}
{% extends "marathon/default/standard.json.tmpl" %}


{% block docker_port_mappings %}
{# Applications using blue-green deployment _must_ expose a port. #}
"portMappings": [
    {
        "containerPort": {{DOCKER_EXPOSED_PORT|require_int}},
        "hostPort": 0,
        "protocol": "tcp"
    }
],
{% endblock %}


{% block healthchecks %}
{# Applications using blue-green deployment _must_ define a healthcheck. #}
"healthChecks": [
    {
        "path": "{{MARATHON_HEALTH_CHECK_PATH}}",
        "protocol": "{{MARATHON_HEALTH_CHECK_PROTOCOL|default("MESOS_HTTP")}}",
        "portIndex": 0,
        "gracePeriodSeconds": {{MARATHON_HEALTH_CHECK_GRACE_PERIOD_SECONDS|default(300)|require_int(min=0)}},
        "intervalSeconds": {{MARATHON_HEALTH_CHECK_INTERVAL_SECONDS|default(10)|require_int(min=0)}},
        "timeoutSeconds": {{MARATHON_HEALTH_CHECK_TIMEOUT_SECONDS|default(5)|require_int(min=0)}},
        "maxConsecutiveFailures": {{MARATHON_HEALTH_CHECK_MAX_CONSECUTIVE_FAILURES|default(3)|require_int(min=0)}}
    }
],
{% endblock %}


{% block labels %}
{#
    Blue-Green deployments require a number of custom labels to be set at deploy
    time. The required labels are configured below.

    For full details of all available configuration options that can be set with
    labels see https://github.com/mesosphere/marathon-lb/blob/master/Longhelp.md
#}
"labels": {
    {#
        Deployment group to which this app belongs. Used to identify
        applications that should be considered when performing a blue-green
        deploy.
    #}
    "HAPROXY_DEPLOYMENT_GROUP": "{{HAPROXY_DEPLOYMENT_GROUP|default(MARATHON_APP_ID)|slugify}}",
    {#
        HAProxy group per service. This allows you to assign the application to
        either the `internal` or `external` group as appropriate.
    #}
    "HAPROXY_GROUP": "{{HAPROXY_GROUP|default("internal")}}",
    {#
        The hostname(s) that that will be proxied to the application (comma
        separated if multiple).
    #}
    "HAPROXY_0_VHOST": "{{HAPROXY_VHOST}}"
    {# Allow setting arbitrary labels as in the parent template. #}
    {% for key, value in _all_env|filter_items("LABEL_", strip_prefix=True) %}
        {% if loop.first %},{% endif %}
        "{{key}}": "{{value}}"{% if not loop.last %},{% endif %}
    {% endfor %}
},
{% endblock %}