Workflows:

This article focuses on some of the best practices for working with workflows that deploy services.  The tenets are:

1.       Reusability – many of the activity from the library of activities for one workflow can and will be reused for another. Very few workflows might have differences in doing tasks that were not covered by the global collection of activities. There should not be any difference between an activity that appears in bootstrapping and its invocation during redeployment/ rehosting in the new environment. Only the parameter values will change for this.

2.       Dependencies – many of the dependencies will be implicit as they originate from system components and services information. A workflow might additionally specify dependencies via the standard way in which workflows indicate dependencies. These will be on a case-by-case basis for tenants since it adds overhead to other services, many of whom are standalone. Implicit dependencies can be articulated in the format specified by the involved components.

3.       Splitting – Workflows are written for on-demand invocation from the web interface or by the system, so there might be more than one for a specific deployment scenario. It is best to include both the bootstrapping and the redeploy in the main workflow for the specific scenario, but they will be mutually exclusive during their respective phases and remain idempotent.

4.       Idempotency – All workflow steps and activities should be idempotent. If there are conditionals involved, they must be part of activities. The signaling and receiving notifications of dependent workflows if any must be specifically called out.

5.       Bootstrapping – This phase is common to many services and usually requires at least a cluster/set of servers to be made ready but there might be activities that require the service stamp to be deployed even if it is not configured along with necessary activities to do one time preparation such as getting secrets. Until the VIPs are ready, the redeployment cannot be kicked off.  Bootstrapping might involve preparations for both primary and secondary where applicable.

6.       Redeployment or rehosting – This phase involves configuration since the bootstrapping is usually for a stamp and this stage converts it into a deployment for a service. Since it involves reconfiguration, it can be for both primary and secondary and typically done inside the new cloud. It is best to parameterize as much as possible.

7.       Naming convention – Though workflows can have any names inside the package that the owning teams upload, it is best to follow a convention for the specific scenario of one workflow calling another. Standalone single workflows do not have this problem. Even in the case when there are many workflows, a prefix/suffix might be helpful. This applies to both work workflows and activities.

8.       System workflow – Requiring separate workflows for bootstrap and redeployment via a system defined workflow to allow system to inject system defined activities between bootstrap and redeploy is a nice-to-have but the less intrusion into service deployment the better. This calls on the service to do their own tracking via passing parameter values between workflows and activities. A standard need not be specified for this, and it can be left to the discretion of the services.

The above list is not intended to be complete but focuses on the strengths of those that have worked well