Agent Phases in VSTS Deployment

VSTS (Visual Studio Team Services) continues to grow and change over time. It seems every few months I see some new features and changes, which are good and bad. Good in that usually things improve. Bad in that I get confused and lost at times, and sometimes have to re-acquaint myself with the system.

One of the changes I noticed recently was the Deployment phases, which come as Server and Agent phases. I won’t cover server here, but I wanted to make a quick note on Agent Phases because I think they’re handy and a nice packaging concept.


There are agents that run for VSTS to do work. I’ve written about how to download an agent so tasks run inside of your network (on a server or client).  This post will look at the other side, how do I control an agent from the release process.

Once I get a new release definition, I’ll see something like this:

2017-04-02 11_18_05-New Empty Definition 02-Apr - Visual Studio Team Services

This is a blank deployment definition. To the left I see the environment I’m working with, in this case, just the generic Environment 1 name. For each environment, I can set up tasks. On the right I have the Add Tasks button, but also the “Run on Agent” item. This is the container where I will add tasks.

I used to just add tasks with VSTS 2015 here, expecting that everything would run on an agent. VSTS has hosted agents that contain a set list of software, and also downloadable agents that you run on your servers or workstations. Things changed recently to include phases.


The phases are place of execution, which allow a series of tasks to be grouped together. VSTS and TFS 2017 give you two choices. We now have Agent or Server phases. The difference between these is that I can choose where items execute, on an agent or on the server (VSTS or TFS). In addition, I can set these to execute in parallel if need be.

If I click the down arrow next to the Add Tasks, I’ll get this dialog. This allows me to set up a process that can run on the VSTS server, or one that can run on the Agent.

2017-04-02 11_18_25-New Empty Definition 02-Apr - Visual Studio Team Services

I haven’t played with server phases, but when I add an agent phase, this gives me a section under which I add tasks. Note that when I click the “Agent phase” item, I get a new blade to the right. Note that the pool for these agents is the default.

2017-04-02 11_18_43-New Empty Definition 02-Apr - Visual Studio Team Services

This threw me early on because I have a separate pool of agents for mobile development. As I upgraded some deployment definitions, I couldn’t figure out why I didn’t have any agents available to execute my tasks. It turns out I needed to change the agent pool here.

There are options here, but I haven’t really played with parallelism or demands since I typically deploy to one system at a time.

Once I’ve selected an agent, I can click Add Tasks and then add a series of tasks to that agent. If you look below, I have added a couple tasks to each of the two agent phases. These will run one phase, then the other.

2017-04-02 11_19_47-New Empty Definition 02-Apr - Visual Studio Team Services

Each of these phases is independent, and as of the time I wrote this, there’s no way to copy a phase and duplicate it.

I’ve used this to upgrade my release definitions by adding new tasks, and then copying settings between one phase and the other. This is a manual, copy/paste operation, but I can easily see if I’ve duplicated everything by going back and forth quickly.

2017-04-02 16_32_43-ST Pipeline_Mobile - Visual Studio Team Services

Once I’m done, I can just click the “x” to the right of the agent phase and delete the entire phase. I have to confirm this action, and then I’ve removed a complete phase.

Right now I haven’t see any benefit outside of the upgrade scenario, but that’s useful. I will duplicate my tasks, disable all the ones in one phase and then see if the other one runs. If it doesn’t, I can always enable the old tasks and disable the new ones.

I expect as I look to perform more complex deployments I will use these to logically separate things, and also perhaps use the server to do some things when I don’t need an agent.

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