VSTS personal build agent on Docker

Using a personal build agent running on docker to speed up compilation times

 Posted on August 31, 2018  |  0 minutes (0 words)

Visual Studio Team Services has a very good build agent: free and with high availability. The only problem is that it is a bit slow because every time you run a build it will start from scratch and download everything. A custom build agent will cache stuff and speed up build times a lot.

For example I am experimenting on a build job that has to build an Angular + .net core API and create a couple docker images.

The steps I use for one of my jobs:

  • Initialize agent + job: 20s
  • Get sources: 5s
  • Nuget package restore: 38s
  • Build: 11s
  • Publish: 4s
  • Build docker image:28s
  • Push docker image: 12s

Imagine that you are experimenting with a new job step and that every time you run a test you a have to wait a few minutes.

Prepare permissions

Open your VSTS profile and go to your security details.

Security settings

Add a personal access token.

Put a description and choose a duration.

For the scope select Agent Pools (read, manage) and clear all the rest.

Personal access token

Save the token in a safe place.

Prepare Docker container

The official image is on docker hub microsoft/vsts-agent

The standard image with all the tools is 4Gb compressed (check for disk space this is a hit on a VPS space)

Create a folder and add a new script

mkdir ~/vsts_agent
cd ~/vsts_agent
nano run_agent.sh
chmod +x run_agent.sh

Simple configuration for run_agent.sh

docker run \
  -e VSTS_ACCOUNT=<your organization name> \
  -e VSTS_TOKEN=<pat> \
  -it microsoft/vsts-agent:ubuntu-16.04

Advanced configuration for run_agent.sh

docker run \
  -e VSTS_ACCOUNT=<your organization name> \
  -e VSTS_TOKEN=<pat> \
  -e VSTS_AGENT='$(hostname)-agent' \
  -e VSTS_POOL=mypool \
  -e VSTS_WORK='/var/vsts/$VSTS_AGENT' \
  -v /var/vsts:/var/vsts \
  -it microsoft/vsts-agent:ubuntu-16.04

The image microsoft/vsts-agent:ubuntu-16.04 has minimal capabilities but uses only 0.5Gb of uncompressed disk space.

Run the container

sh run_agent.sh

Check the agent

Go in the Agent Pools section of VSTS to view the status and the capabilities offered by each agent.

Agent pools

Use the agent

Edit a Build Job and change the Agent Pool to Default to use the agent.

The basic agent microsoft/vsts-agent:ubuntu-16.04 is not able to do much work because no extended capabilities are configured.