New Feature: Self-Hosted Agents

Big news for folks running infrastructure in environments inaccessible from the public internet! Starting today Scalr has an option to execute runs within your own networks thanks to installable and self-hosted "agents".

Problem & Pain

By default, Scalr executes Terraform runs on a pool of shared agents that we maintain. This suffices for the majority of use cases, but sometimes, due to security, compliance, or network requirements, you need the runs to be executed within a special network inaccessible from the outside so that Terraform can make its API calls to various services.

There aren't many workarounds to this: either forgo using Scalr for those workloads, or deploy Scalr on your own premises and forgo the convenience and security of SaaS.

Solution

Enter Scalr self-hosted agents.

These self-hosted agents run in agent pools deployed on your infrastructure, are fully encrypted, and only need network access back to Scalr to pull jobs and push run results.

Each self-hosted agent can execute up to 5 concurrent runs — a cap we set to avoid overloading the host machine — and your account's overall concurrency scales by +5 for every additional agent you deploy. This is a direct consequence of Scalr's usage-based pricing model: because we charge per run rather than using the concurrency-based pricing used by some alternatives — which sell fixed parallel run slots — you can scale out concurrency simply by deploying more agents, with no per-slot fee.

Once a pool of self-hosted agents has been created, workspaces can be configured to use them for runs.

How the Feature Works

The way these agents work is simple. They pull job info from the Scalr service and execute the run from within your network, instead of the push model otherwise used, so they only need outbound internet access. Then, each workspace can be set up to use these agents, or default to using the Scalr service.

How to Get Started

Getting started is easy. Self-hosted agents are available on every plan, including Free — grab from Scalr the command to install them, and deploy one. Then your workspaces will have the option of using them for run execution.

Scalr provides copy-pastable commands to facilitate setup.

We even made a step by step guide for you here.