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AWS Application Discovery Service is a tool that automatically collects configuration, usage, and dependency data from your on-premises servers. It helps you...
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AWS Application Discovery Service is a tool that automatically collects configuration, usage, and dependency data from your on-premises servers. It helps you build a complete inventory of your existing infrastructure, which is essential for planning a cloud migration and assessing which workloads to move first.
What the Service Collects
Application Discovery Service gathers server specifications (CPU, memory, disk), network connections between servers, running processes, and resource utilization over time. This data provides a factual baseline of your current environment rather than relying on outdated documentation or tribal knowledge.
The utilization data is especially valuable. By measuring actual CPU and memory consumption over weeks, you can right-size your AWS instances instead of replicating oversized on-premises hardware. This directly reduces post-migration costs and avoids the common mistake of over-provisioning cloud resources.
Discovery data also reveals usage patterns that inform migration scheduling. Servers with predictable low-utilization windows are easier to cut over during those periods. Servers running at near-capacity around the clock require more careful planning to avoid performance disruptions during the migration itself.
Agent-Based Discovery
The agent-based approach uses the AWS Discovery Agent, a lightweight software agent installed directly on each server. The agent collects detailed data including running processes, network connections between servers, and system performance metrics. It supports Windows and Linux operating systems.
Agent-based discovery provides the richest data set. It captures application-level dependencies by monitoring actual network traffic between servers, revealing relationships that are not visible through network scanning alone. This dependency mapping is essential for grouping servers into migration waves that move together.
The agent runs as a background service and consumes minimal system resources. It does not interfere with application performance or require server restarts. Data collection begins immediately after installation and continues until you explicitly stop or remove the agent from the server.
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Agentless Discovery
The agentless approach uses the Discovery Connector, a virtual appliance deployed in your VMware vCenter environment. It connects to vCenter APIs and collects VM inventory, configuration, and performance data without installing anything on individual servers.
Agentless discovery is faster to deploy since it requires only a single virtual appliance rather than per-server installations. However, it provides less granular data. It does not capture process-level information or application-to-application network dependencies. It works best as a starting point for organizations that need a quick inventory before deciding where to deploy agents.
How It Feeds into Migration Hub
Data collected by Application Discovery Service flows automatically into AWS Migration Hub. Migration Hub displays the discovered servers as an inventory list with their specifications, utilization data, and dependency mappings. This unified view becomes the foundation for migration planning.
From Migration Hub, you can group discovered servers into applications, assign migration strategies (using the 7R framework), and track progress as workloads move to AWS. The discovery data persists in Migration Hub, so teams can reference it throughout the migration project without re-running scans.
Role in the MAP Assess Phase
During the assess phase of the AWS Migration Acceleration Program, Application Discovery Service provides the raw data needed to build the migration business case. The server inventory and utilization metrics feed into the Migration Portfolio Assessment tool, which calculates total cost of ownership comparisons.
Without accurate discovery data, the business case relies on estimates that may not reflect reality. Organizations that skip discovery often face surprises during migration, such as undocumented server dependencies that break applications when individual servers are moved. Running discovery before starting the MAP application strengthens both the business case and the migration plan.
Deployment Considerations
Agent-based discovery requires network connectivity from each server to AWS endpoints. If your servers sit behind strict firewalls, you may need to configure outbound HTTPS access to specific AWS service endpoints. The agent communicates over port 443 and does not require inbound connections.
Data collected by the service is encrypted in transit and at rest. The discovery data is stored in your AWS account and is not shared with other accounts or AWS services beyond Migration Hub. Organizations with strict data governance requirements can review the data retention policies before deployment.
For environments that are not VMware-based, the agentless connector is not an option. In those cases, agent-based discovery is the only method available through the service. Some organizations supplement Application Discovery Service with third-party tools that offer broader platform support for Hyper-V, bare metal, or other hypervisors.
Getting Started
Start with agentless discovery if you run VMware and need a quick inventory count. Follow up with agent-based discovery on servers where dependency mapping and process-level detail are needed, especially for complex multi-tier applications. Most organizations use both methods across different parts of their portfolio.
Opsio includes Application Discovery Service setup as part of our AWS migration services, ensuring proper deployment and data analysis from the first week of engagement. For more context on how discovery fits into the broader migration program, see our overview of the AWS Migration Acceleration Program.
Written By
Country Manager, Sweden at Opsio
Johan leads Opsio's Sweden operations, driving AI adoption, DevOps transformation, security strategy, and cloud solutioning for Nordic enterprises. With 12+ years in enterprise cloud infrastructure, he has delivered 200+ projects across AWS, Azure, and GCP — specialising in Well-Architected reviews, landing zone design, and multi-cloud strategy.
Editorial standards: This article was written by cloud practitioners and peer-reviewed by our engineering team. We update content quarterly for technical accuracy. Opsio maintains editorial independence.