One of the benefits of collecting a distributed trace for every user request is that you always have an accurate representation of all service dependencies at all times. You’re never left with partial (aka. incomplete) data to represent a transaction so you ALWAYS know exactly what path every request takes through your complex microservices applications. You also know exactly where every transaction is slow or throwing errors and what impact that has on the rest of the system.

Instana analyzes all of this data and creates flexible visualizations that enable you to see an accurate map of every service dependency that is important to your specific role. Application Dependency Maps are the latest feature from Instana that extend the usability of personalized APM.

Application Dependency Maps

If you’re not yet familiar with Instana’s innovative Application Perspectives capabilities I suggest you take a few minutes to read about them.

Navigating to Application Dependency Maps is easy. They are accessible through the application dashboards "Dependencies" tab.

Figure 1: Navigating to the Application Dependency Map.

Once you’ve arrived at your Application Dependency Map you can change the visualization of each service to represent throughput, error rate, or latency. Select any of the visualization options and you’ll see the size of the service icons change. Larger icons indicate higher values for each of the respective metrics.

Figure 2: Changing the visual representation of services based upon throughput, error rate, or latency.

You can also change the layout of the map to display how requests flow through the different services from left to right.

Figure 3: Display the flow of requests through services from left to right.

And of course, if there are any sort of issues that appear on the Application Dependency Map you will want to click and drill down to investigate. When you mouse over a service icon you are presented with Total Calls, Error Rate, Avg Latency, and alerts over the selected time period. You also get sparklines to see the trends over that time period.

Figure 4: Mouseover service icon to see more information about that service.

You can also click on any service icon and you will be presented with multiple options to drill down exactly where you want to go. As of right now the options are “Go to Dashboard”, “Go to Flow”, and “Go to Analyze”.

Figure 5: Clicking on a service icon will allow you to drill down to the next screen of your choosing

Use Cases for Dependency Maps

Now that you understand the core functionality of Dependency Maps, let’s explore why they're useful.

Use Case 1: Troubleshooting

When I’m troubleshooting any problem with an application, the first thing I do is look at the Dependency Map. I do this for several reasons.

First, I want to make sure that the application is still deployed the way I think it’s supposed to be. The Dependency Map either confirms that immediately or helps me understand what has changed from a logical architecture perspective.

Second, I want to see if any services are in an alert state. Any services that have issues will appear as either yellow or red. I can choose to drill down directly into the issue by clicking on the service or I can perform more troubleshooting at the map level before I drill down.

Figure 6: Shop service in an alert state showing 1 warning issue.

Third, I want to understand which services within my application talk to each other the most. I can see this visually by looking at Particle Flow between the various services. The more dots you see traversing the connector lines the more traffic is flowing between the services.

Figure 7: Particle flows between services help you quickly understand traffic flow rates.

Use Case 2: Migration to Cloud or Microservices

Cloud migration is one of the most valuable uses of Instana. If you are planning to move anything from your on-prem data center out to a cloud provider there are many considerations to make the migration smooth for everyone involved. Detailing all of the steps will happen in another blog post but the high-level steps are as follows:

• Understand usage patterns of applications and services — choose your migration targets based upon your desired business outcomes and usage patterns
• Understand resource utilization KPIs for all infrastructure that supports your applications and services — Use this information to perform initial sizing of your new cloud infrastructure components.
• Baseline the performance and error profiles of each application and service — If performance is poor and the services throw a bunch of errors, you want to make sure you don’t move the same problems from inside your data center out to a cloud computing environment.
• Understand the architecture and dependencies of every application and service you want to migrate - some applications and/or service may need to be migrated together if they are very chatty. The Dependency Map is vital for this step.
• Rebuild portions of your applications whose architecture is not clou or microservice-friendly — this will save a lot of pain if planned for ahead of time instead of reacted to after the migration.
• Deploy groups of applications and services to your cloud platform — be sure to automate deployment to ensure speed and repeatability.
• Test cloud applications and services using loading patterns gathered from your on-prem installation — fix performance bottlenecks and errors.
• Send a portion of your production workload to your new cloud applications and services — testing in production with real users will expose major issues.
• After you’re satisfied with the performance and scalability of your new cloud services and microservices, you can cut over the rest of your production traffic and decommission your on-prem services.

Use Case 3: Onboarding Employees

What better way to familiarize new employees with your applications and services than to show them a visual representation. Developers, SRE’s, Operations … they all need to understand which services communicate with each other and how applications are glued together. The Dependency Map makes this a simple exercise.