Expense Report

A set of .NET Core and Java Spring Boot services that records expenses and returns a report for a given trip identifier.

What it does

Expense Report uses Consul for service mesh, application configuration, and feature toggling capabilities.

For multiple frameworks, Consul Connect provides service mesh capabilities that enable a consistent method of configuring:

• Service Discovery
• Network Policy (via Consul intentions)
• Load balancing
• Additional Tracing Metadata
• Circuit Breaking (AKA Outlier Detection)

Expense Report Application

The report application connects to the expense application, which retrieves information from a database. You'll find two versions of the expense application, one in .NET and one in Java.

Below are the most useful endpoints for the expense service:

• GET /api/expense: Get a list of expenses
• POST /api/expense: Create a new expense. See schema under example/expense.json.

Java defaults to :8080 and .NET Core defaults to :5001.

Below are the most useful endpoints for the report service:

• GET /api/report/expense/version: Gets the version of the expense application for debugging
• GET /api/report/trip/${trip_id}: Gets a list of expenses for a given trip.

${trip_id} denotes the trip identifier passed in the body of the expense item created in the POST method to expense. Since the report application is currently only available in .NET Core, it runs by default on port :5002.

Kubernetes

Prerequisites

• Kubernetes. The configurations use a cluster set up in GKE as per the /terraform directory. You can use the Terraform to create a Kubernetes cluster for all of the applications.

• Locust to mimic user traffic.

• Consul 1.11+

• Vault 1.9+

• Terraform 1.0+. For creating cluster and configuring Vault.

• Azure

  • Create a service principal with owner access to the subscription.

• Terraform Cloud account and three workspaces

  • infrastructure: working directory under terraform/infrastructure

    • Add Azure credentials
    • prefix variable for identification

  • helm: working directory under terraform/helm

    • prefix variable for identification
    • vault_token variable for logging into Vault
    • tfc_workspace variable referencing infrastructure
    • tfc_organization variable referencing your TFC organization

  • vault: working directory under terraform/vault

    • tfc_workspace variable referencing helm
    • tfc_organization variable referencing your TFC organization

Create resources

• Run terraform apply for infrastructure workspace
• Run terraform apply for helm workspace
• Run terraform apply for vault workspace

Deploy everything to Kubernetes

Deploy tracing and gateway.

bash scripts/kubernetes.sh tracing setup

Deploy databases. Enter yes to continue.

bash scripts/kubernetes.sh databases setup

Deploy expense service.

bash scripts/kubernetes.sh expense setup

Deploy report service.

bash scripts/kubernetes.sh report setup

Deploy split traffic configuration.

bash scripts/kubernetes.sh split setup

Deploy route traffic configuration.

bash scripts/kubernetes.sh route setup

Cleanup

Remove everything from the Kubernetes cluster.

bash scripts/kubernetes.sh clean

Delete everything from the vault TFC workspace.

Delete everything from the helm TFC workspace.

Delete everything from the infrastructure TFC workspace.

Docker-Compose

This is for local demonstration purposes only. The Consul server has a different configuration than what you would expect for production! It does not use Vault for dynamic secrets.

Prerequisites

• Docker
• docker-compose

Startup

To start, bring up the Consul server, MySQL database, Microsoft SQL Server database, Jaeger for tracing, the expense services in .NET and Java, and the report service in .NET.

bash scripts/compose.sh all

This will not only bring up the stack but add the application configuration for the expense service.

Open Jaeger on http://localhost:16686 and Consul on http://localhost:8500.

Service Networking with Consul Service Mesh

To try out:

• Service discovery
• Network policy
• Load balancing
• Additional tracing metadata

Traffic Splitting

When you start the demo by default, it sets a service-splitter and service-router that divides traffic equally between the Java and .NET applications.

Test this by calling the version API endpoint. You'll notice half the responses are 6.0 (.NET) and 0.0.1-SNAPSHOT (Java). This means that the proxy is separating traffic between the two service instances for expense.

bash scripts/compose.sh split test

You can adjust compose_configs/traffic_config/expense-splitter.hcl with the ratio of your choice to test this further. Re-apply the configuration with the following command:

bash scripts/compose.sh split setup

Route Based on Header

Sometimes, you want to test an application but only if you pass a specific header. You can set a service-resolver with a service-router.

Set them up using the following command.

bash scripts/compose.sh route setup

Test this by going into the report proxy's container and passing a header. You'll notice that the response routes to 0.0.1-SNAPSHOT (Java) if you set the header or 6.0 (.NET) by default.

bash scripts/compose.sh route test

Circuit Breaking

To try circuit breaking (outlier detection in Envoy), note that it the configuration requires an unsupported Consul escape hatch override. It cannot have any service resolver or splitter configuration.

Stop the Microsoft SQL Server database. This will fail calls to the .NET Core expense service. As a result, circuit breaker will trip in the report service and route all traffic to the Java expense service.

Issue the command for testing.

bash scripts/compose.sh circuit_break test

After you are done, reset the circuit breaker.

bash scripts/compose.sh circuit_break reset

Clean Up

Remove everything using a command.

bash scripts/compose.sh clean