Microservices Sidecar Pattern Architecture

Architecture

A sidecar pattern architecture diagram showing Envoy proxy, log collector, and config watcher sidecars running alongside application containers in a Kubernetes pod, with a control plane managing configuration. This template demonstrates how auxiliary concerns like logging, monitoring, and configuration are deployed as co-located containers. Foundational for teams adopting cloud-native container orchestration patterns.

Download .fz file

Full FlowZap Code

Pod { # Kubernetes Pod
n1: circle label:"Incoming Request"
n2: rectangle label:"Envoy Sidecar Proxy"
n3: rectangle label:"Application Container"
n4: rectangle label:"Log Collector Sidecar"
n5: rectangle label:"Config Watcher Sidecar"
n6: circle label:"Outgoing Response"
n1.handle(right) -> n2.handle(left)
n2.handle(right) -> n3.handle(left) [label="Decrypted"]
n3.handle(bottom) -> n4.handle(top) [label="Logs"]
n5.handle(right) -> n3.handle(left) [label="Config Update"]
n3.handle(right) -> n6.handle(left)
n2.handle(bottom) -> Observability.n10.handle(top) [label="Metrics"]
}
ControlPlane { # Control Plane
n7: rectangle label:"Service Mesh Control Plane"
n8: rectangle label:"Push Configuration"
n9: rectangle label:"Certificate Authority"
n7.handle(right) -> n8.handle(left) [label="Policy"]
n8.handle(bottom) -> Pod.n2.handle(top) [label="xDS Config"]
n9.handle(bottom) -> Pod.n2.handle(top) [label="mTLS Cert"]
n8.handle(right) -> Pod.n5.handle(top) [label="App Config"]
}
Observability { # Observability Stack
n10: rectangle label:"Prometheus Metrics"
n11: rectangle label:"Jaeger Tracing"
n12: rectangle label:"ELK Log Aggregation"
n13: rectangle label:"Grafana Dashboard"
n10.handle(right) -> n13.handle(left) [label="Metrics"]
n11.handle(right) -> n13.handle(left) [label="Traces"]
n12.handle(right) -> n13.handle(left) [label="Logs"]
n10.handle(top) -> Pod.n4.handle(bottom) [label="Scrape"]
}

Why This Workflow?

Cross-cutting concerns like logging, monitoring, and configuration management clutter application code and vary across programming languages. The sidecar pattern deploys these concerns as separate containers co-located with the application, providing language-agnostic infrastructure capabilities without modifying business logic.

How It Works

Step 1: The application container and sidecar containers are deployed together in a Kubernetes pod.
Step 2: The Envoy sidecar proxy intercepts all network traffic for mTLS and load balancing.
Step 3: The log collector sidecar ships application logs to the centralized logging system.
Step 4: The config watcher sidecar monitors configuration changes and updates the application.
Step 5: The control plane pushes policy updates and certificates to sidecar proxies.
Step 6: The observability stack collects metrics, traces, and logs from all sidecars.

Alternatives

Embedding these concerns in application libraries creates language-specific maintenance burden. DaemonSets handle node-level concerns but not pod-level isolation. This template shows the pod-level sidecar approach used by service meshes.

Key Facts

Template Name	Microservices Sidecar Pattern Architecture
Category	Architecture
Steps	6 workflow steps
Format	FlowZap Code (.fz file)

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