Mermin with GreptimeDB

• Mermin with GreptimeDB

  • Overview

  • Install

    • GreptimeDB

    • Mermin

  • Access

  • Debug charts

Overview

This example deploys Mermin alongside a standalone GreptimeDB instance for persistence. Mermin is configured to write metrics directly to GreptimeDB via HTTP using the OTLP protocol. Although local Kind was used for testing, any kubernetes cluster should work if nodes have sufficient resources

Notes on the example deployment:

• Location in the repository - docs/deployment/examples/local_greptime

• Topology: Mermin runs as a DaemonSet to monitor pod-to-pod communication on all nodes.

• Storage: GreptimeDB is deployed as the persistence layer for network telemetry.

• Connectivity: Mermin sends data directly to GreptimeDB using http_binary protocol.

• GreptimeDB is accessed via K8s Service (ClusterIP) for simplicity.

Install

GreptimeDB

Deploy GreptimeDB to serve as the persistence layer for the collected network telemetry.

• Create a values file for GreptimeDB with contents or use one from the repo, which includes configurations to receive Mermin metrics.

• Deploy GreptimeDB using the values file and the helm chart provided by the Greptime team.

  helm repo add greptime https://greptimeteam.github.io/helm-charts/
  helm repo update
  helm upgrade -i --wait --timeout 15m -n greptimedb --create-namespace \
    -f values_greptime.yaml \
    greptimedb greptime/greptimedb-standalone

Mermin

Deploy Mermin configured to output directly to the GreptimeDB service using HTTP headers required for signal parsing.

• Create a config.hcl file with contents, or use the one from the repo. Modify as desired, but retain the export.traces.otlp.headers and export.traces.otlp.protocol sections.

• Note: TLS is disabled in the repository example. This is not recommended for production deployments.

• Deploy the Mermin chart

  helm repo add mermin https://elastiflow.github.io/mermin/
  helm repo update
  helm upgrade -i --wait --timeout 15m -n elastiflow --create-namespace \
    --set-file config.content=config.hcl \
    mermin mermin/mermin

• Optionally install metrics-server to get metrics if it has not been installed yet

  kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.8.0/components.yaml
  # Patch to use insecure TLS, commonly needed on dev local clusters
  kubectl -n kube-system patch deployment metrics-server --type='json' -p='[{"op":"add","path":"/spec/template/spec/containers/0/args/-","value":"--kubelet-insecure-tls"}]'

Access

You may ensure the data is reaching GreptimeDB by using a GreptimeDB Dashboard App.

• First, port forward the OpenSearch Dashboards service

  kubectl -n greptimedb port-forward svc/greptimedb-greptimedb-standalone 4000:4000

• Use http://localhost:4000 as host and public as database.

• Run following query to ensure data is reaching GreptimeDB

  SELECT * FROM "opentelemetry_traces" WHERE "span_attributes.source.k8s.pod.name" IS NOT NULL ORDER BY "timestamp" DESC LIMIT 100

Debug charts

In order to render K8s manifests you may use following commands

• GreptimeDB

  rm -rf helm_rendered; helm template \
    -n greptimedb \
    -f values_greptime.yaml \
    greptimedb greptime/greptimedb-standalone \
    --output-dir helm_rendered
  
  # Diff with existing K8s resources
  kubectl -n greptimedb diff -R -f helm_rendered/greptimedb-standalone/

• Mermin

  rm -rf helm_rendered; helm template \
    -n elastiflow \
    --set-file config.content=config.hcl \
    mermin mermin/mermin \
    --output-dir helm_rendered
  
  # Diff with existing K8s resources
  kubectl diff -R -f helm_rendered/mermin/