Prometheus Blackbox Exporter

Using the blackbox exporter we can gather metrics around uptime, latency, cert expiry and more for our public endpoints. The blackbox exporter ideally would be ran outside the cluster but can still provide useful information when deployed within it when combined with alerting and visualizations.

Installation

/opt/genestack/bin/install-prometheus-blackbox-exporter.sh

#!/bin/bash
# Description: Fetches the version for SERVICE_NAME_DEFAULT from the specified
# YAML file and executes a helm upgrade/install command with dynamic values files.

# Disable SC2124 (unused array), SC2145 (array expansion issue), SC2294 (eval)
# shellcheck disable=SC2124,SC2145,SC2294

# Service
SERVICE_NAME_DEFAULT="prometheus-blackbox-exporter"
SERVICE_NAMESPACE="prometheus"

# Helm
HELM_REPO_NAME_DEFAULT="prometheus-community"
HELM_REPO_URL_DEFAULT="https://prometheus-community.github.io/helm-charts"

# Base directories provided by the environment
GENESTACK_BASE_DIR="${GENESTACK_BASE_DIR:-/opt/genestack}"
GENESTACK_OVERRIDES_DIR="${GENESTACK_OVERRIDES_DIR:-/etc/genestack}"

# Define service-specific override directories based on the framework
SERVICE_BASE_OVERRIDES="${GENESTACK_BASE_DIR}/base-helm-configs/${SERVICE_NAME_DEFAULT}"
SERVICE_CUSTOM_OVERRIDES="${GENESTACK_OVERRIDES_DIR}/helm-configs/${SERVICE_NAME_DEFAULT}"

# Read the desired chart version from VERSION_FILE
# NOTE: Ensure this file exists and contains an entry for SERVICE_NAME_DEFAULT.
VERSION_FILE="${GENESTACK_OVERRIDES_DIR}/helm-chart-versions.yaml"

if [ ! -f "$VERSION_FILE" ]; then
    echo "Error: helm-chart-versions.yaml not found at $VERSION_FILE" >&2
    exit 1
fi

# Extract version dynamically using the SERVICE_NAME_DEFAULT variable
SERVICE_VERSION=$(grep "^[[:space:]]*${SERVICE_NAME_DEFAULT}:" "$VERSION_FILE" | sed "s/.*${SERVICE_NAME_DEFAULT}: *//")

if [ -z "$SERVICE_VERSION" ]; then
    echo "Error: Could not extract version for '$SERVICE_NAME_DEFAULT' from $VERSION_FILE" >&2
    exit 1
fi

echo "Found version for $SERVICE_NAME_DEFAULT: $SERVICE_VERSION"

# Load chart metadata from custom override YAML if defined
for yaml_file in "${SERVICE_CUSTOM_OVERRIDES}"/*.yaml; do
    if [ -f "$yaml_file" ]; then
        HELM_REPO_URL=$(yq eval '.chart.repo_url // ""' "$yaml_file")
        HELM_REPO_NAME=$(yq eval '.chart.repo_name // ""' "$yaml_file")
        SERVICE_NAME=$(yq eval '.chart.service_name // ""' "$yaml_file")
        break  # use the first match and stop
    fi
done

# Fallback to defaults if variables not set
: "${HELM_REPO_URL:=$HELM_REPO_URL_DEFAULT}"
: "${HELM_REPO_NAME:=$HELM_REPO_NAME_DEFAULT}"
: "${SERVICE_NAME:=$SERVICE_NAME_DEFAULT}"


# Determine Helm chart path
if [[ "$HELM_REPO_URL" == oci://* ]]; then
    # OCI registry path
    HELM_CHART_PATH="$HELM_REPO_URL/$HELM_REPO_NAME/$SERVICE_NAME"
else
    # --- Helm Repository and Execution ---
    helm repo add "$HELM_REPO_NAME" "$HELM_REPO_URL"   # uncomment if needed
    helm repo update
    HELM_CHART_PATH="$HELM_REPO_NAME/$SERVICE_NAME"
fi

# Debug output
echo "[DEBUG] HELM_REPO_URL=$HELM_REPO_URL"
echo "[DEBUG] HELM_REPO_NAME=$HELM_REPO_NAME"
echo "[DEBUG] SERVICE_NAME=$SERVICE_NAME"
echo "[DEBUG] HELM_CHART_PATH=$HELM_CHART_PATH"

# Prepare an array to collect -f arguments
overrides_args=()

# Include all YAML files from the BASE configuration directory
# NOTE: Files in this directory are included first.
if [[ -d "$SERVICE_BASE_OVERRIDES" ]]; then
    echo "Including base overrides from directory: $SERVICE_BASE_OVERRIDES"
    for file in "$SERVICE_BASE_OVERRIDES"/*.yaml; do
        # Check that there is at least one match
        if [[ -e "$file" ]]; then
            echo " - $file"
            overrides_args+=("-f" "$file")
        fi
    done
else
    echo "Warning: Base override directory not found: $SERVICE_BASE_OVERRIDES"
fi

# Include all YAML files from the custom SERVICE configuration directory
# NOTE: Files here have the highest precedence.
if [[ -d "$SERVICE_CUSTOM_OVERRIDES" ]]; then
    echo "Including overrides from service config directory:"
    for file in "$SERVICE_CUSTOM_OVERRIDES"/*.yaml; do
        if [[ -e "$file" ]]; then
            echo " - $file"
            overrides_args+=("-f" "$file")
        fi
    done
else
    echo "Warning: Service config directory not found: $SERVICE_CUSTOM_OVERRIDES"
fi

echo

# Collect all --set arguments, executing commands and quoting safely
set_args=()


helm_command=(
    helm upgrade --install "$SERVICE_NAME_DEFAULT" "$HELM_CHART_PATH"
    --version "${SERVICE_VERSION}"
    --namespace="$SERVICE_NAMESPACE"
    --timeout 120m
    --create-namespace

    "${overrides_args[@]}"
    "${set_args[@]}"

    # Post-renderer configuration
    --post-renderer "$GENESTACK_OVERRIDES_DIR/kustomize/kustomize.sh"
    --post-renderer-args "$SERVICE_NAME_DEFAULT/overlay"

    "$@"
)

echo "Executing Helm command (arguments are quoted safely):"
printf '%q ' "${helm_command[@]}"
echo

# Execute the command directly from the array
"${helm_command[@]}"

If the installation is successful, you should see the related Blackbox exporter pods in the prometheus namespace.