Add process-exporter installation and service to monitor Scylla process

common/install_process_exporter.sh

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+#!/bin/bash -e
+#
+
+# os-release may be missing in container environment by default.
+if [ -f "/etc/os-release" ]; then
+    . /etc/os-release
+elif [ -f "/etc/arch-release" ]; then
+    export ID=arch
+else
+    echo "/etc/os-release missing."
+    exit 1
+fi
+
+go_arch() {
+    local -A GO_ARCH=(
+        ["x86_64"]=amd64
+        ["aarch64"]=arm64
+    )
+    echo ${GO_ARCH["$(arch)"]}
+}
+
+PROCESS_EXPORTER_VERSION=0.8.7
+declare -A PROCESS_EXPORTER_CHECKSUM=(
+    ["x86_64"]=6d274cca5e94c6a25e55ec05762a472561859ce0a05b984aaedb67dd857ceee2
+    ["aarch64"]=4a2502f290323e57eeeb070fc10e64047ad0cd838ae5a1b347868f75667b5ab0
+)
+PROCESS_EXPORTER_DIR=/opt/scylladb/dependencies
+
+process_exporter_base_name() {
+    echo "process-exporter-$PROCESS_EXPORTER_VERSION.linux-$(go_arch)"
+}
+
+process_exporter_filename() {
+    echo "$(process_exporter_base_name).tar.gz"
+}
+
+process_exporter_tar_path() {
+    echo "/tmp/process-exporter.tar.gz"
+}
+
+process_exporter_checksum() {
+	sha256sum "$(process_exporter_tar_path)" | while read -r sum _; do [[ "$sum" == "${PROCESS_EXPORTER_CHECKSUM["$(arch)"]}" ]]; done
+}
+
+process_exporter_url() {
+    echo "https://github.com/ncabatoff/process-exporter/releases/download/v$PROCESS_EXPORTER_VERSION/$(process_exporter_filename)"
+}
+
+if [ -f "$(process_exporter_tar_path)" ] && process_exporter_checksum; then
+    echo "$(process_exporter_filename) already exists, skipping download"
+else
+    mkdir -p "$PROCESS_EXPORTER_DIR"
+    curl -L -o "$(process_exporter_tar_path)" "$(process_exporter_url)"
+    if ! process_exporter_checksum; then
+        echo "$(process_exporter_filename) download failed"
+        exit 1
+    fi
+fi
+
+tar -xzf "$(process_exporter_tar_path)" --strip-components=1 -C "$PROCESS_EXPORTER_DIR" "$(process_exporter_base_name)/process-exporter"
+cp process-exporter.service /usr/lib/systemd/system/
+cp process-exporter.yml "$PROCESS_EXPORTER_DIR"
+systemctl daemon-reload
+systemctl enable process-exporter.service
+

common/process-exporter.service

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+[Unit]
+Description=Process Exporter
+
+[Service]
+ExecStart=/opt/scylladb/dependencies/process-exporter -config.path /opt/scylladb/dependencies/process-exporter.yml
+
+[Install]
+WantedBy=multi-user.target

common/process-exporter.yml

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+process_names:
+  - name: "scylla"
+    cmdline:
+      # Match the main Scylla binary in common installs (system packages or tarballs)
+      - '(?:^|/)(scylla|scylla\.bin)(?:\s|$)'
+