Script to install, enable, and start node-exporter

install-node-exporter.sh

#!/bin/sh

# Copyright (c) 2020 MagnaX Software
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.


NODE_EXPORTER_VERSION="1.2.2"

os=""
arch=""

case "$(uname -s | tr '[:upper:]' '[:lower:]')" in
  linux)
    os=linux
    ;;
  *)
    echo "Unknown kernel: $(uname -s)" >&2
    exit 1
    ;;
esac

case "$(uname -m | tr '[:upper:]' '[:lower:]')" in
  x86_64)
    arch=amd64
    ;;
  armv7l)
    arch=armv7
    ;;
  *)
    echo "Unknown architecture: $(uname -m)" >&2
    exit 1
    ;;
esac

filename="node_exporter-${NODE_EXPORTER_VERSION}.${os}-${arch}.tar.gz"
url="https://github.com/prometheus/node_exporter/releases/download/v${NODE_EXPORTER_VERSION}/${filename}"
init=""

exec 3>&1
log() {
  echo "$(date "+%Y.%m.%d-%H:%M:%S"): $@" >&3
}

which_init() {
  log "Determining init system"

  if [ -d "/run/systemd/system" ]; then
    log "  found systemd"
    init="systemd"
    return 0
  fi

  echo "Unsupported init system" >&2
  exit 1
}

which_firewall() {
  log "Determining firewall"
  
}

should_install() {
  if [ -f "/opt/node_exporter/version" ]; then
    installed=$(cat /opt/node_exporter/version)

    if [ "${NODE_EXPORTER_VERSION}.${os}-${arch}" = "${installed}" ]; then
      return 0
    fi
  fi

  return 1
}

store_version() {
  echo "${NODE_EXPORTER_VERSION}.${os}-${arch}" > /opt/node_exporter/version
}

download_tarball() {
  log "Downloading node_exporter ${NODE_EXPORTER_VERSION}"
  if [ `which curl` ]; then
    curl -sS -L "${url}" -o "/opt/${filename}"
  elif [ `which wget` ]; then
    wget -nv "${url}" -O "/opt/${filename}"
  else
    log "Neither curl nor wget are available"
    exit 1
  fi
}

extract_tarball() {
  log "Extracting..."
  tar xzf "/opt/${filename}" -C /opt/node_exporter --unlink-first --strip-components=1
}

ensure_group() {
  if getent group node_exporter >/dev/null; then
    return 0
  fi

  log "Creating node_exporter group"
  groupadd -r node_exporter
}

ensure_user() {
  if getent passwd node_exporter >/dev/null; then
    return 0
  fi

  log "Creating node_exporter user"
  useradd -d /var/opt/node_exporter -g node_exporter -m -r -s /usr/sbin/nologin node_exporter
}

init_systemd_unit() {
  if [ -f "/etc/systemd/system/node-exporter.service" ]; then
    return 0
  fi

  log "Creating systemd unit for node-exporter service"
  cat > "/etc/systemd/system/node-exporter.service" <<EOF
[Unit]
Description=Node Exporter
Wants=network-online.target
After=network-online.target

[Service]
User=node_exporter
Group=node_exporter
WorkingDirectory=~
Type=simple
ExecStart=/opt/node_exporter/node_exporter

[Install]
WantedBy=multi-user.target
EOF

  systemctl daemon-reload
}

init_systemd_enable_restart() {
  log "Enabling and restarting node-exporter service"
  systemctl enable node-exporter
  systemctl restart node-exporter
}

setup_service() {
  case $init in
    systemd)
      init_systemd_unit
      init_systemd_enable_restart
      ;;
    *)
      echo "Unsupported init system: ${init}" >&2
      exit 1
      ;;
  esac
}


firewall_firewalld_service() {
  log "Creating service file for firewalld"
  cat > /etc/firewalld/services/node-exporter.xml <<EOF
<?xml version="1.0" encoding="utf-8"?>
<service>
  <short>Node Exporter</short>
  <description>Node Exporter presents stats about the running OS</description>
  <port protocol="tcp" port="9100"/>
</service>
EOF

  sleep 5
}


if should_install; then
  exit 0
fi

which_init

download_tarball
mkdir -p /opt/node_exporter
extract_tarball

ensure_group
ensure_user

setup_service

store_version
log "Done"

+1 thanks