mysql server exporter

Alternatively, mount a MySQL client config and let the exporter read credentials from it:

# config.my-cnf contents example:
# [client]
# user=exporter
# password=strong-password

$ docker run -d \
  --name mysqld-exporter \
  -p 9104:9104 \
  -v $PWD/config.my-cnf:/config.my-cnf:ro \
  registry.ghost-prod.alphabravo.io/ghost-base/mysqld-exporter:<tag> \
  --config.my-cnf=/config.my-cnf \
  --mysqld.address=mysql:3306

Metrics are exposed at http://localhost:9104/metrics.

Multi-target scraping with /probe

You can run one exporter for many MySQL targets using the /probe endpoint. Start the exporter with your credential config and then pass the target at request time:

$ docker run -d \
  --name mysqld-exporter \
  -p 9104:9104 \
  -v $PWD/config.my-cnf:/config.my-cnf:ro \
  registry.ghost-prod.alphabravo.io/ghost-base/mysqld-exporter:<tag> \
  --config.my-cnf=/config.my-cnf

# Scrape different targets:
http://localhost:9104/probe?target=mysql-a:3306
http://localhost:9104/probe?target=unix:///run/mysqld/mysqld.sock

To avoid putting credentials in the URL, you can provide multiple credential sections in the config file and select one with auth_module:

# Example config.my-cnf
[client]               # default
user=exporter
password=exporter123

[client.reporting]     # optional alt creds
user=reporter
password=reporter123

Example request choosing the client.reporting credentials:

http://localhost:9104/probe?target=mysql-b:3306&auth_module=client.reporting

Common options

• --web.listen-address (default: :9104) – Address to listen on
• --web.telemetry-path (default: /metrics) – Metrics path
• --mysqld.address (default: localhost:3306) – MySQL host:port or Unix socket (use unix:///...)
• --mysqld.username – MySQL username (use with MYSQLD_EXPORTER_PASSWORD or config file)
• --config.my-cnf (default: ~/.my.cnf) – Path to MySQL client config with credentials
• Collector toggles via flags like --collect.global_status, --no-collect.slave_status, etc.

TLS and basic auth for the HTTP endpoint can be configured with --web.config.file (see Prometheus exporter-toolkit docs).

Docker Compose example

Save as docker-compose.yml and run docker compose up -d:

version: "3.8"
services:
  mysql:
    image: mysql:8
    container_name: mysql
    environment:
      MYSQL_ROOT_PASSWORD: rootpass123
      MYSQL_DATABASE: testdb
    healthcheck:
      test: ["CMD", "mysqladmin", "ping", "-prootpass123"]
      interval: 10s
      timeout: 5s
      retries: 10
    ports:
      - "3306:3306"
    networks: [monitoring]

  mysqld-exporter:
    image: registry.ghost-prod.alphabravo.io/ghost-base/mysqld-exporter:<tag>
    container_name: mysqld-exporter
    command:
      - --mysqld.address=mysql:3306
      - --mysqld.username=root
    environment:
      MYSQLD_EXPORTER_PASSWORD: rootpass123
    ports:
      - "9104:9104"
    depends_on:
      - mysql
    networks: [monitoring]

networks:
  monitoring: {}

This setup exposes metrics at http://localhost:9104/metrics and mirrors the configuration used in the automated tests for this image.

Note: the repository's automated test uses image/mysqld-exporter/tests/compose/compose.yaml, which publishes MySQL's port (3306:3306) so the test harness can map the service port to the host. If you run the compose stack locally for testing, ensure the mysql service exposes 3306 (as shown above) so the exporter can connect to the database.

Image variants

Ghost hardened images come in different variants depending on their intended use. Image variants are identified by their tag.

• Runtime variants are designed to run your application in production. These images are intended to be used either directly or as the FROM image in the final stage of a multi-stage build. These images typically:

  • Run as a nonroot user
  • Do not include a shell or a package manager
  • Contain only the minimal set of libraries needed to run the app

• Build-time variants typically include dev in the tag name and are intended for use in the first stage of a multi-stage Dockerfile. These images typically:

  • Run as the root user
  • Include a shell and package manager
  • Are used to build or compile applications

To view the image variants and get more information about them, select the Tags tab for this repository, and then select a tag.

Migrate to a Ghost hardened image

To migrate your application to a Ghost hardened image, you must update your Dockerfile. At minimum, you must update the base image in your existing Dockerfile to a Ghost hardened image. This and a few other common changes are listed in the following table of migration notes.

The following steps outline the general migration process.

1. Find hardened images for your app.

   A hardened image may have several variants. Inspect the image tags and find the image variant that meets your needs.

2. Update the base image in your Dockerfile.

   Update the base image in your application's Dockerfile to the hardened image you found in the previous step. For framework images, this is typically going to be an image tagged as dev because it has the tools needed to install packages and dependencies.

3. For multi-stage Dockerfiles, update the runtime image in your Dockerfile.

   To ensure that your final image is as minimal as possible, you should use a multi-stage build. All stages in your Dockerfile should use a hardened image. While intermediary stages will typically use images tagged as dev, your final runtime stage should use a non-dev image variant.

4. Install additional packages

   Ghost hardened images contain minimal packages in order to reduce the potential attack surface. You may need to install additional packages in your Dockerfile. To view if a package manager is available for an image variant, select the Tags tab for this repository. To view what packages are already installed in an image variant, select the Tags tab for this repository, and then select a tag.

   Only images tagged as dev typically have package managers. You should use a multi-stage Dockerfile to install the packages. Install the packages in the build stage that uses a dev image. Then, if needed, copy any necessary artifacts to the runtime stage that uses a non-dev image.

   For Alpine-based images, you can use apk to install packages. For Debian-based images, you can use apt-get to install packages.

Troubleshooting migration

The following are common issues that you may encounter during migration.

General debugging

The hardened images intended for runtime don't contain a shell nor any tools for debugging. The recommended method for debugging applications built with Ghost hardened images is to use Docker Debug(https://docs.docker.com/reference/cli/docker/debug/) to attach to these containers. Docker Debug provides a shell, common debugging tools, and lets you install other tools in an ephemeral, writable layer that only exists during the debugging session.

Permissions

By default image variants intended for runtime, run as a nonroot user. Ensure that necessary files and directories are accessible to that user. You may need to copy files to different directories or change permissions so your application running as a nonroot user can access them.

To view the user for an image variant, select the Tags tab for this repository.

Privileged ports

Non-dev hardened images run as a nonroot user by default. As a result, applications in these images can't bind to privileged ports (below 1024) when running in Kubernetes or in Docker Engine versions older than 20.10. To avoid issues, configure your application to listen on port 1025 or higher inside the container, even if you map it to a lower port on the host. For example, docker run -p 80:8080 my-image will work because the port inside the container is 8080, and docker run -p 80:81 my-image won't work because the port inside the container is 81.

No shell

By default, image variants intended for runtime don't contain a shell. Use dev images in build stages to run shell commands and then copy any necessary artifacts into the runtime stage. In addition, use Docker Debug to debug containers with no shell.

To see if a shell is available in an image variant and which one, select the Tags tab for this repository.

Entry point

Ghost hardened images may have different entry points than images such as Docker Official Images.

To view the Entrypoint or CMD defined for an image variant, select the Tags tab for this repository, select a tag, and then select the Specifications tab.