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containerd-healthcheck

A daemon that performs health checks on containers running in containerd. It allows you to register asynchronous health checks for a set of container tasks, and provides a restart mechanism in case of failure.

Rationale

containerd is an abstraction of kernel features that provide a relatively high-level container interface with limited feature set and typically perform low-level tasks for running a container. Due to its nature of being small and focused, containerd doesn't support health checks like higher-level components such as Docker and Kubernetes. Therefore, this project aims to solve this problem by providing a simple way to monitor containers running in containerd. It lets you specify a health check for each container task and provides restart logic in case of failure.

Installation

On Linux, you can install using go get:

go get github.com/vouch-opensource/containerd-healthcheck

Alternatively, you can run it directly by using a Docker image:

docker run -v /run/containerd/containerd.sock:/run/containerd/containerd.sock vouchio/containerd-healthcheck

You can also manually download the binary from the github releases page.

Usage

Arguments

Usage of ./containerd-healthcheck:
  -a, --addr string     HTTP address for prometheus endpoint (default ":9434")
  -c, --config string   Path to configuration file (default "config.yml")
  -v, --version         Print app version

Configuration

The config.yml is the required configuration file for the containerd-healthcheck. It will read the config.yml file in the current working directory or specified with the --config option to be used by the daemon.

Example

containerd:
  socket: /run/containerd/containerd.sock
  namespace: default
checks:
  - container_task: example-api
    http:
      url: 127.0.0.1:8080/health
      method: GET
      expected_body: "OK"
      expected_status: 200
    execution_period: 2
    initial_delay: 2
    threshold: 3
    timeout: 5

containerd

This section specifies the required information to establish a connection with containerd

  • socket: containerd socket path to be used to establish a connection between the client and containerd over GRPC
  • namespace: namespace of containerd which the container resources - tasks, images, snapshots - are located

checks

This section is a list of health checks to be performed by the containerd-healthcheck. Each health check is configured through the following data structure:

  • container_task: task name of the container, mostly the same as container
  • execution_period: check interval to be executed (in seconds)
  • initial_delay: time to delay first check execution (in seconds)
  • restart_delay: time to sleep after restarting a task (in seconds)
  • threshold: the number of consecutive of check failures required before considering a target unhealthy and then marked to be restarted
  • timeout: Timeout used for the request (in seconds)
  • http.url: URL to be called by the check
  • http.method: HTTP method
  • http.expected_body: Operates as a basic 'body should contains < string >'
  • http.expected_status: Expected response status code

Metrics

By default, the containerd-healthcheck daemon serves a prometheus http endpoint with built-in metrics provided by the go-sundheit library; also it includes the total number of restarts per task running on containerd. Once the daemon is running, it can be accessed by the address 127.0.0.1:9434/metrics. A custom address can be defined with the --addr argument as well.

License

MIT