Methods

Methods specify how user logic should be called by the Custom Pod Autoscaler base program.

shell

The shell method allows specifying a shell command, run through /bin/sh. Any relevant information will be provided to the command specified by piping the information in through standard in. Data is returned by writing to standard out. An error is signified by exiting with a non-zero exit code; if an error occurs the autoscaler will capture all standard error and out and log it.

This is an example configuration of the shell method for the metric gatherer:

metric: 
  type: "shell"
  timeout: 2500
  shell: 
    entrypoint: "python"
    command: 
      - "/metric.py"

Breaking this example down:

  • type = the type of the method, for this example it is a shell method.
  • timeout = the maximum time the method can take in milliseconds, for this example it is 2500 (2.5 seconds), if it takes longer than this it will count the method as failing.
  • shell = the shell method to execute.
  • entrypoint = the entrypoint of the shell command, e.g. /bin/bash, defaults to /bin/sh.
  • command = the command to execute.

This is a metric configuration that will always fail:

metric: 
  type: "shell"
  timeout: 2500
  shell: 
    entrypoint: "/bin/sh"
    command: 
      - "-c"
      - "exit 1"

This is a metric configuration that will return 5 as a metric.

metric: 
  type: "shell"
  timeout: 2500
  shell: 
    entrypoint: "/bin/sh"
    command: 
      - "-c"
      - "echo '5'"