scripts.adoc

qDup Scripts

A Script a is tree of commands that run one at a time. Each command accepts a String input from the previous sibling (or parent if no sibling is available) as well as the current Context. Commands pass execution to their children commands by default (depth first execution) but they can skip their children commands when appropriate. The regex command, for example, will skip its children commands if the pattern does not match the input. The abort command is a special case that will not pass execution because it ends the execution.

Scripts are how qDup stores the automation tasks. Think of scripts as a sequence of qDup commands.

scripts:
  scriptName:
  - sh: cd /tmp
  - sh: ls #lists the content of /tmp

The commands run in order and can act on the output from the previous command

  - sh: mktemp -d
  - regex: (?<name>.*) #captures the output of mktemp -d as name

All commands can have a then key which contains a sequence of commands to run if the current command completes successfully. Most commands always complete successfully. The regex command will only invoke the commands under then if the pattern matches. Commands that can select to pass execution to then also support an else to explicitly run only when the command does not invoke then. This gives us the ability to conditionally run commands based on the output from previous commands.

scripts:
  scriptName:
  - sh: ls /tmp
  - regex: ^source.*
    then:
    - sh: rm -rf /tmp/source*
    else:
    - log: "first time running on the host"

The regex: source command checks the output of sh: ls /tmp for anything that starts with source. The rm -rf /tmp/source* will only be called if the pattern matched while the else commands will only run if the pattern failed to match.

The majority of qDup commands get their input from the just pass their input as output therefore multiple commands operate on the same output.

scripts:
  scriptName:
  - sh: ls /tmp
  - regex: ^source.* #matches against sh: ls /tmp
    then:
    - sh: rm -rf /tmp/source*
  - regex: ^dstat.log #matches against the same output from sh: ls /tmp
    then:
    - sh: rm /tmp/dstat.log

qDup passes the input through to the next command because it is designed to behave like an administrator using an ssh connection. This means the command input would conceptually only change if the terminal output changed. The sh command is the main method of changing the terminal output but the following commands can also change the terminal output:

• xml - will change output if used to get the values from an xpath

• upload - will output the path to the file on the remote host

• read-state - will output the state pattern if it was not empty

• js - will output the returned object if it was not true or "true"

• for-each will output the current iteration value

• exec will output the response from the ssh exec operation

• download outputs the local path of the file downloaded from the host

The previous example showed called sh: rm -rf /tmp/source* but the following regex applied to the output of the previous sh becaues rm -rf was nested below the previous regex. Nesting a command under a then will prevent it’s output from being seen by any commands higher up the then heirarchy. Remember it as command output is availabe to chilren (command in then) and siblings (subsequent commands at the same level) but not ancestors (commands above the enclosing then or else)

Check the commands documentation for more on adding commands to scripts