TripleO Style Guidelines

  • Step 1: Read the OpenStack Style Guidelines [1]
  • Step 2: Read Bashate [2]
  • Step 3: See specific guidelines below

TripleO Specific Guidelines

There is plenty of code that does not adhere to these conventions currently. However it is useful to have conventions as consistently formatted code is easier to read and less likely to hide bugs. New code should adhere to these conventions, and developers should consider sensible adjustment of existing code when working nearby.

Formatting

Please follow conventions described in OpenStack style guidelines [1] and Bashate [2].

  • Order lists whenever possible, whether in code or data. If the order doesn’t matter, use a case-insensitive alphabetical sort. This makes them easier to compare with diff-like tools. - “a” < “B” < “c” - “a” < “ab” - “2” < “10”

Bash

As well as those rules described in Bashate [2]:

  • The interpreter is /bin/bash.

  • Provide a shebang #!/bin/bash if you intend your script to be run rather than sourced.

  • Use set -e and set -o pipefail to exit early on errors.

  • Use set -u to catch typos in variable names.

  • Use $() not `` for subshell commands.

  • Double quote substitutions by default. It’s OK to omit quotes if it’s important that the result be multiple words. EG given VAR=”a b”:

    echo "${VAR}"

    Quote variables.

    echo "$(echo a b)"

    Quote subshells.

    echo "$(echo "${VAR}")"

    In subshells, the inner quotes must not be escaped.

    function print_b() { echo "$2"; }; print_b ${VAR}

    You must omit quotes for a variable to be passed as multiple arguments.

    ARRAY=(${VAR}); echo "${#ARRAY[@]}" = 2

    You must omit quotes to form a multi-element array.

  • Avoid repeated/copy-pasted code. Make it a function, or a shared script, etc.

Script Input

  • Avoid environment variables as input. Prefer command-line arguments.
  • If passing structured data, use JSON.
  • Avoid passing substantial amounts of bare data (eg JSON) on the command line. It is preferred to place the data in a file and pass the filename. Using process substitution <() can help with this.

Variables

  • Within a shell script, variables that are defined for local use should be lower_cased. Variables that are passed in or come from outside the script should be UPPER_CASED.