lolaus

A simple monorepo lifecycle/pipeline tool for running one or more commands on one or more directories that have diffs compared to an ancestor. The primary use case is selective CI jobs within a trunk based workflow such Git Flow.

Usage

lolaus has for optional positional arguments: lolaus [glob] [command] [target_ref] [source_ref]

• glob defaults to **

• command does not default

• target_ref defaults to next if available and then master

• source_ref defaults to the current HEAD

Examples:

  lolaus | parallel "wc -l {} > {}.out"
  lolaus "./tests/* :(top,exclude)**requirements.txt" ls
  lolaus "*/*/package.json" "npm test" release_branch

docker_images:
  stage: build
  script:
    - lolaus "services/*/Dockerfile" "docker build -t ${PWD##*/} ."
 
py_tests:
  image: python
  stage: test
  script:
    - lolaus "apps/*/requirements.txt" "python3 tests.py"

Install

lolaus is a Bash script and should be fairly universal but not tested outside of GNU/Linux. OSX users will have a better shell experience (and perhaps life in general) if they install GNU utilities. Contribs increasing portability or with other packaging (pip|curl|gem|other) would be great!

npm install -g lolaus

Design

lolaus is just a convenience shell wrapper of host's git client. The targeted integration branch is used with git merge-base --fork-point to determine the common ancestor node (CA). This is one of several common ancestry node strategies and others could be supported in lolaus, but this seems to provide the most benefit to the pre-integration, monorepo use case.

git diff from the current git ref (Fh) to the CA to determine which files have changes, filtered by the provided glob. From the list of modified files the command is invoked from a sorted and unique list of directories sequentially via eval in a loop.

graph LR
  m1(("Sc"))
  ca(("CA"))
  mh(("Mh"))
  f1(("Fc"))
  f2(("Fc"))
  fh(("Fh"))
 
  m1---ca
  ca-- master ---mh
  ca-- feature ---f1
  ca-. git diff .-fh
  f1---f2
  f2---fh
 
  classDef gitNode fill:#4ED1A1,stroke:#555,stroke-width:4px;
  class m1,m2,mh,f1,f2,fh,ca gitNode
 
  classDef gitDiff fill:#4E63D1,stroke:#555,stroke-width:4px;
  class fh,ca gitDiff

The design also assumes that each microservice or component is contained in its own directory and can be identified by some sort of file such as a package.json, pom.xml, or requirements.txt via the glob.

There is no parallelism, lolaus is intended to be used pre-integration where only one or two components that are effected in the merge request. In cases where target_ref and source_ref defaults work, the command parameter can be omitted and the list of effected directors can be piped to parallel.