Modular Bash Launcher

Module based Bash script launcher or Mobala!

Using resolver:

Copy mobala-resolver.sh content to the file in the root of your project (eg ./run). Execute with ./run --verbose --nix --param :my-mode.

That's it! You are ready to write your modular Bash script!

Mobala project structure:

Mobala project have four environment variables, specifying at where to lookup execution scripts:

• MOBALA_KEEP - file with the list of all environment variables that should be preserved in Nix environment (default $(pwd)/mobala/keep.env);
• MOBALA_ENV - bash script to setup execution environment (default $(pwd)/mobala/env.sh);
• MOBALA_MODS - directory of shell scripts to modify environment (default $(pwd)/mobala/mods);
• MOBALA_PARAMS - directory of shell scripts to pass parameters to environment (default $(pwd)/mobala/params).

MOBALA_ENV environment setup shell script will be sourced after execution environment is prepared. Mobala executor expects run function to be sourced and ready to be executed after MOBALA_ENV sourcing. run function is a main entrypoint of all project.

Mobala builtin commands:

• --help to print auto-generated help;
• --nix to shift script execution to nix develop shell, using local flake.nix definition;
• --verbose or -v to enable verbose logging;
• --env PARAM=123 or -e PARAM=123 to specify environment variable (should be specified AFTER --nix option, or environment might be lost during execution)

Writing your script:

There is two ways of adding a script:

1. Add script file to ${MOBALA_MODS}/my-script.sh, run it with ./run :my-script
2. Add mode file to ${MOBALA_MODS}/my-script.sh to set up script execution:

#!/usr/bin/env bash

set -euo pipefail
if [[ "${DO_VERBOSE}" == 1 ]] ; then set -x ; fi

#[help]Print foo, using provided parameters.

export DO_MY_SCRIPT=1

Update run command in MOBALA_ENV to execute your script if "${DO_MY_SCRIPT}" == 1.

Example:

• Mode environment setup - hello-world.sh;
• Mode script - run-hello-world.sh;
• Runner - run.sh.

Adding parameters to your script

Mobala launcher will automatically parse and pass all CLI arguments from original CLI string to mode script. Arguments parsing should be handled by the mode itself.

Example: hello-world.sh - run with ./mobala-resolver.sh :hello-world --name="John Doe".

Running your script

Mobala launcher will parse CLI arguments, with the following syntax:

• --param - to specify global parameter (should be set before first mode)
• :mode -p1 --mode-arg=foo --param - to apply execution mode and specify its parameters.

Arguments and modes might be combined in any form:

./mobala-resolver.sh \
  --global-parameter \
  --global-parameter-2=foo \
  :mode-1 --mode-1-param --mode-1-arg=John \
  :mode-2 --mode-2-param --mode-2-arg=Doe

Adding global parameters

Add parameter reader shell script to MOBALA_PARAMS as ${MOBALA_PARAMS}/my-parameter.sh. All parameters set as --my-param=123 or --my-param before first mode invocation are used to invoke ${MOBALA_PARAMS}/my-param.sh

Examples:

• version.sh: run with ./mobala-resolver.sh --version=123 :foo;
• version-1.sh: run with ./mobala-resolver.sh --version-1 :bar;

Help

Project help is auto generated. To specify help for env/modes/params helps leave a comment in your script, starting from #[help]. Every line starting with #[help] will be parsed as a manual string and auto-added to the Mobala component help.

Show help with ./mobala-resolver.sh --help.

Examples:

• Parameter help at version.sh;
• Mode help at hello-world.sh;
• Env help at env.sh;