spiegel-keyman/resources/build/build-utils.md

Using the build-utils.sh builder functions

The Keyman repository is standardising on bash scripts for builds. These may call project-specific builders, such as tsc for Typescript projects, meson for our cross-platform C++ projects, xcodebuild on macOS and iOS projects, gradle for Android, nmake in our Windows builds, or worse, but each project should also have a build.sh script in its root.

We have standardised on parameters and structure for build.sh scripts. The objectives are:

1. to be consistent in use of script parameters across all platforms and projects
2. to be self-documenting in usage (--help should always tell you all you need to know)
3. for the scripts to be easily readable, coherent, and straightforward for anyone involved in the project to maintain
4. for dependencies to be simple (a module dependency will always be to a whole module, not to a specific target within that module)

• Jump to API definitions

---

Anatomy of a build script

A build script is made up of three sections:

• Prologue
• Definition
• Processing actions

Build script prologue

A build script should always start with the following prologue:

#!/usr/bin/env bash
#
# <short description of the script purpose>

set -eu

## START STANDARD BUILD SCRIPT INCLUDE
# adjust relative paths as necessary
THIS_SCRIPT="$(greadlink -f "${BASH_SOURCE[0]}" 2>/dev/null || readlink -f "${BASH_SOURCE[0]}")"
. "$(dirname "$THIS_SCRIPT")/<relative-path-to-repo-root>/resources/build/build-utils.sh"
## END STANDARD BUILD SCRIPT INCLUDE

# any other includes, such as jq.inc.sh

################################ Main script ################################

This prologue ensures that we have a consistent environment. Explaining each section:

Shebang

#!/usr/bin/env bash

We use the /usr/bin/env prefix to ensure that we get the right version of bash on macOS (installed via homebrew, rather than the obsolete system-provided one). This also works fine on Linux, git bash on Windows, and WSL.

Bash options (set -eu)

We use set -eu throughout:

• -e to exit on any statement failure
• -u to abort on unset variable use (usually coming from typos)

Standard build script include

## START STANDARD BUILD SCRIPT INCLUDE
# adjust relative paths as necessary
THIS_SCRIPT="$(greadlink -f "${BASH_SOURCE[0]}" 2>/dev/null || readlink -f "${BASH_SOURCE[0]}")"
. "$(dirname "$THIS_SCRIPT")/<relative-path-to-repo-root>/resources/build/build-utils.sh"
## END STANDARD BUILD SCRIPT INCLUDE

This somewhat unwieldy incantation handles all our build environments, with greadlink necessary on macOS (again installed with homebrew) due to the included macOS readlink struggling with canonicalization of symbolic links. The intent is to get a good solid consistent path for the script so that we can safely include the build script, no matter what pwd is when the script is run.

The only modification permissible in this block is the <relative-path-to-repo-root> text which will be a series of ../ paths taking us to the repository root from the location of the script itself.

Inclusion of other scripts should be kept outside this standard build script include section, as we may programatically update (a.ka. global search-and-replace) this section in the future as required.

Any other includes

Once build-utils.sh has been included, the variable $KEYMAN_ROOT will be available, so other include scripts should be sourced accordingly, for example:

. "$KEYMAN_ROOT/resources/build/jq.inc.sh"

Split

The comment line splitting the prologue from the body of the script is optional, but makes the script easy to scan!

################################ Main script ################################

Defining build script parameters

The build script should use the builder functions and variables to process its command line and control its run.

Build scripts can define targets, actions, and options, which are parameters passed in to the script when it is run by a user or called by another script:

• targets: these are the expected outputs of the build script. A target is prefixed with a :, for example :app. If no target is defined for a script, then the default target :project is used.

• actions: these are the various actions that a build script can take, such as clean, or build. If no action is passed in to on a given script invocation, then the default action is build (unless the script defines an alternative default).

• options: these are possible additional options that can be passed to the script to modify the behavior of the script. All options should be prefixed with --, such as --debug, and a shorthand single letter form may also be optionally provided, such as -d.

  Note that when we call scripts from other scripts, particularly in CI, we should always use the longhand form; the shorthand form is for convenience on the command line only.

  Be judicious in use of options; a common one will be --debug to do a debug build, but overuse of options will make scripts hard to use.

  Options can be used to provide additional data, by including =<varname> in their definition. Otherwise, they are treated as a boolean.

The first step in your script is to describe the available parameters, using builder_describe, for example:

builder_describe \
  "Tests the build-utils.sh builder functions. This is merely an example." \
  clean \
  build \
  test \
  "install         Installs something on the local system" \
  :app \
  ":engine         The internal engine for the app" \
  "--power,-p      Use powerful mode" \
  "--zoom,-z       Use zoom mode" \
  "--feature=FOO   Enable feature foo"

After describing the available parameters, you need to pass the command line parameters in for parsing and validation:

builder_parse "$@"

If any parameters are invalid, the script will be terminated by builder_parse with an error and will print the script usage help using builder_display_usage.

Build script actions

Then, check each of the potential actions, in the order that they should be run, for example:

if builder_start_action configure; then
  verify_npm_setup
  builder_finish_action success configure
fi

if builder_start_action clean; then
  npm run clean
  rm -f ./version.inc.ts
  builder_finish_action success clean
fi

if builder_start_action build; then
  npm run build -- $builder_verbose
  builder_finish_action success build
fi

Each step is run separately, is started with builder_start_action, and finishes with builder_finish_action. If a build step is complex, it may be worthwhile splitting it into a separate function or even a separate script include.

Use the longer form of if ...; then rather than the shorter [ ... ] && pattern, for consistency and readability.

Standard builder parameters

The following parameters are pre-defined and should not be overridden:

• --help, -h: displays help on using this script
• --color: forces on ANSI color output for the script
• --no-color: forces off ANSI color output for the script
• --verbose, -v: verbose mode, sets the $builder_verbose variable

Builder API functions and variables

builder_describe function

Describes a build script, defines available parameters and their meanings. Use together with builder_parse to process input parameters.

Usage

builder_describe description param_desc...

Parameters

• description: A short description of what the script does
• param_desc: Space separated name and description of parameter.

Description

The param_desc parameter has two components: first, the parameter definition, and second, an optional description for the parameter. The parameter definition must not include any spaces, and the description, if included, must be preceded by at least one space. This means that the parameters should be surrounded by quote marks so that they are treated as a single parameter, for example:

builder_describe "Sample script" \
  ":app   the app" \
  configure \
  build \
  test \
  "--print-errors,-p    Print errors"

Or, a shorthand version for a simple script:

builder_describe "Build version module" clean configure build test

Each param_desc parameter defines a target, action, or option. All parameters passed on the command line in a call to the script (prior to --, see $builder_extra_params variable) must match one of the parameters defined here.

Targets are defined by including a : prefix, for example:

builder_describe "Sample script" :engine ":proxy  the proxy module"

There are several predefined targets. These will not be available to users of your script unless you include them in the builder_describe call, but when used, they have default descriptions, which can be used instead of adding your own in the call:

• :project: "this project"
• :app: "main app"
• :engine: "engine module"
• :module: "this module"
• :tools: "build tools for this project"

Actions are defined as single words, for example:

builder_describe "Sample script build "install   installs app on local system"

There are several predefined actions. Again, these will not be available to users unless you include them in the call, but they do have default descriptions:

• clean: "remove build/ folder and build artifacts"
• configure: "install dependencies, e.g. npm"
• build: "build target(s)"
• test: "run automated tests"

The default action will be build, unless overridden by using the + suffix on a definition:

builder_describe "Testing script" clean test+

Options are defined by including a -- prefix, for example:

builder_describe "Sample script" \
  --debug,-d \
  "--out-path,-o=OUT_PATH    Specify output path"

A shorthand form may optionally be provided by appending ,-x to the parameter definition, where x is a one letter shorthand form. Currently, shorthand forms may not be combined when invoking the script -- each must be passed separately. Ensure that you do not include a space after the comma.

By default, an option will be treated as a boolean. It can be tested with builder_has_option. If you need to pass additional data, then the =<variable> format specifies an environment variable where the additional data will be stored. When using this format, it is good to use builder_has_option to test for the presence of the parameter before attempting to use the variable.

Note: although the definition uses = to define the variable, when invoking script, the value should be passed in as a separate parameter.

There is one option with a predefined description: --debug. When including this, you should use --debug,-d to enable the shorthand form.

Note that you should not include any of the standard builder parameters here.

builder_display_usage function

Prints the help for the script, constructed from the builder_describe parameters, so must be called after builder_describe.

Usage

builder_describe "sample" clean build test
builder_display_usage

$builder_extra_params variable

If a build script needs to be able to pass arbitrary additional parameters onto another tool, for example, to a test runner, then the -- parameter can be used, for example:

./build.sh test -- test-window-color --verbose

These two additional parameters will be available in the $builder_extra_params array variable, which can then be used in a call to the tool, using the ${var[@]} array expansion format:

npm test -- "${builder_extra_params[@]}"

builder_finish_action function

Finishes an action sequence. Should always be paired with builder_start_action.

Usage

if builder_start_action action:target; then
  # ... do the action
  if something_failed; then
    builder_finish_action "yeah, something failed" action:target
    exit 1
  fi
  builder_finish_action success action:target
fi

Parameters

• result: Result or message -- success, failure, or a more detailed failure message
• action: Action to test
• :target: Target to test

These last two parameters can optionally be space separated.

Description

In normal circumstances, builder_finish_action will then print a corresponding message:

## [common/web/keyman-version] action:target completed successfully

When errors arise, a failure message will be printed, and the script will abort with a non-zero exit code:

## [common/web/keyman-version] action:target failed with message: yeah, something failed

builder_has_action function

This is similar to builder_start_action, testing whether the script invocation included a specific action, but does not start the action, and thus does not print any messages to the console.

Usage

if builder_has_action action:target; then
  # ...
fi

See builder_start_action for more details.

builder_has_option function

Tests if an option has been passed in the script invocation. The option must be defined in builder_describe.

Usage

if builder_has_option --option; then
  # ...
fi

Parameters

• --option: The option to test. Must be the longhand form, and must be prefixed with --.

Description

When testing for presence of options that take additional data, the additional data variable will only be set if the option is passed in the script invocation. So builder_has_option is a clean way to test for the presence of the option in this case too:

builder_describe "Sample" "--path=OUT_PATH"
builder_parse "$@"

if builder_has_option --path; then
  echo "The output path is $OUT_PATH"
fi

builder_parse function

Initializes a build.sh script, parses command line. Will abort the script if invalid parameters are passed in. Use together with builder_describe, which sets up the possible command line parameters.

Usage

builder_parse "$@"

Description

Generally, you will always pass "$@" as the parameter for this call, to pass all the command line parameters from the script invocation, with automatically correct quoting and escaping.

builder_start_action function

Starts an action and prints a message to the console, if the user has provided the action in the script invocation.

Usage

if builder_start_action action:target; then
  # ... do the action
fi

if builder_start_action action :target; then
  # ... do the action
fi

if builder_start_action action; then
  # ... do the action for default target (:project)
fi

Parameters

• action Action to test
• :target Target to test

These two parameters can optionally be space separated.

Description

builder_start_action will only return 0 if the user passes that action as a parameter when invoking the script. If the user has passed that action in, or the action is the default (when no actions are provided), then the function will also print a log message indicating that the action has started, for example:

## [common/web/keyman-version] build:project starting...

builder_term function

Emits the parameters passed to the function, wrapped with the helper function builder_term, which wraps the passed string with $BUILDER_TERM_START and $BUILDER_TERM_END, e.g.: $(builder_term text).

Usage

builder_describe "sample" \
  "--ci    For use with action $(builder_term test) - emits CI-friendly test reports"

builder_use_color function

This will normally be managed internally by build-utils, but can be manually overridden with:

builder_use_color true
# or
builder_use_color false

$builder_verbose variable

This standard variable will be set to "--verbose", if the --verbose or -v parameter is passed on the command line, and otherwise will be set to "".

Usage

For example, can be used to pass --verbose to another app:

npm test -- $builder_verbose

# Can also be used like a standard option:
if builder_has_option --verbose; then
  # ...
fi

Formatting variables

These helper variables define ANSI color escapes when running in color mode, and resolve either to empty string (for $COLOR_*), or equivalent plain-text forms (for $BUILDER_TERM_*) when running without color:

• $BUILDER_TERM_START: Use blue to start definition of a term for builder documentation (or < in plain-text)
• $BUILDER_TERM_END: Return to standard color to finish definition of a term for builder documentation (or > in plain-text)
• $COLOR_RED: Red (error)
• $COLOR_GREEN: Green (success)
• $COLOR_BLUE: Blue (heading / informational)
• $COLOR_YELLOW: Yellow (warning)
• $COLOR_RESET: Back to default (light grey/white)
• $HEADING_SETMARK: Add a setmark, e.g. with VSCode https://code.visualstudio.com/updates/v1_69#_setmark-sequence-support

Note: it is recommended that you use $(builder_term text) instead of ${BUILDER_TERM_START}text${BUILDER_TERM_END}.