Making a build show as failed or succeeded

By default, the build script executed when building an environment on Dropsolid Experience Platform will fail or succeed based on the result of the last command executed in the script.

This may or may not be the expected result, but you can create a more opinionated version so you can rely on the outcome of a build.

Ways to fail the build script

On first error

Depending on what your script does during a build, it can be useful to just stop the script when an error occurs.

Add following line after the shebang line in your script

set -o errexit

There are some caveats you need to be aware of (scripts failing when they shouldn't), see http://mywiki.wooledge.org/BashFAQ/105

Opinionated

A more useful way is to determine per project if how and when you want to fail or succeed a build. The key concept is that you can get the exit code of the last command that ran with $?

example script

    #/bin/bash
    command_result=0

    a_command
    command_result=$(( $command_result + $? ))

    a_command_that_can_fail

    a_command_that_should_fail_immediately || exit 1

    another_commandcommand_result=$(( $command_result + $? ))

    # exit with the combined exit code of all commands that mattered
    exit $command_result

• when a_command a_command_that_should_fail_immediately and another_commandsucceed, the exit code will be 0, marking the build as passed
• when a_command a_command_that_should_fail_immediately or another_commandfails, the exit code would be > 0, marking the build as failed..
• If a_command_that_should_fail_immediately fails, the script will stop immediately, marking the build as failed
• a_command_that_can_fail can fail, it won't affect the outcome of the script.

Other possibilities when an opinionated build fails

As we can store the exit code of every command, we can also react on it.

• create a db dump in the beginning of the script, an restore it on failure (be aware that code changes won't be restored)
• keep the site in maintenance mode until the error is reviewed
• retry certain commands when they fail (don't create endless loops!)

More info

• https://www.cyberciti.biz/faq/bash-get-exit-code-of-command/
• https://www.linuxjournal.com/content/bash-trap-command