Remove temp devlab.sh immediately upon execution

[ksafranski]

The feature added in 3.3.3 which creates a temp devlab.sh to run the commands from the task currently waits until ALL execution is finished to remove the file. This means that if the task errors the file doesn't get removed.

Need to have the devlab.sh file removed immediately after it is executed to prevent issues with overwrites/permissions or accidentally committing the file to version control.

[levithomason]

I wonder if it is possible to execute this script from memory. Why does it need to be persisted to disk?

[ksafranski]

We originally had it working like that, passing the commands joined with && to /bin/sh -c at the end of the docker run command. The issue was writing and parsing the commands. The app joined newlines with &&, but if you had a before task and multiple lines in the task being executed it got messy, creating && && which would then fail.

The goal with this change was to essentially create a 1:1 of the task in a script file with set -e (to halt exec on errors), and prevent weird parsing errors.

At this point I'm thinking I may go back to in-memory and just improve the parsing of tasks.

[ksafranski]

@levithomason the PR above will resolve this issue. If you can test and give me a sign-off I'll merge and release it. May still be wonky on Circle (a problem we had with using temp before) but I can force the temp dir in that case which seems like minor inconvenience for the win of not having this build in the working dir.