First start after make is unstable

[Djennez]

If the containers are newly created and installed (after a clean and make), there is a chance that a few things have failed to run. WordPress is sometimes not correctly installed and databases sometimes don't boot correctly. Powering down the containers and running start.sh generally fixes this.

[Djennez]

@herregroen @noud-github can this maybe be solved by moving the installation of the containers + content to the make.sh, and using start.sh just for bringing the containers up and down?

[moorscode]

I believe that using ./wp.sh to test against wp core is-installed is a bit more reliable than the current method.

[moorscode]

if ! $(./wp.sh $CONTAINER core is-installed); then