Flush wp db theme roots on deploy

[fullyint]

Problem

WSOD with status 200 after deploy (only if you do not navigate to wp-admin or re-activate theme)

Setup

# create DO droplet then set ip to variable
export DO_IP=xx.xx.xx.xxx
# also add IP and staging.example.com to /etc/hosts

# Prepare trellis and provision
mkdir tmp
cd tmp
git clone git@github.com:roots/trellis.git
cd trellis
ansible-galaxy install -r requirements.yml
sed -i '' "s/192.168.50.5/$DO_IP/g" hosts/staging
ansible-playbook -i hosts/staging server.yml

Deploy 1 -- no problem yet

./deploy.sh staging example.com
ssh web@$DO_IP "cd /srv/www/example.com/current && wp core install --url=http://staging.example.com --title='Example Staging Site' --admin_user=admin --admin_password=admin --admin_email=admin@example.com"
ssh web@$DO_IP "cd /srv/www/example.com/current && wp theme activate twentytwelve"

# browse to example.com -- site loads fine

# correct deploy 1 release path in stylesheet_root, template_root, transient
ssh web@$DO_IP "cd /srv/www/example.com/current && wp option get template_root && wp option get stylesheet_root && wp option get _site_transient_theme_roots"

Deploy 2 -- here's the WSOD problem due to out-of-date "theme roots" in db

./deploy.sh staging example.com

# refresh browser at example.com -- WSOD (without first going to wp-admin or activating a theme)

# incorrect deploy 1 release path in db -- should be deploy 2 release path
ssh web@$DO_IP "cd /srv/www/example.com/current && wp option get template_root && wp option get stylesheet_root && wp option get _site_transient_theme_roots"

Deploy 3 -- same WSOD, incorrect deploy 1 release path in db -- should be deploy 3 release path

Potential solution

This PR adds project_post_finalize_commands that...

• clear theme roots transients by running wp_clean_themes_cache()
• update "theme roots" by running switch_theme() to the current theme

git pull https://github.com/fullyint/trellis.git theme-roots

Deploy 4 -- no more WSOD problem

./deploy.sh staging example.com

# refresh browser at example.com -- page loads (no more WSOD)

# correct deploy 4 release path in db
ssh web@$DO_IP "cd /srv/www/example.com/current && wp option get template_root && wp option get stylesheet_root && wp option get _site_transient_theme_roots"

What's happening

Capistrano-style deploys have had trouble with out-of-date theme roots in the db, leading to a white screen. Some have addressed the issue by running a conditional search-replace on the stylesheet_root and template_root in the db.

However, it seems cleaner to run switch_theme() to the current theme, which will refresh the wp_option values for stylesheet_root and template_root. It does so via get_raw_theme_root(), which consults get_theme_roots(), which tries to use get_site_transient( 'theme_roots' ), which consults a wp_options transient named _site_transient_theme_roots.

This _site_transient_theme_roots contains absolute paths that don't update on deploy, so it points to out-of-date release directories. But, as in wp theme unit tests, if we 'wp_clean_themes_cache()', the get_theme_roots() above will search_theme_directories( true ); // Regenerate the transient, getting the release path of the latest deploy, adding it to stylesheet_root and template_root.

Any of you WP pros see any problems with this? Recommend a better solution?

[austinpray]

Ah you know what? I was running into this yesterday. Will give this a try.

[swalkinshaw]

wp core is-installed && wp eval 'wp_clean_themes_cache() && switch_theme(get_stylesheet());'

[fullyint]

Smart, thanks! I'll merge into one command, but I'll keep the if then so it doesn't return 1, which would cause playbook to fail/halt.

[swalkinshaw]

👍 assuming @austinpray's test is good

[austinpray]

Works beautifully. We had this in our previous deploy strategy: https://github.com/roots/bedrock-capistrano/blob/b4893fda905728602356e287164569aca4815a84/config/deploy.rb#L37-L56 so it's good to have it again!