Troubleshooting

Force a redeploy

There are times where you might want to trigger a redeployment of your application. This requires pushing a new Git commit (which can be empty) or setting a variable. It is not recommended to do this if there are builds in a "Pending" state, as these will block deployment. Wait for those builds to complete.

Redeploying using the Platform.sh CLI:

platform vset redeploy "$(date)"

Using Git only:

git commit --allow-empty -m 'force redeploy'
git push platform <branch-name>

HTTP 502 response

If you receive HTTP 502 responses from your site, it means that your site is running out of workers, or the application process is crashing. Here are the typical causes:

  • The amount of traffic coming to your site exceeds the processing power of your application.
  • Certain code path(s) in your application are too slow.
  • A PHP process is crashing because of a segmentation fault.
  • A PHP process is killed by the kernel out-of-memory killer.

Too much traffic or a slow application

If your PHP application is not able to handle the amount of traffic or it is slow, you should see log lines from /var/log/app.log like any of the below:

WARNING: [pool web] server reached max_children setting (2), consider raising it
WARNING: [pool web] child 120, script '/app/public/index.php' (request: "GET /index.php") execution timed out (358.009855 sec), terminating

When you see "execution timed out", that means your application is probably having a infinite loop or the work itself requires a long time to complete. For the latter case, you should consider putting the task into a background job.

When you see "server reached max_children setting", the web traffic exceeded the capacity that your application can handle. You can use the below example Platform.sh CLI command to find the top 20 slowest requests in the last hour.

platform ssh "grep $(date +%Y-%m-%dT%H --date='-1 hours') /var/log/php.access.log | sort -k 4 -r -n | head -20"

If you see that the processing time of certain requests is slow (e.g. taking more than 1000ms), you may wish to consider using a profiler like Blackfire to debug the performance issue.

Otherwise, you may check if the following options are applicable:

  • Find the most visited pages and see if they can be cached and/or put behind a CDN. You may refer to how caching works.
  • Upgrade your subscription on Platform.sh to get more computing resources. To do so, log into your account and edit the project subscription.

PHP process crashed

If your PHP process crashed with a segmentation fault, you should see log lines in /var/log/app.log like below:

WARNING: [pool web] child 112 exited on signal 11 (SIGSEGV) after 7.405936 seconds from start

This is complicated, either a PHP extension is hitting a segmentation fault or your PHP application code is crashing. You should review recent changes in your application and try to find the cause of it, probably with the help of XDebug.

PHP process is killed

If your PHP process is killed by the kernel, you should see log lines in /var/log/app.log like this:

WARNING: [pool web] child 429 exited on signal 9 (SIGKILL) after 50.938617 seconds from start

The memory usage of your container exceeds the limit, the kernel thus kills the offending process. You should try the following:

  • Check if the memory usage of your application is expected and try to optimize it.
  • Use sizing hints to reduce the amount of PHP workers which reduces the memory footprint.
  • Upgrade your subscription on Platform.sh to get more computing resources. To do so, log into your account and edit the project.

Stuck build or deployment

If you see a build or deployment running longer than expected, that may be one of the following cases:

  1. The build is blocked by a process in your build hook.
  2. The deployment is blocked by a long running process in your deploy hook.
  3. The deployment is blocked by a long running cron job in the environment.
  4. The deployment is blocked by a long running cron job in the parent environment.

To determine if your environment is being stuck in the build or the deployment, you should look at the build log available on the UI. When you see a log line like below, your application is built and the deployment is stuck:

Re-deploying environment w6ikvtghgyuty-drupal8-b3dsina.

Here are the things you should do when you see your build or deployment is stuck:

For a blocked build (when you don't find the Re-deployment environment ... line), you have to create a support ticket to let us kill it.

When a deployment is blocked, you should try the following:

  1. Use SSH to connect to your environment. Find any long-running cron jobs on the environment by running ps afx. Once you have identified the long running process on the environment, kill it.
  2. If you're performing "Sync", "Merge", or "Activate" on an environment and the process is stuck, use SSH to connect to the parent environment and identify any long running cron jobs with ps afx. Kill the job(s) if you see any.
  3. If you couldn't find any long running process on your environment or parent environment, or you cannot use SSH to connect to your environment, please create a support ticket.

MySQL lock wait timeout

If you receive MySQL error messages like this:

SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded;

This means a process running in your application acquired a lock from MySQL for a long period of time. That is typically caused by one of the following:

  • There are multiple places acquiring locks in different order. For example, code path 1 first locks record A and then locks record B. Code path 2, in contrast, first locks record B and then locks record A.
  • There is a long running background process executed by your application that holds the lock until it ends.

If you're using MariaDB 10+, you can use the SQL query SHOW FULL PROCESSLIST \G to list DB queries waiting for locks. Find output like the following, and start debugging.

< skipped >
Command: Query
Time: ...
State: Waiting for table metadata lock
Info: SELECT ...
< skipped >

To find active background processes, run ps aufx on your application container.

Also, please make sure that locks are acquired in a pre-defined order and released as soon as possible.

"Read-only file system" error

Everything will be read-only, except the writable mounts you declare. Writable mounts are there for your data: for file uploads, logs and temporary files. Not for your code. In order to change code on Platform.sh you have to go through Git.

This is what gives you all of the benefits of having repeatable deployments, consistent backups, traceability, and the magically fast creation of new staging/dev environments.

In Platform.sh, you cannot just "hack production". It is a constraint, but it is a good constraint.

During the build phase of your application, the main filesystem is writable. So you can do whatever you want (e.g. compile code or generate anything you need). But during and after the deploy phase, the main filesystem will be read-only.

"File not found" in Drupal

If you see a bare "File not found" error when accessing your Drupal site with a browser, this means that you've pushed your code as a vanilla project but no index.php has been found.

Make sure your repository contains an index.php file in the web location root, or that your Drush make files are properly named.