Upstart script needs to run after /tmp is mounted and writable

Question

I have an Ubuntu Linux server that is running in a Vagrant virtual environment. I use the server for development of a web service. When the server starts up I have a shell script that needs to run once in order to setup a cache directory structure on the /tmp/ filesystem.

description "setup web cache"

start on startup

script
    mkdir -p /tmp/cache/persistent
    mkdir -p /tmp/cache/models
    mkdir -p /tmp/cache/views
    chmod -R 777 /tmp/cache/
end script

When I boot the server I get an error message that show up in /var/log/upstart/webcache.log:

mkdir: cannot create directory `/tmp/cache': Read-only file system

Apparently startup is too soon to start on. The question is, when is /tmp available for writing and what do I pass to start on?

Answer 1

Since your job needs to start when local file system is mounted most likely you need following definition: start on local-filesystems

See local-filesystem event example.

You will find overview of well known Upstart events here.

Further on, your job is a short lived job and not a service/daemon. It will be more appropriate to use task stanza. In such way you might run a job that depends on cache directories created once those directories are actually created. Otherwise, if you define all dependent jobs to start runlevel [2345] dependent job might start before needed directories are created e.g. dependent job might use following definition: start on started webcache.

description "setup web cache"

start on  local-filesystems

task

script
    mkdir -p /tmp/cache/persistent
    mkdir -p /tmp/cache/models
    mkdir -p /tmp/cache/views
    chmod -R 777 /tmp/cache/
end script

Finally, you might consider using Vagrant shell provisioner to create needed cache directories.