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Accepted
Howard
Asked: 2012-04-12 07:07:33 +0800 CST

Chef stop and start service in sequence

  • 772

I have the following lines in my recipe

service "apache" do
  action :stop
end

# Do something..

service "apache" do
  action :start
end

I found that the 2nd block is not executed. Any reason?

chef chef-solo

5 Answers

  1. Notifications are the right way to handle this.

    Suppose you want to do the following:

    • Conditionally download a file
    • If the file is downloaded
      • Stop apache immediately
      • Process the file (e.g. unzip it or move it)
      • Start apache again

    You would do it like this:

    # Define the apache service but don't do anything with it
service "apache" do
  action :nothing
end

# Define your post-fetch script but don't actually do it
execute "process my file" do
   ... your code here
  action :nothing
  notifies :start, "service[apache]"
end

# Fetch the file. Maybe the file won't be fetched because of not_if or checksum.
# In that case apache won't be stopped or started, it will just keep running.
remote_file "/tmp/myfile" do
  source "http://fileserver/myfile"
  notifies :stop, "service[apache]", :immediately
  notifies :run, execute["process my file"]
end
    • 10

  2. The problem is that your resources have the same name. service "apache" is not unique, so chef is de-duplicating them. Your options are to give them separate names like this

    service "apache stop" do
  service_name "apache"
  action :stop
end

# Do something

service "apache start" do
  service_name "apache"
  action :start
end

    you could also use a notification from the "# Do something" block to send a :restart to the service "apache". That's the usual pattern people use, a single service, sending it notifications (or using subscribes). More here:

    http://wiki.opscode.com/display/chef/Resources#Resources-Notifications

    • 9

  3. To add to this;

    Chef does not start a service unless /etc/init.d/<DAEMON> status returns something other than 0. If it returns 0 then chef assumes that it's running.

    • 2

  4. Mray's and kgilpin's answers are perfect, but I ran into problems recently.

    Somehow mysql service didn't stop before I needed to restart it and thus my recipe failed. I used workaround using '''Execute''' resource (I need recipes working on Ubuntu only). Execute is waiting for stop/start, while service could end earlier (init script will finish, while daemon not)

    execute "Stop service" do
   command "service  stop"
end

    I not proud for this solution, but it is working for me.

    • 1
  5. Best Answer

    The default for service starts and restarts is to save it all up to the end of the chef-client run. If you really want to have two service starts or restarts, then specify that they are to happen immediately: 

    service "apache" do 
  action :start, :immediately
end

    It isn't usually a good idea to do this since multiple restarts can cause unnecessary service interruptions. That's why Chef tries to save up all the service restarts until the end of the run.

    • -1