Running Commands on Your Linux Instance at Launch

To pass a shell script to an instance with user data

1. Follow the procedure for launching an instance at Launching Your Instance from an AMI, but when you get to Step 6, paste the user data script text into the User data field and then complete the launch procedure. For the example below, the script creates and configures our web server.

   #!/bin/bash
   yum update -y
   yum install -y httpd24 php56 mysql55-server php56-mysqlnd
   service httpd start
   chkconfig httpd on
   groupadd www
   usermod -a -G www ec2-user
   chown -R root:www /var/www
   chmod 2775 /var/www
   find /var/www -type d -exec chmod 2775 {} +
   find /var/www -type f -exec chmod 0664 {} +
   echo "<?php phpinfo(); ?>" > /var/www/html/phpinfo.php

2. Allow enough time for the instance to launch and execute the commands in your script, and then check to see that your script has completed the tasks that you intended. For our example, in a web browser, enter the URL of the PHP test file the script created. This URL is the public DNS address of your instance followed by a forward slash and the file name.

   http://my.public.dns.amazonaws.com/phpinfo.php

   You should see the PHP information page.

   Tip

   If you are unable to see the PHP information page, check that the security group you are using contains a rule to allow HTTP (port 80) traffic. For information about adding an HTTP rule to your security group, see Adding Rules to a Security Group.

3. (Optional) If your script did not accomplish the tasks you were expecting it to, or if you just want to verify that your script completed without errors, examine the cloud-init output log file at /var/log/cloud-init-output.log and look for error messages in the output.

   For additional debugging information, you can create a Mime multipart archive that includes a cloud-init data section with the following directive:

   output : { all : '| tee -a /var/log/cloud-init-output.log' }

   This directive sends command output from your script to /var/log/cloud-init-output.log. For more information on cloud-init data formats and creating Mime multi part archive, see cloud-init Formats.

To pass cloud-init directives to an instance with user data

1. Follow the procedure for launching an instance at Launching Your Instance from an AMI, but when you get to Step 6, paste your cloud-init directive text into the User data field and then complete the launch procedure. For the example below, the directives create and configure a web server.

   #cloud-config
   repo_update: true
   repo_upgrade: all
   
   packages:
    - httpd24
    - php56
    - mysql55
    - server
    - php56-mysqlnd
   
   runcmd:
    - service httpd start
    - chkconfig httpd on
    - groupadd www
    - [ sh, -c, "usermod -a -G www ec2-user" ]
    - [ sh, -c, "chown -R root:www /var/www" ]
    - chmod 2775 /var/www
    - [ find, /var/www, -type, d, -exec, chmod, 2775, {}, + ]
    - [ find, /var/www, -type, f, -exec, chmod, 0664, {}, + ]
    - [ sh, -c, 'echo "<?php phpinfo(); ?>" > /var/www/html/phpinfo.php' ]

2. Allow enough time for the instance to launch and execute the directives in your user data, and then check to see that your directives have completed the tasks you intended. For our example, in a web browser, enter the URL of the PHP test file the directives created. This URL is the public DNS address of your instance followed by a forward slash and the file name.

   http://my.public.dns.amazonaws.com/phpinfo.php

   You should see the PHP information page.

   Tip

   If you are unable to see the PHP information page, check that the security group you are using contains a rule to allow HTTP (port 80) traffic. For information about adding an HTTP rule to your security group, see Adding Rules to a Security Group.

3. (Optional) If your directives did not accomplish the tasks you were expecting them to, or if you just want to verify that your directives completed without errors, examine the cloud-init output log file at /var/log/cloud-init-output.log and look for error messages in the output. For additional debugging information, you can add the following line to your directives:

   output : { all : '| tee -a /var/log/cloud-init-output.log' }

   This directive sends runcmd output to /var/log/cloud-init-output.log.