Most of the DevOps tools are still in beta versions, many times the new version is not compatible with your existing scripts or have an error that stops your scripts working. To be able to keep multiple versions of the applications and easily switch between them, create symbolic links and point to the version you want to execute.

Create version-specific locations

Create a folder for your optional applications.

mkdir /opt

Set you as the owner of the “opt” directory and its children.

YOUR_GROUP should be on:

• MacOS: wheel
• Ubuntu: your username 

sudo chown -R YOUR_USER_NAME:YOUR_GROUP /opt

Set the security of the folder.

sudo chmod 755 /opt

We will create a directory structure to place each version of the application into its own folder. This example uses Packer.

Create a symbolic link to point to the application in the appropriate version folder. These are the examples for Packer, Terraform, and Vagrant. Notice, that the Vagrant application is in the “bin” directory, so the symbolic link has to point there.

If there is an existing symbolic link that points to the latest version of the application, rename it to be able to quickly return to the prior version of the application. This can come handy when we need to destroy instances created with the prior version of Terraform.

cd /opt/terraform
mv terraform terraform_v_0.9.11

cd /opt/packer
mv packer packer_v_1.0.4

Create a new symbolic link that points to the latest version of the application.

# For Packer
cd /opt/packer
ln -s /opt/packer/packer_1.2.0/packer packer

# For Terraform
cd /opt/terraform
ln -s /opt/terraform/terraform_0.10.0/terraform terraform

# For Vagrant
cd /opt/vagrant
ln -s /opt/vagrant/vagrant_1.9.5/bin/vagrant vagrant #The vagrant application is in the bin folder

Add the main application folder to the path in the config file of your terminal

• for iTerm2 with zterminal: ~/.zshrc
• for other terminals: ~/.bash_profile

PATH=/opt/packer:$PATH
PATH=/opt/terraform:$PATH
PATH=/opt/vagrant:$PATH

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Vagrant

For Vagrant installation see Vagrant

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To change the version you want to execute

• Delete the symbolic link,

  cd /opt/packer
  rm packer

• Create a new symbolic link pointing to the other version of the application as above.