Detect host operating system distro in chef-solo deploy bash script - linux

Question

When deploying a chef-solo setup you need to switch between using sudo or not eg:
bash install.sh
and
sudo bash install.sh
Depending on the distro on the host server. How can this be automated?

Answer 1

ohai already populates these attributes and are readily available in your recipe
for example,
"platform": "centos",
"platform_version": "6.4",
"platform_family": "rhel",
you can reference to these as
if node[:platform_family].include?("rhel")
...
end
To see what other attributes ohai sets, just type
ohai
on the command line.

Answer 2

You can detect the distro on the remote host and deploy accordingly. in deploy.sh:
DISTRO=`ssh -o 'StrictHostKeyChecking no' ${host} 'bash -s' < bootstrap.sh`
The DISTRO variable is populated by whatever is echoed by the bootstrap.sh script, which is run on the host machine. So we can now use bootstrap.sh to detect the distro or any other server settings we need to and echo, which will be bubbled to the local script and you can respond accordingly.
example deploy.sh:
#!/bin/bash
# Usage: ./deploy.sh [host]
host="${1}"
if [ -z "$host" ]; then
echo "Please provide a host - eg: ./deploy root#my-server.com"
exit 1
fi
echo "deploying to ${host}"
# The host key might change when we instantiate a new VM, so
# we remove (-R) the old host key from known_hosts
ssh-keygen -R "${host#*#}" 2> /dev/null
# rough test for what distro the server is on
DISTRO=`ssh -o 'StrictHostKeyChecking no' ${host} 'bash -s' < bootstrap.sh`
if [ "$DISTRO" == "FED" ]; then
echo "Detected a Fedora, RHEL, CentOS distro on host"
tar cjh . | ssh -o 'StrictHostKeyChecking no' "$host" '
rm -rf /tmp/chef &&
mkdir /tmp/chef &&
cd /tmp/chef &&
tar xj &&
bash install.sh'
elif [ "$DISTRO" == "DEB" ]; then
echo "Detected a Debian, Ubuntu distro on host"
tar cj . | ssh -o 'StrictHostKeyChecking no' "$host" '
sudo rm -rf ~/chef &&
mkdir ~/chef &&
cd ~/chef &&
tar xj &&
sudo bash install.sh'
fi
example bootstrap.sh:
#!/bin/bash
# Fedora/RHEL/CentOS distro
if [ -f /etc/redhat-release ]; then
echo "FED"
# Debian/Ubuntu
elif [ -r /lib/lsb/init-functions ]; then
echo "DEB"
fi
This will allow you to detect the platform very early in the deploy process.