aheumaier / demo-packer-testing

Best practice of a multiplatform packer build and testing workflow with testinfra

Packer image testing with testinfra

Introduction

Since working on a packer remote host in a local manner is not always sufficient packer provides hook functions like build to access the random generated attributes at run time. Take a look here to read the full documentation.

So we can easily use expression like the following to retrieve Host, User, SSHPrivateKey information:

{
    "type": "shell-local",
    "environment_vars": [
        "key={{build `SSHPrivateKey`}}"
    ],
    "inline": [
        "echo '{{ build `SSHPrivateKey`}}' > /tmp/packer_rsa",
        "chmod 600 /tmp/packer_rsa",
        "ssh-add /tmp/packer_rsa"
        ]
},
{
    "type": "shell-local",
    "environment_vars": [
        "user={{build `User`}}",
        "host={{build `Host`}}"
    ],
    "script": "teardown.sh"
}

Setup

We run the following cycle to setup and relaese images calling make:

=> packer validate
=> packer build:
    => "setup.sh"
    => "prepare ssh connection via ssh-agent"
    => "teardown.sh" - includes running testinfra against the image
=> finish after successful integration run

Testing

We are runnig testinfa using pytest at the last teardown stage: pytest --ssh-identity-file=/tmp/packer_rsa --hosts=ssh://${user}@${host} picking up all infra test files starting with test_ like test_build_integration.py

import pytest

def test_host_system(host):
    '''
    Check properties of the host system.
    '''
    system_type = 'linux'
    distribution = 'ubuntu'
    release = '18.04'

    assert system_type == host.system_info.type
    assert distribution == host.system_info.distribution
    assert release == host.system_info.release