Check for systemd (in distros/rhel.py) is fragile

[ubuntu-server-builder]

This bug was originally filed in Launchpad as LP: #1461201

Launchpad details

affected_projects = []
assignee = None
assignee_name = None
date_closed = None
date_created = 2015-06-02T18:10:04.507759+00:00
date_fix_committed = None
date_fix_released = None
id = 1461201
importance = low
is_complete = False
lp_url = https://bugs.launchpad.net/cloud-init/+bug/1461201
milestone = None
owner = larsks
owner_name = Lars Kellogg-Stedman
private = False
status = confirmed
submitter = larsks
submitter_name = Lars Kellogg-Stedman
tags = []
duplicates = []

Launchpad user Lars Kellogg-Stedman(larsks) wrote on 2015-06-02T18:10:04.507759+00:00

The existing cloud-init code determines if systemd is in use by looking at the distribution name and version. This is prone to error because:

• RHEL derivatives other than CentOS (e.g., Scientific Linux) will fail this test, and
• Distributions that are not derived from RHEL also use systemd

[ubuntu-server-builder]

Launchpad user Lars Kellogg-Stedman(larsks) wrote on 2015-06-02T18:11:05.214429+00:00

The attached patch uses the same semantics as systemd's "sd_booted()" method to determine if systemd was used to boot the system. This should work independent of distribution or version, making it a much more robust mechanism for detecting if systemd is in use.
Launchpad attachments: 0001-detect-systemd-using-sd_booted-semantics.patch

[ubuntu-server-builder]

Launchpad user Lars Kellogg-Stedman(larsks) wrote on 2015-06-02T20:31:13.440681+00:00

Proposed via launchpad as https://code.launchpad.net/~larsks/cloud-init/fix-systemd-detection/+merge/260885