[BUG] `/etc/mariner-release` check in `get_distro()` is dead code on Azure Linux — potential footgun

[jonathanbrenes]

Describe the bug:

get_distro() checks for /etc/mariner-release to override osinfo[0] to "mariner". On Azure Linux, this file does not exist — the distro ships /etc/azurelinux-release instead.

WALinuxAgent/azurelinuxagent/common/version.py

Line 137 in a976115

if os.path.exists("/etc/mariner-release"):

Distro detection works correctly today because get_linux_distribution() (called earlier in the function) reads /etc/os-release (ID=azurelinux) and returns "azurelinux" before the /etc/mariner-release override is reached.

However, the dead code is a potential footgun:

• If /etc/mariner-release is ever added to Azure Linux for backward compatibility, it would incorrectly override "azurelinux" back to "mariner" because the if block runs after get_linux_distribution().
• There is no corresponding /etc/azurelinux-release check in the code for consistency with the other distro-specific overrides (oracle, euleros, photonos, etc.).

Current flow in get_distro():

osinfo = get_linux_distribution(0, 'alpine')  # returns 'azurelinux' from os-release
...
if os.path.exists("/etc/mariner-release"):  # does NOT exist on AZL — skipped
    osinfo[0] = "mariner"
# No check for /etc/azurelinux-release

Steps to reproduce:

python3 -c "import azurelinuxagent.common.version as v; print(v.DISTRO_NAME)"
# azurelinux  <-- works correctly today

ls /etc/*-release
# /etc/azurelinux-release  /etc/os-release  /etc/system-release
# No /etc/mariner-release exists

Distro and WALinuxAgent details:

• Distro and Version: Azure Linux
• WALinuxAgent version: 2.15.0.1 (waagent-2.15.0.1-1.azl4)

Additional context

This is a low-severity/informational issue. No functional impact today. Filing for awareness so the team can decide whether to:

1. Add an /etc/azurelinux-release check for consistency
2. Remove the /etc/mariner-release override entirely (since os-release handles detection)
3. Leave as-is if considered harmless

Log file attached

N/A — no functional failure, detection works correctly.

[eric-desrochers]

Preference would be to rely on /etc/os-release for distro detection looking for these 2 fields/values:

ID=azurelinux
VERSION_ID=4.0