From c5fc44582fcda107977ded15ec9e4c5723d86430 Mon Sep 17 00:00:00 2001
From: Valentin Rothberg <vrothberg@redhat.com>
Date: Thu, 23 Mar 2023 11:08:20 +0100
Subject: [PATCH] add CONTAINERS_CONF_OVERRIDE

Add yet another environment variable for loading containers.conf.
When CONTAINERS_CONF_OVERRIDE is set, the specified config file
will be loaded last - even when CONTAINERS_CONF is set.

This mechanism is needed to preserve system settings and other
environment variables.  Setting CONTAINERS_CONF will load only
the specified config file and ignore all system and user paths.
That makes testing hard as many Podman tests use CONTAINERS_CONF
for testing.

The intended use of CONTAINERS_CONF_OVERRIDE is to set it during tests
and point it to a specific configuration of Podman (e.g., netavark with
sqlite backend).

Similar needs have popped up talking to users in the automotive and
high-performance computing space.  In a way, such a setting allows for
specifying a specific "flavor" of Podman while preserving all existing
settings on the system.

Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>
---
 test/system/005-info.bats | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/test/system/005-info.bats b/test/system/005-info.bats
index 42ea58a1d6..7c6bcf997e 100644
--- a/test/system/005-info.bats
+++ b/test/system/005-info.bats
@@ -182,4 +182,30 @@ host.slirp4netns.executable | $expr_path
     is "$output" "Error: unsupported database backend: \"bogus\""
 }
 
+@test "CONTAINERS_CONF_OVERRIDE" {
+    skip_if_remote "remote does not support CONTAINERS_CONF*"
+
+    containersConf=$PODMAN_TMPDIR/containers.conf
+    cat >$containersConf <<EOF
+[engine]
+database_backend = "boltdb"
+EOF
+
+    overrideConf=$PODMAN_TMPDIR/override.conf
+    cat >$overrideConf <<EOF
+[engine]
+database_backend = "sqlite"
+EOF
+
+    CONTAINERS_CONF="$containersConf" run_podman info --format "{{ .Host.DatabaseBackend }}"
+    is "$output" "boltdb"
+
+    CONTAINERS_CONF_OVERRIDE=$overrideConf run_podman info --format "{{ .Host.DatabaseBackend }}"
+    is "$output" "sqlite"
+
+    # CONTAINERS_CONF will be overriden by _OVERRIDE
+    CONTAINERS_CONF=$containersConf CONTAINERS_CONF_OVERRIDE=$overrideConf run_podman info --format "{{ .Host.DatabaseBackend }}"
+    is "$output" "sqlite"
+}
+
 # vim: filetype=sh