Do not share container log driver for exec

When the container uses journald logging, we don't want to
automatically use the same driver for its exec sessions. If we do
we will pollute the journal (particularly in the case of
healthchecks) with large amounts of undesired logs. Instead,
force exec sessions logs to file for now; we can add a log-driver
flag later (we'll probably want to add a `podman logs` command
that reads exec session logs at the same time).

As part of this, add support for the new 'none' logs driver in
Conmon. It will be the default log driver for exec sessions, and
can be optionally selected for containers.

Great thanks to Joe Gooch (mrwizard@dok.org) for adding support
to Conmon for a null log driver, and wiring it in here.

Fixes #6555

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

2 files changed, 6 insertions, 0 deletions

diff --git a/libpod/define/config.go b/libpod/define/config.go
index 5ca4da4af..900a363d8 100644
--- a/libpod/define/config.go
+++ b/libpod/define/config.go
@@ -72,3 +72,6 @@ const KubernetesLogging = "k8s-file"
 
 // JSONLogging is the string conmon expects when specifying to use the json logging format
 const JSONLogging = "json-file"
+
+// NoLogging is the string conmon expects when specifying to use no log driver whatsoever
+const NoLogging = "none"
diff --git a/libpod/define/errors.go b/libpod/define/errors.go
index 083553b7e..e0c9811fe 100644
--- a/libpod/define/errors.go
+++ b/libpod/define/errors.go
@@ -79,6 +79,9 @@ var (
 	// ErrNoCgroups indicates that the container does not have its own
 	// CGroup.
 	ErrNoCgroups = errors.New("this container does not have a cgroup")
+	// ErrNoLogs indicates that this container is not creating a log so log
+	// operations cannot be performed on it
+	ErrNoLogs = errors.New("this container is not logging output")
 
 	// ErrRootless indicates that the given command cannot but run without
 	// root.