Add default for log-tag

Needed for containers/podman#10204

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

docs/containers.conf.5.md

@@ -186,6 +186,10 @@ that no size limit is imposed. If it is positive, it must be >= 8192 to
 match/exceed conmon's read buffer. The file is truncated and re-opened so the
 limit is never exceeded.
 
+**log_tag**=""
+
+Default format tag for container log messages.  This is useful for creating a specific tag for container log messages. Container log messages default to using the truncated container ID as a tag.
+
 **netns**="private"
 
 Default way to to create a NET namespace for the container.

pkg/config/config.go

@@ -137,6 +137,11 @@ type ContainersConfig struct {
 	// Negative values indicate that the log file won't be truncated.
 	LogSizeMax int64 `toml:"log_size_max,omitempty"`
 
+	// Specifies default format tag for container log messages.
+	// This is useful for creating a specific tag for container log messages.
+	// Containers logs default to truncated container ID as a tag.
+	LogTag string `toml:"log_tag,omitempty"`
+
 	// NetNS indicates how to create a network namespace for the container
 	NetNS string `toml:"netns,omitempty"`
 

pkg/config/config_test.go

@@ -329,6 +329,9 @@ var _ = Describe("Config", func() {
 			gomega.Expect(err).To(gomega.BeNil())
 			gomega.Expect(config).ToNot(gomega.BeNil())
 			gomega.Expect(config.Containers.ApparmorProfile).To(gomega.Equal("overridden-default"))
+			gomega.Expect(config.Containers.LogDriver).To(gomega.Equal("journald"))
+			gomega.Expect(config.Containers.LogTag).To(gomega.Equal("{{.Name}}|{{.ID}}"))
+			gomega.Expect(config.Containers.LogSizeMax).To(gomega.Equal(int64(100000)))
 			gomega.Expect(config.Engine.ImageParallelCopies).To(gomega.Equal(uint(10)))
 			gomega.Expect(config.Engine.ImageDefaultFormat).To(gomega.Equal("v2s2"))
 		})

pkg/config/containers.conf

@@ -166,6 +166,12 @@ default_sysctls = [
 #
 # log_size_max = -1
 
+# Specifies default format tag for container log messages.
+# This is useful for creating a specific tag for container log messages.
+# messages. Containers logs default to truncated container ID as a tag.
+#
+# log_tag = ""
+
 # Default way to to create a Network namespace for the container
 # Options are:
 # `private` Create private Network Namespace for the container.

pkg/config/testdata/containers_override.conf

@@ -1,6 +1,9 @@
 [containers]
 
 apparmor_profile = "overridden-default"
+log_driver = "journald"
+log_tag="{{.Name}}|{{.ID}}"
+log_size_max = 100000
 
 [engine]
 image_parallel_copies=10