config: add CompressionLevel to containers.conf

docs/containers.conf.5.md

@@ -723,6 +723,13 @@ the primary uid/gid of the container.
 
 Specifies the compression format to use when pushing an image. Supported values are: `gzip`, `zstd` and `zstd:chunked`.
 
+**compression_level**="5"
+
+The compression level to use when pushing an image. Valid options
+depend on the compression format used. For gzip, valid options are
+1-9, with a default of 5. For zstd, valid options are 1-20, with a
+default of 3.
+
 ## SERVICE DESTINATION TABLE
 The `engine.service_destinations` table contains configuration options used to set up remote connections to the podman service for the podman API.
 

pkg/config/config.go

@@ -510,6 +510,9 @@ type EngineConfig struct {
 
 	// CompressionFormat is the compression format used to compress image layers.
 	CompressionFormat string `toml:"compression_format,omitempty"`
+
+	// CompressionLevel is the compression level used to compress image layers.
+	CompressionLevel *int `toml:"compression_level,omitempty"`
 }
 
 // SetOptions contains a subset of options in a Config. It's used to indicate if

pkg/config/config_test.go

@@ -34,6 +34,7 @@ var _ = Describe("Config", func() {
 			gomega.Expect(defaultConfig.Containers.ReadOnly).To(gomega.BeFalse())
 			gomega.Expect(defaultConfig.Engine.ServiceTimeout).To(gomega.BeEquivalentTo(5))
 			gomega.Expect(defaultConfig.Engine.CompressionFormat).To(gomega.BeEquivalentTo("gzip"))
+			gomega.Expect(defaultConfig.Engine.CompressionLevel).To(gomega.BeNil())
 			gomega.Expect(defaultConfig.NetNS()).To(gomega.BeEquivalentTo("private"))
 			gomega.Expect(defaultConfig.IPCNS()).To(gomega.BeEquivalentTo("shareable"))
 			gomega.Expect(defaultConfig.Engine.InfraImage).To(gomega.BeEquivalentTo(""))

pkg/config/containers.conf

@@ -381,6 +381,12 @@ default_sysctls = [
 #
 #compression_format = "gzip"
 
+# The compression level to use when pushing an image.
+# Valid options depend on the compression format used.
+# For gzip, valid options are 1-9, with a default of 5.
+# For zstd, valid options are 1-20, with a default of 3.
+#
+#compression_level = 5
 
 # Cgroup management implementation used for the runtime.
 # Valid options "systemd" or "cgroupfs"

pkg/config/containers.conf-freebsd

@@ -311,6 +311,13 @@ default_sysctls = [
 #
 #compression_format = "gzip"
 
+# The compression level to use when pushing an image.
+# Valid options depend on the compression format used.
+# For gzip, valid options are 1-9, with a default of 5.
+# For zstd, valid options are 1-20, with a default of 3.
+#
+#compression_level = 5
+
 # Environment variables to pass into conmon
 #
 #conmon_env_vars = [