Initial implementation of a spec generator package

The current Libpod pkg/spec has become a victim of the better
part of three years of development that tied it extremely closely
to the current Podman CLI. Defaults are spread across multiple
places, there is no easy way to produce a CreateConfig that will
actually produce a valid container, and the logic for generating
configs has sprawled across at least three packages.

This is an initial pass at a package that generates OCI specs
that will supersede large parts of the current pkg/spec. The
CreateConfig will still exist, but will effectively turn into a
parsed CLI. This will be compiled down into the new SpecGenerator
struct, which will generate the OCI spec and Libpod create
options.

The preferred integration point for plugging into Podman's Go API
to create containers will be the new CreateConfig, as it's less
tied to Podman's command line. CRI-O, for example, will likely
tie in here.

Signed-off-by: Matthew Heon <mheon@redhat.com>

2 files changed, 364 insertions, 1 deletions

diff --git a/libpod/container.go b/libpod/container.go
index f29cebf20..5e5c8ab26 100644
--- a/libpod/container.go
+++ b/libpod/container.go
@@ -244,7 +244,7 @@ type ContainerConfig struct {
 	// UID/GID mappings used by the storage
 	IDMappings storage.IDMappingOptions `json:"idMappingsOptions,omitempty"`
 
-	// Information on the image used for the root filesystem/
+	// Information on the image used for the root filesystem
 	RootfsImageID   string `json:"rootfsImageID,omitempty"`
 	RootfsImageName string `json:"rootfsImageName,omitempty"`
 	// Rootfs to use for the container, this conflicts with RootfsImageID
diff --git a/pkg/specgen/specgen.go b/pkg/specgen/specgen.go
new file mode 100644
index 000000000..d59e8025b
--- /dev/null
+++ b/pkg/specgen/specgen.go
@@ -0,0 +1,363 @@
+package specgen
+
+import (
+	"net"
+
+	"github.com/containers/libpod/libpod"
+	spec "github.com/opencontainers/runtime-spec/specs-go"
+)
+
+// TODO
+type Namespace struct {
+}
+
+// ContainerBasicConfig contains the basic parts of a container.
+type ContainerBasicConfig struct {
+	// Name is the name the container will be given.
+	// If no name is provided, one will be randomly generated.
+	// Optional.
+	Name string
+	// Pod is the ID of the pod the container will join.
+	// Optional.
+	Pod string
+	// Entrypoint is the container's entrypoint.
+	// If not given and Image is specified, this will be populated by the
+	// image's configuration.
+	// Optional.
+	Entrypoint []string
+	// Command is the container's command.
+	// If not given and Image is specified, this will be populated by the
+	// image's configuration.
+	// Optional.
+	Command []string
+	// Env is a set of environment variables that will be set in the
+	// container.
+	// Optional.
+	Env map[string]string
+	// Terminal is whether the container will create a PTY.
+	Terminal bool
+	// Stdin is whether the container will keep its STDIN open.
+	Stdin bool
+	// Labels are key-valid labels that are used to add metadata to
+	// containers.
+	// Optional.
+	Labels map[string]string
+	// Annotations are key-value options passed into the container runtime
+	// that can be used to trigger special behavior.
+	// Optional.
+	Annotations map[string]string
+	// StopSignal is the signal that will be used to stop the container.
+	// Must be a non-zero integer below SIGRTMAX.
+	// If not provided, the default, SIGTERM, will be used.
+	// Will conflict with Systemd if Systemd is set to "true" or "always".
+	// Optional.
+	StopSignal *uint
+	// StopTimeout is a timeout between the container's stop signal being
+	// sent and SIGKILL being sent.
+	// If not provided, the default will be used.
+	// If 0 is used, stop signal will not be sent, and SIGKILL will be sent
+	// instead.
+	// Optional.
+	StopTimeout *uint
+	// LogDriver is the container's log driver.
+	// Optional.
+	LogDriver string
+	// LogPath is the path the container's logs will be stored at.
+	// Only available if LogDriver is set to "json-file" or "k8s-file".
+	// Optional.
+	LogPath string
+	// ConmonPidFile is a path at which a PID file for Conmon will be
+	// placed.
+	// If not given, a default location will be used.
+	// Optional.
+	ConmonPidFile string
+	// RestartPolicy is the container's restart policy - an action which
+	// will be taken when the container exits.
+	// If not given, the default policy, which does nothing, will be used.
+	// Optional.
+	RestartPolicy string
+	// RestartRetries is the number of attempts that will be made to restart
+	// the container.
+	// Only available when RestartPolicy is set to "on-failure".
+	// Optional.
+	RestartRetries *uint
+	// OCIRuntime is the name of the OCI runtime that will be used to create
+	// the container.
+	// If not specified, the default will be used.
+	// Optional.
+	OCIRuntime string
+	// Systemd is whether the container will be started in systemd mode.
+	// Valid options are "true", "false", and "always".
+	// "true" enables this mode only if the binary run in the container is
+	// /sbin/init or systemd. "always" unconditionally enables systemd mode.
+	// "false" unconditionally disables systemd mode.
+	// If enabled, mounts and stop signal will be modified.
+	// If set to "always" or set to "true" and conditionally triggered,
+	// conflicts with StopSignal.
+	// If not specified, "false" will be assumed.
+	// Optional.
+	Systemd string
+	// Namespace is the libpod namespace the container will be placed in.
+	// Optional.
+	Namespace string
+
+	// PidNS is the container's PID namespace.
+	// It defaults to private.
+	// Mandatory.
+	PidNS Namespace
+
+	// UtsNS is the container's UTS namespace.
+	// It defaults to private.
+	// Must be set to Private to set Hostname.
+	// Mandatory.
+	UtsNS Namespace
+	// Hostname is the container's hostname. If not set, the hostname will
+	// not be modified (if UtsNS is not private) or will be set to the
+	// container ID (if UtsNS is private).
+	// Conflicts with UtsNS if UtsNS is not set to private.
+	// Optional.
+	Hostname string
+}
+
+// ContainerStorageConfig contains information on the storage configuration of a
+// container.
+type ContainerStorageConfig struct {
+	// Image is the image the container will be based on. The image will be
+	// used as the container's root filesystem, and its environment vars,
+	// volumes, and other configuration will be applied to the container.
+	// Conflicts with Rootfs.
+	// At least one of Image or Rootfs must be specified.
+	Image string
+	// Rootfs is the path to a directory that will be used as the
+	// container's root filesystem. No modification will be made to the
+	// directory, it will be directly mounted into the container as root.
+	// Conflicts with Image.
+	// At least one of Image or Rootfs must be specified.
+	Rootfs string
+	// ImageVolumeMode indicates how image volumes will be created.
+	// Supported modes are "ignore" (do not create), "tmpfs" (create as
+	// tmpfs), and "anonymous" (create as anonymous volumes).
+	// The default is anonymous.
+	// Optional.
+	ImageVolumeMode string
+	// VolumesFrom is a list of containers whose volumes will be added to
+	// this container. Supported mount options may be added after the
+	// container name with a : and include "ro" and "rw".
+	// Optional.
+	VolumesFrom []string
+	// Mounts are mounts that will be added to the container.
+	// These will supersede Image Volumes and VolumesFrom volumes where
+	// there are conflicts.
+	// Optional.
+	Mounts []spec.Mount
+	// Volumes are named volumes that will be added to the container.
+	// These will supersede Image Volumes and VolumesFrom volumes where
+	// there are conflicts.
+	// Optional.
+	Volumes []*libpod.ContainerNamedVolume
+	// Devices are devices that will be added to the container.
+	// Optional.
+	Devices []spec.LinuxDevice
+	// IpcNS is the container's IPC namespace.
+	// Default is private.
+	// Conflicts with ShmSize if not set to private.
+	// Mandatory.
+	IpcNS Namespace
+	// ShmSize is the size of the tmpfs to mount in at /dev/shm, in bytes.
+	// Conflicts with ShmSize if ShmSize is not private.
+	// Optional.
+	ShmSize *int64
+	// WorkDir is the container's working directory.
+	// If unset, the default, /, will be used.
+	// Optional.
+	WorkDir string
+	// RootfsPropagation is the rootfs propagation mode for the container.
+	// If not set, the default of rslave will be used.
+	// Optional.
+	RootfsPropagation string
+}
+
+// ContainerSecurityConfig is a container's security features, including
+// SELinux, Apparmor, and Seccomp.
+type ContainerSecurityConfig struct {
+	// Privileged is whether the container is privileged.
+	// Privileged does the following:
+	// - Adds all devices on the system to the container.
+	// - Adds all capabilities to the container.
+	// - Disables Seccomp, SELinux, and Apparmor confinement.
+	// TODO: this conflicts with things.
+	// TODO: this does more.
+	Privileged bool
+	// User is the user the container will be run as.
+	// Can be given as a UID or a username; if a username, it will be
+	// resolved within the container, using the container's /etc/passwd.
+	// If unset, the container will be run as root.
+	// Optional.
+	User string
+	// Groups are a list of supplemental groups the container's user will
+	// be granted access to.
+	// Optional.
+	Groups []string
+	// CapAdd are capabilities which will be added to the container.
+	// Conflicts with Privileged.
+	// Optional.
+	CapAdd []string
+	// CapDrop are capabilities which will be removed from the container.
+	// Conflicts with Privileged.
+	// Optional.
+	CapDrop []string
+	// SelinuxProcessLabel is the process label the container will use.
+	// If SELinux is enabled and this is not specified, a label will be
+	// automatically generated if not specified.
+	// Optional.
+	SelinuxProcessLabel string
+	// SelinuxMountLabel is the mount label the container will use.
+	// If SELinux is enabled and this is not specified, a label will be
+	// automatically generated if not specified.
+	// Optional.
+	SelinuxMountLabel string
+	// SelinuxOpts are options for configuring SELinux.
+	// Optional.
+	SelinuxOpts []string
+	// ApparmorProfile is the name of the Apparmor profile the container
+	// will use.
+	// Optional.
+	ApparmorProfile string
+	// SeccompProfilePath is the path to a JSON file containing the
+	// container's Seccomp profile.
+	// If not specified, no Seccomp profile will be used.
+	// Optional.
+	SeccompProfilePath string
+	// NoNewPrivileges is whether the container will set the no new
+	// privileges flag on create, which disables gaining additional
+	// privileges (e.g. via setuid) in the container.
+	NoNewPrivileges bool
+	// UserNS is the container's user namespace.
+	// It defaults to host, indicating that no user namespace will be
+	// created.
+	// If set to private, IDMappings must be set.
+	// Mandatory.
+	UserNS Namespace
+	// IDMappings are UID and GID mappings that will be used by user
+	// namespaces.
+	// Required if UserNS is private.
+	IDMappings storage.IDMappingOptions
+}
+
+// ContainerCgroupConfig contains configuration information about a container's
+// cgroups.
+type ContainerCgroupConfig struct {
+	// CgroupNS is the container's cgroup namespace.
+	// It defaults to private.
+	// Conflicts with NoCgroups if not set to host.
+	// Mandatory.
+	CgroupNS Namespace
+	// NoCgroups indicates that the container should not create CGroups.
+	// Conflicts with CgroupParent and CgroupNS if CgroupNS is not set to
+	// host.
+	NoCgroups bool
+	// CgroupParent is the container's CGroup parent.
+	// If not set, the default for the current cgroup driver will be used.
+	// Conflicts with NoCgroups.
+	// Optional.
+	CgroupParent string
+}
+
+// ContainerNetworkConfig contains information on a container's network
+// configuration.
+type ContainerNetworkConfig struct {
+	// NetNS is the configuration to use for the container's network
+	// namespace.
+	// Mandatory.
+	NetNS Namespace
+	// ConfigureNetNS is whether Libpod will configure the container's
+	// network namespace to send and receive traffic.
+	// Only available is NetNS is private - conflicts with other NetNS
+	// modes.
+	ConfigureNetNS bool
+	// StaticIP is the a IPv4 address of the container.
+	// Only available if ConfigureNetNS is true.
+	// Optional.
+	StaticIP *net.IP
+	// StaticIPv6 is a static IPv6 address to set in the container.
+	// Only available if ConfigureNetNS is true.
+	// Optional.
+	StaticIPv6 *net.IP
+	// StaticMAC is a static MAC address to set in the container.
+	// Only available if ConfigureNetNS is true.
+	// Optional.
+	StaticMAC *net.HardwareAddr
+	// PortBindings is a set of ports to map into the container.
+	// Only available if ConfigureNetNS is true.
+	// Optional.
+	PortMappings []ocicni.PortMapping
+	// PublishImagePorts will publish ports specified in the image to random
+	// ports outside.
+	// Requires Image to be set.
+	PublishImagePorts bool
+	// CNINetworks is a list of CNI networks to join the container to.
+	// If this list is empty, the default CNI network will be joined
+	// instead. If at least one entry is present, we will not join the
+	// default network (unless it is part of this list).
+	// Only available if ConfigureNetNS is true.
+	// Optional.
+	CNINetworks []string
+	// UseImageResolvConf indicates that resolv.conf should not be managed
+	// by Podman, but instead sourced from the image.
+	// Conflicts with DNSServer, DNSSearch, DNSOption.
+	UseImageResolvConf bool
+	// DNSServer is a set of DNS servers that will be used in the
+	// container's resolv.conf, replacing the host's DNS Servers which are
+	// used by default.
+	// Conflicts with UseImageResolvConf.
+	// Optional.
+	DNSServer []net.IP
+	// DNSSearch is a set of DNS search domains that will be used in the
+	// container's resolv.conf, replacing the host's DNS search domains
+	// which are used by default.
+	// Conflicts with UseImageResolvConf.
+	// Optional.
+	DNSSearch []string
+	// DNSOption is a set of DNS options that will be used in the
+	// container's resolv.conf, replacing the host's DNS options which are
+	// used by default.
+	// Conflicts with UseImageResolvConf.
+	// Optional.
+	DNSOption []string
+	// UseImageHosts indicates that /etc/hosts should not be managed by
+	// Podman, and instead sourced from the image.
+	// Conflicts with HostAdd.
+	UseImageHosts bool
+	// HostAdd is a set of hosts which will be added to the container's
+	// /etc/hosts file.
+	// Conflicts with UseImageHosts.
+	// Optional.
+	HostAdd []string
+}
+
+// ContainerResourceConfig contains information on container resource limits.
+type ContainerResourceConfig struct {
+	// ResourceLimits are resource limits to apply to the container.
+	// Can only be set as root on cgroups v1 systems, but can be set as
+	// rootless as well for cgroups v2.
+	// Optional.
+	ResourceLimits *spec.LinuxResources
+	// Rlimits are POSIX rlimits to apply to the container.
+	// Optional.
+	Rlimits []spec.POSIXRlimit
+	// OOMScoreAdj adjusts the score used by the OOM killer to determine
+	// processes to kill for the container's process.
+	// Optional.
+	OOMScoreAdj *int
+}
+
+// SpecGenerator creates an OCI spec and Libpod configuration options to create
+// a container based on the given configuration.
+type SpecGenerator struct {
+	ContainerBasicConfig
+	ContainerStorageConfig
+	ContainerSecurityConfig
+	ContainerCgroupConfig
+	ContainerNetworkConfig
+	ContainerResourceConfig
+}