Clean up cached machine images

When initing machines, we download a machine image, and uncompress and
copy the image for the actual vm image. When a user constantly pulls new
machines, there may be a buildup of old, unused machine images. This
commit cleans ups the unused cached images.

Changes:
- If the machine is pulled from a URL or from the FCOS releases, we pull
  them into XDG_DATA_HOME/containers/podman/machine/vmType/cache
- Cache cleanups only happen if there is a cache miss, and we need to
  pull a new image
- For Fedora and FCOS, we actually use the cache, so we go through the
  cache dir and remove any images older than 2 weeks (FCOS's release cycle), on a cache miss.
- For generic files pulled from a URL, we don't actually cache, so we
  delete the pulled file immediately after creating a machine image
- For generic files from a local path, the original file will never be
  cleaned up

Note that because we cache in a different dir, this will not clean up
old images pulled before this commit.

[NO NEW TESTS NEEDED]

Signed-off-by: Ashley Cui <acui@redhat.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/pkg/machine/config.go b/pkg/machine/config.go
index 29cd7bc00..253601dad 100644
--- a/pkg/machine/config.go
+++ b/pkg/machine/config.go
@@ -73,6 +73,7 @@ type Download struct {
 	Arch                  string
 	Artifact              string
 	CompressionType       string
+	CacheDir              string
 	Format                string
 	ImageName             string
 	LocalPath             string
@@ -139,6 +140,7 @@ type VM interface {
 type DistributionDownload interface {
 	HasUsableCache() (bool, error)
 	Get() *Download
+	CleanCache() error
 }
 type InspectInfo struct {
 	ConfigPath     VMFile
@@ -172,6 +174,19 @@ func (rc RemoteConnectionType) MakeSSHURL(host, path, port, userName string) url
 	return uri
 }
 
+// GetCacheDir returns the dir where VM images are downladed into when pulled
+func GetCacheDir(vmType string) (string, error) {
+	dataDir, err := GetDataDir(vmType)
+	if err != nil {
+		return "", err
+	}
+	cacheDir := filepath.Join(dataDir, "cache")
+	if _, err := os.Stat(cacheDir); !errors.Is(err, os.ErrNotExist) {
+		return cacheDir, nil
+	}
+	return cacheDir, os.MkdirAll(cacheDir, 0755)
+}
+
 // GetDataDir returns the filepath where vm images should
 // live for podman-machine.
 func GetDataDir(vmType string) (string, error) {
@@ -180,7 +195,7 @@ func GetDataDir(vmType string) (string, error) {
 		return "", err
 	}
 	dataDir := filepath.Join(dataDirPrefix, vmType)
-	if _, err := os.Stat(dataDir); !os.IsNotExist(err) {
+	if _, err := os.Stat(dataDir); !errors.Is(err, os.ErrNotExist) {
 		return dataDir, nil
 	}
 	mkdirErr := os.MkdirAll(dataDir, 0755)
@@ -205,7 +220,7 @@ func GetConfDir(vmType string) (string, error) {
 		return "", err
 	}
 	confDir := filepath.Join(confDirPrefix, vmType)
-	if _, err := os.Stat(confDir); !os.IsNotExist(err) {
+	if _, err := os.Stat(confDir); !errors.Is(err, os.ErrNotExist) {
 		return confDir, nil
 	}
 	mkdirErr := os.MkdirAll(confDir, 0755)