terraform/internal/providercache/dir_modify.go

125 lines
4.9 KiB
Go

package providercache
import (
"context"
"fmt"
"log"
"os"
"path/filepath"
"github.com/hashicorp/terraform/internal/copydir"
"github.com/hashicorp/terraform/internal/getproviders"
)
// InstallPackage takes a metadata object describing a package available for
// installation, retrieves that package, and installs it into the receiving
// cache directory.
func (d *Dir) InstallPackage(ctx context.Context, meta getproviders.PackageMeta) error {
if meta.TargetPlatform != d.targetPlatform {
return fmt.Errorf("can't install %s package into cache directory expecting %s", meta.TargetPlatform, d.targetPlatform)
}
newPath := getproviders.UnpackedDirectoryPathForPackage(
d.baseDir, meta.Provider, meta.Version, d.targetPlatform,
)
log.Printf("[TRACE] providercache.Dir.InstallPackage: installing %s v%s from %s", meta.Provider, meta.Version, meta.Location)
switch location := meta.Location.(type) {
case getproviders.PackageHTTPURL:
return installFromHTTPURL(ctx, string(location), newPath)
case getproviders.PackageLocalArchive:
return installFromLocalArchive(ctx, string(location), newPath)
case getproviders.PackageLocalDir:
return installFromLocalDir(ctx, string(location), newPath)
default:
// Should not get here, because the above should be exhaustive for
// all implementations of getproviders.Location.
return fmt.Errorf("don't know how to install from a %T location", location)
}
}
// LinkFromOtherCache takes a CachedProvider value produced from another Dir
// and links it into the cache represented by the receiver Dir.
//
// This is used to implement tiered caching, where new providers are first
// populated into a system-wide shared cache and then linked from there into
// a configuration-specific local cache.
//
// It's invalid to link a CachedProvider from a particular Dir into that same
// Dir, because that would otherwise potentially replace a real package
// directory with a circular link back to itself.
func (d *Dir) LinkFromOtherCache(entry *CachedProvider) error {
newPath := getproviders.UnpackedDirectoryPathForPackage(
d.baseDir, entry.Provider, entry.Version, d.targetPlatform,
)
currentPath := entry.PackageDir
log.Printf("[TRACE] providercache.Dir.LinkFromOtherCache: linking %s v%s from existing cache %s to %s", entry.Provider, entry.Version, currentPath, newPath)
absNew, err := filepath.Abs(newPath)
if err != nil {
return fmt.Errorf("failed to make new path %s absolute: %s", newPath, err)
}
absCurrent, err := filepath.Abs(currentPath)
if err != nil {
return fmt.Errorf("failed to make existing cache path %s absolute: %s", currentPath, err)
}
// Before we do anything else, we'll do a quick check to make sure that
// these two paths are not pointing at the same physical directory on
// disk. This compares the files by their OS-level device and directory
// entry identifiers, not by their virtual filesystem paths.
if same, err := copydir.SameFile(absNew, absCurrent); same {
return fmt.Errorf("cannot link existing cache path %s to itself", newPath)
} else if err != nil {
return fmt.Errorf("failed to determine if %s and %s are the same: %s", currentPath, newPath, err)
}
// Invalidate our metaCache so that subsequent read calls will re-scan to
// incorporate any changes we make here.
d.metaCache = nil
// Delete anything that's already present at this path first.
err = os.RemoveAll(newPath)
if err != nil && !os.IsNotExist(err) {
return fmt.Errorf("failed to remove existing %s before linking it to %s: %s", currentPath, newPath, err)
}
// We'll prefer to create a symlink if possible, but we'll fall back to
// a recursive copy if symlink creation fails. It could fail for a number
// of reasons, including being on Windows 8 without administrator
// privileges or being on a legacy filesystem like FAT that has no way
// to represent a symlink. (Generalized symlink support for Windows was
// introduced in a Windows 10 minor update.)
//
// We'd prefer to use a relative path for the symlink to reduce the risk
// of it being broken by moving things around later, but we'll fall back
// on the absolute path we already calculated if that isn't possible
// (e.g. because the two paths are on different "volumes" on an OS with
// that concept, like Windows with drive letters and UNC host/share names.)
linkTarget, err := filepath.Rel(newPath, absCurrent)
if err != nil {
linkTarget = absCurrent
}
parentDir := filepath.Dir(absNew)
err = os.MkdirAll(parentDir, 0755)
if err != nil && os.IsExist(err) {
return fmt.Errorf("failed to create parent directories leading to %s: %s", newPath, err)
}
err = os.Symlink(linkTarget, absNew)
if err == nil {
// Success, then!
return nil
}
// If we get down here then symlinking failed and we need a deep copy
// instead.
err = copydir.CopyDir(absNew, absCurrent)
if err != nil {
return fmt.Errorf("failed to either symlink or copy %s to %s: %s", absCurrent, absNew, err)
}
// If we got here then apparently our copy succeeded, so we're done.
return nil
}