Add support for php 8.1

This commit adds optional support for basing images on php 8.1 as
opposed to php 8.0.

internal/dis/component/instances/create.go

@@ -14,11 +14,34 @@ var (
 	errRestrictedSlug = errors.New("restricted slug")
 )
 
+const (
+	PHP8         = "8.0"
+	PHP8_IMAGE   = "docker.io/library/php:8.0-apache-bullseye"
+	PHP8_1       = "8.1"
+	PHP8_1_IMAGE = "docker.io/library/php:8.1-apache-bullseye"
+)
+
+var errUnknownPHPVersion = errors.New("unknown php version")
+
+// GetBaseImage returns the php base image to use
+func GetBaseImage(php string) (string, error) {
+	switch php {
+	case "":
+		return PHP8_IMAGE, nil
+	case PHP8:
+		return PHP8_IMAGE, nil
+	case PHP8_1:
+		return PHP8_1_IMAGE, nil
+	default:
+		return "", errUnknownPHPVersion
+	}
+}
+
 // Create fills the struct for a new WissKI instance.
 // It validates that slug is a valid name for an instance.
 //
 // It does not perform any checks if the instance already exists, or does the creation in the database.
-func (instances *Instances) Create(slug string) (wissKI *wisski.WissKI, err error) {
+func (instances *Instances) Create(slug string, phpversion string) (wissKI *wisski.WissKI, err error) {
 
 	// make sure that the slug is valid!
 	slug, err = instances.IsValidSlug(slug)
@@ -64,6 +87,12 @@ func (instances *Instances) Create(slug string) (wissKI *wisski.WissKI, err erro
 		return nil, err
 	}
 
+	// docker image
+	wissKI.Liquid.Instance.DockerBaseImage, err = GetBaseImage(phpversion)
+	if err != nil {
+		return nil, err
+	}
+
 	// store the instance in the object and return it!
 	return wissKI, nil
 }

internal/dis/component/instances/purger/purger.go

@@ -37,7 +37,7 @@ func (purger *Purger) Purge(ctx context.Context, out io.Writer, slug string) err
 	instance, err := purger.Dependencies.Instances.WissKI(ctx, slug)
 	if err == instances.ErrWissKINotFound {
 		fmt.Fprintln(out, "Not found in bookkeeping table, assuming defaults")
-		instance, err = purger.Dependencies.Instances.Create(slug)
+		instance, err = purger.Dependencies.Instances.Create(slug, "")
 	}
 	if err != nil {
 		return errPurgeNoDetails.WithMessageF(err)

internal/dis/component/provision/provision.go

@@ -22,11 +22,27 @@ type Provision struct {
 
 // ProvisionFlags are flags for a new instance
 type ProvisionFlags struct {
+	// Slug is the slug of the wisski instance
 	Slug string
+
+	// PHP Version to use
+	PHPVersion string
 }
 
 var ErrInstanceAlreadyExists = errors.New("instance with provided slug already exists")
 
+func (pv *Provision) ValidateFlags(flags ProvisionFlags) error {
+	// check the slug
+	if _, err := pv.Dependencies.Instances.IsValidSlug(flags.Slug); err != nil {
+		return err
+	}
+	// check for known php versions
+	if _, err := instances.GetBaseImage(flags.PHPVersion); err != nil {
+		return err
+	}
+	return nil
+}
+
 // Provision provisions a new docker compose instance.
 func (pv *Provision) Provision(progress io.Writer, ctx context.Context, flags ProvisionFlags) (*wisski.WissKI, error) {
 	// check that it doesn't already exist
@@ -36,7 +52,7 @@ func (pv *Provision) Provision(progress io.Writer, ctx context.Context, flags Pr
 	}
 
 	// make it in-memory
-	instance, err := pv.Dependencies.Instances.Create(flags.Slug)
+	instance, err := pv.Dependencies.Instances.Create(flags.Slug, flags.PHPVersion)
 	if err != nil {
 		return nil, err
 	}

internal/dis/component/server/admin/html/instance.html

@@ -29,6 +29,18 @@
                             <a href="{{ .Info.URL }}" target="_blank" rel="noopener noreferrer">{{ .Info.URL }}</a>
                         </td>
                     </tr>
+                    <tr>
+                        <td>
+                            Docker Base Image
+                        </td>
+                        <td>
+                            {{ if  .Instance.DockerBaseImage }}
+                            <code>{{ .Instance.DockerBaseImage }}</code>
+                            {{ else }}
+                            (none)
+                            {{ end }}
+                        </td>
+                    </tr>
                     <tr>
                         <td>
                             Running