feature(storage): config support for generating physical volumes (#1652)

Add support to the storage config for using a *generate* section for
physical volumes.

~~~json
"physicalVolumes": [
  { "generate": ["first-disk", "second-disk"] }
]
~~~

~~~json
"physicalVolumes": [
  {
    "generate": {
      "targetDevices": ["first-disk"],
      "encryption": {
        "luks2": { "password": "12345" }
      }
    }
  }
]
~~~

The *generate* section allows to indicate the target devices in which to
automatically create physical volumes, if needed. Agama will try to
create physical volumes to allocate the defined logical volumes. If an
*encryption* section is provided by the *generate* section, then the new
physical volumes will be encrypted.

Notes:

* For now, *physicalVolumes* can contain either device aliases or a
*generate*. In the future it will allow both.
* If there is more than one *generate* in the list of physical volumes,
then only the first one will be considered (the rest ones are ignored).
Note that the schema does not complain.

doc/auto_storage.md

@@ -944,6 +944,81 @@ The *mandatory* keyword can be used for only generating the mandatory partitions
 }
 ```
 
+### Generating Physical Volumes
+
+Volume groups can be configured to explicitly use a set of devices as physical volumes. The aliases
+of the devices to use are added to the list of physical volumes:
+
+```json
+"storage": {
+  "drives": [
+    {
+      "search": "/dev/vda",
+      "partitions": [
+        { "alias": "pv2" },
+        { "alias": "pv1" }
+      ]
+    }
+  ],
+  "volumeGroups": [
+    {
+      "physicalVolumes": ["pv1", "pv2"]
+    }
+  ]
+}
+```
+
+The physical volumes can be automatically generated too, by simply indicating the target devices in
+which to create the partitions. For that, a *generate* section is added to the list of physical
+volumes:
+
+```json
+"storage": {
+  "drives": [
+    {
+      "search": "/dev/vda",
+      "alias": "pvs-disk"
+    }
+  ],
+  "volumeGroups": [
+    {
+      "physicalVolumes": [
+        { "generate": ["pvs-disk"] }
+      ]
+    }
+  ]
+}
+```
+
+If the auto-generated physical volumes have to be encrypted, then the encryption config is added to
+the *generate* section:
+
+
+```json
+"storage": {
+  "drives": [
+    {
+      "search": "/dev/vda",
+      "alias": "pvs-disk"
+    }
+  ],
+  "volumeGroups": [
+    {
+      "physicalVolumes": [
+        {
+          "generate": {
+            "targetDevices": ["pvs-disk"],
+            "encryption": {
+              "luks2": { "password": "12345" }
+            }
+          }
+        }
+      ]
+    }
+  ]
+}
+```
+
 ### Using the Automatic Proposal
 
 On the first implementations, Agama can rely on the process known as Guided Proposal to calculate

rust/agama-lib/share/examples/storage/generate_pvs.json

@@ -0,0 +1,48 @@
+{
+  "storage": {
+    "drives": [
+      {
+        "alias": "first-disk"
+      },
+      {
+        "partitions": [
+          {
+            "alias": "pv1",
+            "id": "lvm",
+            "size": { "min": "10 GiB" }
+          }
+        ]
+      }
+    ],
+    "volumeGroups": [
+      {
+        "name": "system",
+        "physicalVolumes": ["pv1"],
+        "logicalVolumes": [
+          {
+            "filesystem": { "path": "/" }
+          }
+        ]
+      },
+      {
+        "name": "logs",
+        "physicalVolumes": [
+          { "generate": ["first-disk"] }
+        ]
+      },
+      {
+        "name": "data",
+        "physicalVolumes": [
+          {
+            "generate": {
+              "targetDevices": ["first-disk"],
+              "encryption": {
+                "luks2": { "password": "12345" }
+              }
+            }
+          }
+        ]
+      }
+    ]
+  }
+}

rust/agama-lib/share/profile.schema.json

@@ -529,11 +529,56 @@
               "physicalVolumes": {
                 "title": "Physical volumes",
                 "description": "Devices to use as physical volumes.",
-                "type": "array",
-                "items": {
-                  "title": "Device alias",
-                  "type": "string"
-                }
+                "$comment": "In the future it would be possible to indicate both aliases and 'generate' items together.",
+                "anyOf": [
+                  {
+                    "type": "array",
+                    "items": {
+                      "title": "Device alias",
+                      "type": "string"
+                    }
+                  },
+                  {
+                    "type": "array",
+                    "items": {
+                      "title": "Generate physical volumes",
+                      "description": "Automatically creates the needed physical volumes in the indicated devices.",
+                      "type": "object",
+                      "additionalProperties": false,
+                      "required": ["generate"],
+                      "properties": {
+                        "generate": {
+                          "anyOf": [
+                            {
+                              "type": "array",
+                              "items": {
+                                "title": "Device alias",
+                                "type": "string"
+                              }
+                            },
+                            {
+                              "type": "object",
+                              "additionalProperties": false,
+                              "required": ["targetDevices"],
+                              "properties": {
+                                "targetDevices": {
+                                  "type": "array",
+                                  "items": {
+                                    "title": "Device alias",
+                                    "type": "string"
+                                  }
+                                },
+                                "encryption": {
+                                  "$ref": "#/$defs/encryption"
+                                }
+                              }
+                            }
+                          ]
+                        }
+                      }
+                    }
+                  }
+                ]
               },
               "logicalVolumes": {
                 "title": "Logical volumes",

service/lib/agama/config.rb

@@ -186,8 +186,31 @@ def arch_elements_from(*keys, property: nil, default: [])
       end.compact
     end
 
+    # Default paths to be created for the product.
+    #
+    # @return [Array<String>]
+    def default_paths
+      data.dig("storage", "volumes") || []
+    end
+
+    # Mandatory paths to be created for the product.
+    #
+    # @return [Array<String>]
+    def mandatory_paths
+      default_paths.select { |p| mandatory_path?(p) }
+    end
+
   private
 
+    def mandatory_path?(path)
+      templates = data.dig("storage", "volume_templates") || []
+      template = templates.find { |t| t["mount_path"] == path }
+
+      return false unless template
+
+      template.dig("outline", "required") || false
+    end
+
     # Simple deep merge
     #
     # @param a_hash       [Hash] Default values

service/lib/agama/storage/config.rb

@@ -55,16 +55,6 @@ def initialize
         @nfs_mounts = []
       end
 
-      # Creates a config from JSON hash according to schema.
-      #
-      # @param config_json [Hash]
-      # @param product_config [Agama::Config]
-      #
-      # @return [Storage::Config]
-      def self.new_from_json(config_json, product_config:)
-        ConfigConversions::FromJSON.new(config_json, product_config: product_config).convert
-      end
-
       # Name of the device that will presumably be used to boot the target system
       #
       # @return [String, nil] nil if there is no enough information to infer a possible boot disk