validate exports/imports (#290)

Author: slashburygin

docs/element_manager/manifest.md

@@ -0,0 +1,114 @@
+# Manifest
+
+## Example manifest
+
+```yaml
+name: "core_service_example"
+description: "Genesis Core Service Example"
+schema_version: 1
+version: "1.0.3"
+api_version: "v1"
+
+requirements:  # Requirements of the manifest
+  core:
+    from_version: "0.0.0"
+    to_version: "1.0.0"
+
+resources: 
+  $core.compute.nodes:
+    example_node:
+      name: "example-service-node"
+      description: "Example service node"
+      cores: "$core_service_example.imports.$var_default_cores:value"
+      ram: "$core_service_example.imports.$var_default_ram:value"
+      project_id: "12345678-c625-4fee-81d5-f691897b8142"
+      disk_spec:
+        kind: "root_disk"
+        size: 10
+        image: "{{ base_image_url | default('https://repository.genesis-core.tech/genesis-base/0.4.1/genesis-base.raw.gz') }}"
+  
+  $core.em.services:
+    example_service:
+      project_id: "12345678-c625-4fee-81d5-f691897b8142"
+      name: "example-service"
+      path: "/usr/bin/python3 -m http.server 8080"
+      user: "ubuntu"
+      group: "ubuntu"
+      target:
+        kind: "node"
+        node: "$core_service_example.compute.nodes.$example_node:uuid"
+      service_type:
+        kind: "simple"
+        count: 1
+      target_status: "enabled"
+
+exports:
+  my_service:
+    link: "$core_service_example.em.services.$example_service"
+    kind: "resource"
+  my_node:
+    link: "$core_service_example.em.services.$example_node"
+    
+imports:
+  var_default_cores:
+    element: "$core"
+    kind: "resource"
+    link: "$core.vs.variables.$default_cores"
+  var_default_ram:
+    element: "$core"
+    kind: "resource"
+    link: "$core.vs.variables.$default_ram"
+```
+
+## name
+
+The name of the manifest.
+
+## description
+
+The description of the manifest.
+
+## schema_version
+
+The schema version of the manifest, now `1`.
+
+## version
+
+Version of the manifest, see docs in [genesis_devtools](https://infraguys.github.io/genesis_devtools/)
+
+## api_version
+
+API version of the manifest, now `v1`
+
+## requirements
+
+```yaml
+core:
+  from_version: "0.0.0"
+  to_version: "1.0.0"
+```
+
+Requirements are used to specify the versions of the elements that are required to run the manifest.
+
+## Resources
+
+Resources are used to specify the resources that are required to run the manifest.
+
+## exports
+
+```yaml
+my_service:
+  link: "$core_service_example.em.services.$example_service"
+  kind: "resource" # kind of the export, now only `resource` is supported, may be omitted
+```
+
+## imports
+
+```yaml
+var_default_cores:
+  element: "$core"  # element, from that the import is made
+  kind: "resource" # kind of the import, now only `resource` is supported, may be omitted
+  link: "$core.vs.variables.$default_cores"   # link to the resource (element, that the import is made, maybe be another)
+```
+
+Imports are used to specify the resources that are imported by the manifest.