Closes #11559: Implement config template rendering (#11769)

* WIP

* Add config_template field to Device

* Pre-fetch referenced templates

* Correct up_to_date callable

* Add config_template FK to Device

* Update & merge migrations

* Add config_template FK to Platform

* Add tagging support for ConfigTemplate

* Catch exceptions when rendering device templates in UI

* Refactor ConfigTemplate.render()

* Add support for returning plain text content

* Add ConfigTemplate model documentation

* Add feature documentation for config rendering

netbox/extras/migrations/0086_configtemplate.py

@@ -0,0 +1,34 @@
+from django.db import migrations, models
+import django.db.models.deletion
+import taggit.managers
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0001_initial'),
+        ('extras', '0085_synced_data'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ConfigTemplate',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False)),
+                ('created', models.DateTimeField(auto_now_add=True, null=True)),
+                ('last_updated', models.DateTimeField(auto_now=True, null=True)),
+                ('data_path', models.CharField(blank=True, editable=False, max_length=1000)),
+                ('data_synced', models.DateTimeField(blank=True, editable=False, null=True)),
+                ('name', models.CharField(max_length=100)),
+                ('description', models.CharField(blank=True, max_length=200)),
+                ('template_code', models.TextField()),
+                ('environment_params', models.JSONField(blank=True, null=True)),
+                ('data_file', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='+', to='core.datafile')),
+                ('data_source', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT, related_name='+', to='core.datasource')),
+                ('tags', taggit.managers.TaggableManager(through='extras.TaggedItem', to='extras.Tag')),
+            ],
+            options={
+                'ordering': ('name',),
+            },
+        ),
+    ]