[GitHub] [trafficcontrol] zrhoffman commented on a change in pull request #5910: Blueprint/refetch

[GitBox <gi...@apache.org>]

zrhoffman commented on a change in pull request #5910:
URL: https://github.com/apache/trafficcontrol/pull/5910#discussion_r645264004



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File path: blueprints/refetch-invalidation.md
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+# Add REFETCH capability option for Content Invalidation
+
+## Problem Description
+
+Currently, within ATC, there is a concept of Invalidation Jobs. These Invalidation Jobs give a user the ability to queue an invalidation for a resource, primarily based on regular expressions. The invalidation is gathered and treated as though there was a cache **STALE**, allowing the cache to query the origin server to **REFRESH** the resource. However, should the cache policy still be incorrect or misconfigured, the resource could be updated on the origin server, but the cache will still receive a 304 - Not Modified HTTP status response.
+
+## Proposed Change
+
+ To address this potential conflict, a proposal to add **REFETCH** as an option for Invalidation Jobs. This will then be treated by caches as a **MISS** (rather than a **STALE**), thusly allowing the cache to retrieve the resource regardless of cache policies. The original **REFRESH**/**STALE** will be the default option, where **REFETCH**/**MISS** will be the addition.
+
+### Traffic Portal Impact
+
+##### Create and Update
+Traffic Portal will need to update the Invalidation Job to account for the different options. When creating an Invalidation Job both options will need to be present (Perhaps a radio button? Default will be the original **REFRESH**).
+
+Tooltips should be added to ensure an understanding of this feature at a high level.
+
+##### Read
+When displaying the information, the **Invalidation Requests** table current shows the `Parameters` field, so the display will be straight forward with no manipulation.
+
+However, we derive and calculate the expiration field based on the TTL. This code will need to be modified to account for the additional information contained in the `Parameters` field.
+
+### Traffic Ops Impact
+
+Both the API and the database schema will likely be updated, which in turn will result in changes downstream (such as T3C/ORT, clients) as well.
+
+#### REST API Impact
+
+No new endpoints will be required. However the current invalidation job will now include an optional field during `Create`. Invalidation jobs are added by submitting a POST to the jobs endpoint. 
+
+**POST** /api/4.0/jobs
+
+##### Current Request
+
+Body:
+```json
+{
+	"startTime":"2021-06-02T15:23:21.348Z",
+	"deliveryService":11,
+	"regex":"/path/.*\\.jpeg",
+	"ttl":24
+}
+```
+
+Which is mapped to a go `struct` in the `go-tc` lib.
+```go
+type InvalidationJobInput struct {
+	DeliveryService *interface{} `json:"deliveryService"`
+	Regex *string `json:"regex"`
+	StartTime *Time `json:"startTime"`
+	TTL *interface{} `json:"ttl"`
+	dsid *uint
+	ttl  *time.Duration
+}
+```
+
+##### Proposed
+
+Add an "InvalidationType" to signify a specific type of invalidation request. The InvalidationType is an optional field and will not break backwards compatibility with previous API versions. If the field is included, it _must_ be either "refetch" or "refresh".
+
+Body:
+```json
+{
+	"startTime":"2021-06-02T15:23:21.348Z",
+	"deliveryService":11,
+	"regex":"/path/.*\\.jpeg",
+	"ttl":24,
+	"invalidationType":"refresh"
+}
+```
+
+This struct now contains the `InvalidationType *string` field.
+```go
+type InvalidationJobInput struct {
+	DeliveryService *interface{} `json:"deliveryService"`
+	Regex *string `json:"regex"`
+	InvalidationType *string `json:"invalidationType,omitempty"`
+	StartTime *Time `json:"startTime"`
+	TTL *interface{} `json:"ttl"`
+	dsid *uint
+	ttl  *time.Duration
+}
+```
+
+##### Parsing the value
+
+Since the field is optional and existing functionality only signifies a **REFRESH**/**STALE** capability, if the field is omitted, empty, malformed, or in any way _not_ `refetch` then it will be treated as `refresh`.
+
+##### Response
+
+The response will be modified, then, to return this new value as well.
+
+Sample current response:
+```json
+{
+	"alerts":[
+		{
+			"text":"Invalidation request created for http://amc-linear-origin.local.tld/path/.*\\.jpeg, start:2021-06-02 15:23:21.348 +0000 UTC end 2021-06-03 15:23:21.348 +0000 UTC",
+			"level":"success"
+		}
+	],
+	"response":{
+		"assetUrl":"http://amc-linear-origin.local.tld/path/.*\\.jpeg",
+		"createdBy":"admin",
+		"deliveryService":"amc-live",
+		"id":1,
+		"keyword":"PURGE",
+		"parameters":"TTL:24h""startTime":"2021-06-02 09:23:21-06"
+	}
+}
+```
+
+Sample new response (includes the `invalidationType` on parameters field):
+```json
+{
+	"alerts":[
+		{
+			"text":"Invalidation request created for http://amc-linear-origin.local.tld/path/.*\\.jpeg, start:2021-06-02 15:23:21.348 +0000 UTC end 2021-06-03 15:23:21.348 +0000 UTC",
+			"level":"success"
+		}
+	],
+	"response":{
+		"assetUrl":"http://amc-linear-origin.local.tld/path/.*\\.jpeg",
+		"createdBy":"admin",
+		"deliveryService":"amc-live",
+		"id":1,
+		"keyword":"PURGE",
+		"parameters":"TTL:24h,invalidationType:refresh",
+		"startTime":"2021-06-02 09:23:21-06"
+	}
+}
+```
+
+___
+
+> Note: There are still 1.x routes that reference `UserInvalidationJob`, such as 
+		`user/current/jobs(/|\.json/?)?$`
+		`user/current/jobs(/|\.json/?)?$`
+		These routes are currently deprecated and the corresponding `structs` will be removed in a future release as well.
+
+#### Client Impact
+
+Likewise with Traffic Portal, the `go` clients will need to be updated to provide this additional functionality. Since an additional field has been added to `InvalidationJobInput` in `go-tc` lib, this can be set by the client as well. If left unset, it will default to "refresh".
+
+#### Data Model / Database Impact
+
+
+The current column `parameters` will now contain a cskv (comma separated key value) string. Currently it only stores the `TTL` for the invalidation request:
+```
+TTL:48h
+```
+
+Moving forward, this column will also contain the type of cache invalidation. For instance, the string may read:
+```
+TTL:48h,invalidationType:refetch
+```
+
+If there is no `invalidationType` in the cskv, it is assumed to be **REFRESH**/**STALE** as it's default value keeping with the current implementation. Otherwise the `invalidationType` will be either `refetch` or `refresh`, defaulting to `refresh` during validation.
+
+*OPTIONAL, BUT RECOMMENDED*: As part of this effort, the _Boy Scout Rule_ will be applied ("Always leave the campground cleaner than you found it."). The `agent`, `status`, `asset_type`, `object_type`, and `object_name` columns will be removed. `agent` and `status` are currently hardcoded to the value of 1. Similarly, `asset_type` is never a anything besides "file". `object_type` and `object_name` are not used at all. This would require a DB migration with Goose as well. If this were not implemented, no migration is necessary.

Review comment:
       > is never a anything
   
   can be reworded




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