rawlinp commented on a change in pull request #4521: Multi-interface Servers blueprint URL: https://github.com/apache/trafficcontrol/pull/4521#discussion_r397340024
########## File path: blueprints/multi-interface-servers.md ########## @@ -0,0 +1,670 @@ +<!-- +Licensed to the Apache Software Foundation (ASF) under one +or more contributor license agreements. See the NOTICE file +distributed with this work for additional information +regarding copyright ownership. The ASF licenses this file +to you under the Apache License, Version 2.0 (the +"License"); you may not use this file except in compliance +with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, +software distributed under the License is distributed on an +"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +KIND, either express or implied. See the License for the +specific language governing permissions and limitations +under the License. +--> +# Additional Server Interfaces + +## Problem Description +Multiple network interfaces may be used by cache servers to service requests. +However, these cannot be expressed as parts of the current "server" object. +Specifically, assuming each interface has its own IP address, then each would +need to be treated as a separate cache server. This means that getting clients +to use one when the other is unavailable requires manual intervention. + +## Proposed Change +Instead, cache servers should be configurable with numerous network interfaces +monitored by Traffic Monitor that are all associated with the server, each +having its own associated network information e.g. IP Address, but Traffic +Router should only be aware of the "main" interface on which the cache server +listens for connections. + +The specific use-case outlined above, obviously, entails some management be done +on the cache servers to actually support multiple interfaces answering to the +same "main" IP address and this should be considered outside of +<abbr title="Apache Traffic Control">ATC</abbr>'s scope of operation. + +## Data Model Impact +The proposed structure of each of these interfaces is given below as a pair of +TypeScript<sup>[1](#typescript)</sup> interfaces: +```typescript +interface IPAddress { + /** + * The actual IP (v4 or v6) address which is used by an interface. + * Any "mask" should be present here as a CIDR-notation suffix. + */ + address: string; + + /** + * The IP (v4 or v6) address of the gateway used by this IP address. + */ + gateway: string; + + /** + * Tells whether or not this address of this interface is the server's + * "service" address. + * At least one address of EXACTLY ONE interface MUST have this set to + * 'true' for a server. + */ + serviceAddress: boolean; +} + +interface Interface { + /** + * The name of the interface device on the server e.g. eth0. + */ + name: string; + /** + * These will be all of the IPv4/IPv6 addresses assigned to the interface, + * including gateways and "masks". + * It is illegal for an interface to not have at least one associated IP + * address. + */ + ipAddresses: Array<IPAddress> & {0: IPAddress}; + /** + * Whether or not Traffic Monitor should monitor this particular interface. + */ + monitor: boolean; + /** + * The interface's Maximum Transmission Unit. + * If this is 'null' it is assumed that the interface's MTU is not known/is + * irrelevant. + */ + mtu: 1500 | 9000 | null; +} +``` +We don't have a real data model for ATC, so what follows is an approximately +defined representation of a "server" that is valid within certain contexts. The +modifications made to it for the purposes of the changes herein proposed should +be considered valid in those same contexts - whatever they may be. + +```typescript +interface Server { + + cachegroup?: string | null; + cachegroupId: number; + cdnId: number; + cdnName?: string | null; + domainName: string; + guid?: string | null; + hostName: string; + httpsPort?: number | null; + id?: number; + + // ILO things aren't being moved in because they also require a + // username/password that aren't used by any other interface type. + iloIpAddress?: string | null; + iloIpGateway?: string | null; + iloIpNetmask?: string | null; + iloPassword?: string | null; + iloUsername?: string | null; + + /** + * New field containing additional interfaces. + * It is illegal for a server to not have at least one interface. + */ + interfaces: Array<Interface> & {0: Interface}; + lastUpdated?: string; + + // notice not here: mgmtIpAddress, mgmtIpGateway, mgmtIpNetmask + // these will be moved into the interfaces property + + offlineReason: string; + physLocation?: string | null; + physLocationId: number; + profile?: string | null; + profileDesc?: string | null; + profileId: number; + revalPending?: boolean; + rack?: string | null; + routerHostName?: string | null; + routerPortName?: string | null; + status?: string | null; + statusId: number; + tcpPort: number; + type?: string | null; + typeId: number; + updPending?: boolean; + xmppId?: string | null; + xmppPassword?: string | null; +} +``` + +`/monitoring` payloads and CDN Snapshots are purposely un-versioned and +un-modeled, so this section will make no attempts to define the model changes to +those objects. + +## Impacted Components +The only components that should need to be modified to accommodate this feature +are Traffic Ops, Traffic Portal, and Traffic Monitor. + +### Traffic Ops Impact + +#### Database +A new table will need to be introduced to contain interface information: +`interface`, which is described below. +```text + Table "public.interface" + Column | Type | Collation | Nullable | Default +---------+---------+-----------+----------+--------- + name | text | | not null | + server | bigint | | not null | + monitor | boolean | | not null | + mtu | integer | | | 1500 Review comment: Per https://www.ietf.org/rfc/rfc2460.txt we should probably constrain it to _at least_ 1280 or higher, but TP should probably still show 1500 and 9000 as the available options until we know we need different sizes. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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