feat(replication): adds read replica functionality

examples/12-replica-db-connection/.env

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+NODE_ENV=development
+PGUSER=postgres
+WARTHOG_APP_HOST=localhost
+WARTHOG_APP_PORT=4100
+WARTHOG_DB_DATABASE=warthog-example-12
+WARTHOG_DB_USERNAME=postgres
+WARTHOG_DB_PASSWORD=
+WARTHOG_DB_SYNCHRONIZE=true
+WARTHOG_DB_HOST=localhost
+WARTHOG_DB_PORT=5432
+WARTHOG_DB_REPLICA_HOST=localhost
+WARTHOG_DB_REPLICA_PORT=5432
+WARTHOG_DB_REPLICA_DATABASE=warthog-example-12
+WARTHOG_DB_REPLICA_USERNAME=postgres
+WARTHOG_DB_REPLICA_PASSWORD=

examples/12-replica-db-connection/README.md

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+# Example 12
+
+## Setup
+
+Run `yarn bootstrap && yarn start`
+
+## Bootstrapping the App
+
+Running `DEBUG=* yarn bootstrap` will do the following:
+
+- Install packages
+- Create the example DB
+- Seed the database with test data
+
+## Running the App
+
+To run the project, run `yarn start`. This will:
+
+- Run the API server
+- Open GraphQL Playground

examples/12-replica-db-connection/generated/binding.ts

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+import 'graphql-import-node'; // Needed so you can import *.graphql files 
+
+import { makeBindingClass, Options } from 'graphql-binding'
+import { GraphQLResolveInfo, GraphQLSchema } from 'graphql'
+import { IResolvers } from 'graphql-tools/dist/Interfaces'
+import * as schema from  './schema.graphql'
+
+export interface Query {
+    users: <T = Array<User>>(args: { offset?: Int | null, limit?: Int | null, where?: UserWhereInput | null, orderBy?: UserOrderByInput | null }, info?: GraphQLResolveInfo | string, options?: Options) => Promise<T> ,
+    usersFromMaster: <T = Array<User>>(args?: {}, info?: GraphQLResolveInfo | string, options?: Options) => Promise<T> ,
+    user: <T = User>(args: { where: UserWhereUniqueInput }, info?: GraphQLResolveInfo | string, options?: Options) => Promise<T> 
+  }
+
+export interface Mutation {
+    createUser: <T = User>(args: { data: UserCreateInput }, info?: GraphQLResolveInfo | string, options?: Options) => Promise<T> ,
+    updateUser: <T = User>(args: { data: UserUpdateInput, where: UserWhereUniqueInput }, info?: GraphQLResolveInfo | string, options?: Options) => Promise<T> ,
+    deleteUser: <T = StandardDeleteResponse>(args: { where: UserWhereUniqueInput }, info?: GraphQLResolveInfo | string, options?: Options) => Promise<T> 
+  }
+
+export interface Subscription {}
+
+export interface Binding {
+  query: Query
+  mutation: Mutation
+  subscription: Subscription
+  request: <T = any>(query: string, variables?: {[key: string]: any}) => Promise<T>
+  delegate(operation: 'query' | 'mutation', fieldName: string, args: {
+      [key: string]: any;
+  }, infoOrQuery?: GraphQLResolveInfo | string, options?: Options): Promise<any>;
+  delegateSubscription(fieldName: string, args?: {
+      [key: string]: any;
+  }, infoOrQuery?: GraphQLResolveInfo | string, options?: Options): Promise<AsyncIterator<any>>;
+  getAbstractResolvers(filterSchema?: GraphQLSchema | string): IResolvers;
+}
+
+export interface BindingConstructor<T> {
+  new(...args: any[]): T
+}
+
+export const Binding = makeBindingClass<BindingConstructor<Binding>>({ schema: schema as any })
+
+/**
+ * Types
+*/
+
+export type UserOrderByInput =   'createdAt_ASC' |
+  'createdAt_DESC' |
+  'updatedAt_ASC' |
+  'updatedAt_DESC' |
+  'deletedAt_ASC' |
+  'deletedAt_DESC' |
+  'firstName_ASC' |
+  'firstName_DESC' |
+  'lastName_ASC' |
+  'lastName_DESC'
+
+export interface BaseWhereInput {
+  id_eq?: String | null
+  id_in?: String[] | String | null
+  createdAt_eq?: String | null
+  createdAt_lt?: String | null
+  createdAt_lte?: String | null
+  createdAt_gt?: String | null
+  createdAt_gte?: String | null
+  createdById_eq?: String | null
+  updatedAt_eq?: String | null
+  updatedAt_lt?: String | null
+  updatedAt_lte?: String | null
+  updatedAt_gt?: String | null
+  updatedAt_gte?: String | null
+  updatedById_eq?: String | null
+  deletedAt_all?: Boolean | null
+  deletedAt_eq?: String | null
+  deletedAt_lt?: String | null
+  deletedAt_lte?: String | null
+  deletedAt_gt?: String | null
+  deletedAt_gte?: String | null
+  deletedById_eq?: String | null
+}
+
+export interface UserCreateInput {
+  firstName: String
+  lastName: String
+}
+
+export interface UserUpdateInput {
+  firstName?: String | null
+  lastName?: String | null
+}
+
+export interface UserWhereInput {
+  id_eq?: ID_Input | null
+  id_in?: ID_Output[] | ID_Output | null
+  createdAt_eq?: DateTime | null
+  createdAt_lt?: DateTime | null
+  createdAt_lte?: DateTime | null
+  createdAt_gt?: DateTime | null
+  createdAt_gte?: DateTime | null
+  createdById_eq?: ID_Input | null
+  createdById_in?: ID_Output[] | ID_Output | null
+  updatedAt_eq?: DateTime | null
+  updatedAt_lt?: DateTime | null
+  updatedAt_lte?: DateTime | null
+  updatedAt_gt?: DateTime | null
+  updatedAt_gte?: DateTime | null
+  updatedById_eq?: ID_Input | null
+  updatedById_in?: ID_Output[] | ID_Output | null
+  deletedAt_all?: Boolean | null
+  deletedAt_eq?: DateTime | null
+  deletedAt_lt?: DateTime | null
+  deletedAt_lte?: DateTime | null
+  deletedAt_gt?: DateTime | null
+  deletedAt_gte?: DateTime | null
+  deletedById_eq?: ID_Input | null
+  deletedById_in?: ID_Output[] | ID_Output | null
+  firstName_eq?: String | null
+  firstName_contains?: String | null
+  firstName_startsWith?: String | null
+  firstName_endsWith?: String | null
+  firstName_in?: String[] | String | null
+  lastName_eq?: String | null
+  lastName_contains?: String | null
+  lastName_startsWith?: String | null
+  lastName_endsWith?: String | null
+  lastName_in?: String[] | String | null
+}
+
+export interface UserWhereUniqueInput {
+  id: ID_Output
+}
+
+export interface BaseGraphQLObject {
+  id: ID_Output
+  createdAt: DateTime
+  createdById: String
+  updatedAt?: DateTime | null
+  updatedById?: String | null
+  deletedAt?: DateTime | null
+  deletedById?: String | null
+  version: Int
+}
+
+export interface DeleteResponse {
+  id: ID_Output
+}
+
+export interface BaseModel extends BaseGraphQLObject {
+  id: ID_Output
+  createdAt: DateTime
+  createdById: String
+  updatedAt?: DateTime | null
+  updatedById?: String | null
+  deletedAt?: DateTime | null
+  deletedById?: String | null
+  version: Int
+}
+
+export interface BaseModelUUID extends BaseGraphQLObject {
+  id: ID_Output
+  createdAt: DateTime
+  createdById: String
+  updatedAt?: DateTime | null
+  updatedById?: String | null
+  deletedAt?: DateTime | null
+  deletedById?: String | null
+  version: Int
+}
+
+export interface PageInfo {
+  hasNextPage: Boolean
+  hasPreviousPage: Boolean
+  startCursor?: String | null
+  endCursor?: String | null
+}
+
+export interface StandardDeleteResponse {
+  id: ID_Output
+}
+
+export interface User extends BaseGraphQLObject {
+  id: ID_Output
+  createdAt: DateTime
+  createdById: String
+  updatedAt?: DateTime | null
+  updatedById?: String | null
+  deletedAt?: DateTime | null
+  deletedById?: String | null
+  version: Int
+  firstName: String
+  lastName: String
+}
+
+/*
+The `Boolean` scalar type represents `true` or `false`.
+*/
+export type Boolean = boolean
+
+/*
+The javascript `Date` as string. Type represents date and time as the ISO Date string.
+*/
+export type DateTime = Date | string
+
+/*
+The `ID` scalar type represents a unique identifier, often used to refetch an object or as key for a cache. The ID type appears in a JSON response as a String; however, it is not intended to be human-readable. When expected as an input type, any string (such as `"4"`) or integer (such as `4`) input value will be accepted as an ID.
+*/
+export type ID_Input = string | number
+export type ID_Output = string
+
+/*
+The `Int` scalar type represents non-fractional signed whole numeric values. Int can represent values between -(2^31) and 2^31 - 1.
+*/
+export type Int = number
+
+/*
+The `String` scalar type represents textual data, represented as UTF-8 character sequences. The String type is most often used by GraphQL to represent free-form human-readable text.
+*/
+export type String = string