feat: optional override for Postmark email From: field (#354)

This change allows an optional `POSTMARK_SENDER` env variable to be set
alongside the existing `POSTMARK_TOKEN` in case the configure token's
account is not approved for sending from the default (main/real) domain.
Without this the "From: …" sender email address is hardcoded at quite a
low-level which makes it difficult for code re-use.

With this change, I'm enabled to set up a local environment and test
from my *own* Postmark account without needing production keys. (Since I
don't own or control the domain, sending an email from
`anything@dag.house` gets rejected by the Postmark server with an error
if requested via my own API token.)

I have avoided touching most of the many places where environment
variables are handled because most of those deal in terms of
**required** env. This new config variable is optional: available for
those who need it, but if not set, the email logic simply stays
defaulted to what was the hardcoded sender.

---------

Co-authored-by: Alan Shaw <alan.shaw@protocol.ai>
Co-authored-by: Travis Vachon <travis.vachon@gmail.com>

packages/access-api/src/bindings.d.ts

@@ -39,6 +39,7 @@ export interface Env {
   PRIVATE_KEY: string
   SENTRY_DSN: string
   POSTMARK_TOKEN: string
+  POSTMARK_SENDER?: string
   LOGTAIL_TOKEN: string
   // bindings
   SPACES: KVNamespace

packages/access-api/src/config.js

@@ -40,6 +40,7 @@ export function loadConfig(env) {
     ENV: parseRuntimeEnv(vars.ENV),
 
     POSTMARK_TOKEN: vars.POSTMARK_TOKEN,
+    POSTMARK_SENDER: env.POSTMARK_SENDER,
     SENTRY_DSN: vars.SENTRY_DSN,
     LOGTAIL_TOKEN: vars.LOGTAIL_TOKEN,
 

packages/access-api/src/utils/context.js

@@ -58,7 +58,10 @@ export function getContext(request, env, ctx) {
       validations: new Validations(config.VALIDATIONS),
       accounts: new Accounts(config.DB),
     },
-    email: new Email({ token: config.POSTMARK_TOKEN }),
+    email: new Email({
+      token: config.POSTMARK_TOKEN,
+      sender: config.POSTMARK_SENDER,
+    }),
     uploadApi: createUploadApiConnection({
       audience: DID.parse(config.DID).did(),
       url: new URL(config.UPLOAD_API_URL),

packages/access-api/src/utils/email.js

@@ -3,8 +3,10 @@ export class Email {
    *
    * @param {object} opts
    * @param {string} opts.token
+   * @param {string} [opts.sender]
    */
   constructor(opts) {
+    this.sender = opts.sender || 'web3.storage <noreply@dag.house>'
     this.headers = {
       Accept: 'text/json',
       'Content-Type': 'text/json',
@@ -22,7 +24,7 @@ export class Email {
       method: 'POST',
       headers: this.headers,
       body: JSON.stringify({
-        From: 'web3.storage <noreply@dag.house>',
+        From: this.sender,
         To: opts.to,
         TemplateAlias: 'welcome',
         TemplateModel: {
@@ -57,7 +59,7 @@ export class Email {
       method: 'POST',
       headers: this.headers,
       body: JSON.stringify({
-        From: 'web3.storage <noreply@dag.house>',
+        From: this.sender,
         To: to,
         TextBody: textBody,
         Subject: subject,