Report specific type of error when credentials can't be fetched

This way, we can inform users what went wrong.

I've decided to try to stick to the error format we use in our internal
infrastructure as much as possible, without updating the JobError.
Because if that, this is accompanied by a small change to our API that
handles these errors.

__tests__/api_client.test.ts

@@ -1,5 +1,5 @@
 import * as core from '@actions/core'
-import {ApiClient} from '../src/api-client'
+import {ApiClient, CredentialFetchingError} from '../src/api-client'
 
 describe('ApiClient', () => {
   const mockAxios: any = {
@@ -88,4 +88,26 @@ describe('ApiClient', () => {
     expect(core.setSecret).toHaveBeenCalledWith('qux-password')
     expect(core.setSecret).toHaveBeenCalledWith('qux-token')
   })
+
+  test('job credentials errors', async () => {
+    const apiResponse = {
+      errors: [
+        {
+          status: 422,
+          title: 'Secret Not Found',
+          detail: 'MISSING_SECRET_NAME'
+        }
+      ]
+    }
+
+    mockAxios.get.mockRejectedValue({
+      isAxiosError: true,
+      response: {status: 422, data: apiResponse}
+    })
+    await expect(api.getCredentials()).rejects.toThrowError(
+      new CredentialFetchingError(
+        'fetching credentials: received code 422: {"errors":[{"status":422,"title":"Secret Not Found","detail":"MISSING_SECRET_NAME"}]}'
+      )
+    )
+  })
 })

src/api-client.ts

@@ -1,5 +1,5 @@
 import * as core from '@actions/core'
-import {AxiosInstance} from 'axios'
+import axios, {AxiosInstance} from 'axios'
 import {JobParameters} from './inputs'
 
 // JobDetails are information about the repository and dependencies to be updated
@@ -26,6 +26,8 @@ export type Credential = {
   token?: string
 }
 
+export class CredentialFetchingError extends Error {}
+
 export class ApiClient {
   constructor(
     private readonly client: AxiosInstance,
@@ -52,24 +54,34 @@ export class ApiClient {
 
   async getCredentials(): Promise<Credential[]> {
     const credentialsURL = `/update_jobs/${this.params.jobId}/credentials`
-    const res: any = await this.client.get(credentialsURL, {
-      headers: {Authorization: this.params.credentialsToken}
-    })
-    if (res.status !== 200) {
-      throw new Error(`Unexpected status code: ${res.status}`)
-    }
+    try {
+      const res: any = await this.client.get(credentialsURL, {
+        headers: {Authorization: this.params.credentialsToken}
+      })
 
-    // Mask any secrets we've just retrieved from Actions logs
-    for (const credential of res.data.data.attributes.credentials) {
-      if (credential.password) {
-        core.setSecret(credential.password)
+      // Mask any secrets we've just retrieved from Actions logs
+      for (const credential of res.data.data.attributes.credentials) {
+        if (credential.password) {
+          core.setSecret(credential.password)
+        }
+        if (credential.token) {
+          core.setSecret(credential.token)
+        }
       }
-      if (credential.token) {
-        core.setSecret(credential.token)
+
+      return res.data.data.attributes.credentials
+    } catch (error) {
+      if (axios.isAxiosError(error)) {
+        const err = error
+        throw new CredentialFetchingError(
+          `fetching credentials: received code ${
+            err.response?.status
+          }: ${JSON.stringify(err.response?.data)}`
+        )
+      } else {
+        throw error
       }
     }
-
-    return res.data.data.attributes.credentials
   }
 
   async reportJobError(error: JobError): Promise<void> {

src/main.ts

@@ -4,7 +4,7 @@ import {Context} from '@actions/github/lib/context'
 import {getJobParameters} from './inputs'
 import {ImageService} from './image-service'
 import {Updater, UpdaterFetchError} from './updater'
-import {ApiClient} from './api-client'
+import {ApiClient, CredentialFetchingError} from './api-client'
 import axios from 'axios'
 
 export const UPDATER_IMAGE_NAME =
@@ -93,7 +93,13 @@ export async function run(context: Context): Promise<void> {
       }
       botSay('finished')
     } catch (error) {
-      await failJob(apiClient, error)
+      if (error instanceof CredentialFetchingError) {
+        core.error('Error retrieving update job credentials')
+        await failJob(apiClient, error, DependabotErrorType.UpdateRun)
+      } else {
+        await failJob(apiClient, error)
+      }
+
       return
     }
   } catch (error) {