fix(backup): Fixed weirdness with streams

refs: TryGhost/Toolbox#334
refs: #468

- the old streams wiring didn't handle the 404 error
- my previous attempt at changing the stream code  hung on success instead
- this is more modern code, but works on node 12 for both the success and failure case

lib/tasks/import/api.js

@@ -5,6 +5,11 @@ const semver = require('semver');
 const FormData = require('form-data');
 const {Cookie} = require('tough-cookie');
 
+const {promisify} = require('util');
+const stream = require('stream');
+const pipeline = promisify(stream.pipeline);
+const fsp = require('fs').promises;
+
 const {SystemError} = require('../../errors');
 
 const bases = {
@@ -15,6 +20,16 @@ const bases = {
     5: '/ghost/api/admin'
 };
 
+function streamFile(url, options, filePath) {
+    return pipeline(
+        got.stream(url, {...options}),
+        fs.createWriteStream(filePath)
+    ).catch((err) => {
+        fsp.unlink(filePath);
+        throw err;
+    });
+}
+
 function getBaseUrl(version, url) {
     const basePath = bases[semver.major(version)];
 
@@ -128,26 +143,27 @@ async function runImport(version, url, auth, exportFile) {
 
 async function downloadContentExport(version, url, auth, outputFile) {
     const authOpts = await getAuthOpts(version, url, auth);
+    let endpoint = '/db/';
 
-    await new Promise((resolve, reject) => {
-        const ws = fs.createWriteStream(outputFile);
-        const resp = got.stream('/db/', {...authOpts}).pipe(ws);
-
-        resp.on('finish', () => resolve()).on('error', reject);
-    });
+    await streamFile(endpoint, authOpts, outputFile);
 }
 
 async function downloadMembersExport(version, url, auth, outputFile) {
     const authOpts = await getAuthOpts(version, url, auth);
+    let endpoint = '/members/upload/';
 
-    await new Promise((resolve, reject) => {
-        const ws = fs.createWriteStream(outputFile);
-        got
-            .stream('/members/upload/', {...authOpts})
-            .on('finish', () => resolve())
-            .on('error', reject)
-            .pipe(ws);
-    });
+    if (semver.lt(version, '3.20.0')) {
+        endpoint = '/members/csv/';
+    }
+
+    try {
+        await streamFile(endpoint, authOpts, outputFile);
+    } catch (error) {
+        // Members endpoint may not exist, we can ignore this
+        if (error.statusCode !== 404) {
+            throw error;
+        }
+    }
 }
 
 module.exports = {

lib/tasks/import/tasks.js

@@ -40,17 +40,6 @@ async function importTask(ui, instance, exportFile) {
     }], false);
 }
 
-async function tryMembersDownload(version, url, authData, membersFile) {
-    try {
-        await downloadMembersExport(version, url, authData, membersFile);
-    } catch (error) {
-        // Members endpoint may not exist, we can ignore this
-        if (!error.statusCode === 404) {
-            throw error;
-        }
-    }
-}
-
 async function exportTask(ui, instance, contentFile, membersFile) {
     const url = instance.config.get('url');
 
@@ -61,14 +50,11 @@ async function exportTask(ui, instance, contentFile, membersFile) {
 
     const authData = await ui.prompt(authPrompts);
 
-    return ui.listr([{
-        title: 'Exporting content',
-        task: () => downloadContentExport(instance.version, url, authData, contentFile)
-    }, {
-        title: 'Exporting members',
-        task: () => tryMembersDownload(instance.version, url, authData, membersFile),
-        enabled: () => !!membersFile
-    }], false);
+    await downloadContentExport(instance.version, url, authData, contentFile);
+
+    if (membersFile) {
+        await downloadMembersExport(instance.version, url, authData, membersFile);
+    }
 }
 
 module.exports = {