fix(image): account for stderr when looking for an image sha

in the case the progress output is set to plain, the build output is
written to stderr rather than stdout. This updates the logic to check
each line with a regex starting from the end of the output

Fixes: #46

lib/docker/image.js

@@ -1,9 +1,11 @@
 'use strict'
 
+const os = require('os')
 const path = require('path')
 const crypto = require('crypto')
 const execa = require('execa')
 const array = require('../lang/array/index.js')
+const SHA_REGEX = /(?:writing image\s)?[^@](?:sha\d{3}):(?<sha>\w+)/i
 
 class Image {
   constructor(opts) {
@@ -160,10 +162,18 @@ class Image {
     const stream = execa('docker', this.build_cmd)
     stream.stdout.pipe(process.stdout)
     stream.stderr.pipe(process.stderr)
-    const {stdout} = await stream
-    const [_, sha] = stdout.split(':')
-    this.sha = sha.substring(0, 12)
-    return this.sha
+    const {stdout, stderr} = await stream
+    const lines = (stdout || stderr).split(os.EOL)
+    const len = lines.length - 1
+
+    for (let x = len; x >= 0; x--) {
+      const line = lines[x]
+      const match = SHA_REGEX.exec(line)
+      if (match) {
+        this.sha = match.groups.sha.substring(0, 12)
+        return this.sha
+      }
+    }
   }
 
   async tag(tag, push = true) {

test/fixture/docker/Dockerfile.publish

@@ -1,4 +1,4 @@
-FROM debian:buster-slim
+FROM debian:bullseye-slim
 COPY . /opt/whizbang
 WORKDIR /opt/whizbang
 CMD ["echo", "$PWD"]

test/integration/prepare.js

@@ -72,11 +72,6 @@ test('steps::prepare', async (t) => {
     tt.equal(image.opts.args.get('MAJOR_TEMPLATE'), '2', 'MAJOR_TEMPLATE value')
     tt.equal(image.opts.args.get('GIT_REF'), 'abacadaba', 'GIT_REF value')
     tt.match(image.opts.args.get('BUILD_DATE'), DATE_REGEX, 'BUILD_DATE value')
-    tt.match(
-      image.opts.flags.get('TAG_TEMPLATE')
-    , ['v2.1.2']
-    , 'TAG_TEMPLATE stored as a flag'
-    )
     tt.equal(image.context, path.join(context.cwd, config.context), 'docker context path')
 
     const {stdout} = await execa('docker', [
@@ -85,4 +80,67 @@ test('steps::prepare', async (t) => {
     ])
     tt.equal(stdout, build_id, 'build image fully built')
   })
+
+  t.test('build image created - progress plain', async (tt) => {
+    const build_id = crypto.randomBytes(5).toString('hex')
+    const context = {
+      env: {
+        ...process.env
+      , DOCKER_REGISTRY_USER: 'iamweasel'
+      , DOCKER_REGISTRY_PASSWORD: 'secretsquirrel'
+      }
+    , cwd: fixturedir
+    , nextRelease: {
+        version: '2.1.2'
+      , gitTag: 'v2.1.2'
+      , gitHead: 'abacadaba'
+      }
+    , logger: {
+        success: sinon.stub()
+      , info: sinon.stub()
+      , debug: sinon.stub()
+      , fatal: sinon.stub()
+      }
+    }
+
+    const config = await buildConfig(build_id, {
+      dockerRegistry: DOCKER_REGISTRY_HOST
+    , dockerProject: 'docker-prepare'
+    , dockerImage: 'alternate'
+    , dockerBuildQuiet: false
+    , dockerBuildFlags: {
+        progress: 'plain'
+      , 'no-cache': null
+      }
+    , dockerArgs: {
+        MY_VARIABLE: '1'
+      , TAG_TEMPLATE: '{{git_tag}}'
+      , MAJOR_TEMPLATE: '{{major}}'
+      , GIT_REF: '{{git_sha}}'
+      , BUILD_DATE: '{{now}}'
+      }
+    , dockerFile: 'docker/Dockerfile.prepare'
+    , dockerContext: 'docker'
+    }, context)
+
+    const image = await prepare(config, context)
+
+    tt.on('end', () => {
+      image.clean()
+    })
+
+    tt.equal(image.opts.args.get('TAG_TEMPLATE'), 'v2.1.2', 'TAG_TEMPLATE value')
+    tt.equal(image.opts.args.get('MAJOR_TEMPLATE'), '2', 'MAJOR_TEMPLATE value')
+    tt.equal(image.opts.args.get('GIT_REF'), 'abacadaba', 'GIT_REF value')
+    tt.match(image.opts.args.get('BUILD_DATE'), DATE_REGEX, 'BUILD_DATE value')
+    tt.equal(image.context, path.join(context.cwd, config.context), 'docker context path')
+
+    const {stdout} = await execa('docker', [
+      'images', image.name
+    , '-q', '--format={{ .Tag }}:{{ .ID}}'
+    ])
+    const [tag, id] = stdout.split(':')
+    tt.equal(image.id, id, 'captured id matches docker image id')
+    tt.equal(tag, build_id, 'build image fully built')
+  })
 }).catch(threw)