ci: add Discord notifications for docker builds

Resolves: https://github.com/acid-info/logos-press-engine/issues/177

Signed-off-by: Jakub Sokołowski <jakub@status.im>

Jenkinsfile

@@ -78,5 +78,49 @@ pipeline {
 
   post {
     cleanup { cleanWs() }
+    always { script {
+      def result  = currentBuild.result.toLowerCase() ?: 'unknown'
+      discordNotify(header: "Logos Press Engine Docker image build ${result}!")
+    } }
+  }
+}
+
+def discordNotify(Map args=[:]) {
+  def opts = [
+    header: args.header ?: 'Deployment successful!',
+    title:  args.title  ?: "${env.JOB_NAME}#${env.BUILD_NUMBER}",
+    cred:   args.cred   ?: 'logos-press-engine-discord-webhook-url',
+  ]
+  def repo = [
+    url: GIT_URL.minus('.git'),
+    branch: GIT_BRANCH.minus('origin/'),
+    commit: GIT_COMMIT.take(8),
+    prev: (
+      env.GIT_PREVIOUS_SUCCESSFUL_COMMIT ?: env.GIT_PREVIOUS_COMMIT ?: 'master'
+    ).take(8),
+  ]
+  wrap([$class: 'BuildUser']) {
+    BUILD_USER_ID = env.BUILD_USER_ID
+  }
+  withCredentials([
+    string(
+      credentialsId: opts.cred,
+      variable: 'DISCORD_WEBHOOK',
+    ),
+  ]) {
+    discordSend(
+      link: env.BUILD_URL,
+      result: currentBuild.currentResult,
+      webhookURL: env.DISCORD_WEBHOOK,
+      title: opts.title,
+      description: """
+        ${opts.header}
+        Image: [`${env.IMAGE_NAME}:${params.IMAGE_TAG}`](https://hub.docker.com/r/${params.DOCKER_NAME}/tags?name=${params.IMAGE_TAG})
+        Branch: [`${repo.branch}`](${repo.url}/commits/${repo.branch})
+        Commit: [`${repo.commit}`](${repo.url}/commit/${repo.commit})
+        Diff: [`${repo.prev}...${repo.commit}`](${repo.url}/compare/${repo.prev}...${repo.commit})
+        By: [`${BUILD_USER_ID}`](${repo.url}/commits?author=${BUILD_USER_ID})
+      """,
+    )
   }
 }