diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 0000000..75d1314
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,3 @@
+webapp/node_modules
+
+webapp/package-lock.json
diff --git a/Dockerfile b/Dockerfile
index a7668fa..a6bd402 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -7,7 +7,11 @@ RUN npm run build
 
 FROM nginx:stable-alpine-slim AS serve
 COPY scripts/docker/docker_nginx.conf /etc/nginx/conf.d/default.conf
+COPY scripts/docker/docker-entrypoint.sh /docker-entrypoint.sh
+RUN chmod +x /docker-entrypoint.sh
 
 WORKDIR /usr/share/nginx/html
 COPY --from=build /app/dist/webapp/browser .
 EXPOSE 80
+
+ENTRYPOINT ["/docker-entrypoint.sh"]
diff --git a/scripts/docker/docker-entrypoint.sh b/scripts/docker/docker-entrypoint.sh
new file mode 100644
index 0000000..431756b
--- /dev/null
+++ b/scripts/docker/docker-entrypoint.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+set -e
+
+# Update runtime variables
+envsubst '${AUTO_ATTACH_PUBSUB_PROJECTS}' < /usr/share/nginx/html/index.html > /usr/share/nginx/html/index.html.tmp
+envsubst '${DEFAULT_PUBSUB_EMULATOR_HOST}' < /usr/share/nginx/html/index.html.tmp > /usr/share/nginx/html/index.html
+
+# Start nginx
+exec nginx -g 'daemon off;'
diff --git a/webapp/src/app/services/pubsub.service.ts b/webapp/src/app/services/pubsub.service.ts
index be9923d..eb4f4b0 100644
--- a/webapp/src/app/services/pubsub.service.ts
+++ b/webapp/src/app/services/pubsub.service.ts
@@ -3,13 +3,23 @@ import { Injectable, inject } from '@angular/core';
 import { BehaviorSubject, EMPTY, map, Observable, ReplaySubject } from 'rxjs';
 import { NewSubscriptionRequest } from '../components/subscription-list/new-subscription-dialog/new-subscription-dialog.component';
 
+// Declare window.APP_CONFIG for runtime configuration
+declare global {
+  interface Window {
+    APP_CONFIG?: {
+      autoAttachPubsubProjects?: string;
+      defaultPubsubEmulatorHost?: string;
+    };
+  }
+}
+
 @Injectable({
   providedIn: 'root'
 })
 export class PubsubService {
   private http = inject(HttpClient);
 
-  public _currentHost$ = new BehaviorSubject<string>("http://localhost:8681")
+  public _currentHost$ = new BehaviorSubject<string>("")
 
   private _projectList = new BehaviorSubject<string[]>([])
   private _currentProject = new ReplaySubject<string>()
@@ -23,21 +33,68 @@ export class PubsubService {
   public currentSubscription$ = this._currentSubscription.asObservable()
 
   constructor() {
+    let defaultHost = window.APP_CONFIG?.defaultPubsubEmulatorHost || ""
+    if (!defaultHost || defaultHost === '${DEFAULT_PUBSUB_EMULATOR_HOST}') {
+      defaultHost = "http://localhost:8681"
+    }
+
+    if (!defaultHost.match(/^http[s]?:\/\//)) {
+      defaultHost = `http://${defaultHost}`
+    }
+
     const prevHost = localStorage.getItem("host")
     if (prevHost) {
       console.log('loaded previous host', prevHost)
       this._currentHost$.next(prevHost)
+    } else {
+      console.log('loaded default host', defaultHost)
+      this._currentHost$.next(defaultHost)
     }
 
     const prevProjects = localStorage.getItem("projects") ?? "[]"
     const projects: string[] = JSON.parse(prevProjects) ?? []
-    this._projectList.next(projects)
+
+    // Auto-attach projects from environment variable (idempotent)
+    const autoAttachProjects = this.getAutoAttachProjects()
+    const mergedProjects = this.mergeProjectsIdempotently(projects, autoAttachProjects)
+
+    this._projectList.next(mergedProjects)
+
+    // Save merged list to localStorage if auto-attach added new projects
+    if (mergedProjects.length !== projects.length) {
+      localStorage.setItem("projects", JSON.stringify(mergedProjects))
+      console.log('auto-attached projects:', autoAttachProjects)
+    }
 
     this.currentProject$.subscribe(project =>
       this.topicList$ = this.listTopics(project)
     )
   }
 
+  private getAutoAttachProjects(): string[] {
+    const autoAttachProjects = window.APP_CONFIG?.autoAttachPubsubProjects || ''
+    if (!autoAttachProjects || autoAttachProjects === "${AUTO_ATTACH_PUBSUB_PROJECTS}") {
+      return []
+    }
+
+    return autoAttachProjects
+      .split(',')
+      .map(project => project.trim())
+      .filter(project => project.length > 0)
+  }
+
+  private mergeProjectsIdempotently(existing: string[], autoAttach: string[]): string[] {
+    const merged = [...existing]
+
+    for (const project of autoAttach) {
+      if (!merged.includes(project)) {
+        merged.push(project)
+      }
+    }
+
+    return merged
+  }
+
   setHost(hostUrl: string) {
     this._currentHost$.next(hostUrl)
 
@@ -141,7 +198,7 @@ export interface ReceivedMessage {
 }
 
 export interface PubsubMessage {
-  data: string 
+  data: string
   attributes?: { [key: string]: string }
   messageId?: string
   publishTime?: string
diff --git a/webapp/src/index.html b/webapp/src/index.html
index c403841..db8f058 100644
--- a/webapp/src/index.html
+++ b/webapp/src/index.html
@@ -15,6 +15,12 @@
   <link href="https://fonts.googleapis.com/icon?family=Material+Icons" rel="stylesheet">
   <link href="http://fonts.cdnfonts.com/css/cascadia-code" rel="stylesheet">
 
+  <script>
+    window.APP_CONFIG = {
+      autoAttachPubsubProjects: '${AUTO_ATTACH_PUBSUB_PROJECTS}',
+      defaultPubsubEmulatorHost: '${DEFAULT_PUBSUB_EMULATOR_HOST}'
+    };
+  </script>
 </head>
 <body class="mat-app-background">
   <app-root></app-root>