#+date: <2024-08-25 Sun 09:45:30>
#+title: Automatic Email Sentiment Analysis With n8n
#+description: Learn how to configure a basic workflow in n8n to analyze the sentiment of incoming emails.
#+filetags: :automation:n8n:
#+slug: n8n-sentiment-analysis

* n8n

This guide will show you how to self-host [[https://n8n.io/][n8n]], a workflow automation platform,
and use it to create a workflow that automatically analyzes the sentiment of all
incoming emails on your account.

This is a completely free process that only requires that you have access to (1)
an email account with IMAP/SMTP options and (2) a computer or machine where you
can install and use Docker.

** Installation

To get started, read the [[https://github.com/n8n-io/self-hosted-ai-starter-kit][self-hosted-ai-starter-kit]] project README or simply
clone the repository and set it up with Docker using the command below.

#+begin_src sh
git clone https://github.com/n8n-io/self-hosted-ai-starter-kit.git
cd self-hosted-ai-starter-kit
docker compose --profile cpu up
#+end_src

This will clone the repository, start the stack of Docker containers with
=compose=, and make the n8n web page available at [[https://localhost:5678]]. The
first run will ask you to configure the administrator account for n8n.

** Reverse Proxy

If you want to use n8n from a public domain name, you'll need to configure a
reverse proxy. I use Nginx on my server for reverse proxies. Nginx configuration
locations and practices vary by distribution, but the following commands will
show you my general reverse proxy configuration.

#+begin_src sh
cd /etc/nginx/conf.d
nano n8n.conf
#+end_src

#+begin_src conf
server {
	listen                  443 ssl;
	listen                  [::]:443 ssl;
	http2			on;
	server_name             n8n.example.com;

	# SSL
	ssl_certificate         /etc/letsencrypt/live/example.com/fullchain.pem;
	ssl_certificate_key     /etc/letsencrypt/live/example.com/privkey.pem;
	ssl_trusted_certificate /etc/letsencrypt/live/example.com/chain.pem;

	# reverse proxy
	location / {
		set $upstream_n8n http://127.0.0.1:5678;

        proxy_set_header Remote-User $user;
		proxy_set_header Remote-Email $email;
		proxy_set_header Remote-Groups $groups;

		client_body_buffer_size 128k;
		proxy_next_upstream error timeout invalid_header http_500 http_502 http_503;

		send_timeout 5m;
		proxy_read_timeout 360;
		proxy_send_timeout 360;
		proxy_connect_timeout 360;

		proxy_set_header Host $host;
		proxy_set_header Upgrade $http_upgrade;
		proxy_set_header Connection upgrade;
		proxy_set_header Accept-Encoding gzip;
		proxy_set_header X-Real-IP $remote_addr;
		proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
		proxy_set_header X-Forwarded-Proto $scheme;
		proxy_set_header X-Forwarded-Host $http_host;
		proxy_set_header X-Forwarded-Uri $request_uri;
		proxy_set_header X-Forwarded-Ssl on;
		proxy_redirect  http://  $scheme://;
		proxy_http_version 1.1;
		proxy_set_header Connection "";
		proxy_cache_bypass $cookie_session;
		proxy_no_cache $cookie_session;
		proxy_buffers 64 256k;
    }

# HTTP redirect
server {
	listen      80;
	listen      [::]:80;
	server_name n8n.example.com;
	include     custom.d/letsencrypt.conf;

	if ($host ~ ^[^.]+\.example\.com$) {
		return 301 https://$host$request_uri;
	}
}
#+end_src

Simply restart Nginx to ensure the new configuration is in-effect.

#+begin_src sh
sudo systemctl restart nginx.service
#+end_src

** Workflow Configuration

You can open the included workflow at
[[http://localhost:5678/workflow/srOnR8PAY3u4RSwb]] or simply open the web interface
and create a new configuration.

#+caption: n8n Workflow
[[https://img.cleberg.net/blog/20240825-n8n-sentiment-analysis/workflow.png]]

This workflow contains the following nodes:
1. Email Trigger (IMAP)
   + Create an IMAP credential with your email's IMAP settings to allow n8n to
      monitor for new emails.
2. If
   + Check ={{ $json.subject }}= to see if it =contains= "n8n Sentiment
     Analysis" to ensure we don't re-check our own emails.
3. Sentiment Analysis
   + Analyze the ={{ $json.textPlain }}= input coming from each email.
   + Ensure you have =Include Detailed Results= enabled so that we can access
     the confidence and strength variables.
4. Ollama Chat Model
   + The Docker stack we used includes Ollama and Llama3, which provide the
     easiest way to test this workflow.
5. Send Email
   + Create an SMTP credential to allow n8n to send emails.
   + Subject: =n8n Sentiment Analysis: {{ $json.sentimentAnalysis.category }}=
   + Email Format: =Text=
   + Text (Expression): This can contain anything you want, but be sure to
     include the variables ={{ $json.sentimentAnalysis.category }}=, ={{
     $json.sentimentAnalysis.strength }}=, and ={{
     $json.sentimentAnalysis.confidence }}=.
   + In the additional options, I enabled the =Append n8n Attribution= option in
     the screenshots below.

** Testing

You can use the =Test Workflow= button at the bottom of the canvas area to test
the workflow. This relies on receiving new messages in your inbox, so be sure to
send yourself a test email!

** Results

After testing each step noted above, n8n provided the results below - it works!

#+caption: Positive Results
[[https://img.cleberg.net/blog/20240825-n8n-sentiment-analysis/positive_results.png]]

#+caption: Negative Results
[[https://img.cleberg.net/blog/20240825-n8n-sentiment-analysis/negative_results.png]]

While this isn't anything earth-shattering, it does show easy it is to get
started with n8n and large language models in a self-hosted environment.