Here’s a step-by-step guide to setting up a **RabbitMQ cluster with replication** correctly:
---
## **Step 1: Prepare the Servers**
Ensure you have at least **three** nodes (recommended for HA) with:
- Ubuntu 22.04 (or a supported OS)
- Sufficient CPU/RAM based on workload
- Open necessary firewall ports (**5672, 15672, 25672**)
Set hostnames for clarity:
```bash
sudo hostnamectl set-hostname rabbitmq-node1 # Change for each node
```
---
## **Step 2: Install Erlang and RabbitMQ**
Run the following on **all nodes**:
### **1. Add the RabbitMQ Repository**
```bash
sudo apt update
sudo apt install -y curl gnupg
curl -fsSL https://packagecloud.io/rabbitmq/rabbitmq-server/gpgkey | sudo tee /usr/share/keyrings/rabbitmq-key.asc
echo "deb [signed-by=/usr/share/keyrings/rabbitmq-key.asc] https://packagecloud.io/rabbitmq/rabbitmq-server/ubuntu/ $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/rabbitmq.list
```
### **2. Install Erlang and RabbitMQ**
```bash
sudo apt update
sudo apt install -y rabbitmq-server
```
### **3. Enable RabbitMQ**
```bash
sudo systemctl enable --now rabbitmq-server
```
---
## **Step 3: Configure Clustering**
### **1. Stop RabbitMQ on All Nodes**
```bash
sudo systemctl stop rabbitmq-server
```
### **2. Configure Cookie for Clustering**
Run on **all nodes** (same cookie ensures clustering works):
```bash
echo "MY_CLUSTER_COOKIE" | sudo tee /var/lib/rabbitmq/.erlang.cookie
sudo chmod 600 /var/lib/rabbitmq/.erlang.cookie
```
Replace `"MY_CLUSTER_COOKIE"` with a strong, identical value on all nodes.
---
## **Step 4: Join Nodes to the Cluster**
Perform this on **nodes 2 and 3**, joining them to **node1**:
```bash
sudo rabbitmqctl stop_app
sudo rabbitmqctl join_cluster rabbit@rabbitmq-node1
sudo rabbitmqctl start_app
```
Check cluster status:
```bash
sudo rabbitmqctl cluster_status
```
---
## **Step 5: Enable High Availability (HA) Mirroring**
To replicate all queues, run on **any one node**:
```bash
rabbitmqctl set_policy ha-all "^.*" '{"ha-mode":"all","ha-sync-mode":"automatic"}'
```
This ensures all queues are **replicated across all nodes**.
---
## **Step 6: Enable Management UI**
Run on **each node** to enable the web interface:
```bash
sudo rabbitmq-plugins enable rabbitmq_management
```
Access at:
**http://[NODE_IP]:15672**
(Default login: `guest/guest`, change this for security.)
---
## **Step 7: Test the Cluster**
Run on **each node**:
```bash
rabbitmqctl list_queues
```
Queues should be visible and synchronized.
---
## **Step 8: Enable Auto-Recovery** (Optional)
Edit `/etc/rabbitmq/rabbitmq.conf` on **each node** and add:
```ini
cluster_formation.peer_discovery_backend = classic_config
cluster_formation.classic_config.nodes.1 = rabbit@rabbitmq-node1
cluster_formation.classic_config.nodes.2 = rabbit@rabbitmq-node2
cluster_formation.classic_config.nodes.3 = rabbit@rabbitmq-node3
```
Then restart RabbitMQ:
```bash
sudo systemctl restart rabbitmq-server
```
---
## **Step 9: Secure the Cluster** (Recommended)
### **1. Create an Admin User**
```bash
rabbitmqctl add_user admin StrongPassword123!
rabbitmqctl set_user_tags admin administrator
rabbitmqctl set_permissions -p / admin ".*" ".*" ".*"
```
Then **disable the guest account**:
```bash
rabbitmqctl delete_user guest
```
### **2. Enable TLS (Optional)**
For security, configure TLS in `/etc/rabbitmq/rabbitmq.conf`. Refer to RabbitMQ’s [TLS guide](https://www.rabbitmq.com/ssl.html).
---
## **Step 10: Setup Monitoring (Optional)**
Install **Prometheus & Grafana** or use **RabbitMQ Prometheus plugin**:
```bash
sudo rabbitmq-plugins enable rabbitmq_prometheus
```
---
Now your RabbitMQ cluster is fully set up with **replication and high availability**! 🚀
---
# Instructions to fix **unexpected** configuration errors
If you can't find the RabbitMQ config file under `/etc/rabbitmq`, it may not exist by default. You need to **create it manually**. Here's how:
## **1️⃣ Create the Configuration File**
RabbitMQ uses either a **`.conf` file** (modern format) or a **`.config` file** (legacy format). The recommended format is `.conf`.
Create the file if it doesn't exist:
```bash
sudo nano /etc/rabbitmq/rabbitmq.conf
```
Then add the following cluster configuration:
```
cluster_formation.peer_discovery_backend = classic_config
cluster_formation.classic_config.nodes.1 = rabbit@rabbitmq-main
cluster_formation.classic_config.nodes.2 = rabbit@rabbitmq-replica
```
Save and exit (`CTRL+X`, then `Y`, then `Enter`).
---
## **2️⃣ Set Correct Permissions**
Ensure the RabbitMQ user can read it:
```bash
sudo chown rabbitmq:rabbitmq /etc/rabbitmq/rabbitmq.conf
sudo chmod 644 /etc/rabbitmq/rabbitmq.conf
```
---
## **3️⃣ Restart RabbitMQ**
After modifying the configuration, restart the RabbitMQ service:
```bash
sudo systemctl restart rabbitmq-server
```
Check the status:
```bash
sudo systemctl status rabbitmq-server
```
---
## **4️⃣ Verify the Cluster Configuration**
After restarting, verify that clustering is working:
```bash
rabbitmqctl cluster_status
```
If the nodes are listed correctly, your setup is working.
---
## **5️⃣ If Using the Legacy `.config` Format**
Some older installations use an **Erlang-based configuration file** (`rabbitmq.config`). If you prefer that, create:
```bash
sudo nano /etc/rabbitmq/rabbitmq.config
```
Add this:
```erlang
[
{rabbit, [
{cluster_formation, [
{peer_discovery_backend, classic_config},
{classic_config, [
{nodes, ['rabbit@rabbitmq-main', 'rabbit@rabbitmq-replica']}
]}
]}
]}
].
```
Then restart RabbitMQ:
```bash
sudo systemctl restart rabbitmq-server
```
---
### **🔍 Troubleshooting**
❌ **RabbitMQ doesn't restart?**
Check logs for errors:
```bash
sudo journalctl -u rabbitmq-server --no-pager | tail -50
```
❌ **Cluster not forming?**
Try forcing a node to join manually:
```bash
rabbitmqctl stop_app
rabbitmqctl join_cluster rabbit@rabbitmq-main
rabbitmqctl start_app
```
---
# Instructions to fix **unexpected** management UI authentication errors
stackoverflow answer [link](https://stackoverflow.com/a/40845332/27251837)
## Answer
### ❌ **Cannot login with guest/guest credentials**
I had the same Problem..
I installed RabbitMQ and Enabled Web Interface also but still couldn't sign in with any user i newly created, this is because you need to be administrator to access this.
Do not create any config file and mess with it..
This is what i did then,
1. Add a new/fresh user, say user test and password test:
```bash
rabbitmqctl add_user test test
```
2. Give administrative access to the new user:
```bash
rabbitmqctl set_user_tags test administrator
```
3. Set permission to newly created user:
```bash
rabbitmqctl set_permissions -p / test ".*" ".*" ".*"
```
That's it, enjoy :)