Create Docker-Swarm.md

Docker/Docker-Swarm.md

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+# Docker Swarm Documentation
+
+## Manager Count
+
+To ensure the cluster remains functional, the number of manager nodes must be more than 50%. If it falls below 51%, the cluster will become non-operational.
+
+## Example: Setting Up Nginx
+
+**Workflow:** API → Allocator → Dispatcher → Scheduler
+
+## Commands
+
+### Cluster Initialization and Management
+
+- **Create Cluster**
+  ```bash
+  docker swarm init
+  ```
+  Initializes a new Docker Swarm cluster.
+
+- **Join Cluster**
+  ```bash
+  docker swarm join
+  ```
+  Joins a node to an existing Docker Swarm cluster.
+
+- **Create Cluster with Specific Interface**
+  ```bash
+  docker swarm init --advertise-addr <ip or interface name>
+  ```
+  Initializes a new Docker Swarm cluster, specifying the IP or interface name to advertise.
+
+- **Leave Cluster**
+  ```bash
+  docker swarm leave
+  ```
+  Removes a node from the Docker Swarm cluster.
+
+- **Unlock Locked Manager**
+  ```bash
+  docker swarm unlock
+  ```
+  Unlocks a locked manager node in the Docker Swarm cluster.
+
+### Node Management
+
+- **List Nodes**
+  ```bash
+  docker node ls
+  ```
+  Displays information about the nodes in the cluster.
+  
+  **Example Output:**
+  ```bash
+  docker node ls
+  ```
+
+  ```
+  ID                            HOSTNAME   STATUS    AVAILABILITY   MANAGER STATUS   ENGINE VERSION
+  8yw8jrjeqczaci0qkuy060g09 *   docker-1   Ready     Active         Leader           24.0.5
+  v4gvf7xenw0izmxgvhr6hb2rj     docker-2   Ready     Active                          24.0.5
+  kd3ujmt1ey3pw6v9189fouxfa     docker-3   Ready     Active         Reachable        24.0.5
+  tm1msy58ztcltt36rs1lb76p7     docker-3   Down      Active                          24.0.5
+  ```
+
+- **Remove Node**
+  ```bash
+  docker node rm <node-id>
+  ```
+  Removes a node from the cluster.
+  
+  **Example:**
+  ```bash
+  docker node rm tm1msy58ztcltt36rs1lb76p7
+  ```
+
+- **Promote Node to Manager**
+  ```bash
+  docker node promote <hostname or ID>
+  ```
+  Promotes a worker node to a manager node.
+  
+  **Example:**
+  ```bash
+  root@docker-1:~# docker node promote v4gvf7xenw0izmxgvhr6hb2rj
+  Node v4gvf7xenw0izmxgvhr6hb2rj promoted to a manager in the swarm.
+  ```
+
+### Service Management
+
+- **Show Task Status on Cluster**
+  ```bash
+  docker node ps
+  ```
+  Displays the status of tasks running on nodes in the cluster.
+
+- **List Services**
+  ```bash
+  docker service ls
+  ```
+  Lists all services running in the cluster.
+
+- **Create Service**
+  ```bash
+  docker service create --name <service-name> <image-name>
+  ```
+  Creates a new service with the specified name and image.
+
+- **Scale Service**
+  ```bash
+  docker service scale <service-name>=<replica-count>
+  ```
+  Scales the number of replicas for a service.
+  
+  **Example:**
+  ```bash
+  docker service scale nginx=5
+  ```
+  Scales the `nginx` service to 5 replicas.
+
+- **Inspect Service**
+  ```bash
+  docker service inspect <service-name>
+  ```
+  Displays detailed information about a service.
+
+- **Create Service with Replicas and Environment Variables**
+  ```bash
+  docker service create --name <service-name> --replicas <replica-count> --env <env-variable> <image-name>
+  ```
+  Creates a new service with the specified name, number of replicas, and environment variables.
+  
+  **Example:**
+  ```bash
+  docker service create --name nginx --replicas 3 --env MY_ENV_VAR=value nginx
+  ```
+  Creates an `nginx` service with 3 replicas and an environment variable `MY_ENV_VAR` set to `value`.