> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Swarm Service Types
> This guide explains Docker Swarm service modes, detailing replicated and global services, their deployment, and use case comparisons.
In Docker Swarm, services define how containers are deployed and managed across a cluster. Swarm supports two primary service modes: **replicated** and **global**. This guide explains each mode, shows how to deploy them, and compares their use cases.
## Replicated Service
A *replicated* service launches a specified number of identical tasks (containers). This is the default mode in Swarm.
If you omit `--replicas`, Swarm defaults to 1 replica. You can also explicitly set `--mode replicated` if you prefer.
To deploy five replicas of a web service:
```bash theme={null}
docker service create \
--name web \
--replicas 5 \
nginx:latest
```
Verify the service mode and replica count:
```bash theme={null}
docker service inspect web \
--format '{{json .Spec.Mode}}'
```
Sample output:
```json theme={null}
{"Replicated":{"Replicas":5}}
```
Key points for replicated services:
* Tasks are spread evenly across available nodes.
* Scale up or down by updating `--replicas`.
* Ideal for stateless applications like web servers or APIs.
## Global Service
A *global* service ensures exactly one task runs on every node in the Swarm.
Do **not** specify `--replicas` with global services. Use only `--mode global`.
To deploy a monitoring agent on all nodes:
```bash theme={null}
docker service create \
--name agent \
--mode global \
my-monitoring-agent:1.0
```
Global mode behavior:
* New nodes automatically receive one task.
* When a node leaves, its task is removed and not rescheduled.
* Perfect for logging, monitoring, and security daemons.
## Comparison Table
| Service Type | Replica Count | Scheduling Behavior | Common Use Case |
| ------------ | ---------------- | ---------------------------------- | -------------------------------- |
| Replicated | User-defined (N) | Distributes tasks evenly | Scalable web apps, microservices |
| Global | One per node | Runs exactly one task on each node | Agents for logging, monitoring |
## References
* [Docker Swarm Overview](https://docs.docker.com/engine/swarm/)
* [docker service create](https://docs.docker.com/engine/reference/commandline/service_create/)
* [docker service inspect](https://docs.docker.com/engine/reference/commandline/service_inspect/)
* [Docker Blog: Introduction to Swarm Mode](https://www.docker.com/blog/docker-swarm-mode-introduction/)