https://github.com/openfaas/nats-connector
An OpenFaaS event-connector to trigger functions from NATS
https://github.com/openfaas/nats-connector
Last synced: about 1 year ago
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An OpenFaaS event-connector to trigger functions from NATS
- Host: GitHub
- URL: https://github.com/openfaas/nats-connector
- Owner: openfaas
- License: mit
- Created: 2018-11-21T16:13:28.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2023-11-17T12:23:02.000Z (over 2 years ago)
- Last Synced: 2025-04-06T23:06:01.568Z (about 1 year ago)
- Language: Go
- Homepage:
- Size: 331 KB
- Stars: 42
- Watchers: 4
- Forks: 15
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# nats-connector
[](https://github.com/openfaas/nats-connector/actions/workflows/build.yml)
[](https://goreportcard.com/report/github.com/openfaas-incubator/nats-connector)
[](https://godoc.org/github.com/openfaas-incubator/nats-connector)
[](https://opensource.org/licenses/MIT)
[](https://www.openfaas.com)
An OpenFaaS event-connector to trigger functions from NATS Core pub/sub topics.
## Is the nats-connector or JetStream for OpenFaaS right for you?
> At most once QoS: Core NATS offers an at most once quality of service. If a subscriber is not listening on the subject (no subject match), or is not active when the message is sent, the message is not received. This is the same level of guarantee that TCP/IP provides. Core NATS is a fire-and-forget messaging system. It will only hold messages in memory and will never write messages directly to disk.
[From the NATS docs](https://docs.nats.io/nats-concepts/what-is-nats)
If no nats-connector is available at the time of a message being published, it will not be delivered to any functions. Likewise, if the function is unavailable or crashing, it will not receive the message. NATS Core has no durability.
For production and commercial use, see: [JetStream for OpenFaaS](https://www.openfaas.com/blog/jetstream-for-openfaas/)
## Quick start
### Deploy the connector to faasd
See the [eBook Serverless For Everyone Else](https://openfaas.gumroad.com/l/serverless-for-everyone-else) for instructions and sample YAML to add to your faasd host.
### Or deploy the connector to Kubernetes
1. Deploy the connector using arkade
```bash
arkade install nats-connector
```
Alternatively, see [the Helm chart](https://github.com/openfaas/faas-netes/tree/master/chart/nats-connector)
2. Deploy the two test functions
```bash
git clone https://github.com/openfaas/nats-connector --depth=1
cd nats-connector/contrib/test-functions
```
Deploy the functions using `stack.yml`, see how the `receive-message` function has the `topic=nats-test` annotation? That's how a function binds itself to a particular *NATS Subject*.
```bash
faas-cli template pull stack
faas-cli deploy
```
3. Now publish a message on the `nats-test` topic.
Invoke the publisher
```bash
faas-cli invoke publish-message <<< "test message"
```
4. Verify that the receiver was invoked by checking the logs
```bash
faas-cli logs receive-message
2019-12-29T19:06:50Z 2019/12/29 19:06:50 received "test message"
```
### Configuration
Configuration of the binary is by environment variable. The names vary for the values.yaml file in [the Helm chart](https://github.com/openfaas/faas-netes/tree/master/chart/nats-connector).
| Variable | Description | Default |
| -------------------- | ------------------------------|--------------------------------------------------|
| `topics` | Delimited list of topics | `nats-test,` |
| `broker_host` | The host, but not the port for NATS | `nats` |
| `async_invocation` | Queue the invocation with the built-in OpenFaaS queue-worker and return immediately | `false` |
| `gateway_url` | The URL for the OpenFaaS gateway | `http://gateway:8080` |
| `upstream_timeout` | Timeout to wait for synchronous invocations | `60s` |
| `rebuild_interval` | Interval at which to rebuild the map of topics <> functions | `5s` |
| `topic_delimiter` | Used to separate items in `topics` variable | `,` |