97 lines
3.0 KiB
Markdown
97 lines
3.0 KiB
Markdown
---
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layout: "intro"
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page_title: "Registering Services"
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sidebar_current: "gettingstarted-services"
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---
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# Registering Services
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In the previous page, we created a simple cluster. Although the cluster members
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could see each other, there were no registered services. In this page, we'll
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modify our client to export a service.
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## Defining a Service
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A service can be registered either by providing a [service definition](/docs/agent/services.html),
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or by making the appropriate calls to the [HTTP API](/docs/agent/http.html). First we
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start by providing a simple service definition. We will by using the same setup as in the
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[last page](/intro/getting-started/join.html). On the second node, we start by creating a
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simple configuration:
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```
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$ sudo mkdir /etc/consul
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$ echo '{"service": {"name": "web", "tags": ["rails"], "port": 80}}' | sudo tee /etc/consul/web.json
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```
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We now restart the second agent, providing the configuration directory as well as the
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first node to re-join:
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```
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$ consul agent -data-dir /tmp/consul -node=agent-two -bind=172.20.20.11 -config-dir /etc/consul/
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==> Starting Consul agent...
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...
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[INFO] agent: Synced service 'web'
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...
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```
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## Querying Services
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Once the agent gets started, we should see a log output indicating that the `web` service
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has been synced with the Consul servers. We can first check using the HTTP API:
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```
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$ curl http://localhost:8500/v1/catalog/service/web
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[{"Node":"agent-two","Address":"172.20.20.11","ServiceID":"web","ServiceName":"web","ServiceTags":["rails"],"ServicePort":80}]
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```
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We can also do a simple DNS lookup for any nodes providing the `web` service:
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```
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$ dig @127.0.0.1 -p 8600 web.service.consul
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; <<>> DiG 9.8.1-P1 <<>> @127.0.0.1 -p 8600 web.service.consul
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; (1 server found)
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;; global options: +cmd
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;; Got answer:
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;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1204
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;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
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;; WARNING: recursion requested but not available
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;; QUESTION SECTION:
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;web.service.consul. IN A
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;; ANSWER SECTION:
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web.service.consul. 0 IN A 172.20.20.11
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```
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We can also filter on tags, here only requesting services matching the `rails` tag,
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and specifically requesting SRV records:
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```
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$ dig @127.0.0.1 -p 8600 rails.web.service.consul SRV
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; <<>> DiG 9.8.1-P1 <<>> @127.0.0.1 -p 8600 rails.web.service.consul SRV
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; (1 server found)
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;; global options: +cmd
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;; Got answer:
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;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 45798
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;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
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;; WARNING: recursion requested but not available
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;; QUESTION SECTION:
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;rails.web.service.consul. IN SRV
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;; ANSWER SECTION:
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rails.web.service.consul. 0 IN SRV 1 1 80 agent-two.node.dc1.consul.
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;; ADDITIONAL SECTION:
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agent-two.node.dc1.consul. 0 IN A 172.20.20.11
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```
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This shows how simple it is to get started with services. Service definitions
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can be updated by changing configuration files and sending a `SIGHUP` to the agent.
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Alternatively the HTTP API can be used to add, remove and modify services dynamically.
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