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Version: Develop

Using a9s Elasticsearch

This topic describes how developers use a9s Elasticsearch.

Use a9s Elasticsearch with an Application

To use a9s Elasticsearch with an application, create a service instance and bind the service instance to your application. For more information on managing service instances, see Managing Service Instances with the cf CLI.

View the a9s Elasticsearch Service

After the service is installed, you can see the a9s-elasticsearch and its service plans appear in your CF marketplace. Run cf marketplace to see the service listing:

$ cf marketplace
Getting services from marketplace in org test / space test as admin...
OK
service plans description
a9s-elasticsearch5 elasticsearch-single-small, elasticsearch-cluster-small, This is the a9s Elasticsearch 5 service.
elasticsearch-single-big, elasticsearch-cluster-big

Create a Service Instance

To provision an Elasticsearch database, run cf create-service. For example:

cf create-service a9s-elasticsearch5 elasticsearch-single-small my-elasticsearch-service

Depending on your infrastructure and service broker utilization, it may take several minutes to create the service instance.

Run the cf services command to view the creation status. This command displays a list of all your service instances. To view the status of a specific service instance, run cf service NAME-OF-YOUR-SERVICE.

Bind an Application to a Service Instance

After your database is created, run cf bind-service to bind the service to your application:

cf bind-service a9s-elasticsearch-app my-elasticsearch5-service

Restage or Restart Your Application

To enable your application to access the service instance, run cf restage or cf restart to restage or restart your application.

Obtain Service Instance Access Credentials

After a service instance is bound to an application, the credentials of your Elasticsearch database are stored in the environment variables of the application. Run cf env APP-NAME to display the environment variables.

You can find the credentials in the VCAP_SERVICES key.

$ cf env a9s-elasticsearch-app
Getting env variables for app a9s-elasticsearch-app in org test / space test as admin...
OK

System-Provided:
{
"VCAP_SERVICES": {
"a9s-elasticsearch5": [
{
"credentials": {
"host": [
"EXAMPLE_HOST"
],
"hosts": [
"EXAMPLE_HOST"
],
"password": "EXAMPLE_USER",
"username": "EXAMPLE_PASSWORD",
"scheme": "http",
"port": 9200
},
"label": "a9s-elasticsearch5",
"name": "my-elasticsearch-service",
"plan": "elasticsearch-cluster-small",
"tags": [
"searchengine"
]
}
]
}
}
...

You can use the host, username and password values to connect to your database with a Elasticsearch client.

Best Practices

There are some best practices for using service binding information in apps in a separate document.

Delete an a9s Elasticsearch Service Instance

WARNING: Before deleting a service instance, you must backup data stored in your database. This operation cannot be undone and all the data is lost when the service is deleted.

Before you can delete a service instance, you must unbind it from all apps.

List Available Services

Run cf services to list your available services.

$ cf services

Getting services in org test / space test as admin...
OK

name service plan bound apps last operation
my-elasticsearch-service a9s-elasticsearch5 elasticsearch-single-small a9s-elasticsearch-app create succeeded

This example shows that my-elasticsearch-service is bound to the a9s-elasticsearch-app application.

Unbind a Service Instance

Run cf unbind-service to unbind the service from your application.

cf unbind-service a9s-elasticsearch-app my-elasticsearch-service

Delete a Service Instance

After unbinding the service, it is no longer bound to an application. Run cf delete-service to delete the service:

cf delete-service my-elasticsearch-service

It may take several minutes to delete the service. Deleting a service deprovisions the corresponding infrastructure resources. Run the cf services command to view the deletion status.

Upgrade the Service Instance to another Service Plan

Once created, you can upgrade your service instance to another, larger service plan. A larger service plan provides more CPU, RAM and storage. For more information, see the Update a Service Instance of the Managing Service Instances with the cf CLI topic.

cf update-service my-elasticsearch-service -p a-bigger-plan

Add a Graphite Endpoint

Important: Streaming of logs and metrics might not be availabale for your plan! If unsure, please check your plan description.

If you want to monitor your service with Graphite, you can set the custom parameter graphite. It expects the host and port where the Graphite metrics should be sent to.

For example, in order to send Graphite metrics to an endpoint yourspace.your-graphite-endpoint.com:12345, you can use the following command:

cf update-service my-instance -c '{ "graphite": "yourspace.your-graphite-endpoint.com:12345" }'

The endpoint would then receive metrics in the format:

<service_guid>.<service_type>.<host>.<metric> <metric value> <metric timestamp>

Metrics Frequency

By default, metrics will be emitted every 10 seconds. You can change the interval via the custom parameter metrics_frequency.

For example, in order to send Graphite metrics to an endpoint every minute, you would set the custom parameter metrics_frequency to 60 using the following command:

cf update-service my-instance -c '{  "metrics_frequency": 60 }'

Metrics Prefix

Depending on your graphite provider, you might need to prefix the metrics with a certain value, like an API key for example. In this case you can leverage the custom parameter metrics_prefix.

cf update-service my-instance -c '{  "metrics_prefix": "my-api-key-for-a-certain-provider" }'

The resulting metric path would have the format:

<metrics_prefix>.<service_guid>.<service_type>.<host>.<metric>

Metrics

These are the all metrics provided by the a9s Elasticsearch.

Metric IdtypeDescription
metric_fetch_statusInteger (1 = true / 0 = false)When the last metric update is successful the result is true.
cluster_health.active_primary_shardsIntegerThe number of active primary shards. documentation
cluster_health.active_shardsIntegerThe total number of active primary and replica shards. documentation
cluster_health.active_shards_percent_as_numberFloatPercent of shards active documentation
cluster_health.delayed_unassigned_shardsIntegerThe number of shards whose allocation has been delayed by this timeout. documentation
cluster_health.initializing_shardsIntegerThe number of shards that are under initialization. documentation
cluster_health.number_of_data_nodesIntegerThe number of nodes that are dedicated data nodes. documentation
cluster_health.number_of_in_flight_fetchIntegerThe number of unfinished fetches. documentation
cluster_health.number_of_nodesIntegerThe number of nodes within the cluster. documentation
cluster_health.number_of_pending_tasksIntegerThe number of cluster-level changes that have not yet been executed. documentation
cluster_health.relocating_shardsIntegerThe number of shards that are under relocation. documentation
cluster_health.statusInteger (0 = green / 1 = yellow / 2 = red / 3 = unknown)Health status of the cluster, based on the state of its primary and replica shards. documentation
cluster_health.task_max_waiting_in_queue_millisIntegerThe time expressed in milliseconds since the earliest initiated task is waiting for being performed. documentation
cluster_health.timed_outInteger (1 = true / 0 = false / 2 = unknown)If false the response returned within the period of time that is specified by the timeout parameter (30s by default). documentation
cluster_health.unassigned_shardsIntegerThe number of shards that are not allocated documentation
Examples
*.elasticsearch.*.*.*.*.metric_fetch_status
*.elasticsearch.*.*.*.*.cluster_health.active_primary_shards
*.elasticsearch.*.*.*.*.cluster_health.active_shards
*.elasticsearch.*.*.*.*.cluster_health.active_shards_percent_as_number
*.elasticsearch.*.*.*.*.cluster_health.delayed_unassigned_shards
*.elasticsearch.*.*.*.*.cluster_health.initializing_shards
*.elasticsearch.*.*.*.*.cluster_health.number_of_data_nodes
*.elasticsearch.*.*.*.*.cluster_health.number_of_in_flight_fetch
*.elasticsearch.*.*.*.*.cluster_health.number_of_nodes
*.elasticsearch.*.*.*.*.cluster_health.number_of_pending_tasks
*.elasticsearch.*.*.*.*.cluster_health.relocating_shards
*.elasticsearch.*.*.*.*.cluster_health.status
*.elasticsearch.*.*.*.*.cluster_health.task_max_waiting_in_queue_millis
*.elasticsearch.*.*.*.*.cluster_health.timed_out
*.elasticsearch.*.*.*.*.cluster_health.unassigned_shards

Cloud Foundry Org and Space Guid

The platform operators can enable support on a global level to prefix the Graphite metrics with the CloudFoundry organization and space. This means that all metrics of all service instances (not only yours!) contain that information.

In this case the Graphite metric paths have the following format:

<organization_guid>.<space_guid>.<service_guid>.<service_type>.<host>.<metric>

When you enable in addition the metrics_prefix for your instance, you will end up with the metric path format:

<metrics_prefix>.<organization_guid>.<space_guid>.<service_guid>.<service_type>.<host>.<metric>

Add a Syslog Endpoint

The cf update-service command used with the -c flag can let you stream your syslog to a third-party service. In this case, the command expects a JSON string containing the syslog key. You can also change the interval for the syslog with the same key used to specify graphite interval.

cf update-service my-elasticsearch-service \
-c '{ "syslog": ["logs4.your-syslog-endpoint.com:54321"], "interval": "5" }'

Enable Custom Plugins

You can use the cf update-service command with the -c flag to enable plugins on demand such as the analysis-phonetic plugin which convert tokens to their phonetic representation using Soundex, Metaphone, and a variety of other algorithms.

To enable the analysis phonetic plugin you would use the following command:

cf update-service my-elasticsearch-service \
-c '{"plugins": ["analysis-phonetic"]}'

The currently available plugins are:

  • repository-s3 (enabled by default, cannot be disabled)
  • repository-azure (enabled by default, cannot be disabled)
  • analysis-phonetic

Cloud Foundry Application Security Groups

This topic describes how to check whether a security group was created.

Each a9s Data Service will automatically create and update Cloud Foundry security groups in order to protect service instances to be accessed by applications not running in the same Cloud Foundry applications space. To get a better understanding about Security Groups you can have a look on the Understanding Application Security Groups topic.

Get Service Instance GUID

Run cf service INSTANCE_NAME --guid to get the guid of the service instance.

$ cf service my-elasticsearch --guid
ca16f111-5073-40b7-973a-156c75dd3028

Check available Security Groups

To see all available security groups use cf security-groups.

$ cf security-groups
Getting security groups as demo@anynines.com
OK

Name Organization Space
#0 public_networks
#1 dns
#2 tcp_open
#3 guard_432fb752-876d-443b-a311-a075f4df2237 demonstrations demo
#4 guard_ca16f111-5073-40b7-973a-156c75dd3028 demonstrations demo

There you can see a security group named guard_ca16f111-5073-40b7-973a-156c75dd3028 was successfully created.

NOTE: in some circumstances the connection between the application and the service instance is not possible, in this case check if a security group was created.

Backup and Restore Service Instances

a9s Elasticsearch provides an easy way to create backups and restore if needed. For a more detailed description, please see the a9s Service Dashboard documentation.

Make a Service Instance Locally Available

It is possible to access any of the a9s Data Services locally. That means you can connect with a local client to the service for any purpose such as debbuging. CF provides a smart way to create SSH forward tunnels via a pushed application. For more information about this feature see the Accessing Apps with SSH section of the CF documentation.

First of all you must have an application bound to the service. How to do this see Bind an Application to a Service Instance.

NOTE: cf ssh support must be enabled in the platform. Ask your administrator if you are not sure.

Get The Service Url and Credentials

When you follow this instructions Obtain Service Instance Access Credentials you will get the hostname of the service and the user credentials.

$ cf env a9s-elasticsearch-app
Getting env variables for app a9s-elasticsearch-app in org test / space test as admin...
OK

System-Provided:
{
"VCAP_SERVICES": {
"a9s-elasticsearch5": [
{
"credentials": {
"host": [
"d67901c.service.dc1.a9svs"
],
"password": "a9s-brk-usr",
"username": "a9s-password"
},
"label": "a9s-elasticsearch5",
"name": "my-elasticsearch-service",
"plan": "elasticsearch-cluster-small"
}
]
}
}
...

Notice the host d67901c.service.dc1.a9svs, the username a9s-brk-usr and the password a9s-password. You will need this in the next step.

Create a Tunnel to The Service

With the cf ssh as mentioned before you can create a ssh forward tunnel to the management dashboard. Use port 9200 to connect to the a9s Elasticsearch Instance.

$ cf ssh a9s-elasticsearch-app -L 9200:d67901c.service.dc1.a9svs:9200
vcap@956aaf4e-6da9-4f69-4b1d-8e631a403312:~$

When the ssh tunnel is open you can access the instance over the address localhost:9200.

NOTE: Don't forget to close the session with exit.

Setup Disk Usage Alerts

Each service comes with the a9s Parachute. This component monitors ephemeral and persistent disk usage. See the a9s Parachute documentation how to configure the component.

Custom Parameters

As an end user, you have the opportunity to customize your service instance by using custom parameters. Custom parameters are passed on to a service instance by using the -c switch of the cf CLI commands cf create-service and cf update-service. For example:

cf update-service my-instance -c '{"ssl_session_timeout": "4h"}'

You don't have to use those settings. There are sane defaults in place that fit your service plan well.

ssl_session_timeout

This property is used to specify a period during which a client may reuse the session parameters by configuring the setting ssl_session_timeout of the nginx sitting in front of Elasticsearch service instances configured with SSL. The content follows the nginx configuration file measurement units.