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05-service-discovery.md

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Service Discovery
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cf-networking-release

Service Discovery

Architecture

Architecture Diagram

Routes are emitted from the Route Emitter. Internal routes are emitted from the Route Emitter as well, on a separate topic.

The NATS message queue cluster that handles routes for the gorouter also handles internal routes.

The Service Discovery Controller (SDC) subscribes to route updates from NATS on the internal routes topic. The SDC is highly available. The SDC has no persistence, it is an in memory store of internal domain names to IPs. The SDC warms (populates routes) before entering service.

Each Diego Cell has a BOSH DNS and a BOSH-DNS Adapter. App containers are configured to use the BOSH DNS server on their Deigo cell as their DNS server. The BOSH-DNS Adapter configures BOSH DNS to route queries for internal domains to itself. When a request for an internal domain hits BOSH DNS it looks at the domain name. If it's internal it directs the request to the BOSH-DNS Adapter. BOSH DNS communicates to the BOSH DNS Adapter via http (following the Google DNS over HTTPS schema).

The BOSH DNS adapter in turn makes a request to the SDC. This HTTP connection is secured using mTLS. Responses from the SDC contain all the IPs of all the app containers associated with the requested route. Responses from the BOSH DNS adapter contain all the IPs returned from the SDC, shuffled. BOSH DNS in turn returns the full set of IPs originally from the SDC. Clients typically use the first IP in the DNS response, the shuffling provides a crude form of load balancing.

Metrics

Below are a list of metrics for service discovery components. To deploy a firehose nozzle to see the metrics, upload the datadog-firehose-nozzle-release and follow the instructions here to deploy.

Metric Name Description
bosh_dns_adapter.GetIPsRequestTime duration of get ip request in milliseconds
bosh_dns_adapter.GetIPsRequestCount number of get ip requests
bosh_dns_adapter.DNSRequstFailures number of failed requests to the Service Discovery Controller
bosh_dns_adapter.uptime process uptime, emitted on 10 second interval
service_discovery_controller.RegistrationRequestTime duration of registration request in milliseconds
service_discovery_controller.RegistrationRequestCount number of registration requests
service_discovery_controller.addressTableLookupTime duration of looking up address table in milliseconds
service_discovery_controller.uptime process uptime, emitted on 10 second interval
service_discovery_controller.dnsRequest count of successful dnsRequests, emitted on a 10 second interval
service_discovery_controller.registerMessagesReceived count of route register messages received via NATS from route emitter
service_discovery_controller.maxRouteMessageTimePerInterval maximum time taken from BBS to SDC, only on new app creation

CF App Service Discovery

Motivation

Previously, Application Developers who wanted to use container to container networking were required to bring their own service discovery. We had provided examples with Eureka and Amalgam8, and received user feedback that usage of c2c was very difficult. Common themes emerging:

  • Polyglot microservices written in languages/frameworks other than Java/Spring cannot easily use Eureka
  • Clustering applications have a requirement to address individual instances
  • Additional VMs need to be deployed and managed to provide external service discovery

In order to support all types of apps, languages and frameworks, we built service discovery for c2c into the platform. With this feature, users no longer have to bring their own service discovery.

App Developer Experience

You can run map-route with the internal domain to create and map an internal route for your app.

Interaction with Policy

By default, apps cannot talk to each other over cf networking. In order for an app to talk to another app, you must still set a policy allowing access.

Internal Domains

Configuring Custom Internal Domains

Creating your own internal domain requires enable-service-discovery opsfile and the following two operations:

  1. Add the custom internal domain name(s) to the internal_domains property on the bosh-dns-adapter job.
- type: replace
  path: /instance_groups/name=diego-cell/jobs/name=bosh-dns-adapter/properties/internal_domains?
  value: ["apps.internal."]

NOTE: The internal domain property in bosh-dns-adapter supports domains with and without the trailing dot.

  1. Run the following command after deployment:
cf create-shared-domain <DOMAIN> --internal

Or, add the custom internal domain to the apps_domains property on cloud_controller_ng job.

- type: replace
  path: /instance_groups/name=api/jobs/name=cloud_controller_ng/properties/app_domains/-
  value:
    name: apps.internal
    internal: true

NOTE: The internal domain property in cloud_controller_ng does not accept domains with a trailing dot.

  1. Deploy.

To delete a shared domain, run one of the following commands:

cf curl -X DELETE /v2/shared_domains/<SHARED DOMAIN GUID>
cf delete-shared-domain <DOMAIN> [-f]

Updating to cf-networking-release v2.11.0 or later

Before v2.11.0, the internal domain apps.internal was the default bosh property for the internal_domains property on the bosh-dns-adapter job. Starting in v2.11.0 this will no longer be the case. It will need to be set on that property in order for apps.internal to continue working.

Notes on CAPI Release

With capi-release versions 1.49.0-1.60.0:

  • The internal domain apps.internal is automatically created for you.

With capi-release versions 1.61.0-1.63.0:

  • The apps.internal internal domain is no longer seeded and must be created using the CAPI api. See the Example steps section for instructions.
  • A custom domain name may be used when creating an internal domain name, but note that the bosh-dns-adapter job's internal_domains property must be updated too. The default value for this property is 'apps.internal'.

With capi-release versions >= 1.63.0:

  • The apps.internal internal domain is included by default with the enable-service-discovery opsfile.
  • A custom domain name may be used and the apps.internal domain may be deleted using the API.

Example steps

Assumes you're running a recent environment from cf-deployment

  • Pull down your current manifest with
bosh manifest > /tmp/cf-manifest.yml
  • Create an internal domain.

Note: this step is not neccessary if using the enable-service-discovery opsfile unless you wish to create a different internal shared domain.

cf curl /v2/shared_domains -d '{
  "name": "CUSTOM_INTERNAL_DOMAIN_NAME",
  "internal": true
}'
  • Use the following command to list the domains, and to verify which of the domains are 'internal': true
cf curl /v2/shared_domains

  • Update the internal_domains job property on the bosh-dns-adapter job if the internal domain is not apps.internal. The list of domains should match the internal domains that have been configured in the prior step. The internal_domains job property defaults to ['apps.internal'].

  • Update your deployment with the ops files

bosh deploy /tmp/cf-manifest.yml \
  -o ~/workspace/cf-deployment/operations/use-bosh-dns-for-containers.yml \
  -o ~/workspace/cf-deployment/operations/use-bosh-dns.yml \
  -o ~/workspace/cf-deployment/operations/enable-service-discovery.yml \
  --vars-store path/to/vars-store.yml
  # The --var-store flag will cause cli variable generation, and
  # your secrets will be stored in the supplied file path. This is probably not what you
  # want. Read more here: https://bosh.io/docs/cli-int.html#vars-store

Logging

Debugging problems

  • To change logging for service-discovery-controller, ssh onto the VM holding the service-discovery-controller and make a request to the log-level server:
curl -X POST -d 'debug' localhost:8055/log-level

where 8055 is the default value of log_level_port.

To switch back to info logging:

curl -X POST -d 'info' localhost:8055/log-level
  • To change logging for bosh-dns-adapter, ssh onto the VM holding the bosh-dns-adapter and make a request to the log-level server:
curl -X POST -d 'debug' localhost:8066/log-level

To switch back to info logging:

curl -X POST -d 'info' localhost:8066/log-level

Tests

Please refer to the contributing guide for information on running unit and integration tests. Service-Discovery specific instructions for running Acceptance and Smoke tests below.

Running Acceptance Tests

Acceptance tests should be run to see that service discovery is still functional at a CF level.

Running the full acceptance test on bosh-lite

./scripts/test-sd-acceptance-local

Running the full acceptance test on specific env

You must set the environment variable $CONFIG which points to a JSON file that contains several pieces of data that will be used to configure the acceptance tests, e.g. telling the tests how to target your running Cloud Foundry deployment and what tests to run.

The following can be pasted into a terminal and will set up a sufficient $CONFIG to run the core test suites against a BOSH-Lite deployment of CF. admin-password and admin-secret need to be replaced with proper values.

cat > integration_config.json <<EOF
{
  "api": "api.bosh-lite.com",
  "admin_user": "admin",
  "admin_password": "{{admin-password}}",
  "admin_secret": "{{admin-secret}}",
  "apps_domain": "bosh-lite.com",
  "skip_ssl_validation": true,
}
EOF
export CONFIG=$PWD/integration_config.json

The full set of config parameters is explained below:

Required parameters:
Param Description
api Cloud Controller API endpoint.
admin_user Name of a user in your CF instance with admin credentials. This admin user must have the network.admin scope.
admin_password Password of the admin user above.
admin_secret Secret of the admin user above.
apps_domain A shared domain that tests can use to create subdomains that will route to applications also created in the tests.
skip_ssl_validation Set to true if using an invalid (e.g. self-signed) cert for traffic routes to your CF instances; this is generally always true for BOSH-Lite deployments of CF.

Once the config is set, to run the acceptance tests do the following

ginkgo -r ./src/code.cloudfoundry.org/test/acceptance-sd

Running Smoke Tests

Smoke tests can be run periodically against live environments to check that basic service discovery remains functional.

Point the environment variable $CONFIG to a JSON file with smoke test params.

The following can be pasted into a terminal and will set up a sufficient $CONFIG to run the core test suites against a BOSH-Lite deployment of CF.

cat > integration_config.json <<EOF
{
  "api": "api.bosh-lite.com",
  "apps_domain": "bosh-lite.com",
  "admin_user": "admin",
  "admin_password": "admin",
  "prefix": "smoke-test-",
  "smoke_org": "smoke_org",
  "smoke_space": "smoke_space"
}
EOF
export CONFIG=$PWD/integration_config.json

The full set of config parameters is explained below:

Parameter Description Required?
api Cloud Controller API endpoint. YES
admin_user Name of a user in the CF instance with admin credentials. This admin user must have the network.admin scope. YES
admin_password Password of the admin user above. YES
prefix Prefix for apps, orgs, and spaces created as part of the smoke tests YES
smoke_org Name of pre-existing org for smoke test NO
smoke_space Name of pre-existing space for smoke test NO

Once the config is set, run the smoke tests:

ginkgo -r ./src/code.cloudfoundry.org/test/smoke-sd

:

Configuring

Configuring Custom Internal Domains

Now that service-discovery is enabled by default in cf-deployment, creating your own internal domain requires an ops file with the following two operations:

  1. Add the custom internal domain name(s) to the internal_domains property on the bosh-dns-adapter job.
- type: replace
  path: /instance_groups/name=diego-cell/jobs/name=bosh-dns-adapter/properties/internal_domains?
  value: ["apps.internal."]

NOTE: The internal domain property in bosh-dns-adapter supports domains with and without the trailing dot.

  1. Run the following command after deployment:
cf create-shared-domain <DOMAIN> --internal

Or, add the custom internal domain to the apps_domains property on cloud_controller_ng job.

- type: replace
  path: /instance_groups/name=api/jobs/name=cloud_controller_ng/properties/app_domains/-
  value:
    name: apps.internal
    internal: true

NOTE: The internal domain property in cloud_controller_ng does not accept domains with a trailing dot.

  1. Deploy.

To delete a shared domain, run one of the following commands:

cf curl -X DELETE /v2/shared_domains/<SHARED DOMAIN GUID>
cf delete-shared-domain <DOMAIN> [-f]