Chapter 3. External Redis database configuration for high availability support in 3scale API Management
Chapter 3. External Redis database configuration for high availability support in 3scale API Management Important Red Hat supports 3scale configurations that use an external Redis database. However, does not officially support setting up Redis for zero downtime, configuring back-end components for 3scale, or Redis database replication and sharding. The content is for reference only. Additionally, Redis cluster mode is not supported in 3scale. High availability (HA) is provided for most components by the OpenShift Container Platform (OCP). Note When you externalize databases from a Red Hat 3scale API Management deployment, this means to provide isolation from the application and resilience against service disruptions at the database level. The resilience to service disruptions depends on the service level agreements (SLAs) provided by the infrastructure or platform provider where you host the databases. This is not offered by 3scale. For more details on externalizing of databases offered by your chosen deployment, see the associated documentation. The database components for HA in Red Hat 3scale API Management include: backend-redis : used for statistics storage and temporary job storage. system-redis : provides temporary storage for background jobs for 3scale and is also used as a message bus for Ruby processes of system-app pods. Both backend-redis and system-redis work with supported Redis high availability variants for Redis Sentinel and Redis Enterprise. If the Redis pod comes to a stop, or if the OpenShift Container Platform stops it, a new pod is automatically created. Persistent storage will restore the data so the pod continues to work. In these scenarios, there will be a small amount of downtime while the new pod starts. This is due to a limitation in Redis that does not support a multi-master setup. You can reduce downtime by preinstalling the Redis images onto all nodes that have Redis deployed to them. This will speed up the pod restart time. Set up Redis for zero downtime and configure back-end components for 3scale: Setting up Redis for zero downtime Configuring back-end components for 3scale API Management Prerequisites A 3scale account with an administrator role. 3.1. Setting up Redis for zero downtime As a 3scale administrator, configure Redis outside of OCP if you require zero downtime. There are several ways to set it up using the configuration options of 3scale pods: Set up your own self-managed Redis Use Redis Sentinel: Reference Redis Sentinel Documentation Redis provided as a service: For example by: Amazon ElastiCache Redis Labs Note Red Hat does not provide support for the above mentioned services. The mention of any such services does not imply endorsement by Red Hat of the products or services. You agree that Red Hat is not responsible or liable for any loss or expenses that may result due to your use of (or reliance on) any external content. 3.2. Configuring back-end components for 3scale API Management As a 3scale administrator, configure Redis HA (failover) for the back-end component environment variables in the following deployment configurations: backend-cron , backend-listener , and backend-worker . These configurations are necessary for Redis HA in 3scale. Note If you want to use Redis with sentinels, you must provide sentinel configuration in either backend-redis , system-redis , or both secrets. 3.2.1. Creating backend-redis and system-redis secrets Follow these steps to create backend-redis and system-redis secrets accordingly: Deploying a fresh installation of 3scale API Management for HA Migrating a non-HA deployment of 3scale API Management to HA 3.2.2. Deploying a fresh installation of 3scale API Management for HA Procedure Create the backend-redis and system-redis secrets with the fields below: backend-redis system-redis When configuring for Redis with sentinels, the corresponding URL fields in backend-redis and system-redis refer to the Redis group in the format redis://[:redis-password@]redis-group[/db] , where [x] denotes optional element x and redis-password , redis-group , and db are variables to be replaced accordingly: Example The SENTINEL_HOSTS fields are comma-separated lists of sentinel connection strings in the following format: For each element of the list, [x] denotes optional element x and sentinel-password , sentinel-hostname-or-ip , and port are variables to be replaced accordingly: Example The SENTINEL_ROLE fields are either master or slave . Deploy 3scale as indicated in Deploying 3scale API Management using the operator . Ignore the errors due to backend-redis and system-redis already present. 3.2.3. Migrating a non-HA deployment of 3scale API Management to HA Edit the backend-redis and system-redis secrets with all fields as shown in Deploying a fresh installation of 3scale API Management for HA . Make sure the following backend-redis environment variables are defined for the back-end pods. Make sure the following system-redis environment variables are defined for the system-(app|sidekiq) pods. Proceed with instructions to continue link:h:Link3scaleMigrating3scale: Upgrading 3scale using templates . 3.2.3.1. Using Redis Enterprise Use Redis Enterprise deployed in OpenShift, with three different redis-enterprise instances: Edit system-redis secret: Set the system redis database in system-redis to URL . Set the back-end database in backend-redis to REDIS_QUEUES_URL . Set the third database to REDIS_STORAGE_URL for backend-redis . 3.2.3.2. Using Redis Sentinel Note You can optionally apply Redis Sentinels to any of the databases. However, Red Hat recommends that you apply Redis Sentinels to all of them for HA. Backend redis for statistics: update backend-redis secret and provide values for: REDIS_STORAGE_URL REDIS_STORAGE_SENTINEL_ROLE REDIS_STORAGE_SENTINEL_HOSTS Set REDIS_STORAGE_SENTINEL_ROLE to a comma-separated list of sentinels hosts and ports, for example: :sentinelpwd@123.45.67.009:2711,:sentinelpwd@other-sentinel:2722 Backend redis for queue: update backend-redis secret and provide values for: REDIS_QUEUES_URL REDIS_QUEUES_SENTINEL_ROLE REDIS_QUEUES_SENTINEL_HOSTS Set REDIS_QUEUES_SENTINEL_ROLE to a comma-separated list of sentinels hosts and ports, for example: :sentinelpwd@123.45.67.009:2711,:sentinelpwd@other-sentinel:2722 Use Redis Sentinel, with these Redis databases: System redis for data: update system-redis secret and provide values for: Note Edit system-redis secret: URL SENTINEL_ROLE NAMESPACE URL SENTINEL_HOSTS Set SENTINEL_HOSTS to a comma-separated list of sentinels hosts and ports, for example: :sentinelpwd@123.45.67.009:2711,:sentinelpwd@other-sentinel:2722 Notes The system-app and system-sidekiq components connect directly to back-end Redis for retrieving statistics. As of 3scale 2.7, these system components can also connect to back-end Redis (storage) when using sentinels. The system-app and system-sidekiq components uses only backend-redis storage, not backend-redis queues. Changes made to the system components support backend-redis storage with sentinels. 3.3. Additional information For more information about 3scale and Redis database support, see Red Hat 3scale API Management Supported Configurations . For more information about Amazon ElastiCache for Redis, see the official Amazon ElastiCache Documentation . For more information about Redis Enterprise, see the latest Documentation .
REDIS_QUEUES_SENTINEL_HOSTS REDIS_QUEUES_SENTINEL_ROLE REDIS_QUEUES_URL REDIS_STORAGE_SENTINEL_HOSTS REDIS_STORAGE_SENTINEL_ROLE REDIS_STORAGE_URL NAMESPACE SENTINEL_HOSTS SENTINEL_ROLE URL redis://:redispwd@mymaster/5 redis://:sentinel-password@sentinel-hostname-or-ip:port :sentinelpwd@123.45.67.009:2711,:sentinelpwd@other-sentinel:2722 name: BACKEND_REDIS_SENTINEL_HOSTS valueFrom: secretKeyRef: key: REDIS_STORAGE_SENTINEL_HOSTS name: backend-redis name: BACKEND_REDIS_SENTINEL_ROLE valueFrom: secretKeyRef: key: REDIS_STORAGE_SENTINEL_ROLE name: backend-redis name: REDIS_SENTINEL_HOSTS valueFrom: secretKeyRef: key: SENTINEL_HOSTS name: system-redis name: REDIS_SENTINEL_ROLE valueFrom: secretKeyRef: key: SENTINEL_ROLE name: system-redis