{"id":348,"date":"2018-10-16T10:36:38","date_gmt":"2018-10-16T10:36:38","guid":{"rendered":"https:\/\/www.appservgrid.com\/paw93\/?p=348"},"modified":"2018-10-17T08:21:06","modified_gmt":"2018-10-17T08:21:06","slug":"health-checking-grpc-servers-on-kubernetes","status":"publish","type":"post","link":"https:\/\/www.appservgrid.com\/paw93\/index.php\/2018\/10\/16\/health-checking-grpc-servers-on-kubernetes\/","title":{"rendered":"Health checking gRPC servers on Kubernetes"},"content":{"rendered":"

Author: Ahmet Alp Balkan<\/a> (Google)<\/p>\n

gRPC<\/a> is on its way to becoming the lingua franca for
\ncommunication between cloud-native microservices. If you are deploying gRPC
\napplications to Kubernetes today, you may be wondering about the best way to
\nconfigure health checks. In this article, we will talk about
\ngrpc-health-probe<\/a>, a
\nKubernetes-native way to health check gRPC apps.<\/p>\n

If you\u2019re unfamiliar, Kubernetes health
\nchecks<\/a>
\n(liveness and readiness probes) is what\u2019s keeping your applications available
\nwhile you\u2019re sleeping. They detect unresponsive pods, mark them unhealthy, and
\ncause these pods to be restarted or rescheduled.<\/p>\n

Kubernetes does not
\nsupport<\/a> gRPC health
\nchecks natively. This leaves the gRPC developers with the following three
\napproaches when they deploy to Kubernetes:<\/p>\n

\"options<\/a><\/p>\n

    \n
  1. httpGet probe: Cannot be natively used with gRPC. You need to refactor
    \nyour app to serve both gRPC and HTTP\/1.1 protocols (on different port
    \nnumbers).<\/li>\n
  2. tcpSocket probe: Opening a socket to gRPC server is not meaningful,
    \nsince it cannot read the response body.<\/li>\n
  3. exec probe: This invokes a program in a container\u2019s ecosystem
    \nperiodically. In the case of gRPC, this means you implement a health RPC
    \nyourself, then write and ship a client tool with your container.<\/li>\n<\/ol>\n

    Can we do better? Absolutely.<\/p>\n

    Introducing \u201cgrpc-health-probe\u201d<\/h2>\n

    To standardize the \u201cexec probe\u201d approach mentioned above, we need:<\/p>\n