host-manager

README

Introduction

This simple application introduces the simplest usages of a couple of common libraries. The application registers hosts and provide get-all and get-by-id operations via rest. There're 2 ways to register a host into the application: environment variables and openshift's routes

To register a host via environment variables just add variable with preconfigured prefix. To register a host via openshift's routes:

• If you start application outside openshift cluster just update config/kube-config.yaml or provide your config-file via ENV_CONFIG_PATH
• If you start application inside openshift cluster you have to provide a namespace (mapping.namespace configuration value)

Note: all default configuration variables placed in config/host-manager.yaml (could be changed via ENV_CONFIG_PATH)

Docker

There're 2 docker-files (see build directory):

• docker1 - single-stage docker-file
• docker2 - multi-stage docker-file

To build an image just: docker build -t host-manager -f build/dockerX/Dockerfile .

OpenShift

To push the image to internal openshift's repository:

• Provide to the user required grants: oc policy add-role-to-user registry-viewer admin and oc policy add-role-to-user registry-editor admin
• Get current internal registry's ip address: oc get svc -n default docker-registry
• Tag the image with current URL: docker tag host-manager:latest <REGISTRY-IP>:5000/openshift/host-manager:<VERSION>
• Login to internal registry: docker login -u admin -p $(oc whoami -t) <REGISTRY-IP>:5000
• Push the image: docker push <REGISTRY-IP>:5000/openshift/host-manager:<VERSION>

To create new application:

• Create new deployment configuration: oc new-app --docker-image <REGISTRY-IP>:5000/openshift/host-manager:<VERSION> --name host-manager
• Add service account to deployment configuration which is has grants to read routes in the namespace:
  • oc create sa host-manager
  • oc adm policy add-role-to-user view -z host-manager
  • oc patch dc/host-manager -p '{"spec":{"template":{"spec":{"serviceAccount":"host-manager"}}}}'
• Create new service: oc expose dc/host-manager --port=8080
• Create new route: oc expose svc/host-manager
• To add a host via environment variable: oc set env dc/host-manager APP_HOST_HOST1=host1:8080
• Add namespace scanning if required: oc set env dc/host-manager APP_MAPPING_NAMESPACE=<NAMESPACE>

To create/process the template:

• Create granted service account:
  • oc create sa <SERVICE_ACCOUNT>
  • oc adm policy add-role-to-user view -z <SERVICE_ACCOUNT> ('view' role for instance only)
• oc create deploy/openshift/templace.yaml
• oc process host-manager NAMESPACE=<NAMESPACE> IMAGE=<IMAGE> PORT=<PORT> SERVICE_ACCOUNT=<SERVICE_ACCOUNT> | oc create -f -

Tracing

For development purposes it's easy to use all-in-one jaeger version:

• Start all-in-one jaeger: docker run --name jgr -p5775:5775/udp -p6831:6831/udp -p16686:16686 -d jaegertracing/all-in-one:latest
• Go to: http://localhost:16686/search

Swagger

Swaggo/swag is used to generate swagger.

To generate swagger:

• go get -u github.com/swaggo/swag/cmd/swag
• <GO_PATH>/bin/swag init --dir ./ --generalInfo ./cmd/host-manager/main.go --output ./api/swagger
• http://<HOST>:<PORT>/swagger/index.html

Testing

• go test -coverprofile=out/test.html ./internal/service/mapping/
• go tool cover -html=out/test.html

Configuration

There's 2 options to configure application: Envconfig and configuration file (config/host-manager.yaml by default)

PProf

• https://github.com/gin-contrib/pprof
• go tool pprof http://localhost:8080/debug/pprof/profile?seconds=5