FAQ

• go-micro service interactions

  

• How to download all dependencies after cloning the repo?

# by default this will download all modules in go.mod
go mod download
# with golang 1.14, some modules are not compatible yet. please use this as temp solution.
go env -w GOPROXY=direct
go env -w GOSUMDB=off
go mod download
# If you are importing internal/private modules, use following setting with `go mod download`
GOPRIVATE=bitbucket.com/banzaicloud/*
go mod download

• How to use go modules from a Fork and branch

  To use a fork, e.g., https://github.com/drnic/fatih-color, and a branch silly-changes, You need to update go.mod to use the replace helper:

  module github.com/starkandwayne/my-go-project
  
  go 1.14
  
  require (
    github.com/fatih/color v1.7.0 // indirect
    github.com/mattn/go-colorable v0.1.2 // indirect
  )
  
  replace github.com/fatih/color => github.com/drnic/fatih-color silly-change

• How to update 3rd party dependencies?

  go get -u # to use the latest minor or patch releases
  go get -u=patch # to use the latest patch releases
  go mod tidy
  # to find out why you have specific dependency
  go mod why -m github.com/DATA-DOG/go-sqlmock
  # if you want to get binaries into $GOHOME/bin or $GOBIN
  GO111MODULE=off go get whatever
  # list modules
  go list -m all

• How to get commitizen and cz-conventional-changelog work for non-node-git-repo?

  You can get commitizen and cz-conventional-changelog work for non-node-git-repo with global installation. Here are the steps that I have followed.

  yarn global add commitizen cz-conventional-changelog
  echo '{ "path": "cz-conventional-changelog" }' > ~/.czrc; # create .czrc
  cd non-node-git-repo
  touch foo
  git cz -a

• How to clean cached go modules?

  rm go.sum
  go clean -modcache
  go mod download
  # this empties $GOPATH/pkg/mod/
  go clean -cache -modcache

• How to Prepare for a Release?

  go mod tidy
  go test all

• how to debug in VS Code?

  every time, make sure file with main() is opened before proceeding to next steps

  1. open GoLang file with main() method you want to debug.

  2. click on debug icon in Action Bar

  3. click on Launch [▶] button.

  4. Optionally edit .vscode/launch.json and add args, env etc.

• How to implement integration tests?

Integration tests are e2e tests that invoke Handler methods directly and ignore networking completely. True e2e tests are Black-box tests that invoke network endpoint.

  func TestEmailService_Welcome(t *testing.T) {
    t.Parallel()
    //...
  }

  func TestEmailService_Welcome_Invalid(t *testing.T) {
      t.Parallel()
      //...
  }

  func TestEmailService_Welcome_Integration(t *testing.T) {
      if testing.Short() {
          t.Skip("skipping integration test")
      }
      //...
  }

  func TestEmailService_Welcome_E2E(t *testing.T) {
      if testing.Short() {
          t.Skip("skipping e2e test")
      }
      //...
  }

Notice the last test has the convention of:

• using Integration in the test name.

• checking if running under -short flag directive.

Basically, the spec goes:

"write all tests normally. if it is a long-running tests, or an integration test, follow this naming convention and check for -short"

When we want to run our unit tests, we would use the -short flag, and omit it for running our integration tests or long running tests.

Use t.Errorf t.Logf for logging. don't use logrus or default log

# Run only Unit tests:
go test -v -short
go test -v -short ./service/emailer/service
# Run only Integration Tests: Useful for smoke testing canaries in production.
go test -v -run Integration
go test -v -run Integration ./service/emailer/service

• How to ssh and debug a scratch container?

  Ephemeral containers are a great way to debug running pods, as you can’t add regular containers to a pod after creation. These containers executes within the namespace of an existing pod and has access to the file systems of its individual containers.

  kubectl debug -c debug-shell --image=busybox target-pod -- sh

• How to debug a pod that is crashing during initialization? If you pod crashing you cannot SSH to it, e.g., to see file system etc. Assuming your container has busybox at /bin/busybox, add following command to your deployment yaml.

  # Just spin & wait forever
  command:
    [
      "/bin/busybox",
      "sh",
      "-ec",
      "while :; do echo '.'; /bin/busybox sleep 5 ; done",
    ]

  Then run kubectl exec -it $POD_NAME -- /bin/busybox sh to SSH to the container.

  /bin/busybox ls config
  /bin/busybox more config/config.yaml

• Why some ORM model fields are pointers?

  all fields having a zero value, like 0, '', false or other zero values, won’t be saved into the database but will use its default value. If you want to avoid this, consider using a pointer type or scanner/valuer, e.g:

  // Use pointer value
  type User struct {
  gorm.Model
  Name string
  Age  *int `gorm:"default:18"`
  }
  
  // Use scanner/valuer
  type User struct {
  gorm.Model
  Name string
  Age  sql.NullInt64 `gorm:"default:18"`
  }

  Note: google wrapper types google.protobuf.StringValue, .BoolValue, .UInt32Value, .FloatValue, etc. map to pointers of the internal type at the ORM level, e.g. string, bool, uint32, float

• How to run go-micro gRPC services and Micro REST Gateway on k8s?

  So you want to use k8s internal CoreDNS as service registry?, then you have to follow some rules:

  • Service name cannot have .(dot) due to k8s DNS limits, so make it simple via environment variables e.g., MICRO_SERVER_NAME=account

  • custom build REST Gateway as micro/micro:latest image is outdated. optionally add CORS plugin.

• performance If you’re concerned about performance, try

  --selector=cache # enables in memory caching of discovered nodes
  --client_pool_size=10 # enables the client side connection pool

  You can now enable profiling in go-micro by setting MICRO_DEBUG_PROFILE=true This will enable pprof and write a cpu profile and heap profile to /tmp the profiles will be [service name].{cpu, mem}.pprof

• How to rollback a git commit?

  # Undoing the Last Commit:
  git reset --soft HEAD~1
  # If you don't want to keep these changes, simply use the --hard flag.
  git reset --hard HEAD~1
  
  # Delete Tag local
  git tag --delete v0.2.6
  # Delete Tag remote
  git push --delete origin v0.2.6

• How to Push Git Tags with Commit? Refer: how-to-push-git-tags-with-commit

  git config --global push.followTags true

• How to debug etcd?

  kubectl port-forward service/etcd-cluster-client -n default  2379
  # then
  ETCDCTL_API=3 etcdctl version
  ETCDCTL_API=3 etcdctl -w table member list
  ETCDCTL_API=3 etcdctl get --from-key ''

Refer

• separating-tests-in-go

• advanced testing tips & tricks