Merge pull request #175 from flant/fix_replace_zombie_reaper_with_tini

fix: use tini for zombie reaping

Author: diafour

.github/workflows/dev-build.yaml

@@ -43,9 +43,7 @@ jobs:
       matrix:
         flavour:
           - ubuntu
-          - alpine3.9
-          - alpine3.10
-          - alpine3.11
+          - alpine
     runs-on: ubuntu-latest
     if: github.event_name == 'pull_request' && github.event.label.id == 1838515600 # ':robot: build dev images' label
     steps:
@@ -63,13 +61,7 @@ jobs:
           dockerFile=Dockerfile
 
           case $FLAVOUR in
-            alpine3.9)
-              dockerFile="Dockerfile-alpine3.9"
-              ;;
-            alpine3.10)
-              dockerFile="Dockerfile-alpine3.10"
-              ;;
-            alpine3.11)
+            alpine)
               dockerFile="Dockerfile-alpine3.11"
               ;;
           esac

Dockerfile

@@ -34,6 +34,7 @@ RUN CGO_ENABLED=1 \
              -o shell-operator \
              ./cmd/shell-operator
 
+FROM krallin/ubuntu-tini:bionic AS tini
 
 # build final image
 FROM ubuntu:18.04
@@ -44,9 +45,10 @@ RUN apt-get update && \
     chmod +x /bin/kubectl && \
     mkdir /hooks
 ADD frameworks /
+COPY --from=tini /usr/local/bin/tini /sbin/tini
 COPY --from=shell-operator /src/shell-operator /
 WORKDIR /
 ENV SHELL_OPERATOR_HOOKS_DIR /hooks
 ENV LOG_TYPE json
-ENTRYPOINT ["/shell-operator"]
+ENTRYPOINT ["/sbin/tini", "--", "/shell-operator"]
 CMD ["start"]

Dockerfile-alpine3.10

@@ -32,7 +32,7 @@ RUN CGO_ENABLED=1 \
 
 # build final image
 FROM alpine:3.10
-RUN apk --no-cache add ca-certificates jq bash sed && \
+RUN apk --no-cache add ca-certificates jq bash sed tini && \
     wget https://storage.googleapis.com/kubernetes-release/release/v1.17.4/bin/linux/amd64/kubectl -O /bin/kubectl && \
     chmod +x /bin/kubectl && \
     mkdir /hooks
@@ -41,5 +41,5 @@ COPY --from=shell-operator /src/shell-operator /
 WORKDIR /
 ENV SHELL_OPERATOR_HOOKS_DIR /hooks
 ENV LOG_TYPE json
-ENTRYPOINT ["/shell-operator"]
+ENTRYPOINT ["/sbin/tini", "--", "/shell-operator"]
 CMD ["start"]

Dockerfile-alpine3.11

@@ -32,7 +32,7 @@ RUN CGO_ENABLED=1 \
 
 # build final image
 FROM alpine:3.11
-RUN apk --no-cache add ca-certificates jq bash sed && \
+RUN apk --no-cache add ca-certificates jq bash sed tini && \
     wget https://storage.googleapis.com/kubernetes-release/release/v1.17.4/bin/linux/amd64/kubectl -O /bin/kubectl && \
     chmod +x /bin/kubectl && \
     mkdir /hooks
@@ -41,5 +41,5 @@ COPY --from=shell-operator /src/shell-operator /
 WORKDIR /
 ENV SHELL_OPERATOR_HOOKS_DIR /hooks
 ENV LOG_TYPE json
-ENTRYPOINT ["/shell-operator"]
+ENTRYPOINT ["/sbin/tini", "--", "/shell-operator"]
 CMD ["start"]

Dockerfile-alpine3.9

@@ -32,7 +32,7 @@ RUN CGO_ENABLED=1 \
 
 # build final image
 FROM alpine:3.9
-RUN apk --no-cache add ca-certificates jq bash sed && \
+RUN apk --no-cache add ca-certificates jq bash sed tini && \
     wget https://storage.googleapis.com/kubernetes-release/release/v1.17.4/bin/linux/amd64/kubectl -O /bin/kubectl && \
     chmod +x /bin/kubectl && \
     mkdir /hooks
@@ -41,5 +41,5 @@ COPY --from=shell-operator /src/shell-operator /
 WORKDIR /
 ENV SHELL_OPERATOR_HOOKS_DIR /hooks
 ENV LOG_TYPE json
-ENTRYPOINT ["/shell-operator"]
+ENTRYPOINT ["/sbin/tini", "--", "/shell-operator"]
 CMD ["start"]

cmd/shell-operator/main.go

@@ -9,7 +9,6 @@ import (
 	"gopkg.in/alecthomas/kingpin.v2"
 
 	"github.com/flant/shell-operator/pkg/app"
-	"github.com/flant/shell-operator/pkg/executor"
 	shell_operator "github.com/flant/shell-operator/pkg/shell-operator"
 	utils_signal "github.com/flant/shell-operator/pkg/utils/signal"
 )
@@ -33,11 +32,6 @@ func main() {
 			app.SetupLogging()
 			log.Infof("%s %s", app.AppName, app.Version)
 
-			// Be a good parent - clean up after the child processes
-			// in case if shell-operator is a PID1.
-			executor.ReapLocked = false
-			go executor.Reap()
-
 			defaultOperator := shell_operator.DefaultOperator()
 			err := shell_operator.InitAndStart(defaultOperator)
 			if err != nil {

pkg/executor/executor.go

@@ -11,24 +11,16 @@ import (
 	utils "github.com/flant/shell-operator/pkg/utils/labels"
 )
 
-var ExecutorLock = &sync.RWMutex{}
-
-// This family of methods use ExecutorLock to not be interfered by zombie reaper.
-
 func Run(cmd *exec.Cmd) error {
-	ExecutorLock.RLock()
-	defer ExecutorLock.RUnlock()
-
 	// TODO context: hook name, hook phase, hook binding
+	// TODO observability
 	log.Debugf("Executing command '%s' in '%s' dir", strings.Join(cmd.Args, " "), cmd.Dir)
 
 	return cmd.Run()
 }
 
 func RunAndLogLines(cmd *exec.Cmd, logLabels map[string]string) error {
-	ExecutorLock.RLock()
-	defer ExecutorLock.RUnlock()
-
+	// TODO observability
 	logEntry := log.WithFields(utils.LabelsToLogFields(logLabels))
 	stdoutLogEntry := logEntry.WithField("output", "stdout")
 	stderrLogEntry := logEntry.WithField("output", "stderr")
@@ -83,9 +75,9 @@ func RunAndLogLines(cmd *exec.Cmd, logLabels map[string]string) error {
 }
 
 func Output(cmd *exec.Cmd) (output []byte, err error) {
-	ExecutorLock.RLock()
-	defer ExecutorLock.RUnlock()
-
+	// TODO context: hook name, hook phase, hook binding
+	// TODO observability
+	log.Debugf("Executing command '%s' in '%s' dir", strings.Join(cmd.Args, " "), cmd.Dir)
 	output, err = cmd.Output()
 	return
 }