Merge pull request #1728 from ashishsachdeva/asachdev/logsredirection

gcs: Support routing container stdio to sidecar

internal/guest/runtime/runc/container.go

@@ -5,6 +5,7 @@ package runc
 
 import (
 	"encoding/json"
+	"fmt"
 	"net"
 	"os"
 	"path/filepath"
@@ -326,7 +327,7 @@ func (c *container) runExecCommand(processDef *oci.Process, stdioSet *stdio.Conn
 
 	args := []string{"exec"}
 	args = append(args, "-d", "--process", filepath.Join(tempProcessDir, "process.json"))
-	return c.startProcess(tempProcessDir, processDef.Terminal, stdioSet, args...)
+	return c.startProcess(tempProcessDir, processDef.Terminal, stdioSet, nil, args...)
 }
 
 // startProcess performs the operations necessary to start a container process
@@ -337,7 +338,9 @@ func (c *container) runExecCommand(processDef *oci.Process, stdioSet *stdio.Conn
 func (c *container) startProcess(
 	tempProcessDir string,
 	hasTerminal bool,
-	stdioSet *stdio.ConnectionSet, initialArgs ...string,
+	stdioSet *stdio.ConnectionSet,
+	annotations map[string]string,
+	initialArgs ...string,
 ) (p *process, err error) {
 	args := initialArgs
 
@@ -389,6 +392,70 @@ func (c *container) startProcess(
 		}
 	}
 
+	// This is for enabling container logging via side car feature. This is in experimental stage now and need to be revisited.
+	var stdoutFifoPipe, stderrFifoPipe *os.File
+	if annotations != nil {
+		pipeNameSuffix, exists := annotations["io.microsoft.bmc.logging.pipelocation"]
+		if exists {
+			if hasTerminal {
+				return nil, fmt.Errorf("logging via side car and TTY are not supported together")
+			}
+			pipeDirectory := "/run/gcs/containerlogs/"
+			stdoutPipeName := pipeDirectory + pipeNameSuffix + "-stdout"
+			stderrPipeName := pipeDirectory + pipeNameSuffix + "-stderr"
+			err = os.MkdirAll(pipeDirectory, 0755)
+			if err != nil {
+				return nil, fmt.Errorf("error creating log directory %s for logging pipe fifo: %w", pipeDirectory, err)
+			}
+
+			_, err = os.Stat(stdoutPipeName)
+			if err != nil {
+				// fifo pipe does not exist, create one
+				err = syscall.Mkfifo(stdoutPipeName, 0666)
+				if err != nil {
+					return nil, fmt.Errorf("error creating fifo %s: %w", stdoutPipeName, err)
+				}
+			}
+
+			_, err = os.Stat(stderrPipeName)
+			if err != nil {
+				// fifo pipe does not exist, create one
+				err = syscall.Mkfifo(stderrPipeName, 0666)
+				if err != nil {
+					return nil, fmt.Errorf("error creating fifo %s: %w", stderrPipeName, err)
+				}
+			}
+
+			// pipe either exist before hand or we have created one above
+			stdoutFifoPipe, err = os.OpenFile(stdoutPipeName, os.O_RDWR|os.O_APPEND, os.ModeNamedPipe)
+			if err != nil {
+				return nil, fmt.Errorf("error opening fifo %s: %w", stdoutPipeName, err)
+			}
+
+			stderrFifoPipe, err = os.OpenFile(stderrPipeName, os.O_RDWR|os.O_APPEND, os.ModeNamedPipe)
+			if err != nil {
+				return nil, fmt.Errorf("error opening fifo %s: %w", stderrPipeName, err)
+			}
+		}
+
+		isLoggingSideCarContainerStr, exists := annotations["io.microsoft.bmc.logging.isLoggingSideCarContainer"]
+		if exists {
+			isLoggingSideCarContainer, err := strconv.ParseBool(isLoggingSideCarContainerStr)
+			if err != nil {
+				return nil, fmt.Errorf("error parsing flag isLoggingSideCarContainer: %w", err)
+			}
+			if !isLoggingSideCarContainer {
+				// workload container needs to redirect stdout and stderr to fifo pipe.
+				cmd.Stdout = stdoutFifoPipe
+				cmd.Stderr = stderrFifoPipe
+			} else {
+				// logging side car container needs to know the pipe fd.
+				cmd.Args = append(cmd.Args, "--preserve-fds", "2")
+				cmd.ExtraFiles = []*os.File{stdoutFifoPipe, stderrFifoPipe}
+			}
+		}
+	}
+
 	if err := cmd.Run(); err != nil {
 		runcErr := getRuncLogError(logPath)
 		return nil, errors.Wrapf(runcErr, "failed to run runc create/exec call for container %s with %v", c.id, err)

internal/guest/runtime/runc/runc.go

@@ -193,7 +193,8 @@ func (r *runcRuntime) runCreateCommand(id string, bundlePath string, stdioSet *s
 	}
 
 	args := []string{"create", "-b", bundlePath, "--no-pivot"}
-	p, err := c.startProcess(tempProcessDir, spec.Process.Terminal, stdioSet, args...)
+
+	p, err := c.startProcess(tempProcessDir, spec.Process.Terminal, stdioSet, spec.Annotations, args...)
 	if err != nil {
 		return nil, err
 	}