podmanV2: implement logs

Implement the `podman {container} logs` for the v2 client. The remote
client does not yet support it.  There's some more work needed for the
rest api; some options are missing (e.g., printing names) while others
are broken (e.g., the until http parameter).

The remote parts will be tackled in a future change.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

cmd/podmanV2/containers/logs.go

@@ -0,0 +1,108 @@
+package containers
+
+import (
+	"os"
+
+	"github.com/containers/libpod/cmd/podmanV2/registry"
+	"github.com/containers/libpod/pkg/domain/entities"
+	"github.com/containers/libpod/pkg/util"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
+)
+
+// logsOptionsWrapper wraps entities.LogsOptions and prevents leaking
+// CLI-only fields into the API types.
+type logsOptionsWrapper struct {
+	entities.ContainerLogsOptions
+
+	SinceRaw string
+}
+
+var (
+	logsOptions     logsOptionsWrapper
+	logsDescription = `Retrieves logs for one or more containers.
+
+  This does not guarantee execution order when combined with podman run (i.e., your run may not have generated any logs at the time you execute podman logs).
+`
+	logsCommand = &cobra.Command{
+		Use:     "logs [flags] CONTAINER [CONTAINER...]",
+		Short:   "Fetch the logs of one or more container",
+		Long:    logsDescription,
+		RunE:    logs,
+		PreRunE: preRunE,
+		Example: `podman logs ctrID
+  podman logs --names ctrID1 ctrID2
+  podman logs --tail 2 mywebserver
+  podman logs --follow=true --since 10m ctrID
+  podman logs mywebserver mydbserver`,
+	}
+
+	containerLogsCommand = &cobra.Command{
+		Use:     logsCommand.Use,
+		Short:   logsCommand.Short,
+		Long:    logsCommand.Long,
+		PreRunE: logsCommand.PreRunE,
+		RunE:    logsCommand.RunE,
+		Example: `podman container logs ctrID
+		podman container logs --names ctrID1 ctrID2
+		podman container logs --tail 2 mywebserver
+		podman container logs --follow=true --since 10m ctrID
+		podman container logs mywebserver mydbserver`,
+	}
+)
+
+func init() {
+	// logs
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Mode:    []entities.EngineMode{entities.ABIMode},
+		Command: logsCommand,
+	})
+
+	logsCommand.SetHelpTemplate(registry.HelpTemplate())
+	logsCommand.SetUsageTemplate(registry.UsageTemplate())
+
+	flags := logsCommand.Flags()
+	logsFlags(flags)
+
+	// container logs
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Mode:    []entities.EngineMode{entities.ABIMode},
+		Command: containerLogsCommand,
+		Parent:  containerCmd,
+	})
+
+	containerLogsFlags := containerLogsCommand.Flags()
+	logsFlags(containerLogsFlags)
+}
+
+func logsFlags(flags *pflag.FlagSet) {
+	flags.BoolVar(&logsOptions.Details, "details", false, "Show extra details provided to the logs")
+	flags.BoolVarP(&logsOptions.Follow, "follow", "f", false, "Follow log output.  The default is false")
+	flags.BoolVarP(&logsOptions.Latest, "latest", "l", false, "Act on the latest container podman is aware of")
+	flags.StringVar(&logsOptions.SinceRaw, "since", "", "Show logs since TIMESTAMP")
+	flags.Int64Var(&logsOptions.Tail, "tail", -1, "Output the specified number of LINES at the end of the logs.  Defaults to -1, which prints all lines")
+	flags.BoolVarP(&logsOptions.Timestamps, "timestamps", "t", false, "Output the timestamps in the log")
+	flags.BoolVarP(&logsOptions.Names, "names", "n", false, "Output the container name in the log")
+	flags.SetInterspersed(false)
+	_ = flags.MarkHidden("details")
+}
+
+func logs(cmd *cobra.Command, args []string) error {
+	if len(args) > 0 && logsOptions.Latest {
+		return errors.New("no containers can be specified when using 'latest'")
+	}
+	if !logsOptions.Latest && len(args) < 1 {
+		return errors.New("specify at least one container name or ID to log")
+	}
+	if logsOptions.SinceRaw != "" {
+		// parse time, error out if something is wrong
+		since, err := util.ParseInputTime(logsOptions.SinceRaw)
+		if err != nil {
+			return errors.Wrapf(err, "error parsing --since %q", logsOptions.SinceRaw)
+		}
+		logsOptions.Since = since
+	}
+	logsOptions.Writer = os.Stdout
+	return registry.ContainerEngine().ContainerLogs(registry.GetContext(), args, logsOptions.ContainerLogsOptions)
+}

pkg/api/handlers/compat/containers.go

@@ -261,6 +261,7 @@ func LogsFromContainer(w http.ResponseWriter, r *http.Request) {
 
 	var until time.Time
 	if _, found := r.URL.Query()["until"]; found {
+		// FIXME: until != since but the logs backend does not yet support until.
 		since, err = util.ParseInputTime(query.Until)
 		if err != nil {
 			utils.BadRequest(w, "until", query.Until, err)

pkg/domain/entities/containers.go

@@ -172,6 +172,26 @@ type AttachOptions struct {
 	Stderr     *os.File
 }
 
+// ContainerLogsOptions describes the options to extract container logs.
+type ContainerLogsOptions struct {
+	// Show extra details provided to the logs.
+	Details bool
+	// Follow the log output.
+	Follow bool
+	// Display logs for the latest container only. Ignored on the remote client.
+	Latest bool
+	// Show container names in the output.
+	Names bool
+	// Show logs since this timestamp.
+	Since time.Time
+	// Number of lines to display at the end of the output.
+	Tail int64
+	// Show timestamps in the logs.
+	Timestamps bool
+	// Write the logs to Writer.
+	Writer io.Writer
+}
+
 // ExecOptions describes the cli values to exec into
 // a container
 type ExecOptions struct {

pkg/domain/entities/engine_container.go

@@ -20,6 +20,7 @@ type ContainerEngine interface {
 	ContainerKill(ctx context.Context, namesOrIds []string, options KillOptions) ([]*KillReport, error)
 	ContainerList(ctx context.Context, options ContainerListOptions) ([]ListContainer, error)
 	ContainerPause(ctx context.Context, namesOrIds []string, options PauseUnPauseOptions) ([]*PauseUnpauseReport, error)
+	ContainerLogs(ctx context.Context, containers []string, options ContainerLogsOptions) error
 	ContainerRestart(ctx context.Context, namesOrIds []string, options RestartOptions) ([]*RestartReport, error)
 	ContainerRestore(ctx context.Context, namesOrIds []string, options RestoreOptions) ([]*RestoreReport, error)
 	ContainerRm(ctx context.Context, namesOrIds []string, options RmOptions) ([]*RmReport, error)

pkg/domain/infra/abi/containers.go

@@ -4,9 +4,11 @@ package abi
 
 import (
 	"context"
+	"fmt"
 	"io/ioutil"
 	"strconv"
 	"strings"
+	"sync"
 
 	"github.com/containers/buildah"
 	"github.com/containers/image/v5/manifest"
@@ -14,6 +16,7 @@ import (
 	"github.com/containers/libpod/libpod/define"
 	"github.com/containers/libpod/libpod/events"
 	"github.com/containers/libpod/libpod/image"
+	"github.com/containers/libpod/libpod/logs"
 	"github.com/containers/libpod/pkg/checkpoint"
 	"github.com/containers/libpod/pkg/domain/entities"
 	"github.com/containers/libpod/pkg/domain/infra/abi/terminal"
@@ -709,3 +712,48 @@ func (ic *ContainerEngine) ContainerRun(ctx context.Context, opts entities.Conta
 	}
 	return &report, nil
 }
+
+func (ic *ContainerEngine) ContainerLogs(ctx context.Context, containers []string, options entities.ContainerLogsOptions) error {
+	if options.Writer == nil {
+		return errors.New("no io.Writer set for container logs")
+	}
+
+	var wg sync.WaitGroup
+
+	ctrs, err := getContainersByContext(false, options.Latest, containers, ic.Libpod)
+	if err != nil {
+		return err
+	}
+
+	logOpts := &logs.LogOptions{
+		Multi:      len(ctrs) > 1,
+		Details:    options.Details,
+		Follow:     options.Follow,
+		Since:      options.Since,
+		Tail:       options.Tail,
+		Timestamps: options.Timestamps,
+		UseName:    options.Names,
+		WaitGroup:  &wg,
+	}
+
+	chSize := len(ctrs) * int(options.Tail)
+	if chSize <= 0 {
+		chSize = 1
+	}
+	logChannel := make(chan *logs.LogLine, chSize)
+
+	if err := ic.Libpod.Log(ctrs, logOpts, logChannel); err != nil {
+		return err
+	}
+
+	go func() {
+		wg.Wait()
+		close(logChannel)
+	}()
+
+	for line := range logChannel {
+		fmt.Fprintln(options.Writer, line.String(logOpts))
+	}
+
+	return nil
+}

pkg/domain/infra/tunnel/containers.go

@@ -305,6 +305,11 @@ func (ic *ContainerEngine) ContainerCreate(ctx context.Context, s *specgen.SpecG
 	return &entities.ContainerCreateReport{Id: response.ID}, nil
 }
 
+func (ic *ContainerEngine) ContainerLogs(ctx context.Context, containers []string, options entities.ContainerLogsOptions) error {
+	// The endpoint is not ready yet and requires some more work.
+	return errors.New("not implemented yet")
+}
+
 func (ic *ContainerEngine) ContainerAttach(ctx context.Context, nameOrId string, options entities.AttachOptions) error {
 	return errors.New("not implemented")
 }