Add --env-file to ctr

Closes #3517

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

cmd/ctr/commands/commands.go

@@ -77,6 +77,10 @@ var (
 			Name:  "env",
 			Usage: "specify additional container environment variables (i.e. FOO=bar)",
 		},
+		cli.StringFlag{
+			Name:  "env-file",
+			Usage: "specify additional container environment variables in a file(i.e. FOO=bar, one per line)",
+		},
 		cli.StringSliceFlag{
 			Name:  "label",
 			Usage: "specify additional labels (i.e. foo=bar)",

cmd/ctr/commands/run/run_unix.go

@@ -64,6 +64,9 @@ func NewContainer(ctx gocontext.Context, client *containerd.Client, context *cli
 			args = context.Args()[2:]
 		)
 		opts = append(opts, oci.WithDefaultSpec(), oci.WithDefaultUnixDevices)
+		if ef := context.String("env-file"); ef != "" {
+			opts = append(opts, oci.WithEnvFile(ef))
+		}
 		opts = append(opts, oci.WithEnv(context.StringSlice("env")))
 		opts = append(opts, withMounts(context))
 

cmd/ctr/commands/run/run_windows.go

@@ -67,6 +67,9 @@ func NewContainer(ctx gocontext.Context, client *containerd.Client, context *cli
 			opts = append(opts, oci.WithWindowNetworksAllowUnqualifiedDNSQuery())
 			opts = append(opts, oci.WithWindowsIgnoreFlushesDuringBoot())
 		}
+		if ef := context.String("env-file"); ef != "" {
+			opts = append(opts, oci.WithEnvFile(ef))
+		}
 		opts = append(opts, oci.WithEnv(context.StringSlice("env")))
 		opts = append(opts, withMounts(context))
 

oci/spec_opts.go

@@ -17,6 +17,7 @@
 package oci
 
 import (
+	"bufio"
 	"context"
 	"encoding/json"
 	"fmt"
@@ -1200,3 +1201,24 @@ func WithLinuxDevice(path, permissions string) SpecOpts {
 		return nil
 	}
 }
+
+// WithEnvFile adds environment variables from a file to the container's spec
+func WithEnvFile(path string) SpecOpts {
+	return func(_ context.Context, _ Client, _ *containers.Container, s *Spec) error {
+		var vars []string
+		f, err := os.Open(path)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+
+		sc := bufio.NewScanner(f)
+		for sc.Scan() {
+			if sc.Err() != nil {
+				return sc.Err()
+			}
+			vars = append(vars, sc.Text())
+		}
+		return WithEnv(vars)(nil, nil, nil, s)
+	}
+}