fix: ability to load configuration from stdin

fixes: [BUG] Honor stdin for config k3d cluster create -c k3d-io#1123

cmd/util/config/config.go

@@ -23,6 +23,7 @@ package config
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -31,6 +32,7 @@ import (
 	"github.com/spf13/viper"
 	"sigs.k8s.io/yaml"
 
+	"github.com/k3d-io/k3d/v5/cmd/util"
 	"github.com/k3d-io/k3d/v5/pkg/config"
 	l "github.com/k3d-io/k3d/v5/pkg/logger"
 )
@@ -46,7 +48,12 @@ func InitViperWithConfigFile(cfgViper *viper.Viper, configFile string) error {
 	// Set config file, if specified
 	if configFile != "" {
 
-		if _, err := os.Stat(configFile); err != nil {
+		streams := util.StandardIOStreams()
+		//flag to mark from where we read the config
+		fromStdIn := false
+		if configFile == "-" {
+			fromStdIn = true
+		} else if _, err := os.Stat(configFile); err != nil {
 			l.Log().Fatalf("Failed to stat config file %s: %+v", configFile, err)
 		}
 
@@ -58,10 +65,20 @@ func InitViperWithConfigFile(cfgViper *viper.Viper, configFile string) error {
 		}
 		defer tmpfile.Close()
 
-		originalcontent, err := os.ReadFile(configFile)
-		if err != nil {
-			l.Log().Fatalf("error reading config file %s: %v", configFile, err)
+		var originalcontent []byte
+		if fromStdIn {
+			// otherwise read from stdin
+			originalcontent, err = ioutil.ReadAll(streams.In)
+			if err != nil {
+				l.Log().Fatalf("Failed to read config file from stdin: %+v", configFile, err)
+			}
+		} else {
+			originalcontent, err = os.ReadFile(configFile)
+			if err != nil {
+				l.Log().Fatalf("error reading config file %s: %v", configFile, err)
+			}
 		}
+
 		expandedcontent := os.ExpandEnv(string(originalcontent))
 		if _, err := tmpfile.WriteString(expandedcontent); err != nil {
 			l.Log().Fatalf("error writing expanded config file contents to temp file %s: %v", tmpfile.Name(), err)

cmd/util/iostreams.go

@@ -0,0 +1,28 @@
+package util
+
+import (
+	"io"
+	"os"
+)
+
+// IOStreams provides the standard names for iostreams.
+// This is useful for embedding and for unit testing.
+// Inconsistent and different names make it hard to read and review code
+// This is based on https://github.com/kubernetes-sigs/kind/blob/main/pkg/cmd/iostreams.go, but just the nice type without the dependency
+type IOStreams struct {
+	// In think, os.Stdin
+	In io.Reader
+	// Out think, os.Stdout
+	Out io.Writer
+	// ErrOut think, os.Stderr
+	ErrOut io.Writer
+}
+
+// StandardIOStreams returns an IOStreams from os.Stdin, os.Stdout
+func StandardIOStreams() IOStreams {
+	return IOStreams{
+		In:     os.Stdin,
+		Out:    os.Stdout,
+		ErrOut: os.Stderr,
+	}
+}

tests/test_config_file_from_stdin.sh

@@ -0,0 +1,140 @@
+#!/bin/bash
+
+CURR_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+[ -d "$CURR_DIR" ] || { echo "FATAL: no current dir (maybe running in zsh?)";  exit 1; }
+
+# shellcheck source=./common.sh
+source "$CURR_DIR/common.sh"
+
+### Step Setup ###
+# Redirect all stdout/stderr output to logfile
+LOG_FILE="$TEST_OUTPUT_DIR/$( basename "${BASH_SOURCE[0]}" ).log"
+exec >${LOG_FILE} 2>&1
+export LOG_FILE
+
+# use a kubeconfig file specific to this test
+KUBECONFIG="$KUBECONFIG_ROOT/$( basename "${BASH_SOURCE[0]}" ).yaml"
+export KUBECONFIG
+### Step Setup ###
+
+
+: "${EXTRA_FLAG:=""}"
+: "${EXTRA_TITLE:=""}"
+
+if [[ -n "$K3S_IMAGE" ]]; then
+  EXTRA_FLAG="--image rancher/k3s:$K3S_IMAGE"
+  EXTRA_TITLE="(rancher/k3s:$K3S_IMAGE)"
+fi
+
+export CURRENT_STAGE="Test | config-file | $K3S_IMAGE"
+
+configfileoriginal="$CURR_DIR/assets/config_test_simple.yaml"
+configfile="/tmp/config_test_simple-tmp_$(date -u +'%Y%m%dT%H%M%SZ').yaml"
+clustername="configtest"
+
+sed -E "s/^  name:.+/  name: $clustername/g" < "$configfileoriginal" > "$configfile" # replace cluster name in config file so we can use it in this script without running into override issues
+cat "$configfile"
+highlight "[START] ConfigTest $EXTRA_TITLE"
+
+info "Creating cluster $clustername..."
+
+cat <<EOF | $EXE cluster create "$clustername" --config=-
+apiVersion: k3d.io/v1alpha4
+kind: Simple
+metadata:
+  name: test
+servers: 3
+agents: 2
+#image: rancher/k3s:latest
+volumes:
+  - volume: $HOME:/some/path
+    nodeFilters:
+      - all
+env:
+  - envVar: bar=baz,bob
+    nodeFilters:
+      - all
+registries:
+  create:
+    name: registry.localhost
+  use: []
+  config: |
+    mirrors:
+      "my.company.registry":
+        endpoint:
+          - http://my.company.registry:5000
+options:
+  k3d:
+    wait: true
+    timeout: "360s" # should be pretty high for multi-server clusters to allow for a proper startup routine
+    disableLoadbalancer: false
+    disableImageVolume: false
+  k3s:
+    extraArgs:
+      - arg: --tls-san=127.0.0.1
+        nodeFilters:
+          - server:*
+    nodeLabels:
+      - label: foo=bar
+        nodeFilters:
+          - server:0
+          - loadbalancer
+  kubeconfig:
+    updateDefaultKubeconfig: true
+    switchCurrentContext: true
+  runtime:
+    labels:
+      - label: foo=bar
+        nodeFilters:
+          - server:0
+          - loadbalancer
+EOF
+
+"$?" || failed "could not create cluster $clustername $EXTRA_TITLE"
+
+info "Sleeping for 5 seconds to give the cluster enough time to get ready..."
+sleep 5
+
+# 1. check initial access to the cluster
+info "Checking that we have access to the cluster..."
+check_clusters "$clustername" || failed "error checking cluster"
+
+info "Checking that we have 5 nodes online..."
+check_multi_node "$clustername" 5 || failed "failed to verify number of nodes"
+
+# 2. check some config settings
+
+## Environment Variables
+info "Ensuring that environment variables are present in the node containers as set in the config (with comma)"
+exec_in_node "k3d-$clustername-server-0" "env" | grep -q "bar=baz,bob" || failed "Expected env var 'bar=baz,bob' is not present in node k3d-$clustername-server-0"
+
+## Container Labels
+info "Ensuring that container labels have been set as stated in the config"
+docker_assert_container_label "k3d-$clustername-server-0" "foo=bar" || failed "Expected label 'foo=bar' not present on container/node k3d-$clustername-server-0"
+
+## K3s Node Labels
+info "Ensuring that k3s node labels have been set as stated in the config"
+k3s_assert_node_label "k3d-$clustername-server-0" "foo=bar" || failed "Expected label 'foo=bar' not present on node k3d-$clustername-server-0"
+
+## Registry Node
+registryname="registry.localhost"
+info "Ensuring, that we have a registry node present"
+$EXE node list "$registryname" || failed "Expected registry node $registryname to be present"
+
+## merged registries.yaml
+info "Ensuring, that the registries.yaml file contains both registries"
+exec_in_node "k3d-$clustername-server-0" "cat /etc/rancher/k3s/registries.yaml" | grep -qi "my.company.registry"  || failed "Expected 'my.company.registry' to be in the /etc/rancher/k3s/registries.yaml"
+exec_in_node "k3d-$clustername-server-0" "cat /etc/rancher/k3s/registries.yaml" | grep -qi "$registryname" || failed "Expected '$registryname' to be in the /etc/rancher/k3s/registries.yaml"
+
+# Cleanup
+
+info "Deleting cluster $clustername (using config file)..."
+$EXE cluster delete --config "$configfile" --trace || failed "could not delete the cluster $clustername"
+
+rm "$configfile"
+
+highlight "[DONE] ConfigTest $EXTRA_TITLE"
+
+exit 0
+
+