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Merge pull request #4710 from fluxcd/envsubst-cmd
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Add `flux envsubst` command
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stefanprodan authored Apr 9, 2024
2 parents 4d86311 + 493c1fb commit f93da6f
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Showing 6 changed files with 171 additions and 3 deletions.
74 changes: 74 additions & 0 deletions cmd/flux/envsubst.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,74 @@
/*
Copyright 2024 The Flux authors
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package main

import (
"bufio"
"fmt"

"github.com/fluxcd/pkg/envsubst"
"github.com/spf13/cobra"
)

var envsubstCmd = &cobra.Command{
Use: "envsubst",
Args: cobra.NoArgs,
Short: "envsubst substitutes the values of environment variables",
Long: withPreviewNote(`The envsubst command substitutes the values of environment variables
in the string piped as standard input and writes the result to the standard output. This command can be used
to replicate the behavior of the Flux Kustomization post-build substitutions.`),
Example: ` # Run env var substitutions on the kustomization build output
export cluster_region=eu-central-1
kustomize build . | flux envsubst
# Run env var substitutions and error out if a variable is not set
kustomize build . | flux envsubst --strict
`,
RunE: runEnvsubstCmd,
}

type envsubstFlags struct {
strict bool
}

var envsubstArgs envsubstFlags

func init() {
envsubstCmd.Flags().BoolVar(&envsubstArgs.strict, "strict", false,
"fail if a variable without a default value is declared in the input but is missing from the environment")
rootCmd.AddCommand(envsubstCmd)
}

func runEnvsubstCmd(cmd *cobra.Command, args []string) error {
stdin := bufio.NewScanner(rootCmd.InOrStdin())
stdout := bufio.NewWriter(rootCmd.OutOrStdout())
for stdin.Scan() {
line, err := envsubst.EvalEnv(stdin.Text(), envsubstArgs.strict)
if err != nil {
return err
}
_, err = fmt.Fprintln(stdout, line)
if err != nil {
return err
}
err = stdout.Flush()
if err != nil {
return err
}
}
return nil
}
50 changes: 50 additions & 0 deletions cmd/flux/envsubst_test.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
/*
Copyright 2024 The Flux authors
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package main

import (
"bytes"
"os"
"testing"

. "github.com/onsi/gomega"
)

func TestEnvsubst(t *testing.T) {
g := NewWithT(t)
input, err := os.ReadFile("testdata/envsubst/file.yaml")
g.Expect(err).NotTo(HaveOccurred())

t.Setenv("REPO_NAME", "test")

output, err := executeCommandWithIn("envsubst", bytes.NewReader(input))
g.Expect(err).NotTo(HaveOccurred())

expected, err := os.ReadFile("testdata/envsubst/file.gold")
g.Expect(err).NotTo(HaveOccurred())
g.Expect(output).To(Equal(string(expected)))
}

func TestEnvsubst_Strinct(t *testing.T) {
g := NewWithT(t)
input, err := os.ReadFile("testdata/envsubst/file.yaml")
g.Expect(err).NotTo(HaveOccurred())

_, err = executeCommandWithIn("envsubst --strict", bytes.NewReader(input))
g.Expect(err).To(HaveOccurred())
g.Expect(err.Error()).To(ContainSubstring("variable not set (strict mode)"))
}
28 changes: 26 additions & 2 deletions cmd/flux/main_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,6 @@ import (
"text/template"
"time"

"github.com/fluxcd/flux2/v2/internal/utils"
"github.com/google/go-cmp/cmp"
"github.com/mattn/go-shellwords"
"k8s.io/apimachinery/pkg/api/errors"
Expand All @@ -40,6 +39,8 @@ import (
"k8s.io/client-go/tools/clientcmd"
"sigs.k8s.io/controller-runtime/pkg/client"
"sigs.k8s.io/controller-runtime/pkg/envtest"

"github.com/fluxcd/flux2/v2/internal/utils"
)

var nextNamespaceId int64
Expand Down Expand Up @@ -393,6 +394,29 @@ func executeCommand(cmd string) (string, error) {
return result, err
}

// Run the command while passing the string as input and return the captured output.
func executeCommandWithIn(cmd string, in io.Reader) (string, error) {
defer resetCmdArgs()
args, err := shellwords.Parse(cmd)
if err != nil {
return "", err
}

buf := new(bytes.Buffer)

rootCmd.SetOut(buf)
rootCmd.SetErr(buf)
rootCmd.SetArgs(args)
if in != nil {
rootCmd.SetIn(in)
}

_, err = rootCmd.ExecuteC()
result := buf.String()

return result, err
}

// resetCmdArgs resets the flags for various cmd
// Note: this will also clear default value of the flags set in init()
func resetCmdArgs() {
Expand Down Expand Up @@ -441,7 +465,7 @@ func resetCmdArgs() {
versionArgs = versionFlags{
output: "yaml",
}

envsubstArgs = envsubstFlags{}
}

func isChangeError(err error) bool {
Expand Down
10 changes: 10 additions & 0 deletions cmd/flux/testdata/envsubst/file.gold
Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
apiVersion: source.toolkit.fluxcd.io/v1
kind: GitRepository
metadata:
name: test
namespace: flux-system
spec:
ref:
branch: main
interval: 5m
url: ssh://git@github.com/example/test
10 changes: 10 additions & 0 deletions cmd/flux/testdata/envsubst/file.yaml
Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
apiVersion: source.toolkit.fluxcd.io/v1
kind: GitRepository
metadata:
name: ${REPO_NAME}
namespace: ${REPO_NAMESPACE:=flux-system}
spec:
ref:
branch: main
interval: 5m
url: ssh://git@github.com/example/${REPO_NAME}
2 changes: 1 addition & 1 deletion go.mod
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ require (
github.com/fluxcd/notification-controller/api v1.2.4
github.com/fluxcd/pkg/apis/event v0.8.0
github.com/fluxcd/pkg/apis/meta v1.4.0
github.com/fluxcd/pkg/envsubst v1.0.0
github.com/fluxcd/pkg/git v0.18.0
github.com/fluxcd/pkg/git/gogit v0.18.0
github.com/fluxcd/pkg/kustomize v1.9.0
Expand Down Expand Up @@ -117,7 +118,6 @@ require (
github.com/felixge/httpsnoop v1.0.4 // indirect
github.com/fluxcd/pkg/apis/acl v0.2.0 // indirect
github.com/fluxcd/pkg/apis/kustomize v1.4.0 // indirect
github.com/fluxcd/pkg/envsubst v1.0.0 // indirect
github.com/fsnotify/fsnotify v1.7.0 // indirect
github.com/go-errors/errors v1.5.1 // indirect
github.com/go-fed/httpsig v1.1.0 // indirect
Expand Down

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