add -check flag to fmt

.changelog/4020.txt

@@ -0,0 +1,4 @@
+```release-note:improvement
+cli/fmt: Add a `-check` flag that will determine if the `waypoint.hcl` is already
+properly formatted, similar to `terraform fmt -check`.
+```

internal/cli/fmt.go

@@ -1,6 +1,7 @@
 package cli
 
 import (
+ "bytes"
  "fmt"
  "io/ioutil"
  "os"
@@ -20,6 +21,7 @@ type FmtCommand struct {
  *baseCommand
 
  flagWrite bool
+ flagCheck bool
 }
 
 func (c *FmtCommand) Run(args []string) int {
@@ -70,6 +72,18 @@ func (c *FmtCommand) Run(args []string) int {
  return 1
  }
 
+ if c.flagCheck {
+ // In the case where we're checking formatting, don't persist data
+ // ultimately this shouldn't even be used because we should return
+ // in this block
+ c.flagWrite = false
+ if bytes.Equal(src, out) {
+ return 0
+ } else {
+ return 3
+ }
+ }
+
  // If we're writing then write it to the file. stdin never writes to a file
  if c.flagWrite && !stdin {
  if err := ioutil.WriteFile(c.args[0], out, 0644); err != nil {
@@ -108,7 +122,15 @@ func (c *FmtCommand) Flags() *flag.Sets {
  Default: true,
  Usage: "Overwrite the input file. If this is false, the formatted " +
  "output will be written to STDOUT. This has no effect when formatting " +
- "from STDIN.",
+ "from STDIN or when using the -check flag.",
+ })
+
+ f.BoolVar(&flag.BoolVar{
+ Name: "check",
+ Target: &c.flagCheck,
+ Default: false,
+ Usage: "Check if the input is formatted. Exit status will be 0 if " +
+ "all input is properly formatted and exit status 3 otherwise.",
  })
  })
 }

website/content/commands/fmt.mdx

@@ -38,6 +38,7 @@ work for older and newer configuration formats.
 
 #### Command Options
 
-- `-write` - Overwrite the input file. If this is false, the formatted output will be written to STDOUT. This has no effect when formatting from STDIN. The default is true.
+- `-write` - Overwrite the input file. If this is false, the formatted output will be written to STDOUT. This has no effect when formatting from STDIN or when using the -check flag. The default is true.
+- `-check` - Check if the input is formatted. Exit status will be 0 if all input is properly formatted and exit status 3 otherwise. The default is false.
 
 @include "commands/fmt_more.mdx"