This possibility was lost in the rewrite to use HCL2, but it's used by
a number of external utilities and text editor integrations, so we'll
restore it here.
Using the stdin/stdout mode is generally preferable for text editor use
since it allows formatting of the in-memory buffer rather than directly
the file on disk, but for editors that don't have support for that sort of
tooling it can be convenient to just launch a single command and directly
modify the on-disk file.
Since the HCL formatter only works with tokens, it can in principle be
called with any input and produce some output. However, when given invalid
syntax it will tend to produce nonsensical results that may drastically
change the input file and be hard for the user to undo.
Since there's no strong reason to try to format an invalid or incomplete
file, we'll instead try parsing first and fail if parsing does not
complete successfully.
Since we talk directly to the HCL API here this is only a _syntax_ check,
and so it can be applied to files that are invalid in other ways as far
as Terraform is concerned, such as using unsupported top-level block types,
resource types that don't exist, etc.
A lot of commands used `c.Meta.flagSet()` to create the initial flagset for the command, while quite a few of them didn’t actually use or support the flags that are then added.
So I updated a few commands to use `flag.NewFlagSet()` instead to only add the flags that are actually needed/supported.
Additionally this prevents a few commands from using locking while they actually don’t need locking (as locking is enabled as a default in `c.Meta.flagSet()`.
This doesn't yet include test updates, since there are problems in core
currently blocking these tests from running. The tests will therefore be
updated in a subsequent commit.
* command/fmt: Document -diff doesn't disable -write
As noted in hashicorp/terraform#6343, this description misleadingly
suggested that the `-diff` option disables the `-write` option.
This isn't the case and because of the default options (described in
c753390) the behaviour of `terraform fmt -diff` is actually the same as
`terraform fmt -write -list -diff`.
Replace the "instead of rewriting" description to clarify that.
Documentation in hcl/fmtcmd is corrected in hashicorp/hcl#117 but it's not
really necessary to bump the dependency version.
* command/fmt: Show flag defaults in help text
These were documented on the website but not in the `-help` text. This
should help to clarify that you need to pass `-list=false -write=false
-diff` if you only want to see diffs.
Accordingly I've replaced the word "disabled" with "always false" in the
STDIN special cases so that it matches the terminology used in the defaults
and better indicates that it is overridden.
NB: The 3x duplicated defaults and documentation makes me feel uneasy once
again. I'm not sure how to solve that, though.
These options don't make sense when passing STDIN. `-write` will raise an
error because there is no file to write to. `-list` will always say
`<standard input>`. So disable whenever using STDIN, making the command
much simpler:
cat main.tf | terraform fmt -
So that you can do automatic formatting from an editor. You probably want to
disable the `-write` and `-list` options so that you just get the
re-formatted content, e.g.
cat main.tf | terraform fmt -write=false -list=false -
I've added a non-exported field called `input` so that we can override this
for the tests. If not specified, like in `commands.go`, then it will default
to `os.Stdin` which works on the command line.
The most common usage usage will be enabling the `-write` and `-list`
options so that files are updated in place and a list of any modified files
is printed. This matches the default behaviour of `go fmt` (not `gofmt`). So
enable these options by default.
This does mean that you will have to explicitly disable these if you want to
generate valid patches, e.g. `terraform fmt -diff -write=false -list=false`
This uses the `fmtcmd` package which has recently been merged into HCL. Per
the usage text, this rewrites Terraform config files to their canonical
formatting and style.
Some notes about the implementation for this initial commit:
- all of the fmtcmd options are exposed as CLI flags
- it operates on all files that have a `.tf` suffix
- it currently only operates on the working directory and doesn't accept a
directory argument, but I'll extend this in subsequent commits
- output is proxied through `cli.UiWriter` so that we write in the same way
as other commands and we can capture the output during tests
- the test uses a very simple fixture just to ensure that it is working
correctly end-to-end; the fmtcmd package has more exhaustive tests
- we have to write the fixture to a file in a temporary directory because it
will be modified and for this reason it was easier to define the fixture
contents as a raw string
