Support reading configuration from stdin

[howardjohn]

Your feature request related to a problem? Please describe.

We would like to read configuration from stdin. The reason is we want to deep merge a few configuration files with yq and pipe them in. This sort of works, but gives an error.

$ echo '' | golangci-lint run -c /dev/stdin
WARN [config_reader] Can't pretty print config file path: can't eval symlinks for path /dev/stdin: lstat /proc/688987/fd/pipe:[50935730]: no such file or directory

(in real world our command is not, echo, of course)

Describe the solution you'd like.

Support config from stdin without warning/error

Describe alternatives you've considered.

For our specific issue, passing multiple config files and having them deep merged would also be suitable. However, this may be complex as different folks have different meanings of "merge"

Additional context.

No response

[ldez]

Hello,

It's not an error but a warning because it's not a "real" file, the warning doesn't stop the analysis or the reading of the configuration.

I guess yq is https://github.com/kislyuk/yq.

I don't know the possibilities of yq but you can already do:

yq '. *= load("bar-golangci.yml")' foo-golangci.yml | golangci-lint run -c /dev/stdin
# OR
golangci-lint run -c <(yq '. *= load("bar-golangci.yml")' foo-golangci.yml)

We will not create a "merge" of configuration files because merging files will lead to unnecessary complexity.

[ldez]

I created a PR to remove the warning when the configuration file explicitly stdin.

#3740

[ldez]

But my fix doesn't work when the command is piped:

$ yq '. *= load("bar-golangci.yml")' foo-golangci.yml | golangci-lint run --config /dev/stdin
WARN [config_reader] Can't pretty print config file path: can't eval symlinks for path /dev/stdin: lstat /proc/3741263/fd/pipe:[62208537]: no such file or directory 

I need to think of a better way to handle that.

[ldez]

I was not using my own fix 🤦, I need to sleep.

Everything works as expected.