Compose: docker-compose run/exec converts unix newlines to CRLF

[SpComb]

With docker-compose version 1.11.1, compared to the raw docker exec output:

$ docker exec composetest_redis_1 hostname | hd
00000000  6c 6f 63 61 6c 68 6f 73  74 0a                    |localhost.|
0000000a

It seems like docker-compose exec and docker-compose run will convert the output to use CRLF:

$ docker-compose run --rm redis hostname | hd    
00000000  6c 6f 63 61 6c 68 6f 73  74 0d 0a                 |localhost..|
0000000b
$ docker-compose exec redis hostname | toolbox hd
00000000  6c 6f 63 61 6c 68 6f 73  74 0d 0a                 |localhost..|
0000000b

This causes issues when using the output with shell command replacements, like

$ curl -v "http://api.example.com/nodes/$(docker-compose exec redis hostname)"
* Illegal characters found in URL
* Closing connection -1
curl: (3) Illegal characters found in URL

which fails on the trailing CR in the resulting http://api.example.com/nodes/localhost\r URL.

[shin-]

By default, a pseudo-tty is allocated when using docker-compose run or docker-compose exec (-t option for docker exec / docker run). You can disable this behavior using the -T option: docker-compose exec -T redis hostname

[SpComb]

Confirm that the docker-compose run -T vs docker exec -t behavior matches:

$ docker-compose run -T redis hostname | hd
00000000  6c 6f 63 61 6c 68 6f 73  74 0a                    |localhost.|
0000000a
$ docker exec -t composetest_redis_1 hostname | hd
00000000  6c 6f 63 61 6c 68 6f 73  74 0d 0a                 |localhost..|
0000000b
$ docker-compose exec -T redis hostname | hd
00000000  6c 6f 63 61 6c 68 6f 73  74 0a                    |localhost.|
0000000a

So the workaround is to use $(docker-compose run -T ...). I would still consider this difference in defaults to be a bit surprising :/