[BUG] Every line in the output gets duplicated

[chocolateimage]

Description

When using docker compose up, every line in the output gets duplicated:

$ docker compose up        
Attaching to app-1
app-1  | Hello
app-1  | Hello
app-1  | Again another line
app-1  | Again another line
app-1 exited with code 0

This does not happen with running Docker directly with docker run

Steps To Reproduce

1. Create these files:

compose.yaml

services:
  app:
    build: .

Dockerfile

FROM alpine:latest

WORKDIR /app

COPY script.sh .

ENTRYPOINT ["sh", "script.sh"]

script.sh

echo "Hello"
sleep 1
echo "Again another line"

2. Run docker compose up --build
3. See duplicated lines in output

Compose Version

Docker Compose version 2.39.1

Docker Environment

Client:
 Version:    28.3.2
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  0.26.1
    Path:     /usr/lib/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  2.39.1
    Path:     /usr/lib/docker/cli-plugins/docker-compose

Server:
 Containers: 25
  Running: 0
  Paused: 0
  Stopped: 25
 Images: 363
 Server Version: 28.3.2
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: true
  Native Overlay Diff: false
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 CDI spec directories:
  /etc/cdi
  /var/run/cdi
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: c787fb98911740dd3ff2d0e45ce88cdf01410486.m
 runc version: 
 init version: de40ad0
 Security Options:
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.12.40-1-lts
 Operating System: Arch Linux
 OSType: linux
 Architecture: x86_64
 CPUs: 32
 Total Memory: 30.98GiB
 Name: bright-sparkle
 ID: 86dad810-1c61-48e7-adc0-29a3bb8fc3ef
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
  ::1/128
  127.0.0.0/8
 Live Restore Enabled: false

Anything else?

No response

[valankar]

Also noticed that my docker service logs are being duplicated in systemd/journald. It happened just when I switched from compose version 2.38.2 to 2.39.1.

[ndeloof]

I can't reproduce.
Can you please check with docker ps -a if you only have a single container created for this compose app ?

[chocolateimage]

I can't reproduce. Can you please check with docker ps -a if you only have a single container created for this compose app ?

It's a weird issue, I tried to reproduce (again) for this test but it didn't duplicate, when I changed the script.sh to change the sleep, it did duplicate again. I think it's more randomly per build. But no, it does not seem to be creating multiple containers (when the lines are duplicated):

$ docker ps -a
CONTAINER ID   IMAGE              COMMAND          CREATED        STATUS        PORTS     NAMES
ca312b82dcbd   docker-issue-app   "sh script.sh"   1 second ago   Up 1 second             docker-issue-app-1
$ docker ps -a
CONTAINER ID   IMAGE              COMMAND          CREATED              STATUS                              PORTS     NAMES
ca312b82dcbd   docker-issue-app   "sh script.sh"   About a minute ago   Exited (0) Less than a second ago             docker-issue-app-1

[ndeloof]

please check docker logs ca312b82dcbd

[chocolateimage]

please check docker logs ca312b82dcbd

Here is the output of docker logs as well as other commands I used right before:

$ docker compose up --build
#1 [internal] load local bake definitions
#1 reading from stdin 523B done
#1 DONE 0.0s

#2 [internal] load build definition from Dockerfile
#2 transferring dockerfile: 121B done
#2 DONE 0.0s

#3 [internal] load metadata for docker.io/library/alpine:latest
#3 DONE 0.0s

#4 [internal] load .dockerignore
#4 transferring context: 2B done
#4 DONE 0.0s

#5 [1/3] FROM docker.io/library/alpine:latest
#5 DONE 0.0s

#6 [internal] load build context
#6 transferring context: 84B done
#6 DONE 0.0s

#7 [2/3] WORKDIR /app
#7 CACHED

#8 [3/3] COPY script.sh .
#8 CACHED

#9 exporting to image
#9 exporting layers done
#9 writing image sha256:43b621b12b8467f020c05483b4c88ce4dec4b2b8fbf97a9777f2875c9bb37237 done
#9 naming to docker.io/library/docker-issue-app done
#9 DONE 0.0s

#10 resolving provenance for metadata file
#10 DONE 0.0s
[+] Running 2/2
 ✔ docker-issue-app              Built                                                                                                                                                                                                 0.0s 
 ✔ Container docker-issue-app-1  Recreated                                                                                                                                                                                             0.1s 
Attaching to app-1
app-1  | Hello
app-1  | Hello
app-1  | Again another line
app-1  | Again another line
app-1 exited with code 0
$ docker ps -a
CONTAINER ID   IMAGE              COMMAND          CREATED         STATUS                     PORTS     NAMES
6679a0f43eef   docker-issue-app   "sh script.sh"   5 seconds ago   Exited (0) 3 seconds ago             docker-issue-app-1
$ docker logs 6679a0f43eef            
Hello
Again another line

[glours]

I can reproduce it, I'll try to find the faulty commit and figure out what happens