DOCKER_HOST env variable being ignored

[eyenalxai]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

nixpacks now ignores the DOCKER_HOST environment variable. It seems that a bug was introduced somewhere between versions 1.27.1 and 1.28.0

This seems related:
#1180
#1176

To reproduce

1.28.0

❯ DOCKER_HOST=unix:///run/user/1000/docker.sock nixpacks build .

╔═══════════════════════ Nixpacks v1.28.0 ═══════════════════════╗
║ setup      │ nodejs_22, yarn-1_x, openssl                      ║
║────────────────────────────────────────────────────────────────║
║ install    │ npm install -g [email protected] && corepack enable ║
║            │ yarn install --check-cache                        ║
║────────────────────────────────────────────────────────────────║
║ build      │ yarn run build                                    ║
║────────────────────────────────────────────────────────────────║
║ start      │ yarn run migrate && yarn run start                ║
╚════════════════════════════════════════════════════════════════╝

ERROR: permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Head "http://%2Fvar%2Frun%2Fdocker.sock/_ping": dial unix /var/run/docker.sock: connect: permission denied
Error: Docker build failed

Notice that it tries to connect to unix:///var/run/docker.sock instead of unix:///run/user/1000/docker.sock from DOCKER_HOST env variable

Expected behavior

1.27.1

❯ DOCKER_HOST=unix:///run/user/1000/docker.sock nixpacks build .

╔═══════════════════════ Nixpacks v1.27.1 ═══════════════════════╗
║ setup      │ nodejs_22, yarn-1_x, openssl                      ║
║────────────────────────────────────────────────────────────────║
║ install    │ npm install -g [email protected] && corepack enable ║
║            │ yarn install --check-cache                        ║
║────────────────────────────────────────────────────────────────║
║ build      │ yarn run build                                    ║
║────────────────────────────────────────────────────────────────║
║ start      │ yarn run migrate && yarn run start                ║
╚════════════════════════════════════════════════════════════════╝

[+] Building 1.0s (2/2) FINISHED  ...

Proceeds as normal

Environment

Arch Linux

[eyenalxai]

Still happens in 1.29.0

❯ DOCKER_HOST=unix:///run/user/1000/docker.sock nixpacks build .

╔═══════════════════════ Nixpacks v1.29.0 ═══════════════════════╗
║ setup      │ nodejs_22, yarn-1_x, openssl                      ║
║────────────────────────────────────────────────────────────────║
║ install    │ npm install -g [email protected] && corepack enable ║
║            │ yarn install --check-cache                        ║
║────────────────────────────────────────────────────────────────║
║ build      │ yarn run build                                    ║
║────────────────────────────────────────────────────────────────║
║ start      │ yarn run migrate && yarn run start                ║
╚════════════════════════════════════════════════════════════════╝

ERROR: permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Head "http://%2Fvar%2Frun%2Fdocker.sock/_ping": dial unix /var/run/docker.sock: connect: permission denied
Error: Docker build failed

[coffee-cup]

You can specify the host by providing the --docker-host argument when building.

nixpacks build --docker-host unix:///run/user/1000/docker.sock .

We should still fix this and support the environment variable though