Executing rails commands from host Bash

Installation
1

Hi all,

I want to execute automated user clean up tasks from the host Bash. Manually, I run

/var/discourse/launcher enter app
rails c
UserDestroyer.new(Discourse.system_user).destroy(User.find_by_username_or_email("user@example.com"), delete_posts: false)

I have a long list of user names from a text file that need to be removed. Manually executing this is not reasonable. I tried to wrap the deletion command in a bash script. When executing rails c with the launcher app subcommand, the Redis connection fails:

/var/discourse/launcher run app "echo \"User.find_by_username_or_email('user@example.com')\" | rails c"
Failed to report error: Error connecting to Redis on localhost:6379 (Errno::EADDRNOTAVAIL) 2 Error connecting to Redis on localhost:6379 (Errno::EADDRNOTAVAIL) subscribe failed, reconnecting in 1 second.

However, when I compare the environments with export between launcher enter app and launcher run app, they look pretty much identical. What am I missing? launcher run starts in / while launcher enter directly enters /var/www/discourse. Using a cd before executing rails does not help.

Any hints? Thanks!

2

I think docker run launches a new container.

For things like that I use docker exec rather than launcher,which does a bunch of stuff you don’t need.

1 Like
3

Thanks for the reply. I find that the behavior of rails with docker exec is also very odd. Manually, it works perfectly well:

docker exec -it de7f5f6f649c '/bin/bash'
root@discourse-app:/# rails c
[1] pry(main)> User.find_by_username_or_email('myname')

But when I try to execute rails c from outside the container, I get the following problems:

docker exec -it de7f5f6f649c "/usr/local/bin/rails console"
OCI runtime exec failed: exec failed: container_linux.go:367: starting container process caused: exec: "/usr/local/bin/rails console": stat /usr/local/bin/rails console: no such file or directory: unknown

But more interesting:

docker exec -it de7f5f6f649c '/bin/bash -c "/usr/local/bin/rails"'
OCI runtime exec failed: exec failed: container_linux.go:367: starting container process caused: exec: "/bin/bash -c \"/usr/local/bin/rails\"": stat /bin/bash -c "/usr/local/bin/rails": no such file or directory: unknown

Why is this different at all?

4

This is expected; you are telling docker to execute the binary /usr/local/bin/rails console in the container. That is, a single file with an embedded space. This file doesn’t exist.

consider the following:

○ → docker run -i debian /bin/echo hello
hello

○ → docker run -i debian '/bin/echo hello'
docker: Error response from daemon: OCI runtime create failed: container_linux.go:367: starting container process caused: exec: "/bin/echo hello": stat /bin/echo hello: no such file or directory: unknown.
ERRO[0000] error waiting for container: context canceled

Quote the command the same way as if you were executing from inside the container:

○ → docker exec -i app rails runner 'puts "hello"'
hello

Using the example from the OP, this should work:

docker exec -i app rails runner 'UserDestroyer.new(Discourse.system_user).destroy(User.find_by_username_or_email("user@example.com"), delete_posts: false)'
2 Likes
5

Okay, it was unexpected for me because I did not RTFM. Thanks for the fast help.

1 Like