Hello everyone!

I’m trying to deploy my blog application into production, and I’m facing a very weird issue: Postgrex doesn’t want to connect to my postgres instance (k8s environment).

iex(10)> {:ok, pid}=Postgrex.start_link(hostname: "pg", username: "postgres", password: "e4aay78iiRiBuzbbnrnD03GqWh9ncVS0376xSpNe8TBdtq6MUvjZjky71Acj402e", data
base: "postgres")                                                                                                                                               
{:ok, #PID<0.1717.0>}                                                                                                                                           
                                                                                                                                                                
12:07:28.421 [error] Postgrex.Protocol (#PID<0.1719.0>) failed to connect: ** (Postgrex.Error) FATAL 28000 (invalid_authorization_specification) pg_hba.conf rejects connection for host "10.1.119.175", user "postgres", database "postgres", no encryption

Now the strange part: psql connects without problems:

/app # export PGPASSWORD="e4aay78iiRiBuzbbnrnD03GqWh9ncVS0376xSpNe8TBdtq6MUvjZjky71Acj402e"
/app # psql -h pg -U postgres -d postgres -c 'SELECT 1'
 ?column? 
----------
        1
(1 row)

I’ve been fighting with the problem for the second day in a row, and I’m running out of ideas. I tried everything I could, including using different dockerfile (I used both my custom image based on alpine, and also mix phx.gen.release --docker). My best guess is that for some reason postgrex doesn’t send password, but I can’t figure why. I tried to set shorter password, that didn’t help. From strace I see that it seems postgrex doesn’t even try to send password:

1235  writev(20, [{iov_base=NULL, iov_len=0}, {iov_base="\0\0\0)\0\3\0\0user\0", iov_len=13}, {iov_base="postgres", iov_len=8}, {iov_base="\0database\0", iov_le
n=10}, {iov_base="postgres", iov_len=8}, {iov_base="\0\0", iov_len=2}], 6 <unfinished ...>

The problem only occurs in my k8s environment, same code works fine locally in docker compose.

Since nobody else reported this issue, I suspect there is something wrong in my environment, but I can’t figure what. Do you guys have any ideas?

PS just in case, I’ll change password after we resolve the topic.