docker exec --user db2inst1, unable to find user db2inst1: no matching entries in passwd file

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                          I'm playing around with docker and db2 but I'm getting into trouble when I try to execute commands as user db2inst1 into a running container. I start the container as (it is 1 line but I split it up for readability):

    docker run -itd --name mydb2 --privileged=true -p 50000:50000 
      -e LICENSE=accept 
      -e DB2INST1_PASSWORD=pelle_paltnacke 
      --mount type=volume,dst=${backupdir},volume-driver=local,volume-opt=type=nfs,\"volume-opt=o=nfsvers=4,addr=${addr}\",volume-opt=device=:${device} 
      -v /etc/passwd:/etc/passwd 
      -v /etc/group:/etc/group 
      -v /opt/nya/users/db2inst1:/opt/nya/users/db2inst1 
      -v /home/system/db2fenc1/:/home/system/db2fenc1/ ibmcom/db2

Now, if I try to do:

    docker exec --user db2inst1 -ti mydb2 bash -c "cat /etc/passwd | grep db2inst1"
    unable to find user db2inst1: no matching entries in passwd file

As root there is no problem:

    docker exec -ti mydb2 bash -c "cat /etc/passwd | grep db2inst1"
    db2inst1:x:422:422:DB2 Instance Administrator 1:/opt/nya/users/db2inst1:/bin/bash

and also --user root works fine:

    docker exec --user root -ti mydb2 bash -c "cat /etc/passwd | grep db2inst1"
    db2inst1:x:422:422:DB2 Instance Administrator 1:/opt/nya/users/db2inst1:/bin/bash

So I tried with the uid from the mounted passwd file:

    docker exec --user 422 -ti mydb2 bash -c "cat /etc/passwd | grep db2inst1"
    db2inst1:x:422:422:DB2 Instance Administrator 1:/opt/nya/users/db2inst1:/bin/bash

/etc/passwd is readable for everyone. Anyhow, using the uid does not get me far:

    docker exec --user 422 -ti mydb2 bash -c "db2licm -l"
    bash: db2licm: command not found

so I try with:

    docker exec --user 422 -ti mydb2 bash -c "whoami; . ~db2inst1/sqllib/db2profile; 
    db2licm -l"
    db2inst1
    bash: /opt/nya/users/db2inst1/sqllib/adm/db2licm: Permission denied

This is just a couples of commands I ran to demonstrate the problem. Does anyone have an explanation as to why the --user db2inst1 is not able to execute them? 


FWIW, I tried without the nfs-mount but I get the same behaviour.

The container itself seems to be working alright. If I spin up the container as above and:

    #> docker exec -ti mydb2 bash
    [root@0ee67959246f /]# mkdir -p /data/db/db2
    [root@0ee67959246f /]# chown db2inst1:db2iadm1 /data/db/db2/
    [root@0ee67959246f /]# su - db2inst1
    [db2inst1@0ee67959246f ~]$ cd /data/backup/db2/wb11/MD000I11/
    [db2inst1@0ee67959246f MD000I11]$ db2 "restore db MD000I11 incremental auto taken at 20220307141244 to /data/db/db2 into WD000I11"
    DB20000I  The RESTORE DATABASE command completed successfully.


EDIT: An interesting observation is:

    docker exec --user 422 -ti mydb2 bash -c "id"
    uid=422(db2inst1) gid=0(root) groups=0(root)

    docker exec --user 422:422 -ti mydb2 bash -c "id"
    uid=422(db2inst1) gid=422(db2iadm1) groups=422(db2iadm1)


    docker exec --user 422:422 -ti mydb2 bash -c "whoami; . 
    ~db2inst1/sqllib/db2profile; db2licm -l"

    db2inst1
    Product name:                     "DB2 Community Edition"
    License type:                     "Community"
    ...

Unfortunate:

    docker exec --user db2inst1:db2iadm1 -ti mydb2 bash -c "id"
    unable to find user db2inst1: no matching entries in passwd file

   
                        
Asked by Lennart - Slava Ukraini (23862 rep)
Mar 7, 2022, 03:37 PM
Last activity: Mar 14, 2022, 10:42 AM
docker exec --user db2inst1, unable to find user db2inst1: no matching entries in passwd file

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