azuredockerazure-container-instancesejbcacontainerd

containerd error "failed to find user by uid" when creating ejbca docker container on azure


When I try to create an Azure container instance for EJBCA-ce I get an error and cannot see any logs.

I expect the following result : azure portal container instance events success

But I get the following error :

azure portal container instance events failure

Failed to start container my-azure-container-resource-name, Error response: to create containerd task: failed to create container e9e48a_________ffba97: guest RPC failure: failed to find user by uid: 10001: expected exactly 1 user matched '0': unknown

Some context:

I run the container on azure cloud container instance

I tried

It runs fine locally using the same env variable (database configuration). It used to run with the same configuration a couple weeks ago.

Here are some logs I get when I attach the container group from az cli.

(count: 1) (last timestamp: 2020-11-03 16:04:32+00:00) pulling image "primekey/ejbca-ce:6.15.2.3"
(count: 1) (last timestamp: 2020-11-03 16:04:37+00:00) Successfully pulled image "primekey/ejbca-ce:6.15.2.3"
(count: 28) (last timestamp: 2020-11-03 16:27:52+00:00) Error: Failed to start container aci-pulsy-ccm-ejbca-snd, Error response: to create containerd task: failed to create container e9e48a06807fba124dc29633dab10f6229fdc5583a95eb2b79467fe7cdffba97: guest RPC failure: failed to find user by uid: 10001: expected exactly 1 user matched '0': unknown

An extract of the dockerfile from dockerhub

I suspect the issue might be related to the commands USER 0 and USER 10001 we found several times in the dockerfile.

COPY dir:89ead00b20d79e0110fefa4ac30a827722309baa7d7d74bf99910b35c665d200 in /
/bin/sh -c rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
CMD ["/bin/bash"]
USER 0
COPY dir:893e424bc63d1872ee580dfed4125a0bef1fa452b8ae89aa267d83063ce36025 in /opt/primekey
COPY dir:756f0fe274b13cf418a2e3222e3f6c2e676b174f747ac059a95711db0097f283 in /licenses
USER 10001
CMD ["/opt/primekey/wildfly-14.0.1.Final/bin/standalone.sh" "-b" "0.0.0.0"
MAINTAINER PrimeKey Solutions AB
ARG releaseTag
ARG releaseEdition

ARM template

{
      "type": "Microsoft.ContainerInstance/containerGroups",
      "apiVersion": "2019-12-01",
      "name": "[variables('ejbcaContainerGroupName')]",
      "location": "[parameters('location')]",
      "tags": "[variables('tags')]",
      "dependsOn": [
        "[resourceId('Microsoft.DBforMariaDB/servers', variables('ejbcaMariadbServerName'))]",
        "[resourceId('Microsoft.DBforMariaDB/servers/databases', variables('ejbcaMariadbServerName'), variables('ejbcaMariadbDatabaseName'))]"
      ],
      "properties": {
        "sku": "Standard",
        "containers": [
          {
            "name": "[variables('ejbcaContainerName')]",
            "properties": {
              "image": "primekey/ejbca-ce:6.15.2.3",
              "ports": [
                {
                  "protocol": "TCP",
                  "port": 443
                },
                {
                  "protocol": "TCP",
                  "port": 8443
                }
              ],
              "environmentVariables": [

                {
                  "name": "DATABASE_USER",
                  "value": "[concat(parameters('mariadbUser'),'@', variables('ejbcaMariadbServerName'))]"
                },
                {
                  "name": "DATABASE_JDBC_URL",
                  "value": "[variables('ejbcaEnvVariableJdbcUrl')]"
                },
                {
                  "name": "DATABASE_PASSWORD",
                  "secureValue": "[parameters('mariadbAdminPassword')]"
                }
              ],
              "resources": {
                "requests": {
                  "memoryInGB": 1.5,
                  "cpu": 2
                }
              }
              ,
               "volumeMounts": [
                 {
                   "name": "certificates",
                   "mountPath": "/mnt/external/secrets"
                 }
               ]
            }
          }
        ],
        "initContainers": [],
        "restartPolicy": "OnFailure",
        "ipAddress": {
          "ports": [
                {
                  "protocol": "TCP",
                  "port": 443
                },
                {
                  "protocol": "TCP",
                  "port": 8443
                }
          ],
          "type": "Public",
          "dnsNameLabel": "[parameters('ejbcaContainerGroupDNSLabel')]"
        },
        "osType": "Linux",
         "volumes": [
           {
             "name": "certificates",
             "azureFile": {
               "shareName": "[parameters('ejbcaCertsFileShareName')]",
               "storageAccountName": "[parameters('ejbcaStorageAccountName')]",
               "storageAccountKey": "[parameters('ejbcaStorageAccountKey')]"
             }
           }
         ]
      }
    }

It runs fine on my local machine on linux (ubuntu 20.04)

docker run -it --rm -p 8080:8080 -p 8443:8443 -h localhost -e DATABASE_USER="mymaridbuser@my-db" -e DATABASE_JDBC_URL="jdbc:mariadb://my-azure-domain.mariadb.database.azure.com:3306/ejbca?useSSL=true" -e DATABASE_PASSWORD="my-pwd" primekey/ejbca-ce:6.15.2.3

Solution

  • In the EJBCA-ce container image, I think they are trying to provide an user different than root to run the EJBCA server. According to the Docker documentation:

    The USER instruction sets the user name (or UID) and optionally the user group (or GID) to use when running the image and for any RUN, CMD and ENTRYPOINT instructions that follow it in the Dockerfile

    In the Dockerfile they reference two users, root, corresponding to UID 0, and another one, with UID 10001.

    Typically, in Linux and UNIX systems, UIDs can be organized in different ranges: it is largely dependent on the concrete operating system and user management praxis, but it is very likely that the first user account created in a linux system will be assigned to UID 1001 or 10001, like in this case. Please, see for instance the UID entry in wikipedia or this article.

    AFAIK, the USER indicated does not need to exist in your container to run it correctly: in fact, if you run it locally, it will start without further problem.

    The user with UID 10001 will be actually setup in your container by the script that is run in the CMD defined in the Dockerfile, /opt/primekey/bin/start.sh, by this code fragment:

    if ! whoami &> /dev/null; then
      if [ -w /etc/passwd ]; then
        echo "${APPLICATION_NAME}:x:$(id -u):0:${APPLICATION_NAME} user:/opt:/sbin/nologin" >> /etc/passwd
      fi
    fi
    

    Please, be aware that APPLICATION_NAME in this context takes the value ejbca and that the user which runs this script, as indicated in the Dockerfile, is 10001. That will be the value provided by the command id -u in this code.

    You can verify it if you run your container locally:

    docker run -it -p 8080:8080 -p 8443:8443 -h localhost primekey/ejbca-ce:6.15.2.3
    

    And initiate bash into it:

     docker exec -it container_name /bin/bash
    

    If you run whoami, it will tell you ejbca.

    If you run id it will give you the following output:

    uid=10001(ejbca) gid=0(root) groups=0(root)
    

    You can verify the user existence in the /etc/passwd as well:

    bash-4.2$ cat /etc/passwd
    root:x:0:0:root:/root:/bin/bash
    bin:x:1:1:bin:/bin:/sbin/nologin
    daemon:x:2:2:daemon:/sbin:/sbin/nologin
    adm:x:3:4:adm:/var/adm:/sbin/nologin
    lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
    sync:x:5:0:sync:/sbin:/bin/sync
    shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
    halt:x:7:0:halt:/sbin:/sbin/halt
    mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
    operator:x:11:0:operator:/root:/sbin/nologin
    games:x:12:100:games:/usr/games:/sbin/nologin
    ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
    nobody:x:99:99:Nobody:/:/sbin/nologin
    systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
    dbus:x:81:81:System message bus:/:/sbin/nologin
    ejbca:x:10001:0:ejbca user:/opt:/sbin/nologin
    

    The reason why Pierre did not get this output is because he ran the container overwriting the provided CMD and, as a consequence, not executing the start.sh script responsible of the user creation, as above mentioned.

    For any reason, and this is where my knowledge fails me, when Azure is trying to run your container, it is failing because the USER 10001 identified in the Dockerfile does not exist.

    I think it could be related with the use of containerd instead of docker.

    The error reported by Azure seems related with the Microsoft project opengcs.

    They say about the project:

    Open Guest Compute Service is a Linux open source project to further the development of a production quality implementation of Linux Hyper-V container on Windows (LCOW). It's designed to run inside a custom Linux OS for supporting Linux container payload.

    And:

    The focus of LCOW v2 as a replacement of LCOW v1 is through the coordination and work that has gone into containerd/containerd and its Runtime V2 interface. To see our containerd hostside shim please look here Microsoft/hcsshim/cmd/containerd-shim-runhcs-v1.

    The error you see in the console is raised by the spec.go file that you can find in their code base, when they are trying to establish the user on behalf of whom the container process should be run:

    func setUserID(spec *oci.Spec, uid int) error {
        u, err := getUser(spec, func(u user.User) bool {
            return u.Uid == uid
        })
        if err != nil {
            return errors.Wrapf(err, "failed to find user by uid: %d", uid)
        }
        spec.Process.User.UID, spec.Process.User.GID = uint32(u.Uid), uint32(u.Gid)
        return nil
    }
    

    This code is executed by this other code fragment - you can see the full function code here:

    parts := strings.Split(userstr, ":")
    switch len(parts) {
    case 1:
        v, err := strconv.Atoi(parts[0])
        if err != nil {
            // evaluate username to uid/gid
            return setUsername(spec, userstr)
        }
        return setUserID(spec, int(v))
    

    And the getUser function:

    func getUser(spec *oci.Spec, filter func(user.User) bool) (user.User, error) {
        users, err := user.ParsePasswdFileFilter(filepath.Join(spec.Root.Path, "/etc/passwd"), filter)
        if err != nil {
            return user.User{}, err
        }
        if len(users) != 1 {
            return user.User{}, errors.Errorf("expected exactly 1 user matched '%d'", len(users))
        }
        return users[0], nil
    }
    

    As you can see, these are exactly the errors that Azure is reporting you.

    As a summary, I think they are providing a Windows LCOW solution that conforms to the OCI Image Format Specification suitable to run containers with containerd.

    As you indicated if It used to run with the same configuration a couple weeks ago my best guest is that, perhaps, they switched your containers from a pure Linux containerd runtime implementation to one based in Windows and in the above mentioned software, and this is why you containers are now failing.

    A possible workaround could be to create a custom image based on the official provided by PrimeKey and create the user 10001, as also Pierre pointed out.

    To accomplish this task, first, create a new custom Dockerfile. You can try, for instance:

    FROM primekey/ejbca-ce:6.15.2.3
    
    USER 0
    
    RUN echo "ejbca:x:10001:0:ejbca user:/opt:/sbin/nologin" >> /etc/passwd
    
    USER 10001
    

    Please, note that you may need to define some of the environment variables from the official EJBCA image.

    With this Dockerfile you can build your image with docker or docker compose with an appropriate docker-compose.yaml file, something like:

    version: "3"
    
    services:
      ejbca:
        image: <your repository>/ejbca
        build: .
        ports:
          - "8080:8080"
          - "8443:8443"
    

    Please, customize it as you consider appropriate.

    With this setup the new container will still run properly in a local environment in the same way as the original one: I hope it will be also the case in Azure.