Running Agents as Unix Users¶
This VOLTTRON feature will cause the platform to create a new, unique Unix user(agent users) on the host machine for each agent installed on the platform. This user will have restricted permissions for the file system, and will be used to run the agent process.
The Unix user starting the VOLTTRON platform will be given limited sudo access to create and delete agent users.
Since this feature requires system level changes (e.g. sudo access, user creation, file permission changes), the initial step needs to be run as root or user with sudo access. This can be a user other than Unix user used to run the VOLTTRON platform.
All files and folder created by the VOLTTRON process in this mode would not have any access to others by default. Permission for Unix group others would be provided to specific files and folder based on VOLTTRON process requirement.
It is recommended that you use a new VOLTTRON_HOME to run VOLTTRON in secure mode. Converting a existing VOLTTRON instance to secure mode is also possible but would involve some manual changes. Please see the section Porting existing volttron home to secure mode.
VOLTTRON has to be bootstrapped as prerequisite to running agents as unique users.
Setup agents to run using unique users¶
This feature requires acl to be installed.
Make sure the acl library is installed. If you are running on a Docker image acl might not be installed by default.
apt-get install acl
Agents now run as a user different from VOLTTRON platform user. Agent users should have read and execute permissions to all directories in the path to the Python executable used by VOLTTRON. For example, if VOLTTRON is using a virtual environment, then agent users should have read permissions to <ENV_DIR>/bin/python and read and execute permission to all the directories in the path <ENV_DIR>/bin. This can be achieved by running:
chmod -R o+rx <ENV_DIR>/bin
Run scripts/secure_user_permissions.sh as root or using sudo
This script MUST be run as root or using sudo. This script gives the VOLTTRON platform user limited sudo access to create a new Unix user for each agent. All users created will be of the format volttron_<timestamp>.
This script prompts for:
volttron platform user - Unix user who would be running the VOLTTRON platform. This should be an existing Unix user. On a development machine this could be the Unix user you logged in as to check out VOLTTRON source
VOLTTRON_HOME directory - The absolute path of the volttron home directory.
Volttron instance name if VOLTTRON_HOME/config does not exist -
If the VOLTTRON_HOME/config file exists then instance name is obtained from that config file. If not, the user will be prompted for an instance name. volttron_<instance_name> MUST be a 23 characters or shorter containing only characters valid as Unix user names.
This script will create necessary entries in /etc/sudoers.d/volttron to allow the VOLTTRON platform user to create and delete agent users, the VOLTTRON agent group, and run any non-sudo command as the agent users.
This script will also create VOLTTRON_HOME and the config file if given a new VOLTTRON home directory when prompted.
Continue with VOLTTRON bootstrap and setup as normal - point to the VOLTTRON_HOME that you provided in step 2.
On agent install (or agent start for existing agents) - a unique agent user(Unix user) is created and the agent is started as this user. The agent user name is recorded in USER_ID file under the agent install directory (VOLTTRON_HOME/agents/<agent-uuid>/USER_ID). Subsequent agent restarts will read the content of the USER_ID file and start the agent process as that user.
On agent uninstall - The agent user is deleted and the agent install directory is deleted.
Creating new Agents¶
In this secure mode, agents will only have read write access to the agent-data directory under the agent install directory - VOLTTRON_HOME/agents/<agent_uuid>/<agent_name>/<agent_name>.agent-data. Attempting to write in any other folder under VOLTTRON_HOME will result in permission errors.
Changes to existing agents in secure mode¶
Due to the above change, SQL historian has been modified to create its database by default under its agent-data directory if no path is given in the config file. If providing a path to the database in the config file, please provide a directory where agent will have write access. This can be an external directory for which agent user (recorded in VOLTTRON_HOME/agents/<agent-uuid>/USER_ID) has read, write, and execute access.
Porting existing VOLTTRON home to secure mode¶
When running scripts/secure_users_permissions.sh you will be prompted for a VOLTTRON_HOME directory. If this directory exists and contains a volttron config file, the script will update the file locations and permissions of existing VOLTTRON files including installed directories. However this step has the following limitations:
You will NOT be able to revert to insecure mode once the changes are done. - Once setup is complete, changing the config file manually to make parameter secure-agent-users to False, may result inconsistent VOLTTRON behavior
The VOLTTRON process and all agents have to be restarted to take effect
Agents can only to write to its own agent-data dir. - If your agents writes to any directory outside $VOLTTRON_HOME/agents/<agent-uuid>/<agent-name>/agent-name.agent-data move existing files and update the agent configuration such that the agent writes to the agent-name.agent-data dir. For example, if you have a SQLHistorian which writes a .sqlite file to a subdirectory under VOLTTRON_HOME that is not $VOLTTRON_HOME/agents/<agent-uuid>/<agent-name>/agent-name.agent-data this needs to be manually updated.