OSConfig

Azure OSConfig is a modular security configuration stack for Linux Edge devices. OSConfig supports multi-authority device management over Azure and Azure Portal/CLI, GitOps, as well as local management.

For more information on OSConfig see OSConfig North Star Architecture and OSConfig Management Modules.

For our code of conduct and contributing instructions see CONTRIBUTING. For our approach to security see SECURITY.

For the list of our published binary packages and instructions how to install them see devops/README.md.

C Standard

OSConfig's C/C++ code currently targets compliance with C11.

Getting started

Prerequisites

Make sure all dependencies are installed. For example, on Ubuntu:

sudo apt-get update
sudo apt-get install -y git cmake build-essential curl libcurl4-openssl-dev libssl-dev uuid-dev libgtest-dev libgmock-dev rapidjson-dev

Verify that CMake is at least version 3.2.0 and gcc is at least version 4.4.7.

cmake --version
gcc --version

Install and configure the Azure IoT Identity Service (AIS) package as described at azure.github.io/iot-identity-service/.

Build

Create a folder build folder under the repo root /build

mkdir build && cd build

Build with the following commands issued from under the build subfolder:

cmake ../src -DCMAKE_BUILD_TYPE=Release|Debug -Duse_prov_client=ON -Dhsm_type_symm_key=ON -DBUILD_TESTS=ON|OFF
cmake --build . --config Release|Debug  --target install

The following OSConfig files are binplaced at build time:

Source	Destination	Description
src/adapters/pnp/	/usr/bin/osconfig	The OSConfig Agent and the main control binary for OSConfig
src/platform/	/usr/bin/osconfig-platform	The OSConfig Platform binary
src/adapters/pnp/daemon/osconfig.conn	/etc/osconfig/osconfig.conn	Holds manual IoT Hub device connection id string (optional)
src/adapters/pnp/daemon/osconfig.json	/etc/osconfig/osconfig.json	The main configuration file for OSConfig
src/modules/commandrunner/assets/osconfig_commandrunner.cache	/etc/osconfig/osconfig_commandrunner.cache	Persistent cache for the CommandRunner module
src/adapters/pnp/daemon/osconfig.service	/etc/systemd/system/osconfig.service	The service unit for the OSConfig Agent
src/platform/daemon/osconfig-platform.service	/etc/systemd/system/osconfig-platform.service	The service unit for the OSConfig Platform
src/adapters/pnp/daemon/osconfig.toml	/etc/aziot/identityd/config.d/osconfig.toml	The OSConfig Module configuration for AIS
src/modules/securitybaseline/	/usr/lib/osconfig/securitybaseline.so	The SecurityBaseline module binary
src/modules/deviceinfo/	/usr/lib/osconfig/deviceinfo.so	The DeviceInfo module binary
src/modules/configuration/	/usr/lib/osconfig/configuration.so	The Configuration module binary
src/modules/commandrunner/	/usr/lib/osconfig/commandrunner.so	The CommandRunner module binary
src/modules/firewall/	/usr/lib/osconfig/firewall.so	The Firewall module binary
src/modules/adhs/	/usr/lib/osconfig/adhs.so	The Azure Device Health Services (ADHS) module binary
src/modules/deliveryoptimization/	/usr/lib/osconfig/deliveryoptimization.so	The Delivery Optimization (DO) module binary
src/modules/hostname/	/usr/lib/osconfig/hostname.so	The HostName module binary
src/modules/networking/	/usr/lib/osconfig/networking.so	The Networking module binary
src/modules/tpm/	/usr/lib/osconfig/tpm.so	The TPM module binary

Enable and start OSConfig for the first time

Enable and start OSConfig for the first time by enabling and starting the OSConfig Agent Daemon (osconfig):

sudo systemctl daemon-reload
sudo systemctl enable osconfig
sudo systemctl start osconfig

The OSConfig Agent service is configured to be allowed to be restarted (automatically by systemd or manually by user) for a maximum number of 3 times at 5 minutes intervals. There is a total delay of 16 minutes before the OSConfig Agent service could be restarted again by the user unless the user reboots the device.

The OSCOnfig Management Platform Daemon (osconfig-platform) is automatically started and stopped by the OSConfig Agent service (osconfig) but also can be manually started and stopped separately by itself.

Other daemon control operations:

sudo systemctl status osconfig | osconfig-platform
sudo systemctl disable osconfig | osconfig-platform
sudo systemctl stop osconfig  | osconfig-platform

To replace a service binary while OSConfig is running: stop the Agent daemon, rebuild, start the Agent daemon. To replace a service unit while the daemon is running: stop the Agent daemon, disable the Agent amnd Platform daemons, rebuild, reload daemons, start and enable the Agent daemon.

Logs

OSConfig logs to its own logs at /var/log/osconfig*.log*:

sudo cat /var/log/osconfig_pnp_agent.log
sudo cat /var/log/osconfig_platform.log
sudo cat /var/log/osconfig_commandrunner.log
sudo cat /var/log/osconfig_networking.log
sudo cat /var/log/osconfig_firewall.log
sudo cat /var/log/osconfig_tpm.log
...

Each of these log files when it reaches maximum size (128 KB) gets rolled over to a file with the same name and a .bak extension (osconfig_agent.bak, for example).

When OSConfig exists prematurely (crashes) the Agent's log (osconfig_pnp_agent.log) at the very end may contain an indication of that. For example:

[ERROR] OSConfig crash due to segmentation fault (SIGSEGV) during MpiGet to Firewall.FirewallRules

Only the root user can view these log files.

Configuration

OSConfig can be configured via /etc/osconfig/osconfig.json. After changing this configuration file, restart OSConfig to apply the configuration changes. Only the root user can view or edit this configuration file.

Adjusting the reporting interval

OSConfig periodically reports device data at a default time period of 30 seconds. This interval period can be adjusted between 1 second and 86,400 seconds (24 hours) via the OSConfig general configuration file at /etc/osconfig/osconfig.json. Edit there the integer value named "ReportingIntervalSeconds" to a value between 1 and 86400:

{
    "ReportingIntervalSeconds": 30
}

This same interval is also used for RC/DC and GitOps DC processing.

Enabling logging of system commands executed by OSConfig for debugging purposes

Command logging means that OSConfig will log all input and output from system commands executed by Agent, Platform and Modules.

Generally it is not recommended to run OSConfig with command logging enabled.

To enable command logging for debugging purposes, edit the OSConfig general configuration file /etc/osconfig/osconfig.json and set there (or add if needed) an integer value named "CommandLogging" to a non-zero value:

{
    "CommandLogging": 1
}

To disable command logging, set "CommandLogging" to 0.

Enabling full logging for debugging purposes

Full logging means that OSConfig will log all input and output from and to IoT Hub, AIS, RC/DC, GitOps DC, etc.

Generally it is not recommended to run OSConfig with full logging enabled.

To enable full logging for debugging purposes, edit the OSConfig general configuration file /etc/osconfig/osconfig.json and set there (or add if needed) an integer value named "FullLogging" to a non-zero value:

{
    "FullLogging": 1
}

To disable full logging, set "FullLogging" to 0.

Local Management over RC/DC

OSConfig uses two local files as local digital twins in MIM JSON payload format:

/etc/osconfig/osconfig_desired.json contains desired configuration (to be applied to the device)

/etc/osconfig/osconfig_reported.json contains reported configuration (to be reported from the device)

This pair of files are called Reported Configuration (RC) and Desired Configuration (DC) or RC/DC.

Once created, only the root user can view these files or change the DC file.

By default, the reported configuration is not saved locally to the DC file at /etc/osconfig/osconfig_reported.json (local reporting is disabled) and desired configuration is not picked-up from the DC file at /etc/osconfig/osconfig_desired.json.

To enable local management, edit the OSConfig general configuration file /etc/osconfig/osconfig.json and set there (or add if needed) an integer value named "LocalManagement" to a non-zero value:

{
    "LocalManagement": 1
}

To disable local management, set "LocalManagement" to 0.

Desired Configuration (DC) management over GitOps

OSConfig can apply to the device desired configuration in MIM JSON payload format (same as for RC/DC) read from a Git repository and branch. The DC file must be named osconfig_desired.json and be placed in the root of the repository.

By default, desired configuration (DC) over GitOps is disabled and there are no configured Git repository or branch.

To enable GitOps DC management, edit the OSConfig general configuration file /etc/osconfig/osconfig.json and there:

1. Set (or add if needed) a string value named "GitRepositoryUrl" to a string value containing the string that can be used to clone a Git repository, for example (this example uses OSConfig's own repository but can be anything):

{
    "GitRepositoryUrl": "https://github.com/Azure/azure-osconfig"
}

For HTTPS cloning of a private Git repository, add necessary credentials to the "GitRepositoryUrl" such as, for example: https://<username>:<password>@github.com/path/to/repo. For SSH cloning, configure authetication separately on the device so OSConfig can use it.

2. Set (or add if needed) a string value named "GitBranch" to a string value containing the Git branch name where the DC file is located, for example:

{
    "GitBranch": "name/branch"
}

Set (or add if needed) an integer value named "GitManagement" to a non-zero value to enable GitOps DC management:

{
    "GitManagement": 1
}

To disable GitOps DC management, set "GitManagement" to 0.

OSConfig clones locally the configured Git DC file and branch to /etc/osconfig/gitops/osconfig_desired.json. This Git clone is automatically deleted when the OSConfig Agent (Watcher) terminates. While active, the cloned DC file is protected for root user access only.

Changing the protocol OSConfig uses to connect to the IoT Hub

The networking protocol that OSConfig uses to connect to the IoT Hub is configured in the OSConfig general configuration file /etc/osconfig/osconfig.json:

{
    "IotHubProtocol": 2
}

OSConfig currently supports the following protocol values:

Value	Description
0	Decided by OSConfig (currently this is MQTT)
1	MQTT
2	MQTT over Web Socket

HTTP proxy configuration

When the configured IotHubProtocol value is set to value 2 (MQTT over Web Socket) OSConfig attempts to use the HTTP proxy information configured in one of the following environment variables, the first such variable that is locally present:

1. http_proxy
2. https_proxy
3. HTTP_PROXY
4. HTTPS_PROXY

OSConfig supports the HTTP proxy configuration to be in one of the following formats:

• http://server:port
• http://username:password@server:port
• http://domain\username:password@server:port

Where the prefix is either lowercase http or uppercase HTTP and the username and password can contain @ characters escaped as \@.

For example: http://username\@mail.foo:p\@ssw\@rd@www.foo.org:100 where username is username@mail.foo, password is p@ssw@rd, the proxy server is www.foo.org and the port is 100.

The environment variable needs to be set for the root user account. For example, for a fictive proxy server, user and password, the environment variable http_proxy can be set for the root user manually via console with:

sudo -E su
export http_proxy=http://user:password@wwww.foo.org:100//

The environment variable can also be set in the OSConfig service unit file by uncommenting and editing the following line in src/adapters/pnp/daemon/osconfig.service:

# Uncomment and edit next line to configure OSConfig with a proxy to connect to the IoT Hub
# Environment="http_proxy=http://user:password@wwww.foo.org:100//"

After editing the service unit file, stop and disable osconfig.service, rebuild OSConfig, then enable and start osconfig.service:

sudo systemctl stop osconfig.service
sudo systemctl disable osconfig.service
cd build
cmake ../src -DCMAKE_BUILD_TYPE=Release|Debug -Duse_prov_client=ON -Dhsm_type_symm_key=ON -DBUILD_TESTS=ON|OFF
cmake --build . --config Release|Debug  --target install
sudo systemctl enable osconfig.service
sudo systemctl start osconfig.service

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