Configure IoT Edge device settings
This article shows settings and options for configuring the IoT Edge /etc/aziot/config.toml file of an IoT Edge device. IoT Edge uses the config.toml file to initialize settings for the device. Each of the sections of the config.toml file has several options. Not all options are mandatory, as they apply to specific scenarios.
A template containing all options can be found in the config.toml.edge.template file within the /etc/aziot directory on an IoT Edge device. You can copy the contents of the whole template or sections of the template into your config.toml file. Uncomment the sections you need. Be aware not to copy over parameters you have already defined.
If you change a device's configuration, use sudo iotedge config apply to apply the changes.
Global parameters
The hostname, parent_hostname, trust_bundle_cert, allow_elevated_docker_permissions, and auto_reprovisioning_mode parameters must be at the beginning of the configuration file before any other sections. Adding parameters before a collection of settings ensures they're applied correctly. For more information on valid syntax, see toml.io .
Hostname
To enable gateway discovery, every IoT Edge gateway (parent) device needs to specify a hostname parameter that its child devices use to find it on the local network. The edgeHub module also uses the hostname parameter to match with its server certificate. For more information, see Why does EdgeGateway need to be told about its own hostname?.
Note
When the hostname value isn't set, IoT Edge attempts to find it automatically. However, clients in the network may not be able to discover the device if it isn't set.
For hostname, replace fqdn-device-name-or-ip-address with your device name to override the default hostname of the device. The value can be a fully qualified domain name (FQDN) or an IP address. Use this setting as the gateway hostname on a IoT Edge gateway device.
hostname = "fqdn-device-name-or-ip-address"
Parent hostname
Parent hostname is used when the IoT Edge device is part of a hierarchy, otherwise known as a nested edge. Every downstream IoT Edge device needs to specify a parent_hostname parameter to identify its parent. In a hierarchical scenario where a single IoT Edge device is both a parent and a child device, it needs both parameters.
Replace fqdn-parent-device-name-or-ip-address with the name of your parent device. Use a hostname shorter than 64 characters, which is the character limit for a server certificate common name.
parent_hostname = "fqdn-parent-device-name-or-ip-address"
For more information about setting the parent_hostname parameter, see Connect Azure IoT Edge devices together to create a hierarchy.
Trust bundle certificate
To provide a custom certificate authority (CA) certificate as a root of trust for IoT Edge and modules, specify a trust_bundle_cert configuration. Replace the parameter value with the file URI to the root CA certificate on your device.
trust_bundle_cert = "file:///var/aziot/certs/trust-bundle.pem"
For more information about the IoT Edge trust bundle, see Manage trusted root CA.
Elevated Docker Permissions
Some docker capabilities can be used to gain root access. By default, the --privileged flag and all capabilities listed in the CapAdd parameter of the docker HostConfig are allowed.
If no modules require privileged or extra capabilities, use allow_elevated_docker_permissions to improve the security of the device.
allow_elevated_docker_permissions = false
Auto reprovisioning mode
The optional auto_reprovisioning_mode parameter specifies the conditions that decide when a device attempts to automatically reprovision with Device Provisioning Service. Auto provisioning mode is ignored if the device has been provisioned manually. For more information about setting DPS provisioning mode, see the Provisioning section in this article for more information.
One of the following values can be set:
| Mode | Description |
|---|---|
| Dynamic | Reprovision when the device detects that it may have been moved from one IoT Hub to another. This mode is the default. |
| AlwaysOnStartup | Reprovision when the device is rebooted or a crash causes the daemons to restart. |
| OnErrorOnly | Never trigger device reprovisioning automatically. Device reprovisioning only occurs as fallback, if the device is unable to connect to IoT Hub during identity provisioning due to connectivity errors. This fallback behavior is implicit in Dynamic and AlwaysOnStartup modes as well. |
For example:
auto_reprovisioning_mode = "Dynamic"
For more information about device reprovisioning, see IoT Hub Device reprovisioning concepts.
Provisioning
You can provision a single device or multiple devices at-scale, depending on the needs of your IoT Edge solution. The options available for authenticating communications between your IoT Edge devices and your IoT hubs depend on what provisioning method you choose.
You can provision with a connection string, symmetric key, X.509 certificate, identity certificate private key, or an identity certificate. DPS provisioning is included with various options. Choose one method for your provisioning. Replace the sample values with your own.
Manual provisioning with connection string
[provisioning]
source = "manual"
connection_string = "HostName=example.azure-devices.net;DeviceId=my-device;SharedAccessKey=<Shared access key>"
For more information about retrieving provisioning information, see Create and provision an IoT Edge device on Linux using symmetric keys.
Manual provisioning with symmetric key
[provisioning]
source = "manual"
iothub_hostname = "example.azure-devices.net"
device_id = "my-device"
[provisioning.authentication]
method = "sas"
device_id_pk = { value = "<Shared access key>" } # inline key (base64), or...
device_id_pk = { uri = "file:///var/aziot/secrets/device-id.key" } # file URI, or...
device_id_pk = { uri = "pkcs11:slot-id=0;object=device%20id?pin-value=1234" } # PKCS#11 URI
For more information about retrieving provisioning information, see Create and provision an IoT Edge device on Linux using symmetric keys.
Manual provisioning with X.509 certificate
[provisioning]
source = "manual"
iothub_hostname = "example.azure-devices.net"
device_id = "my-device"
[provisioning.authentication]
method = "x509"
For more information about provisioning using X.509 certificates, see Create and provision an IoT Edge device on Linux using X.509 certificates.
DPS provisioning with symmetric key
[provisioning]
source = "dps"
global_endpoint = "https://global.azure-devices-provisioning.net"
id_scope = "<DPS-ID-SCOPE>"
# (Optional) Use to send a custom payload during DPS registration
payload = { uri = "file:///var/secrets/aziot/identityd/dps-additional-data.json" }
[provisioning.attestation]
method = "symmetric_key"
registration_id = "my-device"
symmetric_key = { value = "<Device symmetric key>" } # inline key (base64), or...
symmetric_key = { uri = "file:///var/aziot/secrets/device-id.key" } # file URI, or...
symmetric_key = { uri = "pkcs11:slot-id=0;object=device%20id?pin-value=1234" }
For more information about DPS provisioning with symmetric key, see Create and provision IoT Edge devices at scale on Linux using symmetric key.
DPS provisioning with X.509 certificates
[provisioning]
source = "dps"
global_endpoint = "https://global.azure-devices-provisioning.net/"
id_scope = "<DPS-ID-SCOPE>"
# (Optional) Use to send a custom payload during DPS registration
payload = { uri = "file:///var/secrets/aziot/identityd/dps-additional-data.json" }
[provisioning.attestation]
method = "x509"
registration_id = "my-device"
# Identity certificate private key
identity_pk = "file:///var/aziot/secrets/device-id.key.pem" # file URI, or...
identity_pk = "pkcs11:slot-id=0;object=device%20id?pin-value=1234" # PKCS#11 URI
# Identity certificate
identity_cert = "file:///var/aziot/certs/device-id.pem" # file URI, or...
[provisioning.authentication.identity_cert] # dynamically issued via...
method = "est" # - EST
method = "local_ca" # - a local CA
common_name = "my-device" # with the given common name, or...
subject = { L = "AQ", ST = "Antarctica", CN = "my-device" } # with the given DN fields
(Optional) Enable automatic renewal of the device ID certificate
Autorenewal requires a known certificate issuance method. Set method to either est or local_ca.
Important
Only enable autorenewal if this device is configured for CA-based DPS enrollment. Using autorenewal for an individual enrollment causes the device to be unable to reprovision.
[provisioning.attestation.identity_cert.auto_renew]
rotate_key = true
threshold = "80%"
retry = "4%"
For more information about DPS provisioning with X.509 certificates, see Create and provision IoT Edge devices at scale on Linux using X.509 certificates.
DPS provisioning with TPM (Trusted Platform Module)
[provisioning]
source = "dps"
global_endpoint = "https://global.azure-devices-provisioning.net"
id_scope = "<DPS-ID-SCOPE>"
# (Optional) Use to send a custom payload during DPS registration
payload = { uri = "file:///var/secrets/aziot/identityd/dps-additional-data.json" }
[provisioning.attestation]
method = "tpm"
registration_id = "my-device"
If you use DPS provisioning with TPM, and require custom configuration, see the TPM section.
For more information, see Create and provision IoT Edge devices at scale with a TPM on Linux.
Cloud Timeout and Retry Behavior
These settings control the timeout and retries for cloud operations, such as communication with Device Provisioning Service (DPS) during provisioning or IoT Hub for module identity creation.
The cloud_timeout_sec parameter is the deadline in seconds for a network request to cloud services. For example, an HTTP request. A response from the cloud service must be received before this deadline, or the request fails as a timeout.
The cloud_retries parameter controls how many times a request may be retried after the first try fails. The client always sends at least once, so the value is number of retries after the first try fails. For example, cloud_retries = 2 means that the client makes a total of three attempts.
cloud_timeout_sec = 10
cloud_retries = 1
Certificate issuance
If you configured any dynamically issued certs, choose your corresponding issuance method and replace the sample values with your own.
Cert issuance via EST
[cert_issuance.est]
trusted_certs = ["file:///var/aziot/certs/est-id-ca.pem",]
[cert_issuance.est.auth]
username = "estuser"
password = "estpwd"
EST ID cert already on device
identity_cert = "file:///var/aziot/certs/est-id.pem"
identity_pk = "file:///var/aziot/secrets/est-id.key.pem" # file URI, or...
identity_pk = "pkcs11:slot-id=0;object=est-id?pin-value=1234" # PKCS#11 URI
EST ID cert requested via EST bootstrap ID cert
Authentication with a TLS client certificate that is used once to create the initial EST ID certificate. After the first certificate issuance, an identity_cert and identity_pk are automatically created and used for future authentication and renewals. The Subject Common Name (CN) of the generated EST ID certificate is always the same as the configured device ID under the provisioning section. These files must be readable by the users aziotcs and aziotks, respectively.
bootstrap_identity_cert = "file:///var/aziot/certs/est-bootstrap-id.pem"
bootstrap_identity_pk = "file:///var/aziot/secrets/est-bootstrap-id.key.pem" # file URI, or...
bootstrap_identity_pk = "pkcs11:slot-id=0;object=est-bootstrap-id?pin-value=1234" # PKCS#11 URI
# The following parameters control the renewal of EST identity certs. These certs are issued by the EST server after initial authentication with the bootstrap cert and managed by Certificates Service.
[cert_issuance.est.identity_auto_renew]
rotate_key = true
threshold = "80%"
retry = "4%"
[cert_issuance.est.urls]
default = "https://example.org/.well-known/est"
Cert issuance via local CA
[cert_issuance.local_ca]
cert = "file:///var/aziot/certs/local-ca.pem"
pk = "file:///var/aziot/secrets/local-ca.key.pem" # file URI, or...
pk = "pkcs11:slot-id=0;object=local-ca?pin-value=1234" # PKCS#11 URI
TPM (Trusted Platform Module)
If you need special configuration for the TPM when using DPS TPM provisioning, use these TPM settings.
For acceptable TCTI loader strings, see section 3.5 of TCG TSS 2.0 TPM Command Transmission Interface (TCTI) API Specification.
Setting to an empty string causes the TCTI loader library to try loading a predefined set of TCTI modules in order.
[tpm]
tcti = "swtpm:port=2321"
The TPM index persists the DPS authentication key. The index is taken as an offset from the base address for persistent objects such as 0x81000000 and must lie in the range from 0x00_00_00 to 0x7F_FF_FF. The default value is 0x00_01_00.
auth_key_index = "0x00_01_00"
Use authorization values for endorsement and owner hierarchies, if needed. By default, these values are empty strings.
[tpm.hierarchy_authorization]
endorsement = "hello"
owner = "world"
PKCS#11
If you used any PKCS#11 URIs, use the following parameters and replace the values with your PKCS#11 configuration.
[aziot_keys]
pkcs11_lib_path = "/usr/lib/libmypkcs11.so"
pkcs11_base_slot = "pkcs11:slot-id=0?pin-value=1234"
Default Edge Agent
When IoT Edge starts up the first time, it bootstraps a default Edge Agent module. If you need to override the parameters provided to the default Edge Agent module, use this section and replace the values with your own.
Note
The agent.config.createOptions parameter is specified as a TOML inline table. This format looks like JSON but it's not JSON. For more information, see Inline Table of the TOML v1.0.0 documentation.
[agent]
name = "edgeAgent"
type = "docker"
imagePullPolicy = "..." # "on-create" or "never". Defaults to "on-create"
[agent.config]
image = "mcr.microsoft.com/azureiotedge-agent:1.4"
createOptions = { HostConfig = { Binds = ["/iotedge/storage:/iotedge/storage"] } }
[agent.config.auth]
serveraddress = "example.azurecr.io"
username = "username"
password = "password"
[agent.env]
RuntimeLogLevel = "debug"
UpstreamProtocol = "AmqpWs"
storageFolder = "/iotedge/storage"
Daemon management and workload API endpoints
If you need to override the management and workload API endpoints, use this section and replace the values with your own.
[connect]
workload_uri = "unix:///var/run/iotedge/workload.sock"
management_uri = "unix:///var/run/iotedge/mgmt.sock"
[listen]
workload_uri = "unix:///var/run/iotedge/workload.sock"
management_uri = "unix:///var/run/iotedge/mgmt.sock"
Edge Agent watchdog
If you need to override the default Edge Agent watchdog settings, use this section and replace the values with your own.
[watchdog]
max_retries = "infinite" # the string "infinite" or a positive integer. Defaults to "infinite"
Edge CA certificate
If you have your own Edge CA certificate that issues all your module certificates, use one of these sections and replace the values with your own.
Edge CA certificate loaded from a file
[edge_ca]
cert = "file:///var/aziot/certs/edge-ca.pem" # file URI
pk = "file:///var/aziot/secrets/edge-ca.key.pem" # file URI, or...
pk = "pkcs11:slot-id=0;object=edge%20ca?pin-value=1234" # PKCS#11 URI
Edge CA certificate issued over EST
[edge_ca]
method = "est"
For more information about using an EST server, see Tutorial: Configure Enrollment over Secure Transport Server for Azure IoT Edge.
Optional EST configuration for issuing the Edge CA certificate
If not set, the defaults in [cert_issuance.est] are used.
common_name = "aziot-edge CA"
expiry_days = 90
url = "https://example.org/.well-known/est"
username = "estuser"
password = "estpwd"
EST ID cert already on device
identity_cert = "file:///var/aziot/certs/est-id.pem"
identity_pk = "file:///var/aziot/secrets/est-id.key.pem" # file URI, or...
identity_pk = "pkcs11:slot-id=0;object=est-id?pin-value=1234" # PKCS#11 URI
EST ID cert requested via EST bootstrap ID cert
bootstrap_identity_cert = "file:///var/aziot/certs/est-bootstrap-id.pem"
bootstrap_identity_pk = "file:///var/aziot/secrets/est-bootstrap-id.key.pem" # file URI, or...
bootstrap_identity_pk = "pkcs11:slot-id=0;object=est-bootstrap-id?pin-value=1234" # PKCS#11 URI
Edge CA certificate issued from a local CA certificate
Requires [cert_issuance.local_ca] to be set.
[edge_ca]
method = "local_ca"
# Optional configuration
common_name = "aziot-edge CA"
expiry_days = 90
Edge CA quickstart certificates
If you don't have your own Edge CA certificate used to issue all module certificates, use this section and set the number of days for the lifetime of the autogenerated self-signed Edge CA certificate. Expiration defaults to 90 days.
Caution
This setting is NOT recommended for production usage. Please configure your own Edge CA certificate in the Edge CA certificate sections.
[edge_ca]
auto_generated_edge_ca_expiry_days = 90
Edge CA certificate autorenewal
This setting manages autorenewal of the Edge CA certificate. Autorenewal applies when the Edge CA is configured as quickstart or when the Edge CA has an issuance method set. Edge CA certificates loaded from files generally can't be autorenewed as the Edge runtime doesn't have enough information to renew them.
Important
Renewal of an Edge CA requires all server certificates issued by that CA to be regenerated. This regeneration is done by restarting all modules. The time of Edge CA renewal can't be guaranteed. If random module restarts are unacceptable for your use case, disable autorenewal.
[edge_ca.auto_renew]
rotate_key = true
threshold = "80%"
retry = "4%"
Image garbage collection
If you need to override the default image garbage collection configuration, use this section and replace the values in this section with your own.
| Parameter | Description |
|---|---|
enabled |
Runs image garbage collection |
cleanup_recurrence |
How often you want the image garbage collection to run |
image_age_cleanup_threshold |
The age of unused images. Images older than the threshold are removed |
cleanup_time |
24-hour HH:MM format. When the cleanup job runs |
[image_garbage_collection]
enabled = true
cleanup_recurrence = "1d"
image_age_cleanup_threshold = "7d"
cleanup_time = "00:00"
Moby runtime
If you need to override the default Moby runtime configuration, use this section and replace the values with your own.
[moby_runtime]
uri = "unix:///var/run/docker.sock"
network = "azure-iot-edge"
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