There are many secrets that Lemur uses that must be protected. All of these options are set via the Lemur configuration file. It is highly advised that you do not store your secrets in this file! Lemur provides functions that allow you to encrypt files at rest and decrypt them when it’s time for deployment. See Credential Management for more information.


All configuration values are python strings unless otherwise noted.

Basic Configuration

LOG_FILE = "/logs/lemur/lemur-test.log"
LOG_UPGRADE_FILE = "/logs/lemur/db_upgrade.log"

Sets the flask debug flag to true (if supported by the webserver)

DEBUG = False


This should never be used in a production environment as it exposes Lemur to remote code execution through the debug console.


Allows for cross domain requests, this is most commonly used for development but could be use in production if you decided to host the webUI on a different domain than the server.

For CORS configuration options, please refer to Flask-CORS Documentation

Use this cautiously, if you’re not sure. Set it to False

CORS = False

Allows for the creation of multiple response headers. A response header is an HTTP header that can be used in an HTTP response and that doesn’t relate to the content of the message. Response headers, like Age, Location or Server are used to give a more detailed context of the response.



    "Content-Security-Policy": "default-src 'self'",
    "X-Frame-Options": "DENY"

If you have ever used sqlalchemy before this is the standard connection string used. Lemur uses a postgres database and the connection string would look something like:

SQLALCHEMY_DATABASE_URI = 'postgresql://<user>:<password>@<hostname>:5432/lemur'

This is an optional config that handles all engine_options to SQLAlchemy. Please refer to the flask-sqlalchemy website for more details about the individual configs.

The default connection pool size is 5 for sqlalchemy managed connections. Depending on the number of Lemur instances, please specify the per instance connection pool_size. Below is an example to set connection pool_size to 10.

max_overflow allows to create connections in addition to specified number of connections in pool size. By default, sqlalchemy allows 10 connections to create in addition to the pool size. If pool_size and max_overflow are not specified then each Lemur instance may create maximum of 15 connections.

pool_recycle defines number of seconds after which a connection is automatically recycled.

    'pool_size': 10,
    'pool_recycle': 600,
    'pool_timeout': 20,
    'max_overflow': 10,


Specifying pool_size is an optional setting but important to review and set for optimal database connection usage and for overall database performance. Note that SQLALCHEMY_POOL_SIZE, SQLALCHEMY_MAX_OVERFLOW, SQLALCHEMY_POOL_TIMEOUT are deprecated since sqlalchemy v2.4.


Specifying max_overflow to 0 will enforce limit to not create connections above specified pool size.


Specifies whether to allow certificates created by Lemur to expire on weekends. Default is True.


List of regular expressions for domain restrictions; if the list is not empty, normal users can only issue certificates for domain names matching at least one pattern on this list. Administrators are exempt from this restriction.

Cerificate common name is matched against these rules if it does not contain a space. SubjectAltName DNS names are always matched against these rules.

Take care to write patterns in such way to not allow the * wildcard character inadvertently. To match a . character, it must be escaped (as .).


By default, Lemur will add the certificate owner’s email address to certificate subject (for CAs that allow it). Set this to False to disable this.


The TOKEN_SECRET is the secret used to create JWT tokens that are given out to users. This should be securely generated and kept private.

LEMUR_TOKEN_SECRET = 'supersecret'

An example of how you might generate a random string:

>>> import secrets
        >>> import string
>>> chars = string.ascii_uppercase + string.ascii_lowercase + string.digits + "~!@#$%^&*()_+"
>>> secret_key = ''.join(secrets.choice(chars) for x in range(24))

The LEMUR_ENCRYPTION_KEYS is used to encrypt data at rest within Lemur’s database. Without a key Lemur will refuse to start. Multiple keys can be provided to facilitate key rotation. The first key in the list is used for encryption and all keys are tried for decryption until one works. Each key must be 32 URL safe base-64 encoded bytes.

Only fields of type Vault will be encrypted. At present, only the following fields are encrypted:

  • certificates.private_key

  • pending_certificates.private_key

  • dns_providers.credentials

  • roles.password

For implementation details, see Vault in

Running lemur create_config will securely generate a key for your configuration file. If you would like to generate your own, we recommend the following method:

>>> import os
>>> import base64
>>> base64.urlsafe_b64encode(os.urandom(32))
LEMUR_ENCRYPTION_KEYS = ['1YeftooSbxCiX2zo8m1lXtpvQjy27smZcUUaGmffhMY=', 'LAfQt6yrkLqOK5lwpvQcT4jf2zdeTQJV1uYeh9coT5s=']

Use this config to override the limit of 397 days of validity for certificates issued by CA/Browser compliant authorities. The authorities with cab_compliant option set to true will use this config. The example below overrides the default validity of 397 days and sets it to 365 days.


Use this config to override the default validity of 365 days for certificates offered through Lemur UI. Any CA which is not CA/Browser Forum compliant will be using this value as default validity to be displayed on UI. Please note that this config is used for cert issuance only through Lemur UI. The example below overrides the default validity of 365 days and sets it to 1095 days (3 years).


Dump all imported or generated CSR and certificate details to stdout using OpenSSL. (default: False)


When set to True, certificates can be marked as deleted via the API and deleted certificates will not be displayed in the UI. When set to False (the default), the certificate delete API will always return “405 method not allowed” and deleted certificates will always be visible in the UI. (default: False)


This is an optional config applicable for settings where Lemur is deployed in AWS. When specified, this will override the default regional AWS endpoints that are used for accessing STS and services such as IAM for example. You must set this if running in an alternative AWS partition such as GovCloud, for example.


Specifies the AWS partition that Lemur should use. Valid values are ‘aws’, ‘aws-us-gov’, and ‘aws-cn’. Defaults to ‘aws’. If Lemur is deployed in and managing endpoints AWS GovCloud, for example, you must set this to aws-us-gov.


When set to True, this property enforces the default Lemur role functionality. The default Lemur roles are admin, operator, and read-only. Users will be required to have a default role assigned upon creation. The operator and read-only roles are strictly enforced. Users assigned the read-only role will not be able to create/update resources.


To initialize the Sentry integration to capture errors and exceptions, the SENTRY_DSN is required to be set to the respective URL. LEMUR_ENV is also a related variable to define the environment for sentry events, e.g., ‘test’ or ‘prod’.

Note that previously Lemur relied on Raven[flask] before migrating to sentry_sdk. In this case, you might be using the legacy SENTRY_CONFIG, which Lemur attempts to respect, in case SENTRY_DSN is missing, with environment set to empty.

Example for using Senty to capture exceptions:

>>>  from sentry_sdk import capture_exception
>>>  ..
>>>  capture_exception()
>>>  # supplying extra information
>>>  capture_exception(extra={"certificate_name": str(})

Allows authority creation to be an admin-only operation. By default, any user can create new authorities.

Certificate Default Options

Lemur allows you to fine tune your certificates to your organization. The following defaults are presented in the UI and are used when Lemur creates the CSR for your certificates.


Notification Options

Lemur supports a small variety of notification types through a set of notification plugins. By default, Lemur configures a standard set of email notifications for all certificates.

Plugin-capable notifications

These notifications can be configured to use all available notification plugins.

Supported types:

  • Certificate expiration (Celery: notify_expirations, cron: notify expirations)

Email-only notifications

These notifications can only be sent via email and cannot use other notification plugins.

Supported types:

  • CA certificate expiration (Celery: notify_authority_expirations, cron: notify authority_expirations)

  • Pending ACME certificate failure

  • Certificate rotation

  • Certificate reissued with no endpoints

  • Certificate reissue failed

  • Certificate revocation

  • Security certificate expiration summary (Celery: send_security_expiration_summary, cron: notify security_expiration_summary)

  • Certificate expiration where certificates are still detected as deployed at any associated domain (Celery: notify_expiring_deployed_certificates, cron: notify expiring_deployed_certificates)

Default notifications

When a certificate is created, the following email notifications are created for it if they do not exist. If these notifications already exist, they will be associated with the new certificate.

  • DEFAULT_<OWNER>_X_DAY, where X is the set of values specified in LEMUR_DEFAULT_EXPIRATION_NOTIFICATION_INTERVALS and defaults to 30, 15, and 2 if not specified. The owner’s username will replace <OWNER>.

  • DEFAULT_SECURITY_X_DAY, where X is the set of values specified in LEMUR_SECURITY_TEAM_EMAIL_INTERVALS and defaults to LEMUR_DEFAULT_EXPIRATION_NOTIFICATION_INTERVALS if not specified (which also defaults to 30, 15, and 2 if not specified).

These notifications can be disabled if desired. They can also be unassociated with a specific certificate.

Disabling notifications

Notifications can be disabled either for an individual certificate (which disables all notifications for that certificate) or for an individual notification object (which disables that notification for all associated certificates). At present, disabling a notification object will only disable certificate expiration notifications, and not other types, since other notification types don’t use notification objects.

Certificate expiration

Certificate expiration notifications are sent when the scheduled task to send certificate expiration notifications runs (see Periodic Tasks). Specific patterns of certificate names may be excluded using --exclude (when using cron; you may specify this multiple times for multiple patterns) or via the config option EXCLUDE_CN_FROM_NOTIFICATION (when using celery; this is a list configuration option, meaning you specify multiple values, such as ['exclude', 'also exclude']). The specified exclude pattern will match if found anywhere in the certificate name.

When the periodic task runs, Lemur checks for certificates meeting the following conditions:

  • Certificate has notifications enabled

  • Certificate is not expired

  • Certificate is not revoked

  • Certificate name does not match the exclude parameter

  • Certificate has at least one associated notification object

  • That notification is active

  • That notification’s configured interval and unit match the certificate’s remaining lifespan

All eligible certificates are then grouped by owner and applicable notification. For each notification and certificate group, Lemur will send the expiration notification using whichever plugin was configured for that notification object. In addition, Lemur will send an email to the certificate owner and security team (as specified by the LEMUR_SECURITY_TEAM_EMAIL configuration parameter). The security team will be omitted if LEMUR_DISABLE_SECURITY_TEAM_EXPIRATION_EMAILS is enabled.

CA certificate expiration

Certificate authority certificate expiration notifications are sent when the scheduled task to send authority certificate expiration notifications runs (see Periodic Tasks). Notifications are sent via the intervals configured in the configuration parameter LEMUR_AUTHORITY_CERT_EXPIRATION_EMAIL_INTERVALS, with a default of 365 and 180 days.

When the periodic task runs, Lemur checks for certificates meeting the following conditions:

  • Certificate has notifications enabled

  • Certificate is not expired

  • Certificate is not revoked

  • Certificate is associated with a CA

  • Certificate’s remaining lifespan matches one of the configured intervals

All eligible certificates are then grouped by owner and expiration interval. For each interval and certificate group, Lemur will send the CA certificate expiration notification via email to the certificate owner and security team (as specified by the LEMUR_SECURITY_TEAM_EMAIL configuration parameter).

Pending ACME certificate failure

Whenever a pending ACME certificate fails to be issued, Lemur will send a notification via email to the certificate owner and security team (as specified by the LEMUR_SECURITY_TEAM_EMAIL configuration parameter). This email is not sent if the pending certificate had notifications disabled.

Lemur will attempt 3x times to resolve a pending certificate. This can at times result into 3 duplicate certificates, if all certificate attempts get resolved. There is a way to deduplicate these certificates periodically using a celery task disable_rotation_of_duplicate_certificates.

This needs 2 configurations


List names of the authorities for which disable_rotation_of_duplicate_certificates should run. The task will consider certificates issued by authorities configured here.


Use this config (optional) to configure the number of days. The task disable_rotation_of_duplicate_certificates will then consider valid certificates issued only in last those many number of days for deduplication. If not configured, the task considers all the valid certificates. Ideally set this config to a value which is same as the number of days between the two runs of disable_rotation_of_duplicate_certificates


Certificate re-issuance

When a cert is reissued (i.e. a new certificate is minted to replace it), and the re-issuance either fails or succeeds but the certificate has no associated endpoints (meaning the subsequent rotation step will not occur), Lemur will send a notification via email to the certificate owner. This notification is disabled by default; to enable it, you must set the option --notify (when using cron) or the configuration parameter ENABLE_REISSUE_NOTIFICATION (when using celery).

Certificate rotation

Whenever a cert is rotated, Lemur will send a notification via email to the certificate owner. This notification is disabled by default; to enable it, you must set the option --notify (when using cron) or the configuration parameter ENABLE_ROTATION_NOTIFICATION (when using celery).

Certificate revocation

Whenever a cert is revoked, Lemur will send a notification via email to the certificate owner. This notification will only be sent if the certificate’s “notify” option is enabled.

Security certificate expiration summary

If you enable the Celery or cron task to send this notification type, Lemur will send a summary of all certificates with upcoming expiration date that occurs within the number of days specified by the LEMUR_EXPIRATION_SUMMARY_EMAIL_THRESHOLD_DAYS configuration parameter (with a fallback of 14 days). Note that certificates will be included in this summary even if they do not have any associated notifications.

This notification type also supports the same --exclude and EXCLUDE_CN_FROM_NOTIFICATION options as expiration emails.

NOTE: At present, this summary email essentially duplicates the certificate expiration notifications, since all certificate expiration notifications are also sent to the security team. This issue will be fixed in the future.

Notification configuration

The following configuration options are supported:


Specifies CNs to exclude from notifications. This includes both single notifications as well as the notification summary. The specified exclude pattern will match if found anywhere in the certificate name.


This is only used for celery. The equivalent for cron is ‘-e’ or ‘–exclude’.

EXCLUDE_CN_FROM_NOTIFICATION = ['exclude', 'also exclude']

Specifies a set of notification plugins to disable. Notifications will not be sent using these plugins. Currently only applies to expiration notifications, since they are the only type that utilize plugins. This option may be particularly useful in a test environment, where you might wish to enable the notification job without actually sending notifications of a certain type (or all types).


This is only used for celery. The equivalent for cron is ‘-d’ or ‘–disabled-notification-plugins’.

DISABLE_NOTIFICATION_PLUGINS = ['email-notification']

Email notifications

Templates for emails are located under lemur/plugins/lemur_email/templates and can be modified for your needs.

The following configuration options are supported:


Specifies which service will be delivering notification emails. Valid values are SMTP or SES


If using SMTP as your provider you will need to define additional configuration options as specified by Flask-Mail. See: Flask-Mail

If you are using SES the email specified by the LEMUR_EMAIL configuration will need to be verified by AWS before you can send any mail. See: Verifying Email Address in Amazon SES


Specifies an ARN to use as the SourceArn when sending emails via SES.


This parameter is only required if you’re using a sending authorization with SES. See: Using sending authorization with Amazon SES


Specifies a region for sending emails via SES.


This parameter defaults to us-east-1 and is only required if you wish to use a different region.


Lemur sender’s email


This is an email or list of emails that should be notified when a certificate is expiring. It is also the contact email address for any discovered certificate.


This specifies whether or not LEMUR_SECURITY_TEAM_EMAIL will be included on all expiration emails. IMPORTANT: You will also need to disable the DEFAULT_SECURITY_X_DAY notifications to truly disable sending expiration emails to the security team. This double configuration is required for backwards compatibility.


Lemur notification intervals. If unspecified, the value [30, 15, 2] is used.


Alternate notification interval set for security team notifications. Use this if you would like the default security team notification interval for new certificates to differ from the global default as specified in LEMUR_DEFAULT_EXPIRATION_NOTIFICATION_INTERVALS. If unspecified, the value of LEMUR_DEFAULT_EXPIRATION_NOTIFICATION_INTERVALS is used. Security team default notifications for new certificates can effectively be disabled by setting this value to an empty array.


Notification interval set for CA certificate expiration notifications. If unspecified, the value [365, 180] is used (roughly one year and 6 months).


Specifies the set of ports to use when checking if a certificate is still deployed at a given domain. This is utilized for the alert that is sent when an expiring certificate is detected to still be deployed.


Specifies whether or not to commit changes when running the deployed certificate check. If False, the DB will not be updated; network calls will still be made and logs/metrics will be emitted.


Specifies a set of domains to exclude from the deployed certificate checks. Anything specified here is treated as a substring; in other words, if you set this to [‘’], then ‘’ and ‘’ will both be excluded; ‘’ will not be excluded.


Specifies a set of owners to exclude from the deployed certificate checks. Anything specified here is treated as an exact match, NOT as a substring.


Specifies a set of destination labels to exclude from the reissued with endpoint notification checks. If a certificate is reissued without endpoints, but any of its destination labels are specified in this list, no “reissued without endpoints” notification will be sent.


Celery Options

To make use of automated tasks within lemur (e.g. syncing source/destinations, or reissuing ACME certificates), you need to configure celery. See Periodic Tasks for more in depth documentation.


The url to your redis backend (needs to be in the format redis://<host>:<port>/<database>)


The url to your redis broker (needs to be in the format redis://<host>:<port>/<database>)


The module that celery needs to import, in our case thats lemur.common.celery


The timezone for celery to work with


This defines the schedule, with which the celery beat makes the worker run the specified tasks.


This is an optional parameter that defines the expiration time for endpoints when the endpoint expiration celery task is running. Default value is set to 2h.

Since the celery module, relies on the RedisHandler, the following options also need to be set.


Hostname of your redis instance


Port on which redis is running (default: 6379)


Which redis database to be used, by default redis offers databases 0-15 (default: 0)

Authentication Options

Lemur currently supports Basic Authentication, LDAP Authentication, Ping OAuth2, and Google out of the box. Additional flows can be added relatively easily.

LDAP Options

Lemur supports the use of an LDAP server in conjunction with Basic Authentication. Lemur local users can still be defined and take precedence over LDAP users. If a local user does not exist, LDAP will be queried for authentication. Only simple ldap binding with or without TLS is supported.

LDAP support requires the pyldap python library, which also depends on the following openldap packages.

$ sudo apt-get update
$ sudo apt-get install libldap2-dev libsasl2-dev libldap2-dev libssl-dev

To configure the use of an LDAP server, a number of settings need to be configured in

Here is an example LDAP configuration stanza you can add to your config. Adjust to suit your environment of course.

LDAP_CACERT_FILE = '/opt/lemur/trusted.pem'
LDAP_REQUIRED_GROUP = 'certificate-management-access'
LDAP_GROUPS_TO_ROLES = {'certificate-management-admin': 'admin', 'certificate-management-read-only': 'read-only'}

The lemur ldap module uses the user principal name (upn) of the authenticating user to bind. This is done once for each user at login time. The UPN is effectively the email address in AD/LDAP of the user. If the user doesn’t provide the email address, it constructs one based on the username supplied (which should normally match the samAccountName) and the value provided by the config LDAP_EMAIL_DOMAIN. The config LDAP_BASE_DN tells lemur where to search within the AD/LDAP tree for the given UPN (user). If the bind with those credentials is successful - there is a valid user in AD with correct password.

Each of the LDAP options are described below.


This enables the use of LDAP


Specifies the LDAP server connection string

LDAP_BIND_URI = 'ldaps://hostname'

Specifies the LDAP distinguished name location to search for users

LDAP_BASE_DN = 'DC=Users,DC=Evilcorp,DC=com'

The email domain used by users in your directory. This is used to build the userPrincipalName to search with.


The following LDAP options are not required, however TLS is always recommended.


Enables the use of TLS when connecting to the LDAP server. Ensure the LDAP_BIND_URI is using ldaps scheme.


Specify a Certificate Authority file containing PEM encoded trusted issuer certificates. This can be used if your LDAP server is using certificates issued by a private CA.

LDAP_CACERT_FILE = '/path/to/cacert/file'

Lemur has pretty open permissions. You can define an LDAP group to specify who can access Lemur. Only members of this group will be able to login.


You can also define a dictionary of ldap groups mapped to lemur roles. This allows you to use ldap groups to manage access to owner/creator roles in Lemur

LDAP_GROUPS_TO_ROLES = {'lemur_admins': 'admin', 'Lemur Team DL Group': ''}

When set to True, nested group memberships are supported, by searching for groups with the member:1.2.840.113556.1.4.1941 attribute set to the user DN. When set to False, the list of groups will be determined by the ‘memberof’ attribute of the LDAP user logging in.


Authentication Providers

If you are not using an authentication provider you do not need to configure any of these options.

For more information about how to use social logins, see: Satellizer

ACTIVE_PROVIDERS = ["ping", "google", "oauth2"]
PING_SECRET = 'somethingsecret'
PING_ACCESS_TOKEN_URL = "https://<yourpingserver>/as/token.oauth2"
PING_USER_API_URL = "https://<yourpingserver>/idp/userinfo.openid"
PING_JWKS_URL = "https://<yourpingserver>/pf/JWKS"
PING_NAME = "Example Oauth2 Provider"
PING_CLIENT_ID = "client-id"
PING_URL = "https://<yourlemurserver>"
PING_REDIRECT_URI = "https://<yourlemurserver>/api/1/auth/ping"
PING_AUTH_ENDPOINT = "https://<yourpingserver>/oauth2/authorize"
OAUTH2_SECRET = 'somethingsecret'
OAUTH2_ACCESS_TOKEN_URL = "https://<youroauthserver> /oauth2/v1/authorize"
OAUTH2_USER_API_URL = "https://<youroauthserver>/oauth2/v1/userinfo"
OAUTH2_JWKS_URL = "https://<youroauthserver>/oauth2/v1/keys"
OAUTH2_NAME = "Example Oauth2 Provider"
OAUTH2_CLIENT_ID = "client-id"
OAUTH2_URL = "https://<yourlemurserver>"
OAUTH2_REDIRECT_URI = "https://<yourlemurserver>/api/1/auth/oauth2"
OAUTH2_AUTH_ENDPOINT = "https://<youroauthserver>/oauth2/v1/authorize"

The OAUTH_STATE_TOKEN_SECRET is used to sign state tokens to guard against CSRF attacks. Without a secret configured, Lemur will create a fallback secret on a per-server basis that would last for the length of the server’s lifetime (e.g., between redeploys). The secret must be bytes-like <>; it will be used to instantiate the key parameter of HMAC <>.

For implementation details, see generate_state_token() and verify_state_token() in lemur/auth/

Running lemur create_config will securely generate a key for your configuration file. If you would like to generate your own, we recommend the following method:

>>> import os
>>> import base64
>>> KEY_LENGTH = 32  # tweak as needed
>>> base64.b64encode(os.urandom(KEY_LENGTH))
OAUTH_STATE_TOKEN_SECRET = lemur.common.utils.get_state_token_secret()

Defaults to 15 seconds if configuration is not discovered.

GOOGLE_CLIENT_ID = "client-id"
GOOGLE_SECRET = "somethingsecret"

This is an optional parameter to change the case sensitivity of the access token request authorization header. This is required if the oauth provider has implemented the access token request authorization header in a case-sensitive way


An optional plugin to provide membership details. Provide plugin slug here. Plugin is used post user validation to update membership details in Lemur. Also, it is configured to provide APIs to validate user email, team email/DL.

USER_MEMBERSHIP_PROVIDER = "<yourmembershippluginslug>"

Authorization Providers

If you are not using a custom authorization provider you do not need to configure any of these options


An optional plugin to perform domain level authorization during certificate issuance. Provide plugin slug here. Plugin is used to check if caller is authorized to issue a certificate for a given Common Name and Subject Alternative Name (SAN) of type DNSName. Plugin shall be an implementation of DomainAuthorizationPlugin.

USER_DOMAIN_AUTHORIZATION_PROVIDER = "<yourauthorizationpluginslug>"

Lemur can be used to issue certificates with private CA. One can write own issuer plugin to do so. Domain level authorization is skipped for private CA i.e., the one implementing custom issuer plugin. Currently this config is not used elsewhere.

LEMUR_PRIVATE_AUTHORITY_PLUGIN_NAMES = ["issuerpluginslug1", "issuerpluginslug2"]

Metric Providers

If you are not using a metric provider you do not need to configure any of these options.


A list of metric plugins slugs to be ativated.

METRIC_PROVIDERS = ['atlas-metric']

Plugin Specific Options

ACME Plugin


Dictionary of ACME DNS Providers and their requirements.


Enables delegated DNS domain validation using CNAMES. When enabled, Lemur will attempt to follow CNAME records to authoritative DNS servers when creating DNS-01 challenges.

The following configration properties are optional for the ACME plugin to use. They allow reusing an existing ACME account. See Using a pre-existing ACME account for more details.


This is the private key, the account was registered with (in JWK format)


This is the registration for the ACME account, the most important part is the uri attribute (in JSON)


This is an optional parameter to indicate the preferred chain to retrieve from ACME when finalizing the order. This is applicable to Let’s Encrypts recent migration to their own root, where they provide two distinct certificate chains (fullchain_pem vs. alternative_fullchains_pem); the main chain will be the long chain that is rooted in the expiring DTS root, whereas the alternative chain is rooted in X1 root CA. Select “X1” to get the shorter chain (currently alternative), leave blank or “DST Root CA X3” for the longer chain.

Active Directory Certificate Services Plugin


FQDN of your ADCS Server


The chosen authentication method. Either ‘basic’ (the default), ‘ntlm’ or ‘cert’ (SSL client certificate). The next 2 variables are interpreted differently for different methods.


The username (basic) or the path to the public cert (cert) of the user accessing PKI


The passwd (basic) or the path to the private key (cert) of the user accessing PKI


Template to be used for certificate issuing. Usually display name w/o spaces


If there is a config variable ADCS_TEMPLATE_<upper(> take the value as Cert template else default to ADCS_TEMPLATE to be compatible with former versions. Template to be used for certificate issuing. Usually display name w/o spaces


Used in ADCS-Sourceplugin. Minimum id of the first certificate to be returned. ID is increased by one until ADCS_STOP. Missing cert-IDs are ignored


Used for ADCS-Sourceplugin. Maximum id of the certificates returned.


Contains the issuing cert of the CA


Contains the root cert of the CA

Entrust Plugin

Enables the creation of Entrust certificates. You need to set the API access up with Entrust support. Check the information in the Entrust Portal as well. Certificates are created as “SERVER_AND_CLIENT_AUTH”. Caution: Sometimes the entrust API does not respond in a timely manner. This error is handled and reported by the plugin. Should this happen you just have to hit the create button again after to create a valid certificate. The following parameters have to be set in the configuration files.


This is the url for the Entrust API. Refer to the API documentation.


Path to the certificate file in PEM format. This certificate is created in the onboarding process. Refer to the API documentation.


Path to the key file in RSA format. This certificate is created in the onboarding process. Refer to the API documentation. Caution: the request library cannot handle encrypted keys. The keyfile therefore has to contain the unencrypted key. Please put this in a secure location on the server.


String with the API user. This user is created in the onboarding process. Refer to the API documentation.


String with the password for the API user. This password is created in the onboarding process. Refer to the API documentation.


String with the name that should appear as certificate owner in the Entrust portal. Refer to the API documentation.


String with the email address that should appear as certificate contact email in the Entrust portal. Refer to the API documentation.


String with the phone number that should appear as certificate contact in the Entrust portal. Refer to the API documentation.


Contains the issuing cert of the CA


Contains the root cert of the CA


If there is a config variable ENTRUST_PRODUCT_<upper(> take the value as cert product name else default to “STANDARD_SSL”. Refer to the API documentation for valid products names.


This is optional. Entrust provides support for cross-signed subCAS. One can set ENTRUST_CROSS_SIGNED_RSA_L1K to the respective cross-signed RSA-based subCA PEM and Lemur will replace the retrieved subCA with ENTRUST_CROSS_SIGNED_RSA_L1K.


This is optional. Entrust provides support for cross-signed subCAS. One can set ENTRUST_CROSS_SIGNED_ECC_L1F to the respective cross-signed EC-based subCA PEM and Lemur will replace the retrieved subCA with ENTRUST_CROSS_SIGNED_ECC_L1F.


If set to True, Entrust will use the primary client ID of 1, which applies to most use-case. Otherwise, Entrust will first lookup the clientId before ordering the certificate.

Verisign Issuer Plugin

Authorities will each have their own configuration options. There is currently just one plugin bundled with Lemur, Verisign/Symantec. Additional plugins may define additional options. Refer to the plugin’s own documentation for those plugins.


This is the url for the Verisign API


This is the path to the mutual TLS certificate used for communicating with Verisign


This is the first name to be used when requesting the certificate


This is the last name to be used when requesting the certificate


This is the email to be used when requesting the certificate


This is the intermediate to be used for your CA chain


This is the root to be used for your CA chain

Digicert Issuer Plugin

The following configuration properties are required to use the Digicert issuer plugin.


This is the url for the Digicert API (e.g.


This is the type of certificate to order. (e.g. ssl_plus, ssl_ev_plus see:


This is the Digicert API key


This is the Digicert organization ID tied to your API key


This is the root to be used for your CA chain


This is the default validity (in days), if no end date is specified. (Default: 397)


This is the maximum validity (in days). (Default: value of DIGICERT_DEFAULT_VALIDITY_DAYS)


This is whether or not to issue a private certificate. (Default: False)

CFSSL Issuer Plugin

The following configuration properties are required to use the CFSSL issuer plugin.


This is the URL for the CFSSL API


This is the root to be used for your CA chain


This is the intermediate to be used for your CA chain


This is the hmac key to authenticate to the CFSSL service. (Optional)

Hashicorp Vault Source/Destination Plugin

Lemur can import and export certificate data to and from a Hashicorp Vault secrets store. Lemur can connect to a different Vault service per source/destination.


This plugin does not supersede or overlap the 3rd party Vault Issuer plugin.


Vault does not have any configuration properties however it does read from a file on disk for a vault access token. The Lemur service account needs read access to this file.

Vault Source

The Vault Source Plugin will read from one Vault object location per source defined. There is expected to be one or more certificates defined in each object in Vault.

Vault Destination

A Vault destination can be one object in Vault or a directory where all certificates will be stored as their own object by CN.

Vault Destination supports a regex filter to prevent certificates with SAN that do not match the regex filter from being deployed. This is an optional feature per destination defined.

AWS Source/Destination Plugin

In order for Lemur to manage its own account and other accounts we must ensure it has the correct AWS permissions.


AWS usage is completely optional. Lemur can upload, find and manage TLS certificates in AWS. But is not required to do so.

Setting up IAM roles

Lemur’s AWS plugin uses boto heavily to talk to all the AWS resources it manages. By default it uses the on-instance credentials to make the necessary calls.

In order to limit the permissions, we will create two new IAM roles for Lemur. You can name them whatever you would like but for example sake we will be calling them LemurInstanceProfile and Lemur.

Lemur uses to STS to talk to different accounts. For managing one account this isn’t necessary but we will still use it so that we can easily add new accounts.

LemurInstanceProfile is the IAM role you will launch your instance with. It actually has almost no rights. In fact it should really only be able to use STS to assume role to the Lemur role.

Here are example policies for the LemurInstanceProfile:


  "Version": "2012-10-17",
  "Statement": [
      "Effect": "Allow",
      "Action": [
      "Resource": "*"


  "Version": "2012-10-17",
  "Statement": [
      "Effect": "Allow",
      "Resource": "*"

Next we will create the Lemur IAM role.


The default IAM role that Lemur assumes into is called Lemur, if you need to change this ensure you set LEMUR_INSTANCE_PROFILE to your role name in the configuration.

Here is an example policy for Lemur:


    "Statement": [
                     "Action": [
                     "Resource": [
                     "Effect": "Allow",
                     "Sid": "Stmt1404836868000"
    "Statement": [
                     "Action": [
                     "Resource": [
                     "Effect": "Allow",
                     "Sid": "Stmt1404841912000"

Setting up STS access

Once we have setup our accounts we need to ensure that we create a trust relationship so that LemurInstanceProfile can assume the Lemur role.

In the AWS console select the Lemur IAM role and select the Trust Relationships tab and click Edit Trust Relationship

Below is an example policy:

  "Version": "2008-10-17",
  "Statement": [
      "Sid": "",
      "Effect": "Allow",
      "Principal": {
        "AWS": [
      "Action": "sts:AssumeRole"

Adding N+1 accounts

To add another account we go to the new account and create a new Lemur IAM role with the same policy as above.

Then we would go to the account that Lemur is running is and edit the trust relationship policy.

An example policy:

  "Version": "2008-10-17",
  "Statement": [
      "Sid": "",
      "Effect": "Allow",
      "Principal": {
        "AWS": [
      "Action": "sts:AssumeRole"

Setting up SES

Lemur has built in support for sending it’s certificate notifications via Amazon’s simple email service (SES). To force Lemur to use SES ensure you are the running as the IAM role defined above and that you have followed the steps outlined in Amazon’s documentation Setting up Amazon SES

The configuration:


Will be the sender of all notifications, so ensure that it is verified with AWS.

SES if the default notification gateway and will be used unless SMTP settings are configured in the application configuration settings.

NS1 ACME Plugin

The NS1 ACME plugin allows DNS1 validation using NS1 domain services.


The NS1 read/write API key for managing TXT records for domain validation

PowerDNS ACME Plugin

The following configuration properties are required to use the PowerDNS ACME Plugin for domain validation.


This is the FQDN for the PowerDNS API (without path)


This is the ServerID attribute of the PowerDNS API Server (i.e. “localhost”)


This is the Key name to use for authentication (i.e. “X-API-Key”)


This is the API Key to use for authentication (i.e. “Password”)


This is the number of times DNS Verification should be attempted (i.e. 20)


This configures how TLS certificates on the PowerDNS API target are validated. The PowerDNS Plugin depends on the PyPi requests library, which supports the following options for the verify parameter:

True: Verifies the TLS certificate was issued by a known publicly-trusted CA. (Default)

False: Disables certificate validation (Not Recommended)

File/Dir path to CA Bundle: Verifies the TLS certificate was issued by a Certificate Authority in the provided CA bundle.

Command Line Interface

Lemur installs a command line script under the name lemur. This will allow you to perform most required operations that are unachievable within the web UI.

If you’re using a non-standard configuration location, you’ll need to prefix every command with –config (excluding create_config, which is a special case). For example:

lemur --config=/etc/ help

For a list of commands, you can also use lemur help, or lemur [command] --help for help on a specific command.


The script is powered by a library called Flask-Script

Builtin Commands

All commands default to ~/.lemur/ if a configuration is not specified.


Creates a default configuration file for Lemur.

Path defaults to ~/.lemur/

lemur create_config .


This command is a special case and does not depend on the configuration file being set.


Initializes the configuration file for Lemur.

lemur -c /etc/ init

Starts a Lemur service. You can also pass any flag that Gunicorn uses to specify the webserver configuration.

lemur start -w 6 -b
db upgrade

Performs any needed database migrations.

lemur db upgrade

Traverses every certificate that Lemur is aware of and attempts to understand its validity. It utilizes both OCSP and CRL. If Lemur is unable to come to a conclusion about a certificates validity its status is marked ‘unknown’.


Sync attempts to discover certificates in the environment that were not created by Lemur. If you wish to only sync a few sources you can pass a comma delimited list of sources to sync.

lemur sync -s source1,source2

Additionally you can also list the available sources that Lemur can sync.

lemur sync

Will traverse all current notifications and see if any of them need to be triggered.

lemur notify

Handles all ACME related tasks, like ACME plugin testing.

lemur acme


Lemur includes several sub-commands for interacting with Lemur such as creating new users, creating new roles and even issuing certificates.

The best way to discover these commands is by using the built in help pages

lemur --help

and to get help on sub-commands

lemur certificates --help

Upgrading Lemur

To upgrade Lemur to the newest release you will need to ensure you have the latest code and have run any needed database migrations.

To get the latest code from github run

cd <lemur-source-directory>
git pull -t <version>
python develop


It’s important to grab the latest release by specifying the release tag. This tags denote stable versions of Lemur. If you want to try the bleeding edge version of Lemur you can by using the master branch.

After you have the latest version of the Lemur code base you must run any needed database migrations. To run migrations

cd <lemur-source-directory>/lemur
lemur db upgrade

This will ensure that any needed tables or columns are created or destroyed.


Internally, this uses Alembic to manage database migrations.


By default Alembic looks for the migrations folder in the current working directory.The migrations folder is located under <LEMUR_HOME>/lemur/migrations if you are running the lemur command from any location besides <LEMUR_HOME>/lemur you will need to pass the -d flag to specify the absolute file path to the migrations folder.


There are several interfaces currently available to extend Lemur. These are a work in progress and the API is not frozen.

Lemur includes several plugins by default. Including extensive support for AWS, VeriSign/Symantec.



Kevin Glisson <>, Curtis Castrapel <>, Hossein Shafagh <>




Basic support for the VICE 2.0 API



Kevin Glisson <>, Mikhail Khodorovskiy <>




Toy certificate authority that creates self-signed certificate authorities. Allows for the creation of arbitrary authorities and end-entity certificates. This is not recommended for production use.



Kevin Glisson <>, Curtis Castrapel <>, Hossein Shafagh <>, Mikhail Khodorovskiy <>, Chad Sine <>




Adds support for the ACME protocol (including LetsEncrypt) with domain validation using several providers.



Kevin Glisson <>, Curtis Castrapel <>, Hossein Shafagh <>




Adds basic support for the Atlas telemetry system.



Kevin Glisson <>, Curtis Castrapel <>, Hossein Shafagh <>




Adds support for basic email notifications via SES.



Harm Weites <>




Adds support for slack notifications.

AWS (Source)


Kevin Glisson <>, Curtis Castrapel <>, Hossein Shafagh <>




Uses AWS IAM as a source of certificates to manage. Supports a multi-account deployment.

AWS (Destination)


Kevin Glisson <>, Curtis Castrapel <>, Hossein Shafagh <>




Uses AWS IAM as a destination for Lemur generated certificates. Support a multi-account deployment.

AWS (SNS Notification)


Jasmine Schladen <>




Adds support for SNS notifications. SNS notifications (like other notification plugins) are currently only supported for certificate expiration. Configuration requires a region, account number, and SNS topic name; these elements are then combined to build the topic ARN. Lemur must have access to publish messages to the specified SNS topic.



Mikhail Khodorovskiy <>




Allows Lemur to upload generated certificates to the Kubernetes certificate store.



Kevin Glisson <>




Generates java compatible .jks keystores and truststores from Lemur managed certificates.



Kevin Glisson <>




Leverages Openssl to support additional export formats (pkcs12)



Charles Hendrie <>




Basic support for generating certificates from the private certificate authority CFSSL



Christopher Jolley <>




Source plugin imports certificates from Hashicorp Vault secret store.



Christopher Jolley <>




Destination plugin to deploy certificates to Hashicorp Vault secret store.

3rd Party Plugins

The following plugins are available and maintained by members of the Lemur community:



Chris Dorros




Adds support for basic Digicert




Titouan Christophe




Sends key metrics to InfluxDB


Hashicorp Vault


Ron Cohen




Adds support for basic Vault PKI secret backend.


Have an extension that should be listed here? Submit a pull request and we’ll get it added.

Want to create your own extension? See Structure to get started.

Identity and Access Management

Lemur uses a Role Based Access Control (RBAC) mechanism to control which users have access to which resources. When a user is first created in Lemur they can be assigned one or more roles. These roles are typically dynamically created depending on an external identity provider (Google, LDAP, etc.), or are hardcoded within Lemur and associated with special meaning.

Within Lemur there are three main permissions: AdminPermission, CreatorPermission, OwnerPermission. Sub-permissions such as ViewPrivateKeyPermission are compositions of these three main Permissions.

Lets take a look at how these permissions are used:

Each Authority has a set of roles associated with it. If a user is also associated with the same roles that the Authority is associated with, Lemur allows that user to user/view/update that Authority.

This RBAC is also used when determining which users can access which certificate private key. Lemur’s current permission structure is setup such that if the user is a Creator or Owner of a given certificate they are allow to view that private key. Owners can also be a role name, such that any user with the same role as owner will be allowed to view the private key information.

These permissions are applied to the user upon login and refreshed on every request.

See also


To allow integration with external access/membership management tools that may exist in your organization, lemur offers below plugins in addition to it’s own RBAC implementation.

Membership Plugin


Sayali Charhate <>


User Membership


Adds support to learn and validate user membership details from an external service. User memberships are used to create user roles dynamically as described in Identity and Access Management. Configure this plugin slug as USER_MEMBERSHIP_PROVIDER

Authorization Plugins


Sayali Charhate <>


External Authorization


Adds support to implement custom authorization logic that is best suited for your enterprise. Lemur offers AuthorizationPlugin and its extended version DomainAuthorizationPlugin. One can implement DomainAuthorizationPlugin and configure its slug as USER_DOMAIN_AUTHORIZATION_PROVIDER to check if caller is authorized to issue a certificate for a given Common Name and Subject Alternative Name (SAN) of type DNSName