MTLS / Certificate Authentication

How to protect your Controller UI, API, and Registry API with Certificates.
This feature requires an Anka Enterprise (or higher) license.

There are several different ways you can enable Certificate authentication:

  1. With the combined (controller + registry) native macOS package: You’ll edit the /usr/local/bin/anka-controllerd, enable TLS/HTTPS (required), and then enable certificate authentication.
  2. With the docker package: You’ll edit the docker-compose.yml, enable TLS/HTTPS, and then enable certificate authentication.
  3. With either the controller or registry standalone packages: You’ll edit the proper config files, enable TLS/HTTPS, and then enable certification authentication.


  1. Root Token Authentication must be enabled.
  2. A Root CA certificate. For more information about CAs, see Usually provided by your organization or where you obtain your certificate signing. We will generate a self-signed one in this guide and refer to this as anka-ca-crt.pem and anka-ca-key.pem.
  3. Certificate[s] (signed with the Root CA) for the Anka Build Cloud Controller & Registry.
  4. Certificate[s] (signed with the Root CA) for your Anka Build Nodes so they can connect/authenticate with the Anka Build Cloud Controller & Registry.
If bringing your own certs, make sure they are not password protected (“encrypted”) (use openssl rsa -in <encrypted_private.key> -out <decrypted_private.key> to decrypt).

1. Create a self-signed Root CA certificate

If you don’t have a Root CA yet, you can create it with openssl:

cd ~
openssl req -new -nodes -x509 -days 365 -keyout anka-ca-key.pem -out anka-ca-crt.pem \
  -subj "/O=MyGroup/OU=MyOrgUnit/CN=MyUser"

You can add the Root CA to the System keychain so the Root CA is trusted and you can avoid warnings when you go to access the Controller UI.

sudo security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain anka-ca-crt.pem

2. Configuring TLS for Controller & Registry

  • TLS/HTTPS is required for Certificate Authentication.
  • Your HTTPS/TLS cert can be from any root CA and does not need to be from the same CA as your authentication certs.

Create a self-signed cert for the services (optional)

Certificates should be in PEM (PKCS #8) format.
Ensure your certs are decrypted! They cannot have passwords.
For this guide, we’re running the Controller & Registry locally, so we use If you’re running the registry on a different IP, and especially in your certs only allow specific IPs, you’ll need to set ANKA_REGISTRY_LISTEN_ADDRESS to the IP:PORT vs the default :PORT.

If you do not have TLS certificates for your Controller & Registry from a signed source, you can create them using your own CA:

openssl genrsa -out anka-controller-key.pem 4096
openssl req -new -nodes -sha256 -key anka-controller-key.pem -out anka-controller-csr.pem -subj "/O=MyGroup/OU=MyOrgUnit/CN=MyUser" \
  -reqexts SAN -extensions SAN \
  -config <(cat /etc/ssl/openssl.cnf <(printf "[SAN]\nextendedKeyUsage = serverAuth\nsubjectAltName=IP:$CONTROLLER_ADDRESS"))
openssl x509 -req -days 365 -sha256 -in anka-controller-csr.pem -CA anka-ca-crt.pem -CAkey anka-ca-key.pem -CAcreateserial \
  -out anka-controller-crt.pem -extfile <(echo subjectAltName = IP:$CONTROLLER_ADDRESS)
You can use the same certificate for both the Controller and Registry.
Beginning in Controller version 1.12.0, you can control the allowed TLS Cipher Suites and minimum/maximum TLS versions.

Configure the services to use the TLS cert

MacOS combined Controller & Registry package

Edit /usr/local/bin/anka-controllerd:

  1. Change the listen address to 443: export ANKA_LISTEN_ADDR=":443"
SSL will actually work on any port you want.
  1. Add the following ENVs to enable HTTPS:

    # SSL + Cert Auth
    export ANKA_USE_HTTPS="true"
    export ANKA_SERVER_CERT="/Users/MyUser/anka-controller-crt.pem"
    export ANKA_SERVER_KEY="/Users/MyUser/anka-controller-key.pem"
  2. Ensure https is in the registry URL:

    export ANKA_ANKA_REGISTRY="https://anka.registry:8089"
The Controller & Registry runs as root. This is why you need to specify the absolute path to the location where you generated or are storing your certs.

Linux/Docker Controller & Registry package

Within the docker-compose.yml:

  1. Change the anka-controller ports from 80:80 to 443:80. You can keep the anka-registry ports the same (default: 8089).
  2. Under the anka-controller, modify or set ANKA_ANKA_REGISTRY to use https://.
  3. Ensure there is a volumes item that points the local cert location inside of the container at /mnt/cert.

Now let’s configure the Controller & Registry containers/services to use those certificates:

version: '2'
    container_name: anka-controller
      context: controller
      - "443:80"
      - etcd
      - anka-registry
    restart: always
      - "/opt/secure/certs:/mnt/certs"
      ANKA_ANKA_REGISTRY: "https://anka.registry:8089"
      ANKA_USE_HTTPS: "true"
      ANKA_SKIP_TLS_VERIFICATION: "true" # Only needed if registry cert is self-signed
      ANKA_SERVER_CERT: "/mnt/certs/anka-controller-crt.pem"
      ANKA_SERVER_KEY: "/mnt/certs/anka-controller-key.pem"
    container_name: anka-registry
      context: registry
      - "8089:8089"
    restart: always
      - "/opt/anka-storage:/mnt/vol"
      - "/opt/secure/certs:/mnt/certs"
      ANKA_USE_HTTPS: "true"
      ANKA_SERVER_CERT: "/mnt/certs/anka-controller-crt.pem"
      ANKA_SERVER_KEY: "/mnt/certs/anka-controller-key.pem"
For the standalone package (separate docker containers for the controller and registry): If the SERVER_CERT and KEY is self-signed, you will need to set ANKA_SKIP_TLS_VERIFICATION to true in the controller config so it can connect to the registry.

Test the Configuration

Start or restart your Controller and/or Registry and test the new TLS configuration using https://. You can also try using curl -v https://$CONTROLLER_OR_REGISTRY_URL/api/v1/status.

If that doesn’t work, try to repeat the above steps and validate that the file names and paths are correct. If you are still having trouble, debug the system as explained in the Debugging Controller section.

Answers to Frequently Asked Questions

  • Load balancers must also have both the root CA and intermediate certificates in order to function properly.

3. Creating self-signed Node Certificates

The Controller’s authentication module uses the Root CA (anka-ca-crt.pem) to authenticate any incoming requests. When the Node sends the requests to the Controller, it will present its certificates. Those certificates must have been generated from the Root CA and also, if using Enterprise Plus, have the necessary permissions.

You can use the following openssl commands to create Node certificates using the Root CA:

openssl genrsa -out node-$NODE_NAME-key.pem 4096
openssl req -new -sha256 -key node-$NODE_NAME-key.pem -out node-$NODE_NAME-csr.pem \
openssl x509 -req -days 365 -sha256 -in node-$NODE_NAME-csr.pem -CA anka-ca-crt.pem -CAkey anka-ca-key.pem \
  -CAcreateserial -out node-$NODE_NAME-crt.pem

4. Configuring the Controller & Registry to enable authentication

In addition to the node certificates, the controller itself makes API calls to the Registry (you’ve enabled registry auth, right?) to get templates, etc, and will need a client cert to communicate with it. This is where ANKA_CA_CERT comes in as it’s used to validate the incoming requests.

openssl genrsa -out $NAME-key.pem 4096
openssl req -new -sha256 -key $NAME-key.pem -out $NAME-csr.pem \
openssl x509 -req -days 365 -sha256 -in $NAME-csr.pem -CA anka-ca-crt.pem -CAkey anka-ca-key.pem \
  -CAcreateserial -out $NAME-crt.pem

MacOS combined Controller & Registry package

Edit the /usr/local/bin/anka-controllerd and ensure the following ENVs exist:

export ANKA_ENABLE_AUTH="true"
export ANKA_CA_CERT="/Users/MyUser/anka-ca-crt.pem"
export ANKA_CLIENT_CERT="/Users/MyUser/anka-controller-crt.pem"
export ANKA_CLIENT_CERT_KEY="/Users/MyUser/anka-controller-key.pem"

Linux/Docker Controller & Registry package

Within the docker-compose.yml, add the following ENVs:

version: '2'
    container_name: anka-controller
    . . .
      . . .
      ANKA_ENABLE_AUTH: "true"
      ANKA_CA_CERT: "/mnt/certs/anka-ca-crt.pem"
      ANKA_CLIENT_CERT: "/mnt/certs/anka-controller-crt.pem"
      ANKA_CLIENT_CERT_KEY: "/mnt/certs/anka-controller-key.pem"
    container_name: anka-registry
    . . .
      . . .
      ANKA_ENABLE_AUTH: "true"
      ANKA_CA_CERT: "/mnt/certs/anka-ca-crt.pem"
The ANKA_CA_CERT is the authority that is used to validate the Anka Node Agent (ankacluster join) certs.
Until you have an Enterprise licensed Node joined to the Controller, it won’t enable authentication for the Controller.
If you’re connecting the Anka CLI with the HTTPS Registry URL, you can use the Node certificates: anka registry --cert /Users/$USER_WHERE_CERTS_ARE/node-$NODE_NAME-crt.pem --key /Users/$USER_WHERE_CERTS_ARE/node-$NODE_NAME-key.pem add $REGISTRY_NAME https://$REGISTRY_ADDRESS:8089 (--cacert may also be needed if you’re using a self-signed HTTPS cert and it’s not in your keychain)

Joining and Testing your Node and Controller Auth

First, copy both the Node certificates (node-$NODE_NAME-crt.pem, node-$NODE_NAME-key.pem) and the anka-ca-crt.pem to the host/node you wish to join.

If you previously joined your Nodes to the Controller, you’ll want to sudo ankacluster disjoin on each before proceeding (if it hangs, use ps aux | grep anka_agent | awk '{print $2}' | xargs kill -9 and try disjoin again).

Note: Certificates are cached, so if you update/renew them, you need to either:

  1. disjoin and re-join them to the controller, issue sudo pkill -9 anka_agent on each node to restart the agent
  2. or, issue a <controller>/v1/node/update PUT to the controller API to forcefully update all nodes.
If you’re using a signed certificate for the controller dashboard, but self-signed certificates for your nodes and CI tools, you’ll need to specify the --cacert for ankacluster join and anka registry add commands and point it to the signed CA certificate. You’ll usually see SSLError: ("bad handshake: Error([('SSL routines', 'tls_process_server_certificate', 'certificate verify failed')],)",) if the wrong CA is being used.

Then, use the ankacluster command to connect it to the Controller with:

sudo ankacluster join https://$CONTROLLER_ADDRESS --skip-tls-verification \
  --cert /Users/$USER_WHERE_CERTS_ARE/node-$NODE_NAME-crt.pem --cert-key /Users/$USER_WHERE_CERTS_ARE/node-$NODE_NAME-key.pem --cacert /Users/nathanpierce/anka-ca-crt.pem
Testing connection to Controller...: OK
Testing connection to registry….: OK
Cluster join success
The --skip-tls-verification is only necessary if using a self-signed cert. Please avoid using --skip-tls-verification AND the --cacert.


Restart your Controller & Registry and then test the status endpoint with curl:

curl --insecure -v https://$HOST/api/v1/status 

The response you should get is a 401 Authentication Required similar to below:

> GET /api/v1/status HTTP/2
> Host: localhost:80
> User-Agent: curl/7.58.0
> Accept: */*
* Connection state changed (MAX_CONCURRENT_STREAMS updated)!
< HTTP/2 401 
< content-type: application/json
< content-length: 54
< date: Thu, 28 Nov 2019 16:58:23 GMT
{"status":"FAIL","message":"Authentication Required"}

If this is the response you get, it means the authentication module is working.

Let’s try to get a response using the Node certificate we created. Execute the same command, but now pass Node certificate and key:

curl --insecure -v https://$CONTROLLER_ADDRESS/api/v1/status --cert /Users/$USER_WHERE_CERTS_ARE/node-$NODE_NAME-crt.pem --key /Users/$USER_WHERE_CERTS_ARE/node-$NODE_NAME-key.pem

If everything is configured correctly, you should see something like this (I used to setup this example):

*   Trying

. . .

> GET /api/v1/status HTTP/2
> Host:
> User-Agent: curl/7.64.1
> Accept: */*
* Connection state changed (MAX_CONCURRENT_STREAMS == 250)!
< HTTP/2 200 
< cache-control: no-store
< content-type: application/json
< content-length: 184
< date: Sun, 12 Apr 2020 04:26:13 GMT
{"status":"OK","message":"","body":{"status":"Running","version":"1.7.0-4e6617d3","registry_address":"","registry_status":"Running","license":"enterprise plus"}}
* Connection #0 to host left intact
* Closing connection 0

6. Configuring your Builder Node to push to the Registry

Typically you want to assign a specific Anka Node as a “builder node”. This node will run a licensed Anka installation and allow you to create and prepare VMs to be pushed to the Anka Build Cloud Registry as templates/tags. With Certificate Authentication enabled, you won’t be able to do this unless you specify the certs on the anka registry command:

> anka registry --help
usage: registry [options] <command>

   Configure and control template registries

  -r,--remote <val>        Sets an alternate registry
  --insecure               Skip TLS verification
  --cert <val>             Path to a client certificate (if user authentication is configured)
  --key <val>              Path to private key if the client certificate doesn't contain one
  --cacert <val>           Use custom CA certificates location (default is /etc/ssl/certs)
  --api-key-id <val>       UAK/TAP identity
  --api-key <val>          UAK/TAP key in PEM format (path or string)

  list-repos               List registries configured
  add                      Add a registry
  set                      Set default registry
  remove                   Remove a registry from the configuration
  list                     List templates in registry (see anka-push/pull commands)
  show                     Show a template's properties
  revert                   Delete a template or tag

You can also use anka registry add to add it to the default configuration and not need to pass these in as options each execution:

> anka registry add --help
usage: add [options] name url

   Add a registry

  name                     Registry name
  url                      Registry URL

  -f,--force               Do not perform a connectivity checks for the url

Accessing the Controller UI

Once Cert Auth as been enabled, loading your Controller UI will show Controller Not Connected. This is because the Controller is fully protected. In order to access the UI, you can set up your browser to use client certificates to access the page. Alternatively, you can enable root token auth with ANKA_ROOT_TOKEN which must be set to a minimum of 10 characters. You can read more about it here.

Certificate Revocation

Starting in 1.32.0, users can now revoke certificates without needing to change the CA or permissions.

Generating the Certificate Revocation List

  1. Locally on your machine you’ll create openssl.cnf (anywhere on your machine), containing various definitions:
[ ca ]
default_ca = CA_default                 # The name of the CA configuration to be used.
                                        # can be anything that makes sense to you.
[ CA_default ]
dir = .                                 # Directory where everything is kept
certs = $dir                            # Directory where the issued certs are kept
crl_dir = $dir                          # Directory where the issued crl are kept
database = $dir/index.txt               # database index file.
#unique_subject = no                    # Set to 'no' to allow creation of
                                        # several certificates with same subject.
new_certs_dir = $dir                    # Default directory for new certs.

certificate = $dir/anka-ca-crt.pem           # The CA certificate
serial = $dir/serial                    # The current serial number
crlnumber = $dir/crlnumber              # The current crl number
                                        # must be commented out to leave a V1 CRL
crl = $dir/crl.pem                      # The current CRL
private_key = $dir/anka-ca-key.pem           # The private key
RANDFILE    = $dir/.rand                # private random number file

x509_extensions = usr_cert              # The extentions to add to the cert

name_opt = ca_default                   # Subject Name options
cert_opt = ca_default                   # Certificate field options

default_days    = 365                   # how long to certify for
default_crl_days= 30                    # how long before next CRL
default_md    = sha1                    # use public key default MD
preserve    = no                        # keep passed DN ordering

policy = policy_match
  1. Next, create index.txt and crlnumber and store them in a centralized location:
Any revocations must happen against the latest index.txt and crlnumber (openssl.cnf is optional). It’s best to store these in a repo or somewhere that admins revoking can pull the latest versions and then commit them once complete.
touch index.txt         # stores revoked certificates database
echo "01" > crlnumber   # needs to be only initialized once
  1. Generate your first Certificate Revocation List (a.k.a “CRL”):
openssl ca -gencrl \
  -config openssl.cnf \
  -keyfile anka-ca-key.pem \
  -cert anka-ca-crt.pem \
  -out crl.pem \
  -crldays 365
  1. If Certificate Authentication is enabled for both the Controller and Registry, you’ll need to set ANKA_CRL in both configs to the Revocation List File (.pem). If using Docker, you’ll need to attach a mount/volume that contains this file and target the destination/location inside of the container.
  2. Generate your client certificates with openssl as you normally would, using the same root CA you used to generate the CRL.

Revoking a certificate

  1. When you need to revoke a certificate, you can use the following to add the cert to the index.txt database file:
openssl ca -config openssl.cnf \
  -revoke node-Veertu.local-crt.pem \
  -keyfile anka-ca-key.pem \
  -cert anka-ca-crt.pem
  1. Once revoked, you must re-generate the CRL file and update it on the Controller and Registry, restarting them once updated:
openssl ca -gencrl \
  -config openssl.cnf \
  -keyfile anka-ca-key.pem \
  -cert anka-ca-crt.pem \
  -out crl.pem \
  -crldays 365
Some things to note
  • You can check if a certificate is revoked with openssl verify -crl_check -CAfile anka-ca-crt.pem -CRLfile crl.pem node-Veertu.local-crt.pem.
  • The index.txt, crlnumber, and certs generated should be stored in a centralized location. We recommend a repo or a server with openssl on it that only admins have access to. Any changes made should be checked into the repo so that others can pull them and start from the latest version of the revocation DB (index.txt).
  • If the crl.pem expires, the controller and registry will fail.
  • The crl.pem must be generated with CA Root cert that the Controller and Registry are using.

Managing User/Group Permissions (Authorization)

Certificate Authentication users:

When creating certificates, you’ll want to specify CSR values using openssl’s -subj option. For example, if we’re going to generate a certificate so our Jenkins instance can access the Controller & Registry, you’ll want to use something like this:

-subj "/O=MyOrgName/OU=$ORG_UNIT/CN=Jenkins"
  • At least one O= AND CN= is required.
  • You can specify multiple O= like so: /O=DevOps/O=iOSDEV/ . . .
  • Within the Controller’s Permission administration panel, we use O= as the Group Name.
  • Spaces are supported in O= and Anka Build Cloud Controller version >= 1.10.

By default, Authentication methods (enabled with ANKA_ENABLE_AUTH) will not use Authorization/permissions and allow any credential to connect to all API endpoints or pages in the UI. In order to enable Authorization, you will need to include specific ENVs in your config:

  • ANKA_ENABLE_CONTROLLER_AUTHORIZATION works for both combined and standalone (docker) packages.
  • ANKA_ENABLE_AUTHORIZATION is only for the standalone (native or docker) registry packages.
  • ANKA_ENABLE_REGISTRY_AUTHORIZATION is for the combined (controller + registry in one binary) package only.
This feature requires Enterprise Plus. The regular enterprise license automatically adds all permissions to each certificate or token that is used and gives no control over them.
This also requires that you’ve enabled Root Token Authentication, giving you super user access to the controller UI and permissions.
Do not confuse Node Groups with Permission Groups.

Permission Groups

Permission groups are configurable from your Controller’s https://<controller address>/#/permission-groups page. You can target and add permissions for either the group name or the username (which is different between the various Advanced Security Features we offer).

6. Final Notes

  • If you enabled AUTH for the registry, you’ll need to ensure that you set the ANKA_CLIENT_CERT and ANKA_CLIENT_CERT_KEY in your controller config or else it won’t be able to communicate with the registry.
    ANKA_CLIENT_CERT	(string)	(Certificate Authentication) The Controller will use this when making http requests, mainly to the Registry
    ANKA_CLIENT_CERT_KEY	(string)	(Certificate Authentication) The Controller will use this when making http requests, mainly to the Registry
  • You may notice that the Controller UI doesn’t load or acts strangely. You will need to enable Root Token Authentication to access the controller UI.
  • If you get an invalid cert error from the Controller UI, make sure that you add the root CA you generated to your system keychain.

Kubernetes & NGINX Ingress Header Passthrough

Available in Controller >= 1.33.0

Customers who rely on NGINX Ingress controllers which terminate the HTTPS connection inside of the cluster will be able to now pass through TLS headers used for Controller & Registry communication with Certificate Auth.

  • This feature requires ANKA_ENABLE_AUTH: "true" and ANKA_ENABLE_INGRESS_NGINX: "true" env vars or corresponding flags to be specified. When these flags are enabled controller/registry will check Ssl-Client-Cert and Ssl-Client-Verify headers (enabled by true). For successful authentication, Ssl-Client-Verify has to be exactly SUCCESS and Ssl-Client-Cert has to contain an url encoded pem certificate.
  • The ingress controller should be configured to perform SSL client authentication on its own – See here and here. Note that its required to have set to true. This will enable passing of client certificate to the controller/registry.
  • This whole setup implies that ingress controller performs SSL termination of all traffic inside the cluster is regular unencrypted HTTP, controller/registry will not validate received certificate, it will trust it by default, because all traffic authentication/validation is performed by nginx.

Here is an example ingress config:

kind: Ingress
  name: anka-controller-registry-ingress
  annotations: "on" "true" "default/ca-secret" "1" "http://ingress-certificate-validation-failed.local"