A default installation of the Looker application uses self-signed SSL certificates for HTTPS. For production environments of customer-hosted instances, we recommend installing an SSL certificate from a trusted vendor.
To use an SSL certificate with Looker, you will need to create a Java keystore with your certificate and key.
You should have the following files:
- A certificate file named
looker.pem
that contains your primary certificate - An associated key file named
looker.key
- Optionally, an intermediate Certificate Authority (CA) chain file named
ca.pem
Your
.pem
file does not need to contain a root certificate.
Install the certificate
These files should all exist in the same directory. The default is /home/looker/looker/.ssl
.
Create the new directory and make it the current directory:
mkdir /home/looker/looker/.ssl cd /home/looker/looker/.ssl
Choose a password for the keystore and put it in a file called
.keystorepass
:echo "some_password_here" > .keystorepass
If you have a CA file, append it to the end of your certificate file:
echo >> looker.pem cat ca.pem >> looker.pem
Convert the certificate and key to a
pkcs12
keystore:openssl pkcs12 -export \ -in looker.pem \ -inkey looker.key \ -out importme.p12
You will be prompted for an export password. Use the one that you put in the
.keystorepass
file.Convert the pkcs12 keystore to a Java keystore:
keytool -importkeystore \ -srckeystore importme.p12 \ -destkeystore looker.jks \ -srcstoretype pkcs12 \ -alias 1
You will be prompted for the new keystore password and the pkcs12 keystore password. Keep using the one in the
.keystorepass
file.Create a file named
lookerstart.cfg
in the same directory as yourlooker.jar
. This file will configure the requisite Looker options every time Looker starts. The file should contain:
LOOKERARGS="--ssl-keystore=/home/looker/looker/.ssl/looker.jks --ssl-keystore-pass-file=/home/looker/looker/.ssl/.keystorepass"
Validate the certificate
Once Looker is running, you can verify that your cert is correctly installed with OpenSSL s_client
.
openssl s_client -connect localhost:9999
If your hostname is looker.yourdomain.com
, you should see a line in the output like this:
subject=/OU=Domain Control Validated/CN=looker.yourdomain.com
Another way to check is with wget
. This test can be performed from any host which has network access to your Looker instance via HTTPS.
On a Looker using the default self-signed certificate, the output shows the certificate common name self-signed.looker.com
:
$ wget https://looker.yourdomain.com:9999
--2014-12-31 12:06:03-- https://looker.yourdomain.com:9999/
Resolving looker.yourdomain.com (looker.yourdomain.com)... 192.168.23.66
Connecting to looker.yourdomain.com (looker.yourdomain.com)|192.168.23.66|:9999... connected.
ERROR: cannot verify looker.yourdomain.com's certificate, issued by '/CN=self-signed.looker.com':
Self-signed certificate encountered.
ERROR: certificate common name 'self-signed.looker.com' doesn't match requested host name 'looker.yourdomain.com'.
To connect to looker.yourdomain.com insecurely, use `--no-check-certificate'.
On a Looker using a certificate from a certificate authority, the certificate common name must match the DNS name that clients use to access Looker (or an equivalent wildcard certificate).
Here is an example of a server using a "real" (non-self signed) certificate:
$ wget https://looker.yourdomain.com:9999
--2014-12-31 12:06:47-- https://looker.yourdomain.com:9999/
Resolving looker.yourdomain.com (looker.yourdomain.com)... 10.10.10.10
Connecting to looker.yourdomain.com (looker.yourdomain.com)|10.10.10.10|:9999... connected.
HTTP request sent, awaiting response... 302 Found
Location: https://looker.yourdomain.com:9999/login [following]
--2014-12-31 12:06:48-- https://looker.yourdomain.com:9999/login
Connecting to looker.yourdomain.com (looker.yourdomain.com)|10.10.10.10|:9999... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3491 (3.4K) [text/html]
Saving to: 'index.html'
100%[====================================================>] 3,491 --.-K/s in 0.07s
2014-12-31 12:06:48 (50.5 KB/s) - 'index.html' saved [3491/3491]
Validating a site's certificate against the CA bundle
As of Looker 5.18, Looker uses the Java Certificate Authority (CA) root certificate bundle. Looker uses the CA bundle to verify the authenticity of the hosts with which it communicates when making outbound requests from the Looker server. This includes actions like making requests to outbound webhooks, performing S3 backups, requesting various forms of authentication, and communicating with the license-verification server.
Java provides and manages the CA bundle, which resides on disk. This lets the admins of customer-hosted Looker instances add or remove certificates from the CA bundle.
If you choose to modify the CA bundle, you can use Looker's test_ssl_cert_validation
utility to test whether or not Looker can validate a server certificate when making an outbound HTTP connection. The utility accepts the name of a file that contains a list of URLs you want to test, with one URL per line, like this:
https://www.google.com
https://looker.com
https://wrong.host.badssl.com/
If the name of this file was hosts
, you would use test_ssl_cert_validation
like this:
$ ./looker test_ssl_cert_validation hosts
The output of test_ssl_cert_validation
would look like this:
Using CA file from .../jre/lib/security/cacerts
Attempting connection to https://www.google.com
Certificate verified successfully, connection returned with:
HTTP/1.1 200 OK
Attempting connection to https://looker.com
Certificate verified successfully, connection returned with:
HTTP/1.1 200 OK
Attempting connection to https://wrong.host.badssl.com/
Error connecting to https://wrong.host.badssl.com/: OpenSSL::SSL::SSLError: hostname
"wrong.host.badssl.com" does not match the server certificate
Summary:
Successes: 3, Redirects: 0, Failures: 1
Disabling insecure SSL protocols
To disable inbound TSL1.0 connections to Looker, follow one of these two methods:
Modify the
ssl_protocols
line in your Nginx configuration file and remove the option for TLSv1, as shown in this code snippet:ssl-protocols: "TLSv1.2 TLSv1.3"
Set up a proxy or load balancer in front of Looker that terminates the TLS or SSL protocol. Then, disable SSL at the Looker level.
Next steps
After you have set up your SSL certificate, you will be ready to add port forwarding for a cleaner URL.