A default installation of the Looker application uses self-signed SSL certificates for HTTPS. For production environments, 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.
We assume you have the following files:
- A certificate file named looker.pem
- An associated key file named looker.key
- Optionally, an intermediate certificate authority (CA) chain file named ca.pem
Install the Certificate
These files should all exist in the same directory. The default is
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
openssl pkcs12 -export \ -in looker.pem \ -inkey looker.key \ -out importme.p12
You will be prompted for an export password. Use the one you put in the .keystorepass file above.
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 your looker.jar. This file will configure the requisite Looker options every time Looker starts. The file should contain:
Validate the Certificate
Once Looker is running, you can verify that your cert is correctly installed with OpenSSL
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
$ 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
Looker uses Java’s CA bundle. For more information on CA bundles see this Community article.
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 called
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
If you need to remove insecure TLS for security compliance, add this line to your
jdk.tls.disabledAlgorithms= SSLv2Hello, SSLv3, TLSv1, TLSv1.1
After you have set up your SSL certificate you’re ready to add port forwarding for a cleaner URL.