Running a Grails 3 App with a Self-Signed SSL certificate
By Zachary Klein
June 28, 2017
The Grails run-app command documentation describes how to use the -https flag to serve your app over HTTPS.
https - Start an HTTPS server (on port 8443 by default) alongside the main server. Just to be clear, the application will be accessible via HTTPS and HTTP. A self-signed key will be generated. Intended for development use only.
If you run the following command:
grails run-app -https // with HTTPS
Your app will be served at https://localhost:8443
However, as stated in the documentation, the https flag is intended for development use only. In real-world applications, an SSL certificate from a Certificate Authority would be used to verify your application's identity with clients. However, it is also possible to generate a self-signed certificate for testing purposes.
A self-signed certificate doesn't provide the identity protection that a CA offers, but the steps involved in configuring a self-signed certificate with your Grails app will be largely the same with a CA certificate.
Generate your self-signed SSL certificate
We can use
req command to create a self-signed certificate:
openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365
We're using several command options:
- x509 This option outputs a self-signed certificate instead of a certificate request.
- newkey This option creates a new certificate request and a new private key.
nbitsis the number of bits, generates an RSA key nbits in size.
- keyout This specifies the filename for the the newly created private key.
- out This specifies the output filename to write the certificate
- days When used with the
daysspecifies the number of days to certify the certificate for. The default is 30.
You can learn about other
req options by running
The previous command will prompt you to supply metadata about the certificate, such as Country, Organization, etc. Moreover, it will ask you to provide a PEM pass phrase. Enter a random password and keep it safe; we will need in the next step.
Now you have you self-signed certificate. Unfortunately Grails (and Spring Boot) doesn’t support the PEM format directly. Instead, we need to use the PKCS12 format for our keys. Fortunately, there is another
openssl command to make the conversion:
openssl pkcs12 -export -in cert.pem -inkey key.pem -out keystore.p12 -name tomcat -caname root
Again, we're using a few options:
- export This option specifies that a PKCS#12 file will be created rather than parsed.
- name This specifies the certificate entry for the certificate and private key. When we edit our
application.ymlfile, we will use this name as the
- in This specifies filename of the PKCS#12 file to be parsed.
- inkey File from which to read the private key.
- caname This specifies the "friendly name" for other certificates
You can learn more about the
pkcs121 command by running
grails-app/conf/application.yml with the following lines:
server: port: 8443 ssl: keyStore: /certificates/keystore.p12 keyStorePassword: secret keyAlias: tomcat
You can read more about pkcs121 by running
If you are deploying your app to a container like Tomcat, you will need to use a Java KeyStore (JKS) to store your SSL certificate. We can use the
keytool command-line utility (provided by Java) to create a JKS from our PKCS#12 keystore.
importkeystore command to import and create the new keystore:
keytool -importkeystore -srckeystore keystore.p12 -srcstoretype pkcs12 -srcalias tomcat -destkeystore keystore.jks -deststoretype jks -deststorepass secret -destalias tomcat
- srckeystore Source keystore (in our case,
- srcstoretype Source keystore type
- srcalias Certificate entry in the source keystore (in our case, "tomcat")
- destkeystore File name for the JKS
- deststoretype Keystore type (JKS)
- deststorepass Password for the JKS
- destalias Certificate entry in the JKS
Now we can update our
application.yml to use the JKS file instead of the PKCS#12 keystore.
server: port: 8443 ssl: enabled: true keyStore: /certificates/keystore.jks keyStorePassword: secret keyAlias: tomcat