Table of Contents

• Installation
• Features
• Basic examples
• Advanced examples
  • Generating Alpine Docker SSL certificate
    • Generate
    • Upload
    • Test
• Credits
  • Why

Installation

Use as sslgen --help

docker pull tarach/sslg
echo 'alias sslgen="docker run -it --rm -v \$(pwd):/app tarach/sslg sslgen.sh"' >> ~/.bashrc
source ~/.bashrc

Features

• Generate SSL by answering questions
• Generate SSL by passing arguments on cli
• Generate SSL by selecting presets ( schema ) from configuration file or on CLI -e, --schema
• Overwrite schema options

Basic examples

Generate by answering questions

Most basic version of the command will ask user some questions necessary to generate the SSL certificate.

Command

sslgen -vv

Output

Country Name (2 letter code - ISO 3166-1 alfa-2)
: UK
State or province
: Wales
Locality name (e.g., city)
: Newport
Organization Name (e.g., company)
: My Company ltd.
Organization Unit Name (e.g., section)
: IT Department
Common Name (e.g., server FQDN)
: domain.com
Email address
: [email protected]
[2024-02-03T03:37:41.139266+00:00] logger.INFO: Output directory set to [/app/ssl-cert/]. [] []
[2024-02-03T03:37:41.140534+00:00] logger.INFO: Saving certificate signing request (CSR) as file [csr.req]. [] []
[2024-02-03T03:37:41.140662+00:00] logger.INFO: Saving certificate as file [cert.pem]. [] []
[2024-02-03T03:37:41.140735+00:00] logger.INFO: Saving private key as file [pkey.key]. [] []

Generate by providing answers as arguments

Options used below set default answers to questions. Using -s or --skip make confirming those answers not necessary.

Command

sslgen -vv -s --un=DE \
  --sp=Hesse \
  --ln=Frankfurt \
  --on="Name der Firma" \
  --oun="IT Abteilung" \
  --cn=domain.com \
  [email protected]

Output

[2024-02-03T03:22:07.988076+00:00] logger.INFO: Output directory set to [/app/ssl-cert/]. [] []
[2024-02-03T03:22:07.988709+00:00] logger.INFO: Saving certificate signing request (CSR) as file [csr.req]. [] []
[2024-02-03T03:22:07.988827+00:00] logger.INFO: Saving certificate as file [cert.pem]. [] []
[2024-02-03T03:22:07.988958+00:00] logger.INFO: Saving private key as file [pkey.key]. [] []

Advanced examples

Generating Alpine Docker SSL certificate

Code snippets to generate and upload SSL certificate for Docker API calls

Generate

Get configuration file

wget https://raw.githubusercontent.com/tarach/self-signed-ssl-generator/master/example/sslgen.yaml

Generate certificate authority and it's private key

When asked to choose schema type 1 ( caSchema ) and press Enter

Command

sslgen -vv

Output

[1] caSchema
[2] serverSchema
[3] clientSchema
Choose schema: 1
[2024-01-28T05:10:48.683176+00:00] logger.INFO: Using schema [caSchema]. [] []
[2024-01-28T05:10:48.712605+00:00] logger.INFO: Output directory set to [/app/ssl-cert/]. [] []
[2024-01-28T05:10:48.712759+00:00] logger.INFO: Saving certificate as file [ca.pem]. [] []
[2024-01-28T05:10:48.713027+00:00] logger.INFO: Saving private key as file [privkey.pem]. [] []

Generate server set of files

Command

Use IP Address or domain name of your docker server that will be used to invoke the connection. When incorrect the client connecting to the server won't be able to confirm server identity, and it will cause an error.

export COMMON_NAME=192.168.56.10
sslgen -vv --schema=2 -o --cn=${COMMON_NAME}

Output

[2024-01-28T05:15:41.434671+00:00] logger.INFO: Using schema [serverSchema]. [] []
[2024-01-28T05:15:41.435481+00:00] logger.INFO: Directory [/app/ssl-cert/] already exists. Will overwrite files. [] []
[2024-01-28T05:15:41.453789+00:00] logger.INFO: Output directory set to [/app/ssl-cert/]. [] []
[2024-01-28T05:15:41.454168+00:00] logger.INFO: Saving certificate signing request (CSR) as file [server.req]. [] []
[2024-01-28T05:15:41.454423+00:00] logger.INFO: Saving certificate as file [server.pem]. [] []
[2024-01-28T05:15:41.455042+00:00] logger.INFO: Saving private key as file [server.key]. [] []

Generate client set of files

Command

sslgen -vv --schema=clientSchema

Output

[2024-01-28T05:36:23.078259+00:00] logger.INFO: Using schema [clientSchema]. [] []
[2024-01-28T05:36:23.079187+00:00] logger.INFO: Directory [/app/ssl-cert/] already exists. Will overwrite files. [] []
Country Name (2 letter code - ISO 3166-1 alfa-2)
default: "PL"
:
State or province
default: "Mazovia"
:
Locality name (e.g., city)
default: "Warsaw"
:
Organization Name (e.g., company)
default: "My Company Ltd."
:
Organization Unit Name (e.g., section)
default: "IT Dept."
:
Common Name (e.g., server FQDN)
default: "docker-client"
:
Email address
default: "[email protected]"
:
[2024-01-28T05:36:23.144258+00:00] logger.INFO: Output directory set to [/app/ssl-cert/]. [] []
[2024-01-28T05:36:23.144507+00:00] logger.INFO: Saving certificate signing request (CSR) as file [client.req]. [] []
[2024-01-28T05:36:23.144620+00:00] logger.INFO: Saving certificate as file [client.pem]. [] []
[2024-01-28T05:36:23.144810+00:00] logger.INFO: Saving private key as file [client.key]. [] []

Upload

export USR=userName
ssh ${USR}@192.168.56.10 mkdir ssl-cert/
cd ssl-cert/
sftp ${USR}@192.168.56.10:ssl-cert
put *

ssh ${USR}@192.168.56.10:ssl-cert
sudo cp ca.pem /root/.docker/
sudo cp server.key /root/.docker/key.pem
sudo cp server.pem /root/.docker/cert.pem

Test

cat client.pem >> cert-and-key.pem
cat client.key >> cert-and-key.pem
curl -vv --cacert ca.pem --cert cert-and-key.pem https://192.168.56.10:2376/version

Credits

Some time ago I've stumbled upon necessity to generate a self-signed SSL certificate and convert it a bunch of times. I found myself completely lost trying to navigate between CSR, PKEY, CRT, PEM and a bunch of other files. The topic I've created on SO clearly proves than I'm not the only person this is confusing.

Then again after a while I needed to generate a certificate again to communicate with Docker API. After going through complete hell re-learning how to do it again I've found this code.

What struck me the most was a complete lack of generators written in PHP. Some existed but relied on terminal openssl command.

Why

• To create a PHP CLI capable of generating Self-Signed SSL Certificate without relying on external command tools.
• To over-engineer the hell out of symfony/console