ssh/README.md

🚀 SSH for GitHub Actions

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GitHub Action for executing remote ssh commands.

Important: Only support Linux docker container.

This thing is built using Golang and drone-ssh. 🚀

Input variables

See action.yml for more detailed information.

Input Parameter	Description	Default Value
host	SSH host address
port	SSH port number	22
passphrase	SSH key passphrase
username	SSH username
password	SSH password
sync	Enable synchronous execution if multiple hosts	false
use_insecure_cipher	Include more ciphers with use_insecure_cipher	false
cipher	Allowed cipher algorithms. If unspecified, a sensible default
timeout	Timeout duration for SSH to host	30s
command_timeout	Timeout duration for SSH command	10m
key	Content of SSH private key. e.g., raw content of ~/.ssh/id_rsa
key_path	Path of SSH private key
fingerprint	SHA256 fingerprint of the host public key
proxy_host	SSH proxy host
proxy_port	SSH proxy port	22
proxy_username	SSH proxy username
proxy_password	SSH proxy password
proxy_passphrase	SSH proxy key passphrase
proxy_timeout	Timeout for SSH to proxy host	30s
proxy_key	Content of SSH proxy private key
proxy_key_path	Path of SSH proxy private key
proxy_fingerprint	SHA256 fingerprint of the proxy host public key
proxy_cipher	Allowed cipher algorithms for the proxy
proxy_use_insecure_cipher	Include more ciphers with use_insecure_cipher for the proxy	false
script	Execute commands
script_stop	Stop script after first failure	false
envs	Pass environment variables to shell script
envs_format	Flexible configuration of environment value transfer
debug	Enable debug mode	false
allenvs	pass the environment variables with prefix value of GITHUB_ and INPUT_ to the script	false
request_pty	Request a pseudo-terminal from the server	false

Usage

Executing remote ssh commands.

name: remote ssh command
on: [push]
jobs:

  build:
    name: Build
    runs-on: ubuntu-latest
    steps:
    - name: executing remote ssh commands using password
      uses: appleboy/ssh-action@v1.0.3
      with:
        host: ${{ secrets.HOST }}
        username: ${{ secrets.USERNAME }}
        password: ${{ secrets.PASSWORD }}
        port: ${{ secrets.PORT }}
        script: whoami

output:

======CMD======
whoami
======END======
out: ***
==============================================
✅ Successfully executed commands to all host.
==============================================

Setting up a SSH Key

Make sure to follow the below steps while creating SSH Keys and using them. The best practice is create the SSH Keys on local machine not remote machine. Login with username specified in Github Secrets. Generate a RSA Key-Pair:

Generate rsa key

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

Generate ed25519 key

ssh-keygen -t ed25519 -a 200 -C "your_email@example.com"

Add newly generated key into Authorized keys. Read more about authorized keys here.

Add rsa key into Authorized keys

cat .ssh/id_rsa.pub | ssh b@B 'cat >> .ssh/authorized_keys'

Add ed25519 key into Authorized keys

cat .ssh/id_ed25519.pub | ssh b@B 'cat >> .ssh/authorized_keys'

Copy Private Key content and paste in Github Secrets.

Copy rsa Private key

clip < ~/.ssh/id_rsa

Copy ed25519 Private key

clip < ~/.ssh/id_ed25519

See the detail information about SSH login without password.

A note from one of our readers: Depending on your version of SSH you might also have to do the following changes:

• Put the public key in .ssh/authorized_keys2
• Change the permissions of .ssh to 700
• Change the permissions of .ssh/authorized_keys2 to 640

If you are using OpenSSH

If you are currently using OpenSSH and are getting the following error:

ssh: handshake failed: ssh: unable to authenticate, attempted methods [none publickey]

Make sure that your key algorithm of choice is supported. On Ubuntu 20.04 or later you must explicitly allow the use of the ssh-rsa algorithm. Add the following line to your OpenSSH daemon file (which is either /etc/ssh/sshd_config or a drop-in file under /etc/ssh/sshd_config.d/):

CASignatureAlgorithms +ssh-rsa

Alternatively, ed25519 keys are accepted by default in OpenSSH. You could use this instead of rsa if needed:

ssh-keygen -t ed25519 -a 200 -C "your_email@example.com"

Example

Executing remote ssh commands using password

- name: executing remote ssh commands using password
  uses: appleboy/ssh-action@v1.0.3
  with:
    host: ${{ secrets.HOST }}
    username: ${{ secrets.USERNAME }}
    password: ${{ secrets.PASSWORD }}
    port: ${{ secrets.PORT }}
    script: whoami

Using private key

- name: executing remote ssh commands using ssh key
  uses: appleboy/ssh-action@v1.0.3
  with:
    host: ${{ secrets.HOST }}
    username: ${{ secrets.USERNAME }}
    key: ${{ secrets.KEY }}
    port: ${{ secrets.PORT }}
    script: whoami

Multiple Commands

- name: multiple command
  uses: appleboy/ssh-action@v1.0.3
  with:
    host: ${{ secrets.HOST }}
    username: ${{ secrets.USERNAME }}
    key: ${{ secrets.KEY }}
    port: ${{ secrets.PORT }}
    script: |
      whoami
      ls -al      

Multiple Hosts

  - name: multiple host
    uses: appleboy/ssh-action@v1.0.3
    with:
-     host: "foo.com"
+     host: "foo.com,bar.com"
      username: ${{ secrets.USERNAME }}
      key: ${{ secrets.KEY }}
      port: ${{ secrets.PORT }}
      script: |
        whoami
        ls -al

Multiple hosts with different port

  - name: multiple host
    uses: appleboy/ssh-action@v1.0.3
    with:
-     host: "foo.com"
+     host: "foo.com:1234,bar.com:5678"
      username: ${{ secrets.USERNAME }}
      key: ${{ secrets.KEY }}
      script: |
        whoami
        ls -al

Synchronous execution on multiple hosts

  - name: multiple host
    uses: appleboy/ssh-action@v1.0.3
    with:
      host: "foo.com,bar.com"
+     sync: true
      username: ${{ secrets.USERNAME }}
      key: ${{ secrets.KEY }}
      port: ${{ secrets.PORT }}
      script: |
        whoami
        ls -al

Pass environment variable to shell script

  - name: pass environment
    uses: appleboy/ssh-action@v1.0.3
+   env:
+     FOO: "BAR"
+     BAR: "FOO"
+     SHA: ${{ github.sha }}
    with:
      host: ${{ secrets.HOST }}
      username: ${{ secrets.USERNAME }}
      key: ${{ secrets.KEY }}
      port: ${{ secrets.PORT }}
+     envs: FOO,BAR,SHA
      script: |
        echo "I am $FOO"
        echo "I am $BAR"
        echo "sha: $SHA"

Inside env object, you need to pass every environment variable as a string, passing Integer data type or any other may output unexpected results.

Stop script after first failure

ex: missing abc folder

  - name: stop script if command error
    uses: appleboy/ssh-action@v1.0.3
    with:
      host: ${{ secrets.HOST }}
      username: ${{ secrets.USERNAME }}
      key: ${{ secrets.KEY }}
      port: ${{ secrets.PORT }}
+     script_stop: true
      script: |
        mkdir abc/def
        ls -al

output:

======CMD======
mkdir abc/def
ls -al

======END======
2019/11/21 01:16:21 Process exited with status 1
err: mkdir: cannot create directory ‘abc/def’: No such file or directory
##[error]Docker run failed with exit code 1

How to connect remote server using ProxyCommand?

+--------+       +----------+      +-----------+
| Laptop | <-->  | Jumphost | <--> | FooServer |
+--------+       +----------+      +-----------+

in your ~/.ssh/config, you will see the following.

Host Jumphost
  HostName Jumphost
  User ubuntu
  Port 22
  IdentityFile ~/.ssh/keys/jump_host.pem

Host FooServer
  HostName FooServer
  User ubuntu
  Port 22
  ProxyCommand ssh -q -W %h:%p Jumphost

How to convert to YAML format of GitHubActions

  - name: ssh proxy command
    uses: appleboy/ssh-action@v1.0.3
    with:
      host: ${{ secrets.HOST }}
      username: ${{ secrets.USERNAME }}
      key: ${{ secrets.KEY }}
      port: ${{ secrets.PORT }}
+     proxy_host: ${{ secrets.PROXY_HOST }}
+     proxy_username: ${{ secrets.PROXY_USERNAME }}
+     proxy_key: ${{ secrets.PROXY_KEY }}
+     proxy_port: ${{ secrets.PROXY_PORT }}
      script: |
        mkdir abc/def
        ls -al

Protecting a Private Key

The purpose of the passphrase is usually to encrypt the private key. This makes the key file by itself useless to an attacker. It is not uncommon for files to leak from backups or decommissioned hardware, and hackers commonly exfiltrate files from compromised systems.

  - name: ssh key passphrase
    uses: appleboy/ssh-action@v1.0.3
    with:
      host: ${{ secrets.HOST }}
      username: ${{ secrets.USERNAME }}
      key: ${{ secrets.KEY }}
      port: ${{ secrets.PORT }}
+     passphrase: ${{ secrets.PASSPHRASE }}
      script: |
        whoami
        ls -al

Using host fingerprint verification

Setting up SSH host fingerprint verification can help to prevent Person-in-the-Middle attacks. Before setting this up, run the command below to get your SSH host fingerprint. Remember to replace ed25519 with your appropriate key type (rsa, dsa, etc.) that your server is using and example.com with your host.

In modern OpenSSH releases, the default key types to be fetched are rsa (since version 5.1), ecdsa (since version 6.0), and ed25519 (since version 6.7).

ssh example.com ssh-keygen -l -f /etc/ssh/ssh_host_ed25519_key.pub | cut -d ' ' -f2

Now you can adjust you config:

  - name: ssh key passphrase
    uses: appleboy/ssh-action@v1.0.3
    with:
      host: ${{ secrets.HOST }}
      username: ${{ secrets.USERNAME }}
      key: ${{ secrets.KEY }}
      port: ${{ secrets.PORT }}
+     fingerprint: ${{ secrets.FINGERPRINT }}
      script: |
        whoami
        ls -al

Contributing

We would love for you to contribute to appleboy/ssh-action, pull requests are welcome!

License

The scripts and documentation in this project are released under the MIT License