Introduction
Docker is a utility that lets you create a container for running applications. A Docker container is a fully-contained virtual machine.
This guide will show you three methods to SSH into a Docker container and run commands.
- A Linux system running Docker
- Preconfigured containers loaded and running
- Access to a terminal window/command prompt (Ctrl+Alt+T or Ctrl+Alt+F2)
- A user account with sudo privileges
Adding users. You can create user accounts on a CoreOS Container Linux machine manually with useradd or via a Container Linux Config when the machine is created. Add Users via Container Linux Configs. In your Container Linux Config, you can specify many different parameters for each user. Jul 29, 2019 Learn how to set up a secure connection to a remote host by generating SSH Keys on Ubuntu 18.04. An SSH Key is a secure method of logging into your server! Then it will prompt you to enter the password for the server user account. Type it in (the system won’t. How to Override Entrypoint Using Docker Run; How to Install Ubuntu Mate on.
Method 1: Use docker exec to Run Commands in a Docker Container
The
docker exec
command runs a specified command within an already running container. You can use it to SSH into a Docker container by creating a bash shell (a shell where you can type commands).![Docker Docker](/uploads/1/2/5/8/125870210/288679729.png)
Start by pulling a Docker image if you haven’t already. For example, you can load Nginx:
Then, run the image:
List all running containers to verify:
You should now see your nginx-test image loaded.
To get access and run commands in that Docker container, type the following:
Now, you are logged in to the nginx-test container. Therefore, any commands you enter will perform in that container. The
–i
option specifies interactive, and the –t
enables a terminal typing interface.Method 2: Use the docker attach Command to Connect to a Running Container
The
docker attach
command links a local input, output, and error stream to a container. By default, it launches in a bashshell. To connect to a running container, enter the following:In the example below, the system will connect to the nginx-testcontainer:
Once the command is executed, you will be working in the container. Any commands you run will affect the virtual Docker environment.
Method 3: Use SSH to Connect to a Docker Container
You can connect to a Docker container using SSH (Secure Shell). Normally, SSH is used to connect remotely over a network to a server. The technology works the same when connecting to a virtual Docker container on your system.
Important: We do not recommend this method, since it inflates the image beyond the normal scope. You will need to have an image with SSL already configured for this to work.
Step 1: Enable SSH on System
Start by installing and enabling the SSH service:
Enable SSH on Ubuntu 18.04:
Get the container’s IP address by using the
docker inspect
command and filtering out the results:Generate Ssh Key For Docker User List
The system will display the IP address as seen in the image above.
Note: The targeted docker container must be running to be able to get its IP address. If you need to start an existing docker container, run
sudo docker start container_name
.Step 3: SSH Into Docker Container
Ping the IP address to make sure it’s available:
Use the SSH tool to connect to the image:
The system should prompt for a password of the root user for that container. If it says Connection refused, likely the container is not provisioned for SSH. If the prompt changes, you are now connected via SSH, and can run commands in the container.
Docker containers are lightweight and transitional, so a traditional SSH connection isn’t recommended. The recommended method to run commands in a Docker container is either
docker exec
or docker attach
.If you are provisioning multiple remote virtual machines, you could use the
docker-machine ssh
command to connect to a virtual machine through Docker. For most users, the first two command methods are recommended.Next you should also read
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On Windows, you can create SSH keys in many ways. This document explains how to use two SSH applications, PuTTY and Git Bash.
Joyent recommends RSA keys because the node-manta CLI programs work with RSA keys both locally and with the ssh agent. DSA keys will work only if the private key is on the same system as the CLI, and not password-protected.
PuTTY
PuTTY is an SSH client for Windows. You can use PuTTY to generate SSH keys. PuTTY is a free open-source terminal emulator that functions much like the Terminal application in macOS in a Windows environment. This section shows you how to manually generate and upload an SSH key when working with PuTTY in the Windows environment.
About PuTTY
PuTTY is an SSH client for Windows that you will use to generate your SSH keys. You can download PuTTY from www.chiark.greenend.org.uk.
When you install the PuTTY client, you also install the PuTTYgen utility. PuTTYgen is what you will use to generate your SSH key for a Windows VM.
This page gives you basic information about using PuTTY and PuTTYgen to log in to your provisioned machine. For more information on PuTTY, see the PuTTY documentation |
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Generating an SSH key
To generate an SSH key with PuTTYgen, follow these steps:
- Open the PuTTYgen program.
- For Type of key to generate, select SSH-2 RSA.
- Click the Generate button.
- Move your mouse in the area below the progress bar. When the progress bar is full, PuTTYgen generates your key pair.
- Type a passphrase in the Key passphrase field. Type the same passphrase in the Confirm passphrase field. You can use a key without a passphrase, but this is not recommended.
- Click the Save private key button to save the private key. You must save the private key. You will need it to connect to your machine.
- Right-click in the text field labeled Public key for pasting into OpenSSH authorized_keys file and choose Select All.
- Right-click again in the same text field and choose Copy.
Importing your SSH key
Now you must import the copied SSH key to the portal.
- After you copy the SSH key to the clipboard, return to your account page.
- Choose to Import Public Key and paste your SSH key into the Public Key field.
- In the Key Name field, provide a name for the key. Note: although providing a key name is optional, it is a best practice for ease of managing multiple SSH keys.
- Add the key. It will now appear in your table of keys under SSH.
Generate Ssh Key For Docker User Download
PuTTY and OpenSSH use different formats of public SSH keys. If the text you pasted in the SSH Key starts with
—— BEGIN SSH2 PUBLIC KEY
, it is in the wrong format. Be sure to follow the instructions carefully. Your key should start with ssh-rsa AAAA…
.Once you upload your SSH key to the portal, you can connect to your virtual machine from Windows through a PuTTY session.
Git Bash
The Git installation package comes with SSH. Using Git Bash, which is the Git command line tool, you can generate SSH key pairs. Git Bash has an SSH client that enables you to connect to and interact with Triton containers on Windows.
To install Git:
- (Download and initiate the Git installer](https://git-scm.com/download/win).
- When prompted, accept the default components by clicking Next.
- Choose the default text editor. If you have Notepad++ installed, select Notepad++ and click Next.
- Select to Use Git from the Windows Command Prompt and click Next.
- Select to Use OpenSSL library and click Next.
- Select to Checkout Windows-style, commit Unix-style line endings and click Next.
- Select to Use MinTTY (The default terminal of mYSYS2) and click Next.
- Accept the default extra option configuration by clicking Install.
When the installation completes, you may need to restart Windows.
Launching GitBash
To open Git Bash, we recommend launching the application from the Windows command prompt:
- In Windows, press Start+R to launch the Run dialog.
- Type
C:Program FilesGitbinbash.exe
and press Enter.
Generating SSH keys
First, create the SSH directory and then generate the SSH key pair.
One assumption is that the Windows profile you are using is set up with administrative privileges. Given this, you will be creating the SSH directory at the root of your profile, for example:
- At the Git Bash command line, change into your root directory and type.
- Change into the .ssh directory
C:Usersjoetest.ssh
- To create the keys, type:
- When prompted for a password, type apassword to complete the process. When finished, the output looks similar to:
Uploading an SSH key
![Docker Docker](/uploads/1/2/5/8/125870210/974440775.png)
To upload the public SSH key to your Triton account:
- Open Triton Service portal, select Account to open the Account Summary page.
- From the SSH section, select Import Public Key.
- Enter a Key Name. Although naming a key is optional, labels are a best practice for managing multiple SSH keys.
- Add your public SSH key.
When Triton finishes the adding or uploading process, the public SSH key appears in the list of SSH keys.
What are my next steps?
Docker Enable Ssh
- Adding SSH keys to agent.
- Set up the Triton CLI and CloudAPI on Windows.
- Set up the Triton CLI and CloudAPI.
- Create an instance in the Triton Service Portal.
- Set up the
triton-docker
command line tool. - Visit PuTTYgen to learn more about the PuTTYgen and to seethe complete installation and usage guide.