Microsoft Azure Linux Agent
Master branch status
Each badge below represents our basic validation tests for an image, which are executed several times each day. These include provisioning, user account, disk, extension and networking scenarios.
The Microsoft Azure Linux Agent (waagent) manages Linux provisioning and VM interaction with the Azure Fabric Controller. It provides the following functionality for Linux IaaS deployments:
- Creation of a user account
- Configuring SSH authentication types
- Deployment of SSH public keys and key pairs
- Setting the host name
- Publishing the host name to the platform DNS
- Reporting SSH host key fingerprint to the platform
- Resource Disk Management
- Formatting and mounting the resource disk
- Configuring swap space
- Manages routes to improve compatibility with platform DHCP servers
- Ensures the stability of the network interface name
- Configure virtual NUMA (disable for kernel <2.6.37)
- Consume Hyper-V entropy for /dev/random
- Configure SCSI timeouts for the root device (which could be remote)
- Console redirection to the serial port
- Detect and bootstrap the VMM agent for Linux when running in a System Center Virtual Machine Manager 2012R2 environment
- Inject component authored by Microsoft and Partners into Linux VM (IaaS) to enable software and configuration automation
- VM Extension reference implementation on GitHub
The information flow from the platform to the agent occurs via two channels:
A boot-time attached DVD for IaaS deployments. This DVD includes an OVF-compliant configuration file that includes all provisioning information other than the actual SSH keypairs.
A TCP endpoint exposing a REST API used to obtain deployment and topology configuration.
The agent will use an HTTP proxy if provided via the
http requests) or
https requests) environment variables. The
HttpProxy.Port configuration variables (see below), if used, will override the environment
settings. Due to limitations of Python, the agent does not support HTTP proxies requiring
The following systems have been tested and are known to work with the Azure Linux Agent. Please note that this list may differ from the official list of supported systems on the Microsoft Azure Platform as described here.
Waagent depends on some system packages in order to function properly:
- Python 2.6+
- OpenSSL 1.0+
- OpenSSH 5.3+
- Filesystem utilities: sfdisk, fdisk, mkfs, parted
- Password tools: chpasswd, sudo
- Text processing tools: sed, grep
- Network tools: ip-route
Installation via your distribution's package repository is preferred. You can also customize your own RPM or DEB packages using the configuration samples provided (see deb and rpm sections below).
For more advanced installation options, such as installing to custom locations or prefixes, you can use setuptools to install from source by running:
sudo python setup.py install --register-service
You can view more installation options by running:
sudo python setup.py install --help
The agent's log file is kept at
Upgrading via your distribution's package repository is strongly preferred.
If upgrading manually, same with installation above by running:
sudo python setup.py install --force
Restart waagent service,for most of linux distributions:
sudo service waagent restart
For Ubuntu, use:
sudo service walinuxagent restart
For CoreOS, use:
sudo systemctl restart waagent
Command line options
-verbose: Increase verbosity of specified command
-force: Skip interactive confirmation for some commands
-help: Lists the supported commands and flags.
-deprovision: Attempt to clean the system and make it suitable for re-provisioning, by deleting the following:
All SSH host keys (if Provisioning.RegenerateSshHostKeyPair is 'y' in the configuration file)
Nameserver configuration in /etc/resolv.conf
Root password from /etc/shadow (if Provisioning.DeleteRootPassword is 'y' in the configuration file)
Cached DHCP client leases
Resets host name to localhost.localdomain
WARNING! Deprovision does not guarantee that the image is cleared of all sensitive information and suitable for redistribution.
-deprovision+user: Performs everything under deprovision (above) and also deletes the last provisioned user account and associated data.
-version: Displays the version of waagent
-serialconsole: Configures GRUB to mark ttyS0 (the first serial port) as the boot console. This ensures that kernel bootup logs are sent to the serial port and made available for debugging.
-daemon: Run waagent as a daemon to manage interaction with the platform. This argument is specified to waagent in the waagent init script.
-start: Run waagent as a background process
A configuration file (/etc/waagent.conf) controls the actions of waagent. Blank lines and lines whose first character is a
# are ignored (end-of-line comments are not supported).
A sample configuration file is shown below:
Extensions.Enabled=y Provisioning.Enabled=y Provisioning.UseCloudInit=n Provisioning.DeleteRootPassword=n Provisioning.RegenerateSshHostKeyPair=y Provisioning.SshHostKeyPairType=rsa Provisioning.MonitorHostName=y Provisioning.DecodeCustomData=n Provisioning.ExecuteCustomData=n Provisioning.PasswordCryptId=6 Provisioning.PasswordCryptSaltLength=10 ResourceDisk.Format=y ResourceDisk.Filesystem=ext4 ResourceDisk.MountPoint=/mnt/resource ResourceDisk.MountOptions=None ResourceDisk.EnableSwap=n ResourceDisk.EnableSwapEncryption=n ResourceDisk.SwapSizeMB=0 Logs.Verbose=n OS.AllowHTTP=n OS.RootDeviceScsiTimeout=300 OS.EnableFIPS=n OS.OpensslPath=None OS.SshClientAliveInterval=180 OS.SshDir=/etc/ssh HttpProxy.Host=None HttpProxy.Port=None CGroups.EnforceLimits=y CGroups.Excluded=customscript,runcommand
The various configuration options are described in detail below. Configuration options are of three types : Boolean, String or Integer. The Boolean configuration options can be specified as "y" or "n". The special keyword "None" may be used for some string type configuration entries as detailed below.
Configuration File Options
This allows the user to enable or disable the extension handling functionality in the agent. Valid values are "y" or "n". If extension handling is disabled, the goal state will still be processed and VM status is still reported, but only every 5 minutes. Extension config within the goal state will be ignored. Note that functionality such as password reset, ssh key updates and backups depend on extensions. Only disable this if you do not need extensions at all.
Note: disabling extensions in this manner is not the same as running completely
without the agent. In order to do that, the
provisionVMAgent flag must be set at
provisioning time, via whichever API is being used. We will provide more details on
this on our wiki when it is generally available.
This allows the user to enable or disable the provisioning functionality in the agent. Valid values are "y" or "n". If provisioning is disabled, SSH host and user keys in the image are preserved and any configuration specified in the Azure provisioning API is ignored.
This options enables / disables support for provisioning by means of cloud-init. When true ("y"), the agent will wait for cloud-init to complete before installing extensions and processing the latest goal state. Provisioning.Enabled must be disabled ("n") for this option to have an effect. Setting Provisioning.Enabled to true ("y") overrides this option and runs the built-in agent provisioning code.
If set, the root password in the /etc/shadow file is erased during the provisioning process.
If set, all SSH host key pairs (ecdsa, dsa and rsa) are deleted during the provisioning process from /etc/ssh/. And a single fresh key pair is generated. The encryption type for the fresh key pair is configurable by the Provisioning.SshHostKeyPairType entry. Please note that some distributions will re-create SSH key pairs for any missing encryption types when the SSH daemon is restarted (for example, upon a reboot).
This can be set to an encryption algorithm type that is supported by the SSH daemon on the VM. The typically supported values are "rsa", "dsa" and "ecdsa". Note that "putty.exe" on Windows does not support "ecdsa". So, if you intend to use putty.exe on Windows to connect to a Linux deployment, please use "rsa" or "dsa".
If set, waagent will monitor the Linux VM for hostname changes (as returned by the "hostname" command) and automatically update the networking configuration in the image to reflect the change. In order to push the name change to the DNS servers, networking will be restarted in the VM. This will result in brief loss of Internet connectivity.
If set, waagent will decode CustomData from Base64.
If set, waagent will execute CustomData after provisioning.
Algorithm used by crypt when generating password hash.
- 1 - MD5
- 2a - Blowfish
- 5 - SHA-256
- 6 - SHA-512
Length of random salt used when generating password hash.
If set, the resource disk provided by the platform will be formatted and mounted by waagent if the filesystem type requested by the user in "ResourceDisk.Filesystem" is anything other than "ntfs". A single partition of type Linux (83) will be made available on the disk. Note that this partition will not be formatted if it can be successfully mounted.
This specifies the filesystem type for the resource disk. Supported values vary by Linux distribution. If the string is X, then mkfs.X should be present on the Linux image. SLES 11 images should typically use 'ext3'. BSD images should use 'ufs2' here.
This specifies the path at which the resource disk is mounted.
Specifies disk mount options to be passed to the mount -o command. This is a comma separated list of values, ex. 'nodev,nosuid'. See mount(8) for details.
If set, a swap file (/swapfile) is created on the resource disk and added to the system swap space.
If set, the swap file (/swapfile) is mounted as an encrypted filesystem.
The size of the swap file in megabytes.
If set, log verbosity is boosted. Waagent logs to /var/log/waagent.log and leverages the system logrotate functionality to rotate logs.
If set to
y and SSL support is not compiled into Python, the agent will fall-back to
use HTTP. Otherwise, if SSL support is not compiled into Python, the agent will fail
all HTTPS requests.
Note: Allowing HTTP may unintentionally expose secure data.
If set, the agent will attempt to install and then load an RDMA kernel driver that matches the version of the firmware on the underlying hardware.
If set, the agent will emit into the environment "OPENSSL_FIPS=1" when executing OpenSSL commands. This signals OpenSSL to use any installed FIPS-compliant libraries. Note that the agent itself has no FIPS-specific code. If no FIPS-compliant certificates are installed, then enabling this option will cause all OpenSSL commands to fail.
This configures the SCSI timeout in seconds on the root device. If not set, the system defaults are used.
This can be used to specify an alternate path for the openssl binary to use for cryptographic operations.
This values sets the number of seconds the agent uses for the SSH ClientAliveInterval configuration option.
This option can be used to override the normal location of the SSH configuration directory.
If set, the agent will use this proxy server to access the internet. These values
will override the
https_proxy environment variables. Lastly,
HttpProxy.Host is required (if to be used) and
HttpProxy.Port is optional.
If set, the agent will attempt to set cgroups limits for cpu and memory for the agent process itself as well as extension processes. See the wiki for further details on this.
The list of extensions which will be excluded from cgroups limits. This should be comma separated.
WALinuxAgent collects usage data and sends it to Microsoft to help improve our products and services. The data collected is used to track service health and assist with Azure support requests. Data collected does not include any personally identifiable information. Read our privacy statement to learn more.
WALinuxAgent does not support disabling telemetry at this time. WALinuxAgent must be removed to disable telemetry collection. If you need this feature, please open an issue in GitHub and explain your requirement.
We do not maintain packaging information in this repo but some samples are shown below as a reference. See the downstream distribution repositories for officially maintained packaging.
The official Ubuntu WALinuxAgent package can be found here.
Install required packages
sudo apt-get -y install ubuntu-dev-tools pbuilder python-all debhelper
Create the pbuilder environment
sudo pbuilder create --debootstrapopts --variant=buildd
waagent.dscfrom a downstream package repo
To compile the package, from the top-most directory:
Build the source package
Build the package
sudo pbuilder build waagent.dsc
Fetch the built package, usually from
The instructions below describe how to build an rpm package.
curl https://bootstrap.pypa.io/ez_setup.py -o - | python
The following command will build the binary and source RPMs:
python setup.py bdist_rpm