v2.1 to 2.2
- Upgraded Helm Version
- Support for private repo SSH keys using the SHA-1 signature hash algorithm is removed in 2.2.12
  - Workaround

v2.1 to 2.2

Upgraded Helm Version

Note that bundled Helm has been upgraded from 3.6.0 to v3.7+. This includes following breaking changes:

Repository credentials are no longer passed to download charts that are being served from a different domain than the repository.

You can still force older behavior with --helm-pass-credentials option to argocd app create.

More information in the Helm v3.6.1 release notes.

Experimental OCI support has been rewritten.

More information in the Helm v3.7.0 release notes.

Support for private repo SSH keys using the SHA-1 signature hash algorithm is removed in 2.2.12

Argo CD 2.2.12 upgraded its base image from Ubuntu 21.10 to Ubuntu 22.04, which upgraded OpenSSH to 8.9. OpenSSH starting with 8.8 dropped support for the ssh-rsa SHA-1 key signature algorithm.

The signature algorithm is not the same as the algorithm used when generating the key. There is no need to update keys.

The signature algorithm is negotiated with the SSH server when the connection is being set up. The client offers its list of accepted signature algorithms, and if the server has a match, the connection proceeds. For most SSH servers on up-to-date git providers, acceptable algorithms other than ssh-rsa should be available.

Before upgrading to Argo CD 2.2.12, check whether your git provider(s) using SSH authentication support algorithms newer than rsa-ssh.

Make sure your version of SSH >= 8.9 (the version used by Argo CD). If not, upgrade it before proceeding.

shell ssh -V

Example output: OpenSSH_8.9p1 Ubuntu-3, OpenSSL 3.0.2 15 Mar 2022

Once you have a recent version of OpenSSH, follow the directions from the OpenSSH 8.8 release notes:

To check whether a server is using the weak ssh-rsa public key algorithm, for host authentication, try to connect to it after removing the ssh-rsa algorithm from ssh(1)’s allowed list:

shell ssh -oHostKeyAlgorithms=-ssh-rsa user@host

If the host key verification fails and no other supported host key types are available, the server software on that host should be upgraded.

If the server does not support an acceptable version, you will get an error similar to this;

$ ssh -oHostKeyAlgorithms=-ssh-rsa vs-ssh.visualstudio.com Unable to negotiate with 20.42.134.1 port 22: no matching host key type found. Their offer: ssh-rsa

This indicates that the server needs to update its supported key signature algorithms, and Argo CD will not connect to it.

Workaround

The OpenSSH 8.8 release notes describe a workaround if you cannot change the server’s key signature algorithms configuration.

Incompatibility is more likely when connecting to older SSH implementations that have not been upgraded or have not closely tracked improvements in the SSH protocol. For these cases, it may be necessary to selectively re-enable RSA/SHA1 to allow connection and/or user authentication via the HostkeyAlgorithms and PubkeyAcceptedAlgorithms options. For example, the following stanza in ~/.ssh/config will enable RSA/SHA1 for host and user authentication for a single destination host:

Host old-host HostkeyAlgorithms +ssh-rsa PubkeyAcceptedAlgorithms +ssh-rsa

We recommend enabling RSA/SHA1 only as a stopgap measure until legacy implementations can be upgraded or reconfigured with another key type (such as ECDSA or Ed25519).

To apply this to Argo CD, you could create a ConfigMap with the desired ssh config file and then mount it at /home/argocd/.ssh/config.