SFTPGo fails to start: "could not start SFTP server: open id_rsa: read-only file system"

[Valexico]

Hi,

SFTPGo 2.7.6 fails to start on my Cloudron instance because it cannot create its SSH host key. The app restarts in a loop and the healthcheck never passes.

Environment

• Cloudron version: 10.0.5
• SFTPGo package version: com.sftpgo.cloudronapp@1.4.5

Logs
No host keys configured and "id_rsa" does not exist; try to create a new host key
error creating host key "id_rsa": open id_rsa: read-only file system
could not start SFTP server: open id_rsa: read-only file system
Healthcheck error: AbortError: The operation was aborted

The log shows HostKeys:[] in the SFTP config and config dir: .. SFTPGo therefore tries to write id_rsa into its working directory, which is on the read-only filesystem (/app/code). The failure is retried every minute (restart loop).

Everything else initializes fine: PostgreSQL migration (schema v33), SMTP, OIDC, HTTP on 8080 and WebDAV on 8888.

Workaround
Setting the host keys explicitly to a writable location fixed it for me. In /app/data/sftpgo.json:

"sftpd": {
"bindings": [{"port": 2022}],
"host_keys": ["/app/data/id_rsa", "/app/data/id_ecdsa", "/app/data/id_ed25519"]
}

[james]

Hello @valexico
Thanks for reporting, I will look into this.

[james]

Hello @valexico
I could not reproduce this with a fresh @sftpgo installation.

@Valexico said:

No host keys configured

By default, the @sftpgo app always generates the /app/data/sftpgo_host_key and automatically configures the /app/data/sftpgo.json file.
Only when the app is started without the SFTPd port the config file does not automatically configure the '.sftpd.host_keys[0]' config entry:
When enabling the SFTPd port it configures it again.
Just tested this.

Could please share the real log file from your @sftpgo app via https://paste.cloudron.io/ ?

[Valexico]

I did install it like this :

is this the cause ?

[james]

Hello @valexico

When SFTPd is not enabled the host_key for SFTPd will not be configured.
So when you enable SFTPd and save, it will restart the app and configure the default host_key.

Please answer the following question:

You did install the app without SFTPd enabled.
Then you did what exactly to get to the state of:

@Valexico said:

No host keys configured and "id_rsa" does not exist; try to create a new host key
error creating host key "id_rsa": open id_rsa: read-only file system
could not start SFTP server: open id_rsa: read-only file system
Healthcheck error: AbortError: The operation was aborted

[Valexico]

I just install the app without SFTPd and then the app was not able to start with those logs
https://paste.cloudron.io/p/mole-panda-whale

then I did my workaround and restarted the app to boot properly

Workaround
"sftpd": {
"bindings": [{"port": 2022}],
"host_keys": ["/app/data/id_rsa", "/app/data/id_ecdsa", "/app/data/id_ed25519"]
}

[james]

Hello @valexico

I am trying to reproduce this and will report back.

[james]

Hello @valexico

I have reproduced it and identified the cause.
An app update will be available soon that will fix starting the @sftpgo app without SFTPd initially configured.